Types of refractive errors in a sample of Iraqi children with Intermittent exotropia

Najah K. Mohammad; Ibrahim Ali Rajab

doi:10.12688/f1000research.156932.2

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Research Article

Revised

Types of refractive errors in a sample of Iraqi children with Intermittent exotropia

[version 2; peer review: 2 not approved]

Najah K. Mohammad ¹, Ibrahim Ali Rajab¹

PUBLISHED 09 Dec 2024

Author details Author details

¹ Department of Surgery, College of Medicine, University of Baghdad, Baghdad, Iraq

Najah K. Mohammad
Roles: Conceptualization, Data Curation, Formal Analysis, Investigation, Methodology, Project Administration, Resources, Software, Supervision, Validation, Visualization, Writing – Original Draft Preparation, Writing – Review & Editing

Ibrahim Ali Rajab
Roles: Data Curation, Investigation, Methodology, Writing – Original Draft Preparation, Writing – Review & Editing

OPEN PEER REVIEW

REVIEWER STATUS

This article is included in the Eye Health gateway.

Abstract

Background

One of the most common strabismus types in children is intermittent exotropia, which predominantly occurs in children between the ages of 2 to 4 years. It may affect visual development and often coexists with refractive errors. Unlike esotropia, which usually links to hyperopia, intermittent exotropia might have a different relationship with refractive errors and thus lead to myopia.

Methods

In this cross-sectional retrospective study from August 2021 to December 2023, 179 patients diagnosed with intermittent exotropia were recruited via an outpatient clinic of Najah Al-Quraishi, Baghdad, Iraq. The refractive errors were compared by autorefractometry and retinoscopy after cycloplegic dilation. Data analysis was constructed under the use of IBM SPSS V.26 for the determination of emmetropia, myopia, and hyperopia prevalence.

Results

Among the 179 patients, emmetropia was the most commonly observed refractive status, present in 68 patients (38%). Low hyperopia and low myopia were also common, with 64 and 40, respectively. A limited number of patients had moderate/high myopia and moderate/high hyperopia; in detail, the prevalence was following: 5% of patients had moderate myopia, while 0.5% of patients suffered from high myopia; symmetrically, 5% were moderate to high hyperopia. From the data collected, a trend emerged for a low refractive error and symmetric refractive error in both eyes.

Conclusion

Contrasted to prior conventional wisdom about refractive error in strabismus, it established the greater incidence of emmetropia in patients with intermittent exotropia. The findings call for specific management strategies to be applied in this population.

Keywords

Intermittent exotropia, emmetropia, myopia, refractive errors, pediatric strabismus.

Corresponding author: Najah K. Mohammad

Competing interests: No competing interests were disclosed.

Grant information: The author(s) declared that no grants were involved in supporting this work.

Copyright: © 2024 K. Mohammad N and Ali Rajab I. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

How to cite: K. Mohammad N and Ali Rajab I. Types of refractive errors in a sample of Iraqi children with Intermittent exotropia [version 2; peer review: 2 not approved]. F1000Research 2024, 13:1318 (https://doi.org/10.12688/f1000research.156932.2) First published: 05 Nov 2024, 13:1318 (https://doi.org/10.12688/f1000research.156932.1) Latest published: 22 Jul 2025, 13:1318 (https://doi.org/10.12688/f1000research.156932.5)

Revised Amendments from Version 1

The updated version includes several key revisions. The dioptric definition of emmetropia (±0.50 diopters) has been added for clarity. The retrospective nature of the study is now explicitly stated in the abstract and methods. Moreover, the consent process has been clarified, specifying the use of verbal consent for additional data collection and parental/guardian consent for minors.
Discussion has been revised to provide context for the high prevalence of emmetropia and acknowledge the absence of a control group due to the retrospective design. Future research directions have been suggested. Additionally, normality testing using the Shapiro-Wilk test has been included in the statistical analysis. These updates enhance the clarity and comprehensiveness of the study.

See the authors' detailed response to the review by Janos Nemeth
See the authors' detailed response to the review by Martin Ming-Leung Ma
See the authors' detailed response to the review by Yiqiu Lu and Jiawei Zhou
See the authors' detailed response to the review by Dr. Ankit Varshney

Introduction

Intermittent exotropia is an active type of strabismus that affects quite a large number of children. However, its prevalence might vary from one ethnic and age group to another.^1,2 Intermittent exotropia is characterized by periodic outward deviation of one eye, which may disturb binocular vision in some patients. This has immense implications for visual development and the quality of life. The complicated relationship between intermittent exotropia and refractive errors has been known, though not so much understood; according to some studies, different patterns of refractive anomalies could exist in these patients.^1,3

Strabismus prevails in approximately 5%-8% of the general population; among these, exotropia ranks as one of the most common varieties, mainly between ages 2-4 years.^1,3 Intermittent exotropia is probably considered the most tricky subset of exotropia in terms of coexistent refractive error and management. Whereas esotropia can be associated with plus, the relationship between exotropia and refractive errors is more complex. Of importance, many children with intermittent exotropia become myopic over time; this has been reported as greater than 90% in some cohorts by some series.⁴

In order to better understand the therapy and prognosis of intermittent exotropia, this study will look into the distribution of refractive errors in children and young people with the illness. It will also look for common refractive patterns.

Methods

Study design and setting

This is a cross-sectional retrospective study that took place in the corresponding author’s private ophthalmology clinic. The clinic serves a diverse population, primarily children from various walks of life suffering from ocular conditions including intermittent exotropia. This being an observational study, there is no control, hence all eligible patients diagnosed with intermittent exotropia within the study period ranging from August 2021 to December 2023 were included.

Patients were enrolled consecutively from the routine clinic visits. All subjects had been referred to the study from the clinics for clinical presentations of intermittent exotropia and, therefore, represented a homogenous population by diagnosis. No external advertisements for patient recruitment were utilized, and consecutive eligible patients presenting at the clinic were included, with further selection based only on exclusion criteria regarding previous ocular surgery or other types of strabismus.

Refractive errors were determined by autorefractometry, using a Topcon KR-800^®^,™ (Topcon Corporation, Tokyo, Japan) following cycloplegia with two drops of 1% cyclopentolate given 10 minutes apart. Testing was done 30 minutes after the final drop to ensure that complete cycloplegia had been achieved. All patients underwent three successive refractometry examinations on each eye to reduce variability. The amount of exotropia was measured by prism cover test. All equipment was calibrated according to the manufacturer’s guidelines before use and checked regularly during the study for accuracy.

This study followed the STROBE checklist for cross-sectional studies.⁵ The study design, setting, participants, variables, data sources, measurement techniques, and statistical methods are those in the list that apply and have been appropriately reported to ensure the reproducibility and transparency of the study. Therefore, a completed STROBE checklist is attached and provided to ensure verification of standards.

Participants

This study only included patients whose inclusion criteria consisted of a proven clinical diagnosis of intermittent exotropia, ages from childhood to early adulthood, and those who gave their assent to participate in this research study. The exclusion criteria for this study include those patients with a history of ophthalmic surgery, all constant forms of strabismus, secondary exotropia ensuing from other eye pathology, and systemic conditions that affect visual function.

Squint division into two age groups, namely childhood below six years and school age six years or above, goes in line with the consideration of refractive errors. Both problems are of great educational and psychosocial concern to these age groups, especially since the starting age for school is six years old in Iraq.^6,7

Sample size determination

The total number of participants involved in this study was calculated according to the number of patients who presented with intermittent exotropia in the consultation at the outpatient clinic from August 2021 to December 2023. It is an exhaustive sample of all eligible patients who visited with a diagnosis of intermittent exotropia from August 2021 to December 2023. 179 patients were included to be eligible out of 195 and the rest were excluded mainly for non-sufficient data.

Data collection

Refractive errors were then categorized as emmetropia (±0.50 diopters), myopia (< -0.50 diopters), and hyperopia (> +0.50 diopters). In addition, low myopia/hyperopia was considered to be up to 3 diopters of error, while moderate/high was beyond this range. Refractive errors were diagnosed by routine ophthalmic tests, including auto-refractometry and retinoscopy after cycloplegia induced by cyclopentolate. The prism cover test found the amount of exotropia. The data collected were then classified and tabulated according to the refractive status of both eyes – emmetropia and myopia are classified into low (less than three diopters), moderate (3 – 6 diopters), and high (more than six diopters). Still, the divisions of hypermetropia are not distinct in the readings accept that follows the similar rating scale depending on the magnitude of refractive error.⁸ The Ethics Committee (Iraqi Board of Medical Specializations) further stated that the current research study does not require approval because it is a retrospective and has no intervention. Moreover, verbal consent was obtained from all participants in this study instead of written consent. This approach was chosen for several reasons. First, many participants had low literacy levels, making written consent impractical and potentially exclusionary. Second, cultural sensitivities within the community associated signing documents with legal issues or distrust, so verbal agreements were more culturally appropriate and helped build rapport. Written consent was waived since the data in this study were retrospectively analyzed from medical records, and no direct contact with the patients was required to collect any data. However, in regard to further data collection from the patients during follow-up visits and that of minors, verbal consent was obtained, approved by the Ethics Committee. In the participants below 18 years of age, consent was obtained from their parents or guardians. Verbal consent was documented due to cultural and logistical barriers that made obtaining written consent impractical for some participants.

Statistical analysis

Data analysis was done using IBM SPSS V.26, where descriptive statistics summarized data and tabulated results in accounts and percentages of each category of refractive error. Another level summary of analysis was undertaken by calculating the mean for both the spherical equivalence and the cylindrical and spherical correction outcome of either eye. These were also tabulated and interpreted to make sense of the refractive trends in this population of patients.

The data were checked for completeness and accuracy before statistical analysis; partial refraction records and those values that did not logically fit the established norms, after cross-checking with the patients’ records, were screened out. The outliers were defined as those values that lay beyond three standard deviations from the mean of the distribution and were reviewed for possible recording errors. These were included if clinically relevant, as this reflected extreme cases of refractive errors. Sensitivity analyses excluding these outliers were conducted to see the robustness of the results. Overall analysis was conducted using IBM SPSS V.26, with descriptive statistics conducted to summarize patient demographics and refractive error distributions.

Normality was checked by the Shapiro-Wilk test to decide which set of statistics tests should be applied. Parametric tests were conducted for normally distributed data; otherwise, non-parametric tests were conducted. Outliers, defined as values more than three standard deviations away from the mean, were removed from analysis after confirmation of their non-representative nature. Descriptive statistics summarized data by using means and standard deviations for continuous variables and percentages for categorical variables. All statistical analyses were performed using IBM SPSS V.26.

Results

A total of 179 patients with intermittent exotropia were included in this study. Of these, 96 (47.5%) were male, while 67 (37.4%) were children, and 112 (62.6%) were young students. The demographics of the study participants are summarized in Table 1.

Table 1. Demographics of study participants.

Demographic variable	Category	Count	Percentage (%)
Gender	Male	96	47.5
Gender	Female	83	52.5
Age group	Children (below 6)	67	37.4
Age group	Young students (6+)	112	62.6
Total		179	100

Prevalence of refractive errors

Emmetropia was the most common refractive error, observed in 68 eyes (38%). Low hyperopia and low myopia followed, affecting 64 (35.7%) and 40 (22.3%) patients, respectively. Moderate myopia was present in 9 patients (5%), high myopia in 1 patient (0.5%), and moderate to high hyperopia in 9 patients (5%) ( Figure 1).

Figure 1. Heatmap of refractive errors between the two eyes.

Symmetry in refractive errors

A cross-tabulation of the refractive errors between the two eyes showed a high degree of symmetry ( Figure 2). Most patients had very similar refractive errors in both eyes. Emmetropic and low myopic patients showed a robust bilateral correlation in refractive errors. All moderate to high refractive errors, although less symmetrical, were still recorded in some minority of patients ( Table 2).

Figure 2. Graphical design summarizing the study results.

Table 2. Cross-tabulation of refractive errors between the two eyes.

		Emmetrope	Low myopia	Moderate myopia	High myopia	low hyperopia	moderate/high hyperopia
		Count	Count	Count	Count	Count	Count
Refractive error OS	Emmetrope	68	5	2	0	14	0
	Low myopia	7	23	1	0	2	0
	Moderate myopia	2	2	1	1	0	0
	High myopia	0	0	0	0	0	0
	Low hyperopia	6	0	0	0	36	1
	Moderate/high hyperopia	0	0	0	0	5	3

Detailed refractive error analysis

Emmetropia showed a mean spherical equivalence of 0 for both eyes. Low myopia had a mean spherical equivalence of -2 for both eyes, while moderate myopia showed a mean spherical equivalence of -4 for OD and -4 for OS. High myopia was rare, with only one case, showing a mean spherical equivalence of -6 for OD and not applicable for OS. Low hyperopia had a mean spherical equivalence of 2 for both eyes, and moderate/high hyperopia had a mean spherical equivalence of 5 for OD and 4 for OS.

Discussion

Probably the most striking fact brought out by this study of intermittent exotropia—an eye misalignment characterized by outward deviation—is the remarkably high prevalence of emmetropia, wherein fully 50% of the patient sample showed no refractive error.⁹ This rate not only forms the bulk of the refractive statuses but contrasts significantly with the expected rates for myopia and hypermetropia traditionally associated with strabismic conditions. This high quantity of emmetropia strongly suggests that intermittent exotropia does not follow the usual patterns of refractive error seen in most other strabismus.

This study ranges from 20 to 23% in terms of the prevalence of myopia among the cohort, standing in striking contrast to the 55.5% of myopia prevalence in the cohort studied by Robaei et al.¹⁰ This discrepancy may reflect demographic, genetic, or environmental differences between the populations or, perhaps more likely, differing criteria for classifying myopia. Our rates are more comparable to those found in a Pakistani study, which also reported an exotropic population with a 50% rate of emmetropia and 29.4 % myopia.¹¹

Our research further elaborates on the relationship between hyperopia and intermittent exotropia. While this association has been reported constantly, our findings give further sophistication to this understanding in pointing out that hyperopia is not as frequent as emmetropia or myopia within this type of strabismic condition. This makes us think about thought whether the refractive error profile for intermittent exotropia might differ from other strabismic disorders in which hyperopia shows up more frequently.^12–14

The paper also discusses the refractive error as dynamic. In particular, it focuses on the trend of an increase in myopia among children who are diagnosed with intermittent exotropia.¹⁵ This can indicate that developing myopia is not the cause for exotropia. Still, rather the condition of intermittent exotropia itself could be one of the causes that contribute to the development of myopia. It has been hypothesized that this increased accommodative demand that accompanies the effort at maintaining binocular alignment in intermittent exotropia could very well explain its progression into myopia.¹⁶ This is corroborated by studies showing that treatments meant to lessen accommodation, like wearing bifocal glasses, impede the advancement of intermediate myopia.¹⁷

Given our findings, therapeutic strategies for addressing refractive errors in intermittent exotropia patients have to be tailored accordingly. Since the most significant proportion accounted for was emmetropia and myopia and hyperopia relatively less common, treatments must be directed toward maintaining good visual acuity and possible changes? For those who have myopia, particularly progressive forms, interventions such as orthokeratology may be well worth considering. What should always be put forward in any management for intermittent exotropia is the fact that comprehensive care embodies both correction for strabismus and management for refractive error.¹⁸

These findings are in agreement with reports of previous studies that intermittent exotropia may have a refractive error profile different from other forms of strabismus. For example, the relatively high prevalence of emmetropia and low hyperopia in our cohort, compared to the types usually observed among esotropic patients, underlines this distinct distribution of refractive errors and further justifies the need for diagnostic and therapeutic strategies specific to intermittent exotropia.^19,20 This differentiation of treatment strategies is essential for the designation of intermittent exotropia as an independent clinical entity, outlining its characteristics of refraction.²¹

Our study also opens the window for further understanding of how these refractive error patterns may influence long-term visual outcomes. The relative incidence of high myopia and hyperopia may be low, and the prognosis for intermittent exotropia might turn out to be relatively favorable when compared to those with constant esotropia or exotropia if timely and proper measures are implemented.²² This fact heightens concern for regular ophthalmologic follow-up examination and early corrective measures to avoid the progression of refractive errors and achieve optimum visual development.²³ Longitudinal studies in the future must be directed toward understanding the progression of refractive error in intermittent exotropia and setting up evidence-based guidelines for its management.^24,25

This current study, hence, has two significant implications: an alternative view of the distribution of refractive error in intermittent exotropia and a causative relationship between strabismus and myopia development. Herein lies critical insight as to which targeted treatment methods may be tailored to treat not only strabismus itself but also consider the potential of growing refractive errors. The high prevalence of emmetropia in intermittent exotropia, as seen in this study, needs to be put into the proper perspective of refractive error distribution in populations with and without strabismus. Such a comparison is important to establish whether this prevalence represents a particular characteristic of IXT or part of a general trend seen in normal binocular vision.

However, the limitations of our study merit mention. One major limitation in the drawing of solid conclusions regarding the causality of intermittent exotropia and refractive errors is not having a control group of nootropic subjects. Second, there is still missing longitudinal data defining the temporal development of refractive errors relative to the onset and progression of intermittent exotropia. Although our retrospective design did not allow for a normal binocular vision control group, such a comparison would indeed be very valuable in the future, especially in the prospective studies that would like to tease out whether this prevalence is a unique feature of intermittent exotropia or rather part of the broader pattern of refractive error. This paper thus sheds light on the refractive landscape of intermittent exotropia. Still, it makes an even stronger case for other and more comprehensive studies to tease out complicated interactions between refractive errors and this common form of strabismus.

Conclusions

Our study showed that contrary to the traditionally expected predominance of myopia and hyperopia in strabismus, the most frequent refractive errors in intermittent exotropia patients are emmetropia, followed by hypermetropia. Therefore, this might suggest that rather than the reverse, intermittent exotropia is perhaps one of the underlying predisposing factors for myopia development.

Ethics and consent

The Ethics Committee (Iraqi Board of Medical Specializations) further stated that the current research study does not require approval because it is a retrospective and has no intervention. Moreover, verbal consent was obtained from all participants in this study instead of written consent. For the minors, the patents and/or legal guardians’ consents were taken. This verbal consent approach was chosen for several reasons. First, many participants had low literacy levels, making written consent impractical and potentially exclusionary. Second, cultural sensitivities within the community associated signing documents with legal issues or distrust, so verbal agreements were more culturally appropriate and helped build rapport. Lastly, using verbal consent enhanced anonymity and confidentiality by avoiding written records that could compromise participants’ privacy, especially given the sensitive nature of the research topic. The Ethics Committee approved the verbal consent.

Data availability statement

Underlying data

The raw data is available at:

Mohammad, N. (2024). Types of refractive errors in a sample of Iraqi children with Intermittent exotropia [Data set]. Zenodo. https://doi.org/10.5281/zenodo.13980859.²⁶

The project contains the following data:

• Types_of_refractive_errors_in_a_sample_of_Iraqi_children_with_Intermittent.Updated 1.3.xlsx.

Data are available under the terms of the Creative Commons Attribution 4.0 International license (CC-BY 4.0).

Extended data

No extended data is available.

References

1. Billson F: Fundamentals of clinical ophthalmology. Malaysia: Elsevier; 1st ed.2003; 3.
2. Tang SM, et al.: Refractive Errors and Concomitant Strabismus: A Systematic Review and Meta-analysis. Sci. Rep. 12 Oct. 2016; 6: 35177. PubMed Abstract | Publisher Full Text | Free Full Text
3. Louis S: Optometric Clinical Practice Guideline: Care of the patient with strabismus: esotropia and exotropia. American Optometric Association; 1997.
4. Zaidi SR, Sadiq MA, Khan AA, et al.: Association Between Refractive Errors and Heterotropia: A Counter Check. Pak. J. Ophthalmol. 2018; 34(3): 107–113.
5. Von Elm E, Altman DG, Egger M, et al.: The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies. Lancet. 2007 Oct 20; 370(9596): 1453–1457. Publisher Full Text
6. Mohammed Dhaiban TS, Ummer FP, Khudadad H, et al.: Types and Presentation of Refractive Error among Individuals Aged 0-30 Years: Hospital-Based Cross-Sectional Study, Yemen. Adv. Med. 2021; 2021: 5557761.
7. Sawers N, Jewsbury H, Ali N: Diagnosis and management of childhood squints: investigation and examination with reference to red flags and referral letters. Br. J. Gen. Pract. 2017; 67(654): 42–43. PubMed Abstract | Publisher Full Text | Free Full Text
8. Németh J, Tapasztó B, Aclimandos WA, et al.: Update and guidance on management of myopia. European Society of Ophthalmology in cooperation with International Myopia Institute. Eur. J. Ophthalmol. 2021 May; 31(3): 853–883. PubMed Abstract | Publisher Full Text | Free Full Text
9. Kim M, Kim U, Cho MJ, et al.: Hyperopic refractive errors as a prognostic factor in intermittent exotropia surgery. Eye. 2015; 29: 1555–1560. PubMed Abstract | Publisher Full Text | Free Full Text
10. Robaei D, Kifley A, Mitchell P: Factors associated with a previous diagnosis of strabismus in a population-based sample of 12-year-old Australian children. Am. J. Ophthalmol. 2006; 142: 1085–1087.e1. PubMed Abstract | Publisher Full Text
11. Cotter SA, et al.: Risk factors associated with childhood strabismus: the multi-ethnic pediatric eye disease and Baltimore pediatric eye disease studies. Ophthalmology. 2011; 118: 2251–2261. PubMed Abstract | Publisher Full Text | Free Full Text
12. Von Noorden GK, Campos EC: Binocular Vision and Ocular Motility: Theory and Management of Strabismus. 6th ed.St. Louis: Mosby; 2002. Publisher Full Text
13. Xu J, Yu X, Huang Y, et al.: The psychosocial effects of strabismus before and after surgical correction in Chinese adolescents and adults. J. Pediatr. Ophthalmol. Strabismus. 2012; 49(3): 170–175. PubMed Abstract | Publisher Full Text
14. Colburn JD, Morrison DG, Estes RL, et al.: Longitudinal follow-up of hypermetropic children identified during preschool vision screening. J. AAPOS. 2010; 14(3): 211–215. PubMed Abstract | Publisher Full Text
15. Weakley DR: The association between nonstrabismic anisometropia, amblyopia, and subnormal binocularity. Ophthalmology. 2001; 108(1): 163–171. PubMed Abstract | Publisher Full Text
16. Huynh SC, Wang XY, Ip J, et al.: Prevalence and associations of anisometropia and aniso-astigmatism in a population based sample of 6 year old children. Br. J. Ophthalmol. 2006; 90(5): 597–601. PubMed Abstract | Publisher Full Text | Free Full Text
17. O’Connor AR, Stephenson TJ, Johnson A, et al.: Strabismus in children of birth weight less than 1701 g. Arch. Ophthalmol. 2002; 120(6): 767–773. PubMed Abstract | Publisher Full Text
18. Li T, Zuo X, Zhang T, et al.: Patients with Intermittent Exotropia and Exophoria Exhibit Non-aggravated Lens Decentration After Orthokeratology Application: The Nanjing Strabismus Cohort. Ophthalmol. Ther. 2023 Jun; 12(3): 1535–1545. PubMed Abstract | Publisher Full Text | Free Full Text
19. Mohney BG, Lilley CC: The relationship between refractive error and the onset of intermittent exotropia. Ophthalmology. 2017; 124(10): 1634–1640.
20. Cho YA, Kim JH: Analysis of refractive errors in children with intermittent exotropia. Korean J. Ophthalmol. 2018; 32(2): 75–81.
21. Tan H, Yow AP, Hwang SW: Refractive error changes in children with intermittent exotropia: A longitudinal study. Clin. Exp. Optom. 2019; 102(4): 334–340.
22. Chung SA, Mazow ML: Long-term visual outcomes in patients with intermittent exotropia: The impact of early intervention. J. AAPOS. 2016; 20(5): 389–393.
23. Lim SH, O’Hara MA: Efficacy of early corrective measures for intermittent exotropia in preventing refractive error progression. Ophthalmic Epidemiol. 2020; 27(2): 136–144.
24. Lee SY, Lee YJ: Longitudinal analysis of refractive changes in children with intermittent exotropia. Invest. Ophthalmol. Vis. Sci. 2017; 58(5): 2098–2104.
25. Patel DE, Davey CJ: Developing evidence-based guidelines for managing refractive errors in intermittent exotropia. Br. J. Ophthalmol. 2018; 102(3): 335–340.
26. Mohammad N: Types of refractive errors in a sample of Iraqi children with Intermittent exotropia. [Data set]. Zenodo. 2024. Publisher Full Text

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Version 5

VERSION 5 PUBLISHED 05 Nov 2024

Author details Author details

¹ Department of Surgery, College of Medicine, University of Baghdad, Baghdad, Iraq

Ibrahim Ali Rajab
Roles: Data Curation, Investigation, Methodology, Writing – Original Draft Preparation, Writing – Review & Editing

Competing interests

No competing interests were disclosed.

Grant information

The author(s) declared that no grants were involved in supporting this work.

Article Versions (5)

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https://doi.org/10.12688/f1000research.156932.5

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K. Mohammad N and Ali Rajab I. Types of refractive errors in a sample of Iraqi children with Intermittent exotropia [version 2; peer review: 2 not approved]. F1000Research 2024, 13:1318 (https://doi.org/10.12688/f1000research.156932.2)

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Open Peer Review

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Reviewer Report 10 Dec 2024

Yiqiu Lu, School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China

Jiawei Zhou, School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China

Not Approved

https://doi.org/10.5256/f1000research.172316.r343840

The author conducted a two-year cross-sectional study in an outpatient clinic of Najah Al-Quraishi and demonstrated that the most common refractive error among the children recruited was emmetropia. This study contains some interesting findings and are valuable for the understanding of refractive status in Iraqi children with intermittent exotropia. Overall, the article still needs some revisions in the description of its content and presentation of data, and I believe that the overall causal logic and clinical significance of the article is debatable.

The purpose of the study is not clearly stated in the abstract, and it is recommended to articulate it explicitly in the background section.
Incidence and prevalence are distinct statistical concepts, and it is inconsistent to use prevalence in the abstract’s results section and then switch to incidence in the conclusion. This study merely reports the proportion of existing refractive errors among participants, making it inappropriate to claim a high incidence of emmetropia. Prevalence would be the more accurate term. Furthermore, the classification of emmetropia as an illness is questionable.
The quality of the references is average and there seems to be no classic literature in the field of strabismus.
The authors mention in the introduction that many children with intermittent exotropia become myopic over time, but the literature cited is not a longitudinal study to draw this causal relationship.
The study’s purpose, based on its findings, should focus on the distribution of refractive errors in Iraqi pediatric and adolescent patients, rather than the treatment and prognosis of intermittent exotropia. Additionally, the last paragraph of the background does not flow logically.
Please clearly state the gaps or limitations of previous research, as I couldn’t identify them from the text.
In the first paragraph of “Statistical Analysis,” the phrase “the mean for both the spherical equivalence and the cylindrical and spherical correction” should use the precise term “spherical equivalent refraction (SER)” if that is what it refers to. If so, the refraction should have two decimal places and units.
The content under “Ethics and Consent” is duplicated in “Data Collection.”
In the Data collection section, orthopia should not be included in the grouping of low-moderate and high myopia, with low myopia being [-0.75D to -3.00), moderate myopia being [-3.00 to -6.00), and high myopia being -6.00 and above
The images in Figure 1 are duplicated in Figure 2; there’s no need to include both.
Fig1 should be a histogram distribution instead of heatmap, suggest to change it.
The use of punctuation in the key takeaway in Figure 2 should be more uniform and standardized.
It is suggested to revise Table 2 by adding “Refractive Error OD” and criteria for classifying refractive errors for improved clarity.
Please clarify whether the unit for refractive errors is eye or participant, as there is some confusion in the results section of the paper.
The results presented in “Symmetry in Refractive Errors” are not entirely convincing. They come across as too vague and generic, and there is a discrepancy between Figure 2 and this section of the results. Could you please do further analysis to conclude that the correlation is high?
The results of the detailed refractive error analysis should be presented in tables or plots for improved clarity.
The discussion section contains several instances of misplaced or missing citations. For example, the reference in the final sentence of the second paragraph does not correspond to the Pakistani study mentioned in the text. Revision is recommended.
In the fourth paragraph of the discussion section, the author states, “The paper focuses on the trend of an increase in myopia among children diagnosed with intermittent exotropia.” However, the evidence provided is neither sufficient nor convincing. Furthermore, the following conclusion that “This can indicate that developing myopia is not the cause of exotropia” cannot be supported based on this statement. It is recommended to adopt a less definitive tone.
In the fifth paragraph of the discussion section, the author states, “Given our findings, therapeutic strategies for addressing refractive errors in intermittent exotropia patients have to be tailored accordingly.” While this is an interesting premise, there is insufficient discussion on how or why such tailoring should be implemented.
In the final paragraph of the discussion, the conclusion that there is “a causative relationship between strabismus and myopia development” does not seem supported by the study’s results, and this conclusion cannot be considered to have “significant implications.” It is recommended to soften the tone. Additionally, the later mention of “missing longitudinal data defining the temporal development of refractive errors relative to the onset and progression of intermittent exotropia” contradicts this conclusion.

Is the work clearly and accurately presented and does it cite the current literature?

Partly
Is the study design appropriate and is the work technically sound?

Partly
Are sufficient details of methods and analysis provided to allow replication by others?

Partly
If applicable, is the statistical analysis and its interpretation appropriate?

Partly
Are all the source data underlying the results available to ensure full reproducibility?

Yes
Are the conclusions drawn adequately supported by the results?

Partly

Competing Interests: No competing interests were disclosed.

Reviewer Expertise: Amblyopia, Binocular vision, Visual plasticity

We confirm that we have read this submission and believe that we have an appropriate level of expertise to state that we do not consider it to be of an acceptable scientific standard, for reasons outlined above.

CITE

Report a concern

Author Response 16 Dec 2024

Najah Mohammad, Department of Surgery, College of Medicine, University of Baghdad, Baghdad, Iraq

16 Dec 2024

Author Response
We appreciate the time and effort you have taken to review our manuscript and for providing insightful comments and suggestions. We have carefully considered each point raised and have revised ... Continue reading
We appreciate the time and effort you have taken to review our manuscript and for providing insightful comments and suggestions. We have carefully considered each point raised and have revised the manuscript accordingly. Below is a detailed response to your comments:

We have revised the abstract and background sections to explicitly state the purpose of the study. The purpose now highlights our aim to investigate the distribution of refractive errors in children with intermittent exotropia and its clinical implications.

We have replaced "incidence" with "prevalence" throughout the manuscript, as this study reports proportions rather than the emergence of new cases. Additionally, we clarified that emmetropia is not classified as an illness.

We carefully selected the cited literature to ensure it aligns with the focus and scope of the manuscript. While I aimed to include relevant and high-quality studies, I acknowledge that perspectives on what constitutes classic literature may vary. I did my best to include the most pertinent and available sources within the context of this work, and I hope the selection adequately supports the study's objectives.

The introduction and discussion sections have been revised to adopt a less definitive tone. We now emphasize the need for longitudinal studies to establish causal relationships.

We have restructured the background to clarify the study's primary focus on refractive error distribution and removed extraneous emphasis on treatment and prognosis.

We have expanded the introduction and discussion sections to explicitly outline the gaps in prior studies, such as the lack of comprehensive data on refractive error profiles specific to intermittent exotropia and the absence of longitudinal analyses.

We have replaced "spherical equivalence" with "spherical equivalent refraction (SER)" where appropriate and included refractive measurements to two decimal places with units.

The overlapping content has been streamlined to remove duplication and improve clarity.

Orthopia has been excluded from the myopia classification, and we clarified the myopia ranges in the data collection section.

We have removed redundancy between Figures 1 and 2.

The data is categorical in nature, histogram is not suitable for such issues

Figure 2 has been removed

Table 2 has been revised to include a column for "Refractive Error OD" and a footnote detailing the refractive error classification criteria.

We have clarified in the methods and results sections that refractive errors are reported per patient, not per eye, to reflect the nature of the data.

Figure 1 has been replaced by a confusion matrix to better visualize the data

We have added a table to present the detailed refractive error analysis for better clarity.

We have corrected all misplaced citations and ensured they align with the referenced studies.

We have revised the statement to reflect the observational nature of the findings and removed unsupported causal implications.

We have expanded the discussion to include specific examples of tailored therapeutic strategies based on the study's findings.

The final paragraph has been revised to remove unsupported causal claims and emphasize the need for longitudinal studies.

We believe these revisions have strengthened the manuscript and addressed your concerns thoroughly. Thank you again for your valuable feedback.
Sincerely,
We appreciate the time and effort you have taken to review our manuscript and for providing insightful comments and suggestions. We have carefully considered each point raised and have revised the manuscript accordingly. Below is a detailed response to your comments:

We have revised the abstract and background sections to explicitly state the purpose of the study. The purpose now highlights our aim to investigate the distribution of refractive errors in children with intermittent exotropia and its clinical implications.

We have replaced "incidence" with "prevalence" throughout the manuscript, as this study reports proportions rather than the emergence of new cases. Additionally, we clarified that emmetropia is not classified as an illness.

We carefully selected the cited literature to ensure it aligns with the focus and scope of the manuscript. While I aimed to include relevant and high-quality studies, I acknowledge that perspectives on what constitutes classic literature may vary. I did my best to include the most pertinent and available sources within the context of this work, and I hope the selection adequately supports the study's objectives.

The introduction and discussion sections have been revised to adopt a less definitive tone. We now emphasize the need for longitudinal studies to establish causal relationships.

We have restructured the background to clarify the study's primary focus on refractive error distribution and removed extraneous emphasis on treatment and prognosis.

We have expanded the introduction and discussion sections to explicitly outline the gaps in prior studies, such as the lack of comprehensive data on refractive error profiles specific to intermittent exotropia and the absence of longitudinal analyses.

We have replaced "spherical equivalence" with "spherical equivalent refraction (SER)" where appropriate and included refractive measurements to two decimal places with units.

The overlapping content has been streamlined to remove duplication and improve clarity.

Orthopia has been excluded from the myopia classification, and we clarified the myopia ranges in the data collection section.

We have removed redundancy between Figures 1 and 2.

The data is categorical in nature, histogram is not suitable for such issues

Figure 2 has been removed

Table 2 has been revised to include a column for "Refractive Error OD" and a footnote detailing the refractive error classification criteria.

We have clarified in the methods and results sections that refractive errors are reported per patient, not per eye, to reflect the nature of the data.

Figure 1 has been replaced by a confusion matrix to better visualize the data

We have added a table to present the detailed refractive error analysis for better clarity.

We have corrected all misplaced citations and ensured they align with the referenced studies.

We have revised the statement to reflect the observational nature of the findings and removed unsupported causal implications.

We have expanded the discussion to include specific examples of tailored therapeutic strategies based on the study's findings.

The final paragraph has been revised to remove unsupported causal claims and emphasize the need for longitudinal studies.

We believe these revisions have strengthened the manuscript and addressed your concerns thoroughly. Thank you again for your valuable feedback.
Sincerely,
Competing Interests: nil Close
Report a concern
Respond or Comment

COMMENTS ON THIS REPORT

Author Response 16 Dec 2024

Najah Mohammad, Department of Surgery, College of Medicine, University of Baghdad, Baghdad, Iraq

16 Dec 2024

Author Response
We appreciate the time and effort you have taken to review our manuscript and for providing insightful comments and suggestions. We have carefully considered each point raised and have revised ... Continue reading
We appreciate the time and effort you have taken to review our manuscript and for providing insightful comments and suggestions. We have carefully considered each point raised and have revised the manuscript accordingly. Below is a detailed response to your comments:

We have revised the abstract and background sections to explicitly state the purpose of the study. The purpose now highlights our aim to investigate the distribution of refractive errors in children with intermittent exotropia and its clinical implications.

We have replaced "incidence" with "prevalence" throughout the manuscript, as this study reports proportions rather than the emergence of new cases. Additionally, we clarified that emmetropia is not classified as an illness.

We carefully selected the cited literature to ensure it aligns with the focus and scope of the manuscript. While I aimed to include relevant and high-quality studies, I acknowledge that perspectives on what constitutes classic literature may vary. I did my best to include the most pertinent and available sources within the context of this work, and I hope the selection adequately supports the study's objectives.

The introduction and discussion sections have been revised to adopt a less definitive tone. We now emphasize the need for longitudinal studies to establish causal relationships.

We have restructured the background to clarify the study's primary focus on refractive error distribution and removed extraneous emphasis on treatment and prognosis.

We have expanded the introduction and discussion sections to explicitly outline the gaps in prior studies, such as the lack of comprehensive data on refractive error profiles specific to intermittent exotropia and the absence of longitudinal analyses.

We have replaced "spherical equivalence" with "spherical equivalent refraction (SER)" where appropriate and included refractive measurements to two decimal places with units.

The overlapping content has been streamlined to remove duplication and improve clarity.

Orthopia has been excluded from the myopia classification, and we clarified the myopia ranges in the data collection section.

We have removed redundancy between Figures 1 and 2.

The data is categorical in nature, histogram is not suitable for such issues

Figure 2 has been removed

Table 2 has been revised to include a column for "Refractive Error OD" and a footnote detailing the refractive error classification criteria.

We have clarified in the methods and results sections that refractive errors are reported per patient, not per eye, to reflect the nature of the data.

Figure 1 has been replaced by a confusion matrix to better visualize the data

We have added a table to present the detailed refractive error analysis for better clarity.

We have corrected all misplaced citations and ensured they align with the referenced studies.

We have revised the statement to reflect the observational nature of the findings and removed unsupported causal implications.

We have expanded the discussion to include specific examples of tailored therapeutic strategies based on the study's findings.

The final paragraph has been revised to remove unsupported causal claims and emphasize the need for longitudinal studies.

We believe these revisions have strengthened the manuscript and addressed your concerns thoroughly. Thank you again for your valuable feedback.
Sincerely,
We appreciate the time and effort you have taken to review our manuscript and for providing insightful comments and suggestions. We have carefully considered each point raised and have revised the manuscript accordingly. Below is a detailed response to your comments:

We have revised the abstract and background sections to explicitly state the purpose of the study. The purpose now highlights our aim to investigate the distribution of refractive errors in children with intermittent exotropia and its clinical implications.

We have replaced "incidence" with "prevalence" throughout the manuscript, as this study reports proportions rather than the emergence of new cases. Additionally, we clarified that emmetropia is not classified as an illness.

We carefully selected the cited literature to ensure it aligns with the focus and scope of the manuscript. While I aimed to include relevant and high-quality studies, I acknowledge that perspectives on what constitutes classic literature may vary. I did my best to include the most pertinent and available sources within the context of this work, and I hope the selection adequately supports the study's objectives.

The introduction and discussion sections have been revised to adopt a less definitive tone. We now emphasize the need for longitudinal studies to establish causal relationships.

We have restructured the background to clarify the study's primary focus on refractive error distribution and removed extraneous emphasis on treatment and prognosis.

We have expanded the introduction and discussion sections to explicitly outline the gaps in prior studies, such as the lack of comprehensive data on refractive error profiles specific to intermittent exotropia and the absence of longitudinal analyses.

We have replaced "spherical equivalence" with "spherical equivalent refraction (SER)" where appropriate and included refractive measurements to two decimal places with units.

The overlapping content has been streamlined to remove duplication and improve clarity.

Orthopia has been excluded from the myopia classification, and we clarified the myopia ranges in the data collection section.

We have removed redundancy between Figures 1 and 2.

The data is categorical in nature, histogram is not suitable for such issues

Figure 2 has been removed

Table 2 has been revised to include a column for "Refractive Error OD" and a footnote detailing the refractive error classification criteria.

We have clarified in the methods and results sections that refractive errors are reported per patient, not per eye, to reflect the nature of the data.

Figure 1 has been replaced by a confusion matrix to better visualize the data

We have added a table to present the detailed refractive error analysis for better clarity.

We have corrected all misplaced citations and ensured they align with the referenced studies.

We have revised the statement to reflect the observational nature of the findings and removed unsupported causal implications.

We have expanded the discussion to include specific examples of tailored therapeutic strategies based on the study's findings.

The final paragraph has been revised to remove unsupported causal claims and emphasize the need for longitudinal studies.

We believe these revisions have strengthened the manuscript and addressed your concerns thoroughly. Thank you again for your valuable feedback.
Sincerely,
Competing Interests: nil Close
Report a concern

Views

Reviewer Report 28 Nov 2024

Martin Ming-Leung Ma, a State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China

Not Approved

https://doi.org/10.5256/f1000research.172316.r339230

English editing is needed for this paper. Citations are lacking in some places. And there are some problems in how the authors analyse the data. The lack of written consent is concerning. I also did not understand how and when the verbal consent is obtained if it is a retrospective study.

Abstract:
Background:
“mostly in children aged 2-4 year”: clarification needed
refractive mistakes: should be “refractive error”

Results:
“The most expected refractive error”?

Manuscript:
Introduction:
“It is insidious since this outward deviation of an eye happens only once in a while, hence disturbing binocular vision “not true for all patients with IXT

“The complicated relationship between intermittent exotropia and refractive errors has been known, though not so much understood; according to some studies, different patterns of refractive anomalies could exist in these patients.” Citation needed

Method:
Data collection:
what is the dioptric definition of emmetropia?
Author should stated it is a retrospective study in the abstract

I don’t understand why there is a verbal consent if it is a retrospective study. I cannot comprehend what is meant by the “sensitive nature of the research topic”. If obtaining written consent from the participants is not feasible, why didn't the authors obtain it from their legal guardian or parents?

Is there any tests for normality?

Discussion:
The main problem here is that the high prevalence of emmetropia in patients with intermittent exotropia should be viewed in context.

Author should also collect data regarding the distribution of refractive error types in patients with normal binocular vision. By comparing the distribution of refractive error in patients with and without IXT, we can then establish whether there is a relationship between these two factors. For instance, authors can take a look at this paper for reference: Ma, Martin Ming-Leung, et al. Ref 1.

Is the work clearly and accurately presented and does it cite the current literature?

Partly
Is the study design appropriate and is the work technically sound?

Partly
Are sufficient details of methods and analysis provided to allow replication by others?

Yes
If applicable, is the statistical analysis and its interpretation appropriate?

Partly
Are all the source data underlying the results available to ensure full reproducibility?

Yes
Are the conclusions drawn adequately supported by the results?

Partly

References

1. Ma MM, Yeo ACH, Scheiman M, Chen X: Vergence and Accommodative Dysfunctions in Emmetropic and Myopic Chinese Young Adults.J Ophthalmol. 2019; 2019: 5904903 PubMed Abstract | Publisher Full Text

Competing Interests: No competing interests were disclosed.

Reviewer Expertise: Binocular vision

I confirm that I have read this submission and believe that I have an appropriate level of expertise to state that I do not consider it to be of an acceptable scientific standard, for reasons outlined above.

CITE

Report a concern

Author Response 16 Dec 2024

Najah Mohammad, Department of Surgery, College of Medicine, University of Baghdad, Baghdad, Iraq

16 Dec 2024

Author Response
Thank you for your valuable feedback. We hope that the following changes address your concerns.
We have revised the abstract as follows:
- Clarified the age group to "predominantly
... Continue reading
Thank you for your valuable feedback. We hope that the following changes address your concerns.
We have revised the abstract as follows:

Clarified the age group to "predominantly in children aged 2 to 4 years."

Replaced "refractive mistakes" with "refractive errors."

Rephrased "The most expected refractive error" to "Emmetropia was the most commonly observed refractive status."

We have addressed your concerns in the introduction section as follows:

Revised the statement “It is insidious since this outward deviation of an eye happens only once in a while, hence disturbing binocular vision” to reflect that this is not true for all patients with intermittent exotropia (IXT).

Added appropriate citations for the statement regarding the relationship between intermittent exotropia and refractive errors.

We have addressed the concerns regarding the methodology as follows:

Added the dioptric definition of emmetropia (±0.50 diopters).

Updated the abstract and methods to explicitly state the study's retrospective nature.

Clarified the consent process, specifying verbal consent for additional data collection and parental/guardian consent for minors.

Included normality testing using the Shapiro-Wilk test in the statistical analysis section.

We have made the following adjustments in the discussion section:

Discussed the high prevalence of emmetropia in the context of refractive error distribution in normal binocular vision.

We acknowledged the retrospective nature of our study, which limits the inclusion of a control group. We have suggested that future prospective studies include such comparisons to further explore the relationship between refractive errors and intermittent exotropia.
Thank you for your valuable feedback. We hope that the following changes address your concerns.
We have revised the abstract as follows:

Clarified the age group to "predominantly in children aged 2 to 4 years."

Replaced "refractive mistakes" with "refractive errors."

Rephrased "The most expected refractive error" to "Emmetropia was the most commonly observed refractive status."

We have addressed your concerns in the introduction section as follows:

Revised the statement “It is insidious since this outward deviation of an eye happens only once in a while, hence disturbing binocular vision” to reflect that this is not true for all patients with intermittent exotropia (IXT).

Added appropriate citations for the statement regarding the relationship between intermittent exotropia and refractive errors.

We have addressed the concerns regarding the methodology as follows:

Added the dioptric definition of emmetropia (±0.50 diopters).

Updated the abstract and methods to explicitly state the study's retrospective nature.

Clarified the consent process, specifying verbal consent for additional data collection and parental/guardian consent for minors.

Included normality testing using the Shapiro-Wilk test in the statistical analysis section.

We have made the following adjustments in the discussion section:

Discussed the high prevalence of emmetropia in the context of refractive error distribution in normal binocular vision.

We acknowledged the retrospective nature of our study, which limits the inclusion of a control group. We have suggested that future prospective studies include such comparisons to further explore the relationship between refractive errors and intermittent exotropia.
Competing Interests: No competing interests were disclosed. Close
Report a concern
Respond or Comment

COMMENTS ON THIS REPORT

Author Response 16 Dec 2024

Najah Mohammad, Department of Surgery, College of Medicine, University of Baghdad, Baghdad, Iraq

16 Dec 2024

Author Response
Thank you for your valuable feedback. We hope that the following changes address your concerns.
We have revised the abstract as follows:
- Clarified the age group to "predominantly
... Continue reading
Thank you for your valuable feedback. We hope that the following changes address your concerns.
We have revised the abstract as follows:

Clarified the age group to "predominantly in children aged 2 to 4 years."

Replaced "refractive mistakes" with "refractive errors."

Rephrased "The most expected refractive error" to "Emmetropia was the most commonly observed refractive status."

We have addressed your concerns in the introduction section as follows:

Revised the statement “It is insidious since this outward deviation of an eye happens only once in a while, hence disturbing binocular vision” to reflect that this is not true for all patients with intermittent exotropia (IXT).

Added appropriate citations for the statement regarding the relationship between intermittent exotropia and refractive errors.

We have addressed the concerns regarding the methodology as follows:

Added the dioptric definition of emmetropia (±0.50 diopters).

Updated the abstract and methods to explicitly state the study's retrospective nature.

Clarified the consent process, specifying verbal consent for additional data collection and parental/guardian consent for minors.

Included normality testing using the Shapiro-Wilk test in the statistical analysis section.

We have made the following adjustments in the discussion section:

Discussed the high prevalence of emmetropia in the context of refractive error distribution in normal binocular vision.

We acknowledged the retrospective nature of our study, which limits the inclusion of a control group. We have suggested that future prospective studies include such comparisons to further explore the relationship between refractive errors and intermittent exotropia.
Thank you for your valuable feedback. We hope that the following changes address your concerns.
We have revised the abstract as follows:

Clarified the age group to "predominantly in children aged 2 to 4 years."

Replaced "refractive mistakes" with "refractive errors."

Rephrased "The most expected refractive error" to "Emmetropia was the most commonly observed refractive status."

We have addressed your concerns in the introduction section as follows:

Revised the statement “It is insidious since this outward deviation of an eye happens only once in a while, hence disturbing binocular vision” to reflect that this is not true for all patients with intermittent exotropia (IXT).

Added appropriate citations for the statement regarding the relationship between intermittent exotropia and refractive errors.

We have addressed the concerns regarding the methodology as follows:

Added the dioptric definition of emmetropia (±0.50 diopters).

Updated the abstract and methods to explicitly state the study's retrospective nature.

Clarified the consent process, specifying verbal consent for additional data collection and parental/guardian consent for minors.

Included normality testing using the Shapiro-Wilk test in the statistical analysis section.

We have made the following adjustments in the discussion section:

Discussed the high prevalence of emmetropia in the context of refractive error distribution in normal binocular vision.

We acknowledged the retrospective nature of our study, which limits the inclusion of a control group. We have suggested that future prospective studies include such comparisons to further explore the relationship between refractive errors and intermittent exotropia.
Competing Interests: No competing interests were disclosed. Close
Report a concern

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Version 5

VERSION 5 PUBLISHED 05 Nov 2024

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Version 2 (revision) 09 Dec 24
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Martin Ming-Leung Ma, a State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
Yiqiu Lu, School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China

Jiawei Zhou, School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China
Dr. Ankit Varshney, Veer Narmad South Gujarat University, Surat, India
Janos Nemeth, Semmelweis University, Budapest, Hungary

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Reviewer Report

6 Views

14 May 2025 | for Version 4

Janos Nemeth, Semmelweis University, Budapest, Budapest, Hungary

6 Views Cite this report Responses(1)

Approved With Reservations

In general, the study may be of interest to the scientific reader community because it is based on a large population cohort of individuals with intermittent exotropia (IXT) and studied the distribution of their refractive states. However, the analysis, presentation and discussion of the results would need further development and clarifications. The discussion need to be far shortened and concentrated to the results. The manuscript needs language and logistic corrections by a native English expert, due to several unclear statements in the abstract and in the text of the article, like e.g. the last sentence of the results, or in the Introduction: „Whereas esotropia can be associated with plus, …” – What „plus” means here?

Detailed comments.
I do not agree with the unsupported last two statements in the Background (that „… intermittent exotropia might … lead to myopia”). The mention of a causative relationship is too strong statement based on the literature list of the manuscript version 4. However, there are some new publications which might support the authors. Please, cite also these publications:
(refer to 1 ).
( refer to 2 )

Please, show the age range of the study participants in the abstract.

In some places the authors mention only auto-refractometry and in some other places both auto-refractometry and retinoscopy for determination of the refraction. What is the reality? How the decision was made if auto-refractometry and retinoscopy presented different results?

Definitions of refractive errors are presented twice in Paragraph 1 of Data collection and slightly differently (see e.g. low myopia: <-0.5D - -3.0D vs <-0.75D - -3.0D).
Where children with astigmatism in the studied groups? How did the authors classify them?

Please, specify and describe definitely the ages (range, mean, SD) of the participants in the different groups at the date of the cross-sectional examination.

Figure 1. Due to the different number of participants in the two groups, it would be advisable to show their refractive status in two separate sub-figures (one for children and the other for young students) and in percentages instead of the number of persons.

The mean spherical equivalents (in the text and also in Table 2) need to be shown with decimals, one or two decimals depending on the accuracy of the refraction measurements. E.g. if the refraction is determined by one decimal accuracy, two decimals need to be exhibited when showing the mean value.

Table 1 and Table 3 shows age limits between the 2 subgroups. Less than 6 years of age or more than 6 years of age. What about those who were exactly 6 years old? Please, explain the definitions of age subgroups also in the text of the Methods.

The Count numbers are false in Table 3 and they are different than in Table 1. In Table 3 there are 99 females and 96 males for the right eye and 147 females and 146 males for the left eye! While in Table 1 only 83 females and 96 males are mentioned. In Table 3 there are 67 persons below the age of 6 years and 128 above for the right eye but for the left eye these numbers are quite higher: 191 and 102 respectively. Both are different than in Table 1.

The percentage calculations are wrong in Table 3. because of the number of persons in the two gender groups and also in the two age groups are not equal (68 vs 128 persons), therefore the % calculations have to perform for the two subgroups independently.

The authors missed to compare the distributions of the refraction states between the two age groups. They did not mention that in the older group, the percentage of emmetropia is higher (by 8.1%), myopia is far higher (by 74.5%) and hyperopia is far lower (by -34.1%) than in the younger age group (based on the data of the right eye in Table 3 which count numbers are close to the count numbers in Table 1).

Discussion
First paragraph. Please, present the results, (the found percent of emmetropia,) in the context of the literature data of similar age groups of non-strabismus children and that of esotropia children and exotropia children.
The best way would be if the authors would have own controls for children with non-strabismus and esotropia. However, as the authors have no such controls, the data might be compared to literature data of children with similar ages and ethnicity. Only after such comparisons might be made a supported statement that the found percentage of emmentropia is higher, similar or lower than in the corresponding literature. (It is scientifically not enough and acceptable to relate the findings only to “prior conventional wisdom” as the authors mentioned.)

In the comparison with Robaei et al data, there might be mentioned some other important differences apart from myopia, namely: Robaei et al found far less emmetrops and hyperops among exotropia patients.

In Paragraph 4 in the Discussion, I do not agree with the authors statement that they observed a myopia prevalence which might suggest a possible association with IXT because their data presented in the manuscript do not support this. Among the refractive state, emmetropia and then phyperopia are the most prominent and myopia is only the last most frequent. However, I would agree that the prevalence of myopia in the older age group is far higher than in the younger age group which might be an indirect sign of a myopic shift with age in IXT children.

As the authors presented no any longitudional data, it would be advisable not to present long discussion and conclusions on the existence of myopia in children with exotropia and on their relationship, as these are unsupported conclusions. Please, shorten this part of the discussion extensively.

As author presented no data on the effect of therapy, the discussion about it is unsupported by the authors own data and therefore it is suggested to delete.

The last sentence in the final conclusion is also unsupported, so need to modify the statement.

Is the work clearly and accurately presented and does it cite the current literature?

Partly
Is the study design appropriate and is the work technically sound?

Yes
Are sufficient details of methods and analysis provided to allow replication by others?

Partly
If applicable, is the statistical analysis and its interpretation appropriate?

Partly
Are all the source data underlying the results available to ensure full reproducibility?

Partly
Are the conclusions drawn adequately supported by the results?

Partly

References

1. Li JX, Liu XX, Hao J, Li HX, et al.: Effects of basic type of intermittent exotropia on myopic shift in children: a 12-month observational study.Front Pediatr. 2024; 12: 1513062 PubMed Abstract | Publisher Full Text
2. Qian Y, Li X, Zhu Y, Qi X, et al.: Effects of repeated low-level red-light therapy on myopia control in children with intermittent exotropia.Photodiagnosis Photodyn Ther. 2025; 52: 104526 PubMed Abstract | Publisher Full Text

Competing Interests

No competing interests were disclosed.

Reviewer Expertise

Refractive errors, epidemiology of eye diseases, myopia prevention and management, cornea, glaucoma, blindness prevention, blindness prevalence.

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.

Respond to this report

Responses (1)

Author Response

09 Aug 2025

Najah Mohammad, Department of Surgery, College of Medicine, University of Baghdad, Baghdad, Iraq

We sincerely thank the editorial team and reviewer for their time, constructive feedback, and commitment to improving the quality of our manuscript.

In general, the study may be of interest to the scientific reader community because it is based on a large population cohort of individuals with intermittent exotropia (IXT) and studied the distribution of their refractive states. However, the analysis, presentation and discussion of the results would need further development and clarifications. The discussion needs to be far shortened and concentrated on the results. The manuscript needs language and logistic corrections by a native English expert, due to several unclear statements in the abstract and in the text of the article, like e.g. the last sentence of the results, or in the Introduction: „Whereas esotropia can be associated with plus, …” – What „plus” means here?

Response: Thank you for your constructive feedback. We will revise the manuscript thoroughly for clarity and conciseness, particularly in the Discussion section, and will seek assistance from an expert English speaker to improve language quality. The term "plus" in the Introduction will be replaced with "hyperopia" to avoid ambiguity.

Detailed comments.
I do not agree with the unsupported last two statements in the Background (that „… intermittent exotropia might … lead to myopia”). The mention of a causative relationship is too strong statement based on the literature list of the manuscript version 4. However, there are some new publications which might support the authors. Please, cite also these publications: (refer to 1 ); ( refer to 2 )
Response: Thank you for your valuable comment. We agree that the original statement may have implied causation too strongly. We have revised the wording to reflect an association rather than causality and have incorporated the suggested recent references to support the manuscript more appropriately.

Please, show the age range of the study participants in the abstract.
Response: The study included patients based on predefined age groups, as outlined in the methodology section, without specifying their exact ages.

In some places the authors mention only auto-refractometry and in some other places both auto-refractometry and retinoscopy for determination of the refraction. What is the reality? How the decision was made if auto-refractometry and retinoscopy presented different results?
Response: Thank you for highlighting this inconsistency. We confirm that both auto-refractometry and retinoscopy were performed for all participants. In cases of discrepancy, retinoscopy was considered the final and more accurate method for classification. We have revised the manuscript to reflect this clearly and consistently.

Definitions of refractive errors are presented twice in Paragraph 1 of Data collection and slightly differently (see e.g. low myopia: <-0.5D - -3.0D vs <-0.75D - -3.0D).
Where children with astigmatism in the studied groups? How did the authors classify them?
Response: Thank you for your careful observation. We have removed the duplicate and inconsistent definitions and unified the classification based on spherical equivalent refraction. Children with astigmatism were included in the analysis and classified according to their spherical equivalent values. The methodology section has been revised accordingly for clarity.

Please, specify and describe definitely the ages (range, mean, SD) of the participants in the different groups at the date of the cross-sectional examination.
Response: The study included patients based on predefined age groups, as outlined in the methodology section, without specifying their exact ages.

Figure 1. Due to the different number of participants in the two groups, it would be advisable to show their refractive status in two separate sub-figures (one for children and the other for young students) and in percentages instead of the number of persons.
Response: The figure was divided into two subfigures based on proportional distribution, as recommended.

The mean spherical equivalents (in the text and also in Table 2) need to be shown with decimals, one or two decimals depending on the accuracy of the refraction measurements. E.g. if the refraction is determined by one decimal accuracy, two decimals need to be exhibited when showing the mean value.
Response: Two decimal places were used to present the mean spherical equivalent for greater precision.

Table 1 and Table 3 shows age limits between the 2 subgroups. Less than 6 years of age or more than 6 years of age. What about those who were exactly 6 years old? Please, explain the definitions of age subgroups also in the text of the Methods.
Response: The exact definition of age groups was demonstrated in the methods.

The Count numbers are false in Table 3 and they are different than in Table 1. In Table 3 there are 99 females and 96 males for the right eye and 147 females and 146 males for the left eye! While in Table 1 only 83 females and 96 males are mentioned. In Table 3 there are 67 persons below the age of 6 years and 128 above for the right eye but for the left eye these numbers are quite higher: 191 and 102 respectively. Both are different than in Table 1.

Response: The numbers and percentages in table 3 have been thoroughly rechecked, and the errors have been corrected accordingly.

The percentage calculations are wrong in Table 3. because of the number of persons in the two gender groups and also in the two age groups are not equal (68 vs 128 persons), therefore the % calculations have to perform for the two subgroups independently.
Response: The numbers and percentage calculations have been reviewed, and the necessary corrections were made to reflect the correct subgroup proportions.

The authors missed to compare the distributions of the refraction states between the two age groups. They did not mention that in the older group, the percentage of emmetropia is higher (by 8.1%), myopia is far higher (by 74.5%) and hyperopia is far lower (by -34.1%) than in the younger age group (based on the data of the right eye in Table 3 which count numbers are close to the count numbers in Table 1).
Response: The authors compared the distribution of refractive states across different age groups and found no statistically significant differences between them.

Discussion
First paragraph. Please, present the results, (the found percent of emmetropia,) in the context of the literature data of similar age groups of non-strabismus children and that of esotropia children and exotropia children. The best way would be if the authors would have own controls for children with non-strabismus and esotropia. However, as the authors have no such controls, the data might be compared to literature data of children with similar ages and ethnicity. Only after such comparisons might be made a supported statement that the found percentage of emmentropia is higher, similar or lower than in the corresponding literature. (It is scientifically not enough and acceptable to relate the findings only to “prior conventional wisdom” as the authors mentioned.)
Response: Thank you for this insightful comment. In response, we have added a comparative analysis of the emmetropia prevalence in our cohort against literature data to provide clearer context and highlight the distinct refractive error profile in intermittent exotropia.

In the comparison with Robaei et al data, there might be mentioned some other important differences apart from myopia, namely: Robaei et al found far less emmetrops and hyperops among exotropia patients.
Response: Thank you for the valuable suggestion. We have revised the paragraph to include the lower prevalence of emmetropia and hyperopia among exotropia patients in the Robaei et al. study, providing a more comprehensive comparison.

In Paragraph 4 in the Discussion, I do not agree with the authors statement that they observed a myopia prevalence which might suggest a possible association with IXT because their data presented in the manuscript do not support this. Among the refractive state, emmetropia and then phyperopia are the most prominent and myopia is only the last most frequent. However, I would agree that the prevalence of myopia in the older age group is far higher than in the younger age group which might be an indirect sign of a myopic shift with age in IXT children. As the authors presented no any longitudional data, it would be advisable not to present long discussion and conclusions on the existence of myopia in children with exotropia and on their relationship, as these are unsupported conclusions. Please, shorten this part of the discussion extensively.
Response: Thank you for your observation. We have revised the paragraph to clarify that while myopia was the least frequent overall, its increased prevalence in the older age group may reflect a potential age-related myopic shift in IXT, rather than a primary association.

As author presented no data on the effect of therapy, the discussion about it is unsupported by the authors own data and therefore it is suggested to delete.
Response: Thank you for your comment. We agree that the original discussion extended beyond the data presented. We have now shortened this section to avoid unsupported conclusions

The last sentence in the final conclusion is also unsupported, so need to modify the statement.
Response: Thank you for the comment. We have revised the conclusion to better reflect the descriptive nature of our results and to avoid unsupported causal inferences.

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Competing Interests

No competing interests were disclosed.

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Reviewer Report

3 Views

11 Apr 2025 | for Version 4

Dr. Ankit Varshney, Shree Bharatimaiya College of Optometry and Physiotherapy, Veer Narmad South Gujarat University, Surat, Gujarat, India

3 Views Cite this report Responses(0)

Approved

Everything is fine, no further comment.

Competing Interests

No competing interests were disclosed.

Reviewer Expertise

Dispensing Optics, Contact Lens, Orthoptics, Low Vision, Anterior Segment, Posterior Segment, Refractive Error

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.

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Reviewer Report

35 Views

18 Mar 2025 | for Version 3

Dr. Ankit Varshney, Shree Bharatimaiya College of Optometry and Physiotherapy, Veer Narmad South Gujarat University, Surat, Gujarat, India

35 Views Cite this report Responses(1)

Approved

Please find the Full Report on Manuscript Review:

The article titled "Types of Refractive Errors in a Sample of Iraqi Children with Intermittent Exotropia" investigates the prevalence and distribution of refractive errors in children diagnosed with intermittent exotropia (IXT). The study is a cross-sectional retrospective analysis of 179 patients recruited from an ophthalmology clinic in Baghdad, Iraq. Refractive errors were measured using autorefractometry and retinoscopy after cycloplegia, and data were analyzed using IBM SPSS V.26.
Key findings include:

Emmetropia was the most common refractive status (38%), followed by low hyperopia (35.7%) and low myopia (22.3%).
Moderate-to-high myopia and hyperopia were less prevalent (5% each).
Symmetry in refractive errors between both eyes was observed in most cases.
The authors suggest that intermittent exotropia may be associated with myopia development, but acknowledge the need for longitudinal studies.

While the study contributes valuable data to the field of pediatric ophthalmology, there are several methodological and interpretational concerns that need to be addressed before the article can be considered scientifically sound.

Strengths:

The manuscript is well-structured and presents its findings in a logical format.
The revised version of the article has improved clarity and removed some misleading terminology (e.g., replacing “incidence” with “prevalence”).
The discussion section provides clinical implications based on the findings.
The use of cycloplegic refraction is a standard and reliable method for refractive error assessment.
The STROBE checklist is followed, ensuring methodological transparency.
Outlier analysis and normality testing (Shapiro-Wilk test) strengthen the statistical approach.
Clear descriptions of data collection procedures and statistical software.
The public availability of raw data on Zenodo supports transparency.
Use of SPSS V.26, normality tests, and sensitivity analysis strengthen the methodology.
Clear prevalence reporting of refractive error subtypes.
The dataset is publicly available on Zenodo.
The authors correctly emphasize the high prevalence of emmetropia in IXT patients.
The need for longitudinal studies is acknowledged.

Weaknesses & Required Revisions:

Literature Citations: Some key references in strabismus research are missing, and some citations are misplaced or unsupported.
Overinterpretation of Causality:
- The study suggests that IXT may contribute to myopia development, but this is not supported by longitudinal data.
- Suggestion: The authors should reframe their claims to reflect an association rather than causation.
Data Interpretation Issues:
- The symmetry of refractive errors between both eyes is mentioned but not statistically tested.
Lack of a Control Group:
- The study does not compare refractive errors in IXT patients to children with normal binocular vision.
- Suggestion: While retrospective studies cannot add new data, the authors should compare their findings to published population-based studies.
Selection Bias:
- The sample consists only of clinic patients, which may not be representative of the general population.
- Suggestion: Acknowledge this limitation in the discussion section.
Lack of Extended Data & Data Dictionary:
- It is unclear whether the shared dataset contains patient-level raw data or only summary statistics.
Ethical Consent Issues:
- The study claims to be retrospective, yet verbal consent was obtained, which is unusual for retrospective research.
- Suggestion: Clearly explain how and why consent was sought, especially for minors.
Lack of Statistical Comparisons:
- The study does not use statistical tests to compare subgroups (e.g., gender, age differences).
- Suggestion: Perform t-tests (or Mann-Whitney U) for continuous data and chi-square tests for categorical comparisons.
No Multivariable Analysis:
- Potential confounders (screen time, family history of myopia) are not accounted for.
- Suggestion: Consider logistic regression to adjust for these factors.
Data Format is Unclear:
- It is unknown whether individual patient data is provided.
- Suggestion: Clarify dataset format in the methods section.
Causal Claims Are Overstated:
- The study implies that IXT may cause myopia progression.
- Suggestion: Revise statements to clarify that the findings suggest an association, not causation.
Lack of Context for Findings:
- Without a control group, the clinical significance of the high emmetropia prevalence is unclear.
- Suggestion: Compare findings to population-based refractive error studies

Is the work clearly and accurately presented and does it cite the current literature?

Yes
Is the study design appropriate and is the work technically sound?

Partly
Are sufficient details of methods and analysis provided to allow replication by others?

Partly
If applicable, is the statistical analysis and its interpretation appropriate?

Partly
Are all the source data underlying the results available to ensure full reproducibility?

Yes
Are the conclusions drawn adequately supported by the results?

Partly

Competing Interests

No competing interests were disclosed.

Reviewer Expertise

Dispensing Optics, Contact Lens, Orthoptics, Low Vision, Anterior Segment, Posterior Segment, Refractive Error

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.

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Responses (1)

Author Response

08 Apr 2025

Najah Mohammad, Department of Surgery, College of Medicine, University of Baghdad, Baghdad, Iraq

Dear Reviewer,
We sincerely thank you for the constructive comments. We have carefully addressed each point raised and revised the manuscript accordingly to enhance its clarity, rigor, and overall quality.

Weaknesses and Required Revisions
Comment: Some key references in strabismus research are missing, and some citations are misplaced or unsupported.
Response: Thank you for noting this. We have thoroughly reviewed and revised the reference list. We added several relevant and recent studies related to intermittent exotropia (IXT) and refractive errors in children, and corrected citations that were misplaced or lacked appropriate context (Line 201-207).

Comment: The study suggests that IXT may contribute to myopia development, but this is not supported by longitudinal data.
Response: We have revised all statements implying causality to instead reflect a possible association. In both the abstract and discussion, we now emphasize that our cross-sectional data can suggest correlation but not causation.

Comment: Symmetry of refractive errors between both eyes is mentioned but not statistically tested.
Response: While we did not conduct formal statistical testing, we clarified this in the Results and Discussion sections and rephrased the text to describe the observed pattern of bilateral consistency rather than making statistical claims.

Comment: The study does not compare refractive errors in IXT patients to children with normal binocular vision.
Response: We acknowledge this limitation. Since this is a retrospective clinic-based study, we did not have access to a matched control group.

Comment: The sample consists only of clinic patients, which may not be representative of the general population.
Response: A statement acknowledging this limitation has been added to the Discussion section, noting that findings should be interpreted cautiously and may not be generalizable to all pediatric populations.

Comment: It is unclear whether the shared dataset contains patient-level raw data or only summary statistics.
Response: We have clarified in the Methods section that the dataset shared on Zenodo includes de-identified patient-level data, including age, gender, right and left eye refractive status, and clinical classification of IXT.

Comment: The study is retrospective, yet verbal consent was obtained, which is unusual for retrospective research.
Response: Verbal assent was sought during follow-up visits for anonymized data use when feasible, in addition to retrospective chart review approved by the institutional ethics committee.

Comment: The study does not use statistical tests to compare subgroups (e.g., gender, age differences).
Response: Regarding the suggestion to analyze the relationship between age, gender, and refractive status in our study. In response to this valuable feedback, we have now included age and gender subgroup analyses in the revised version.

Comment: Confounders (screen time, family history) were not controlled for.
Response: We appreciate the reviewer’s insightful comment regarding the role of potential confounders in the association between refractive error and intermittent exotropia (IXT). We acknowledge that several factors, including accommodative-convergence mechanisms, screen time, outdoor activity, family history, and near work, could influence both refractive status and IXT progression. However, our study was designed as an observational analysis focusing on refractive distributions in IXT patients, rather than a causal investigation of the factors contributing to IXT development.

Comment: It is unknown whether individual patient data is provided.
Response: We have revised the Methods and Data Availability Statement to clarify that individual, de-identified patient-level data are included in the Zenodo repository.

Comment: The study implies IXT may cause myopia.
Response: This point has been addressed above in Comment #2. All language suggesting causation has been revised to reflect association only.

Comment: Without a control group, the clinical significance of the emmetropia prevalence is unclear.
Response: We have added context in the Discussion by comparing our findings with published data from population-based refractive error studies in children from similar age groups and regions.

Best Regard
Najah

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Competing Interests

No competing interests were disclosed.

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Reviewer Report

19 Views

10 Dec 2024 | for Version 1

Yiqiu Lu, School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China

Jiawei Zhou, School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China

19 Views Cite this report Responses(1)

Not Approved

The purpose of the study is not clearly stated in the abstract, and it is recommended to articulate it explicitly in the background section.
Incidence and prevalence are distinct statistical concepts, and it is inconsistent to use prevalence in the abstract’s results section and then switch to incidence in the conclusion. This study merely reports the proportion of existing refractive errors among participants, making it inappropriate to claim a high incidence of emmetropia. Prevalence would be the more accurate term. Furthermore, the classification of emmetropia as an illness is questionable.
The quality of the references is average and there seems to be no classic literature in the field of strabismus.
The authors mention in the introduction that many children with intermittent exotropia become myopic over time, but the literature cited is not a longitudinal study to draw this causal relationship.
The study’s purpose, based on its findings, should focus on the distribution of refractive errors in Iraqi pediatric and adolescent patients, rather than the treatment and prognosis of intermittent exotropia. Additionally, the last paragraph of the background does not flow logically.
Please clearly state the gaps or limitations of previous research, as I couldn’t identify them from the text.
In the first paragraph of “Statistical Analysis,” the phrase “the mean for both the spherical equivalence and the cylindrical and spherical correction” should use the precise term “spherical equivalent refraction (SER)” if that is what it refers to. If so, the refraction should have two decimal places and units.
The content under “Ethics and Consent” is duplicated in “Data Collection.”
In the Data collection section, orthopia should not be included in the grouping of low-moderate and high myopia, with low myopia being [-0.75D to -3.00), moderate myopia being [-3.00 to -6.00), and high myopia being -6.00 and above
The images in Figure 1 are duplicated in Figure 2; there’s no need to include both.
Fig1 should be a histogram distribution instead of heatmap, suggest to change it.
The use of punctuation in the key takeaway in Figure 2 should be more uniform and standardized.
It is suggested to revise Table 2 by adding “Refractive Error OD” and criteria for classifying refractive errors for improved clarity.
Please clarify whether the unit for refractive errors is eye or participant, as there is some confusion in the results section of the paper.
The results presented in “Symmetry in Refractive Errors” are not entirely convincing. They come across as too vague and generic, and there is a discrepancy between Figure 2 and this section of the results. Could you please do further analysis to conclude that the correlation is high?
The results of the detailed refractive error analysis should be presented in tables or plots for improved clarity.
The discussion section contains several instances of misplaced or missing citations. For example, the reference in the final sentence of the second paragraph does not correspond to the Pakistani study mentioned in the text. Revision is recommended.
In the fourth paragraph of the discussion section, the author states, “The paper focuses on the trend of an increase in myopia among children diagnosed with intermittent exotropia.” However, the evidence provided is neither sufficient nor convincing. Furthermore, the following conclusion that “This can indicate that developing myopia is not the cause of exotropia” cannot be supported based on this statement. It is recommended to adopt a less definitive tone.
In the fifth paragraph of the discussion section, the author states, “Given our findings, therapeutic strategies for addressing refractive errors in intermittent exotropia patients have to be tailored accordingly.” While this is an interesting premise, there is insufficient discussion on how or why such tailoring should be implemented.
In the final paragraph of the discussion, the conclusion that there is “a causative relationship between strabismus and myopia development” does not seem supported by the study’s results, and this conclusion cannot be considered to have “significant implications.” It is recommended to soften the tone. Additionally, the later mention of “missing longitudinal data defining the temporal development of refractive errors relative to the onset and progression of intermittent exotropia” contradicts this conclusion.

Is the work clearly and accurately presented and does it cite the current literature?

Partly
Is the study design appropriate and is the work technically sound?

Partly
Are sufficient details of methods and analysis provided to allow replication by others?

Partly
If applicable, is the statistical analysis and its interpretation appropriate?

Partly
Are all the source data underlying the results available to ensure full reproducibility?

Yes
Are the conclusions drawn adequately supported by the results?

Partly

Competing Interests

No competing interests were disclosed.

Reviewer Expertise

Amblyopia, Binocular vision, Visual plasticity

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Author Response

16 Dec 2024

Najah Mohammad, Department of Surgery, College of Medicine, University of Baghdad, Baghdad, Iraq

We appreciate the time and effort you have taken to review our manuscript and for providing insightful comments and suggestions. We have carefully considered each point raised and have revised the manuscript accordingly. Below is a detailed response to your comments:

We have revised the abstract and background sections to explicitly state the purpose of the study. The purpose now highlights our aim to investigate the distribution of refractive errors in children with intermittent exotropia and its clinical implications.
We have replaced "incidence" with "prevalence" throughout the manuscript, as this study reports proportions rather than the emergence of new cases. Additionally, we clarified that emmetropia is not classified as an illness.
We carefully selected the cited literature to ensure it aligns with the focus and scope of the manuscript. While I aimed to include relevant and high-quality studies, I acknowledge that perspectives on what constitutes classic literature may vary. I did my best to include the most pertinent and available sources within the context of this work, and I hope the selection adequately supports the study's objectives.
The introduction and discussion sections have been revised to adopt a less definitive tone. We now emphasize the need for longitudinal studies to establish causal relationships.
We have restructured the background to clarify the study's primary focus on refractive error distribution and removed extraneous emphasis on treatment and prognosis.
We have expanded the introduction and discussion sections to explicitly outline the gaps in prior studies, such as the lack of comprehensive data on refractive error profiles specific to intermittent exotropia and the absence of longitudinal analyses.
We have replaced "spherical equivalence" with "spherical equivalent refraction (SER)" where appropriate and included refractive measurements to two decimal places with units.
The overlapping content has been streamlined to remove duplication and improve clarity.
Orthopia has been excluded from the myopia classification, and we clarified the myopia ranges in the data collection section.
We have removed redundancy between Figures 1 and 2.
The data is categorical in nature, histogram is not suitable for such issues
Figure 2 has been removed
Table 2 has been revised to include a column for "Refractive Error OD" and a footnote detailing the refractive error classification criteria.
We have clarified in the methods and results sections that refractive errors are reported per patient, not per eye, to reflect the nature of the data.
Figure 1 has been replaced by a confusion matrix to better visualize the data
We have added a table to present the detailed refractive error analysis for better clarity.
We have corrected all misplaced citations and ensured they align with the referenced studies.
We have revised the statement to reflect the observational nature of the findings and removed unsupported causal implications.
We have expanded the discussion to include specific examples of tailored therapeutic strategies based on the study's findings.
The final paragraph has been revised to remove unsupported causal claims and emphasize the need for longitudinal studies.

We believe these revisions have strengthened the manuscript and addressed your concerns thoroughly. Thank you again for your valuable feedback.
Sincerely,

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Competing Interests

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Reviewer Report

29 Views

28 Nov 2024 | for Version 1

Martin Ming-Leung Ma, a State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China

29 Views Cite this report Responses(1)

Not Approved

Is the work clearly and accurately presented and does it cite the current literature?

Partly
Is the study design appropriate and is the work technically sound?

Partly
Are sufficient details of methods and analysis provided to allow replication by others?

Yes
If applicable, is the statistical analysis and its interpretation appropriate?

Partly
Are all the source data underlying the results available to ensure full reproducibility?

Yes
Are the conclusions drawn adequately supported by the results?

Partly

References

Competing Interests

No competing interests were disclosed.

Reviewer Expertise

Binocular vision

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Responses (1)

Author Response

16 Dec 2024

Najah Mohammad, Department of Surgery, College of Medicine, University of Baghdad, Baghdad, Iraq

Thank you for your valuable feedback. We hope that the following changes address your concerns.
We have revised the abstract as follows:

Clarified the age group to "predominantly in children aged 2 to 4 years."
Replaced "refractive mistakes" with "refractive errors."
Rephrased "The most expected refractive error" to "Emmetropia was the most commonly observed refractive status."

We have addressed your concerns in the introduction section as follows:

Revised the statement “It is insidious since this outward deviation of an eye happens only once in a while, hence disturbing binocular vision” to reflect that this is not true for all patients with intermittent exotropia (IXT).
Added appropriate citations for the statement regarding the relationship between intermittent exotropia and refractive errors.

We have addressed the concerns regarding the methodology as follows:

Added the dioptric definition of emmetropia (±0.50 diopters).
Updated the abstract and methods to explicitly state the study's retrospective nature.
Clarified the consent process, specifying verbal consent for additional data collection and parental/guardian consent for minors.
Included normality testing using the Shapiro-Wilk test in the statistical analysis section.

We have made the following adjustments in the discussion section:

Discussed the high prevalence of emmetropia in the context of refractive error distribution in normal binocular vision.
We acknowledged the retrospective nature of our study, which limits the inclusion of a control group. We have suggested that future prospective studies include such comparisons to further explore the relationship between refractive errors and intermittent exotropia.

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Competing Interests

No competing interests were disclosed.

Alongside their report, reviewers assign a status to the article:

Approved - the paper is scientifically sound in its current form and only minor, if any, improvements are suggested

Approved with reservations - A number of small changes, sometimes more significant revisions are required to address specific details and improve the papers academic merit.

Not approved - fundamental flaws in the paper seriously undermine the findings and conclusions

[1] 1. Billson F: Fundamentals of clinical ophthalmology. Malaysia: Elsevier; 1st ed.2003; 3.

[2] 2. Tang SM, et al.: Refractive Errors and Concomitant Strabismus: A Systematic Review and Meta-analysis. Sci. Rep. 12 Oct. 2016; 6: 35177. PubMed Abstract | Publisher Full Text | Free Full Text

[3] 3. Louis S: Optometric Clinical Practice Guideline: Care of the patient with strabismus: esotropia and exotropia. American Optometric Association; 1997.

[4] 4. Zaidi SR, Sadiq MA, Khan AA, et al.: Association Between Refractive Errors and Heterotropia: A Counter Check. Pak. J. Ophthalmol. 2018; 34(3): 107–113.

[5] 5. Von Elm E, Altman DG, Egger M, et al.: The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies. Lancet. 2007 Oct 20; 370(9596): 1453–1457. Publisher Full Text

[6] 6. Mohammed Dhaiban TS, Ummer FP, Khudadad H, et al.: Types and Presentation of Refractive Error among Individuals Aged 0-30 Years: Hospital-Based Cross-Sectional Study, Yemen. Adv. Med. 2021; 2021: 5557761.

[7] 7. Sawers N, Jewsbury H, Ali N: Diagnosis and management of childhood squints: investigation and examination with reference to red flags and referral letters. Br. J. Gen. Pract. 2017; 67(654): 42–43. PubMed Abstract | Publisher Full Text | Free Full Text

[8] 8. Németh J, Tapasztó B, Aclimandos WA, et al.: Update and guidance on management of myopia. European Society of Ophthalmology in cooperation with International Myopia Institute. Eur. J. Ophthalmol. 2021 May; 31(3): 853–883. PubMed Abstract | Publisher Full Text | Free Full Text

[9] 9. Kim M, Kim U, Cho MJ, et al.: Hyperopic refractive errors as a prognostic factor in intermittent exotropia surgery. Eye. 2015; 29: 1555–1560. PubMed Abstract | Publisher Full Text | Free Full Text

[10] 10. Robaei D, Kifley A, Mitchell P: Factors associated with a previous diagnosis of strabismus in a population-based sample of 12-year-old Australian children. Am. J. Ophthalmol. 2006; 142: 1085–1087.e1. PubMed Abstract | Publisher Full Text

[11] 11. Cotter SA, et al.: Risk factors associated with childhood strabismus: the multi-ethnic pediatric eye disease and Baltimore pediatric eye disease studies. Ophthalmology. 2011; 118: 2251–2261. PubMed Abstract | Publisher Full Text | Free Full Text

[12] 12. Von Noorden GK, Campos EC: Binocular Vision and Ocular Motility: Theory and Management of Strabismus. 6th ed.St. Louis: Mosby; 2002. Publisher Full Text

[13] 13. Xu J, Yu X, Huang Y, et al.: The psychosocial effects of strabismus before and after surgical correction in Chinese adolescents and adults. J. Pediatr. Ophthalmol. Strabismus. 2012; 49(3): 170–175. PubMed Abstract | Publisher Full Text

[14] 14. Colburn JD, Morrison DG, Estes RL, et al.: Longitudinal follow-up of hypermetropic children identified during preschool vision screening. J. AAPOS. 2010; 14(3): 211–215. PubMed Abstract | Publisher Full Text

[15] 15. Weakley DR: The association between nonstrabismic anisometropia, amblyopia, and subnormal binocularity. Ophthalmology. 2001; 108(1): 163–171. PubMed Abstract | Publisher Full Text

[16] 16. Huynh SC, Wang XY, Ip J, et al.: Prevalence and associations of anisometropia and aniso-astigmatism in a population based sample of 6 year old children. Br. J. Ophthalmol. 2006; 90(5): 597–601. PubMed Abstract | Publisher Full Text | Free Full Text

[17] 17. O’Connor AR, Stephenson TJ, Johnson A, et al.: Strabismus in children of birth weight less than 1701 g. Arch. Ophthalmol. 2002; 120(6): 767–773. PubMed Abstract | Publisher Full Text

[18] 18. Li T, Zuo X, Zhang T, et al.: Patients with Intermittent Exotropia and Exophoria Exhibit Non-aggravated Lens Decentration After Orthokeratology Application: The Nanjing Strabismus Cohort. Ophthalmol. Ther. 2023 Jun; 12(3): 1535–1545. PubMed Abstract | Publisher Full Text | Free Full Text

[19] 19. Mohney BG, Lilley CC: The relationship between refractive error and the onset of intermittent exotropia. Ophthalmology. 2017; 124(10): 1634–1640.

[20] 20. Cho YA, Kim JH: Analysis of refractive errors in children with intermittent exotropia. Korean J. Ophthalmol. 2018; 32(2): 75–81.

[21] 21. Tan H, Yow AP, Hwang SW: Refractive error changes in children with intermittent exotropia: A longitudinal study. Clin. Exp. Optom. 2019; 102(4): 334–340.

[22] 22. Chung SA, Mazow ML: Long-term visual outcomes in patients with intermittent exotropia: The impact of early intervention. J. AAPOS. 2016; 20(5): 389–393.

[23] 23. Lim SH, O’Hara MA: Efficacy of early corrective measures for intermittent exotropia in preventing refractive error progression. Ophthalmic Epidemiol. 2020; 27(2): 136–144.

[24] 24. Lee SY, Lee YJ: Longitudinal analysis of refractive changes in children with intermittent exotropia. Invest. Ophthalmol. Vis. Sci. 2017; 58(5): 2098–2104.

[25] 25. Patel DE, Davey CJ: Developing evidence-based guidelines for managing refractive errors in intermittent exotropia. Br. J. Ophthalmol. 2018; 102(3): 335–340.

[26] 26. Mohammad N: Types of refractive errors in a sample of Iraqi children with Intermittent exotropia. [Data set]. Zenodo. 2024. Publisher Full Text

Types of refractive errors in a sample of Iraqi children with Intermittent exotropia

Abstract

Background

Methods

Results

Conclusion

Keywords

Revised Amendments from Version 1

Introduction

Methods

Study design and setting

Participants

Sample size determination

Data collection

Statistical analysis

Results

Table 1. Demographics of study participants.

Prevalence of refractive errors

Figure 1. Heatmap of refractive errors between the two eyes.

Symmetry in refractive errors

Figure 2. Graphical design summarizing the study results.

Table 2. Cross-tabulation of refractive errors between the two eyes.

Detailed refractive error analysis

Discussion

Conclusions

Ethics and consent

Data availability statement

Underlying data

Extended data

References

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