Optimal Timing of Surgical Correction for Congenital Esotropia: A Retrospective Cohort Analysis of 86 Patients

Optimal Timing of Surgical Correction for Congenital Esotropia: A Retrospective Cohort Analysis of 86 Patients | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Optimal Timing of Surgical Correction for Congenital Esotropia: A Retrospective Cohort Analysis of 86 Patients Daniel Havalda¹, Klára Hodálová², Veronika Popova², Anton Gerinec² This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7851132/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version Abstract Background The timing of surgical intervention for congenital esotropia is crucial for the restoration of binocular vision. Published data provide diverse recommendations, most frequently indicating an optimal age for the first surgery before 24 months, with some authors advocating intervention before one year of age. The goal of early surgery is to maximize the potential for normal binocular development. However, very early operations (6–12 months) raise concerns about technical difficulty, anesthetic safety, and healthcare system constraints. This study aimed to determine whether surgery performed between 12 and 18 months yields better functional and anatomical outcomes compared with other age groups. Methods We conducted a retrospective cohort analysis of 86 patients with congenital esotropia operated between January 2010 and December 2021. Patients were categorized by age at first surgery into four groups: 24 months. The primary outcome was the degree of binocular function; the secondary outcome was residual horizontal deviation. Statistical analyses included Kruskal–Wallis, Mann–Whitney U tests with Bonferroni correction, Spearman correlation, and ordinal logistic regression. Results The group operated at 12–18 months achieved the highest mean level of binocular function and the highest proportion of patients with stereopsis (16.7%). Age at surgery and the number of procedures were significant predictors of outcome (p < 0.05). Poorer results in the < 12 months group may partly reflect a higher prevalence of the cross-fixation subtype. Conclusion Based on our findings, surgery for congenital esotropia performed between 12 and 18 months of age provides the optimal balance between functional and anatomical outcomes and practical feasibility within real-world clinical settings. congenital esotropia binocular vision stereopsis strabismus surgical treatment Figures Figure 1 Figure 2 Figure 3 1 Introduction Congenital esotropia is a form of convergent strabismus characterized by a large, constant ocular deviation that typically appears within the first six months of life. It is rarely present immediately after birth but develops over several weeks [ 1 ]. The reported incidence varies from 0.2% to 2% across populations [ 2 , 3 ]. The etiology of congenital esotropia is multifactorial. It is believed to result from cortical fusion dysfunction secondary to severe motor imbalance. Asymmetry in the myelination process of the oculomotor nerves innervating the medial and lateral rectus muscles may play an important role [ 4 , 5 ]. Risk factors include a positive family history of strabismus, low birth weight, prematurity, and neurological comorbidities such as cerebral palsy or hydrocephalus [ 6 ]. Clinically, congenital esotropia presents with a large-angle convergent deviation (often > 30 prism diopters), usually equal at distance and near fixation, accompanied by hypermetropia up to + 3 diopters, which is physiologic in infancy [ 7 ]. Common findings include alternating fixation, cross-fixation, and latent nystagmus. Differential diagnosis encompasses sixth-nerve palsy, accommodative esotropia, Duane retraction syndrome, and congenital fibrosis of the extraocular muscles [ 8 , 9 ]. The treatment of congenital esotropia is primarily surgical. The objective is to achieve stable ocular alignment and create conditions for monofixation or at least partial binocular function [ 10 ]. The timing of surgery has a decisive impact on outcomes. Operations performed before two years of age increase the probability of restoring fusional mechanisms and, in exceptional cases, stereopsis [ 2 , 11 ]. Despite well-established surgical approaches, the optimal timing of intervention remains controversial. A recent Cochrane systematic review (2023) emphasized that current evidence is insufficient to define the ideal age for surgery and called for additional high-quality studies [ 10 ]. A comprehensive review by Bhate et al. (2022) confirmed that earlier operations (before 12 months) improve stereopsis development but also highlighted the practical limitations of such early interventions [ 12 ]. Similarly, the retrospective analysis by Castro et al. (2011) showed that most surgeries were performed before two years of age, with orthotropia achieved in more than 60% of cases [ 7 ]. The aim of the present study was to retrospectively analyze clinical outcomes in 86 patients with congenital esotropia and to verify the hypothesis that surgery performed between 12 and 18 months of age provides the optimal balance between functional and anatomical results, while remaining feasible in standard clinical practice. 2 Materials and Methods 2.1 Study Design and Patient Cohort This retrospective cohort study analyzed data from 86 patients with congenital esotropia who underwent surgical correction at the Department of Pediatric Ophthalmology, National Institute of Children’s Diseases, between January 1, 2010, and December 31, 2021. 2.2 Inclusion and Exclusion Criteria Patients were included if they met the following criteria: Complete medical documentation; Manifestation of strabismus before six months of age; Preoperative deviation ≥ 20 prism diopters; Absence of severe neurological disease (e.g., cerebral palsy, hydrocephalus); Participation in follow-up ophthalmologic examinations at least three years after the final operation, including assessment of binocular function. Each record was required to contain detailed anamnesis, data on the duration and onset of deviation, associated symptoms, ophthalmologic findings in both eyes (including uncorrected and best-corrected visual acuity, ocular motility, and angle of deviation), anterior segment examination, and complete surgical reports. The following parameters were analyzed before and after surgery: Age at first surgery, Magnitude of deviation (preoperatively, one year after the first surgery, and ≥ 3 years after the last surgery), Degree of binocular function after all surgeries, Number of operations per patient, Presence of associated conditions, Type of surgical procedure performed, Visual acuity, Degree of refractive error, and Severity of amblyopia. Patients with incomplete records or neurological comorbidities were excluded. During the study period, 108 patients underwent their first operation for congenital esotropia. Eleven lacked complete documentation, five did not attend postoperative follow-ups, and six were excluded due to severe neurological complications. Ultimately, 86 patients met all inclusion criteria and were analyzed ( see Flowchart 1 ). 2.3 Patient Stratification Patients were divided into four age groups according to age at first surgery (Table 1 : Basic characteristics of the cohort ): Table 1 Basic characteristics of the patient cohort Age group Number of patients (n) Sex ratio (M:F) Prematurity (%) Mean number of surgeries 24 months 19 10:9 15.8% 1.58 < 12 months (n = 9), 12–18 months (n = 30), 18–24 months (n = 28), 24 months (n = 19). 2.4 Examination Methods In addition to the retrospective review of medical records, all patients underwent standardized ophthalmologic evaluation focused on binocular function at least three years after the first surgery. The examination included: Assessment of simultaneous macular perception, fusion, and stereopsis using a synoptophore, Evaluation of stereopsis with the Titmus and Lang tests, and Measurement of residual horizontal deviation (in degrees) using a synoptophore. 2.5 Outcome Measures The primary outcome was the degree of binocular function, rated on a six-point scale: 0 = no binocular function 1 = simultaneous macular perception 2 = first-degree fusion 3 = second-degree fusion 4 = third-degree fusion 5 = stereopsis The secondary outcome was residual horizontal deviation following surgery. Additional variables analyzed included age at surgery, sex, prematurity, and number of surgical procedures. 2.6 Statistical Analysis Statistical analyses were performed using the following methods: Kruskal–Wallis test to compare differences among groups, Mann–Whitney U test with Bonferroni correction for pairwise comparisons, Spearman correlation to evaluate relationships between the number of operations and binocular function, and Ordinal logistic regression for multivariate analysis of predictors affecting outcomes. A p-value < 0.05 was considered statistically significant. 3 Results A total of 86 patients with congenital esotropia who underwent surgical treatment between January 1, 2010, and December 31, 2021, were included in the retrospective analysis. Patients were divided into four age groups according to age at the first surgery: 24 months (n = 19). 3.1 Binocular Function The mean degree of binocular function was highest in the group operated between 12 and 18 months (mean = 3.07), corresponding to advanced binocular fusion or stereopsis. The lowest mean score was observed in the group operated after 24 months (mean = 1.67) (Table 2 : Results of binocular function ). Table 2 Results of binocular function Age group Mean binocular function score Kruskal-Wallis significance (p) Significant pairwise differences (Mann–Whitney U test) 24 months (p = 0.0017) 18–24 months 2.04 0.0042 Worse than 12–18 months > 24 months 1.67 0.0042 Worse than 12–18 months The Kruskal–Wallis test demonstrated a statistically significant difference between groups (H = 13.235, p = 0.0042). Pairwise comparisons using the Mann–Whitney U test with Bonferroni correction (Fig. 1 : Binocular function by age group ) revealed: Significantly better functional outcomes in the 12–18 month group compared with the 18–24 month group (p = 0.0019); Significantly better outcomes compared with the > 24 month group (p = 0.0017). Differences between the 0.05), likely due to the smaller sample size and a higher proportion of patients with the cross-fixation subtype (6 of 9 patients), in whom earlier intervention (around 6 months of age) is generally recommended [ 2 , 5 , 9 , 10 ]. Surgical age in this subgroup ranged from 7 to 13 months, which may explain the lower functional results compared with expectations. 3.2 Recovery of Stereopsis Stereopsis (score 5) was achieved in seven patients (8.1% of the total cohort). Of these, five (71.4%) belonged to the group operated between 12 and 18 months, representing 16.7% of all patients in that age category (Fig. 2 : Stereopsis distribution by age group ): < 12 months: 1 patient (11.1%), 12–18 months: 5 patients (16.7%), 18–24 months: 1 patient (3.6%), 24 months: 0 patients (0%). 3.3 Residual Horizontal Deviation The mean residual horizontal deviation was lowest in the 12–18 month group both one year after the first operation (mean = 5.38°, SD = 2.97°) and at the final follow-up (≥ 3 years after the last operation; mean = 3.89°, SD = 2.21°). Mean residual horizontal deviation one year after the first operation : < 12 months: 7.22° (SD = 3.41°) 12–18 months: 5.38° (SD = 2.97°) 18–24 months: 7.71° (SD = 3.86°) 24 months: 8.15° (SD = 4.09°) Mean residual horizontal deviation three or more years after the final operation (Fig. 3 : Residual horizontal deviation over time ): < 12 months: 5.56° (SD = 2.68°) 12–18 months: 3.89° (SD = 2.21°) 18–24 months: 6.14° (SD = 2.97°) 24 months: 7.12° (SD = 3.05°) The Kruskal–Wallis test (final evaluation) showed a statistically significant difference between groups (H = 11.04, p = 0.0115). Pairwise Mann–Whitney U tests with Bonferroni correction (Table 3: Residual horizontal deviation ≥ 3 years after last operation) confirmed: Table 3 Horizontal deviation results (≥ 3 years after last surgery) Age group Mean deviation (°) Kruskal–Wallis significance (p) Significant pairwise differences (Mann–Whitney U test) 24 months (p = 0.008) 18–24 months 6.14 0.0115 Worse than 12–18 months > 24 months 7.12 0.0115 Worse than 12–18 months Significantly lower residual deviation in the 12–18 month group vs. the 18–24 month group (p = 0.034); Significantly lower deviation vs. the > 24 month group (p = 0.008); A significant difference also compared with the < 12 month group (p = 0.048). Summary : The lowest mean deviation was achieved in patients operated between 12 and 18 months. These results suggest that surgery during this age window is associated with the highest likelihood of parallel ocular alignment and stable functional outcomes. 3.4 Influence of Additional Factors Sex: No statistically significant effect on binocular function (p = 0.96) or residual deviation (p = 0.89). Prematurity: No significant influence on binocular function (p = 0.14) or residual deviation (p = 0.21). Number of operations : Spearman correlation analysis revealed a weak but statistically significant negative correlation between the number of surgeries and final binocular function (ρ = − 0.237, p = 0.029) and a positive correlation with residual deviation (ρ = 0.264, p = 0.018). Multivariate analysis (Ordinal logistic regression) : Surgery at 18–24 months (β = − 1.34, p = 0.007) and > 24 months (β = − 1.36, p = 0.011) was significantly associated with poorer functional outcomes compared with the reference group (12–18 months). The number of operations was an independent negative predictor of functional outcome (β = − 0.65, p = 0.012). Sex and prematurity had no statistically significant impact (Table 4: Ordinal logistic regression results). Table 4 Results of ordinal logistic regression Factor Beta coefficient (β) Significance (p) Surgery at 18–24 months -1.34 0.007 Surgery after 24 months -1.36 0.011 Number of surgeries -0.65 0.012 Sex n.s. > 0.05 Prematurity n.s. > 0.05 4 Discussion The results of this retrospective cohort study confirm that surgical correction of congenital esotropia performed between 12 and 18 months of age leads to superior functional and anatomical outcomes. Patients operated within this age range achieved the highest mean degree of binocular function (3.07 out of 5) and the lowest residual horizontal deviation at long-term follow-up (mean 3.89° after ≥ 3 years). These differences were statistically significant compared with patients operated after 18 months (p < 0.05). Our findings support the existence of a “critical period” for surgical intervention in congenital esotropia, occurring approximately between 6 and 24 months of age [ 1 – 3 ]. During this period, the neuroplastic potential of the visual pathways is greatest, enabling the most effective development of binocular vision [ 4 , 5 ]. According to the most recent Cochrane systematic review (Mehner et al., 2023), current evidence remains insufficient to define the ideal age for surgical correction, and further high-quality studies are required [ 6 ]. The present work directly addresses this research gap by providing new clinical data supporting intervention between 12 and 18 months of age. Bhate et al. (2022) analyzed 28 studies and also recommended surgery within the 12–18-month window, emphasizing that interventions before 6 months are technically challenging and often impractical [ 7 ]. Our results corroborate this view: the 12–18-month group achieved the best functional and anatomical outcomes. Similarly, the retrospective analysis by Castro et al. (2011) demonstrated that most successful realignments occurred in children operated before two years of age [ 8 ]. Our findings are consistent with those of von Noorden and Campos, who described higher success rates in patients operated before 24 months [ 1 ]. Mohney’s population-based study also confirmed the positive influence of early alignment on binocular outcomes [ 2 ]. Moreover, the meta-analysis by Simonsz et al. showed that early surgery significantly improves the likelihood of achieving stereopsis [ 6 ]. The study further demonstrated a negative association between the number of operations and binocular outcomes. Spearman correlation analysis revealed that more surgical procedures were linked to poorer binocular function (ρ = − 0.237, p = 0.029) and greater residual deviation (ρ = 0.264, p = 0.018), consistent with previous research [ 9 , 10 ]. Sex and prematurity showed no significant influence, in agreement with other published studies [ 11 – 16 ]. From a clinical perspective, these results have important implications. When planning surgical treatment for congenital esotropia, priority should be given to performing the procedure between 12 and 18 months of age whenever feasible. Surgery within this window not only optimizes functional recovery but also reduces the likelihood of repeated interventions, which are associated with poorer prognosis [ 18 – 20 ]. The main limitation of this study lies in its retrospective, single-center design, which may limit generalizability. However, the uniform follow-up of patients by one specialized department and standardized surgical and assessment protocols strengthen the internal validity of the results. In summary, our findings align with current international recommendations and underline the importance of timely surgical intervention. Future research should focus on prospective, multicenter studies to confirm these observations and further refine the optimal age range for surgery [ 21 – 28 ]. 5 Conclusion Based on our retrospective cohort analysis, we conclude that performing the first surgical correction for congenital esotropia between 12 and 18 months of age represents the optimal timing in terms of functional outcome, including the potential restoration of stereopsis. This period offers the best balance between developmental benefit, surgical feasibility, and organizational practicality. From the standpoint of binocular vision development and ocular alignment, this interval constitutes a critical window that should be the target for clinical management. Our results emphasize the necessity of an efficient system for early diagnosis and coordinated surgical care. The presented data respond directly to the call of the latest Cochrane review (2023) for observational studies investigating optimal surgical timing in congenital esotropia. Declarations Author Contributions Daniel Havalda: Conceptualization; Methodology; Investigation; Data curation; Formal analysis; Writing – original draft; Visualization; Klára Hodálová: Methodology; Data validation; Writing – original draft; Writing – review & editing; Veronika Popova: Investigation; Resources; Data curation; Writing – review & editing; Anton Gerinec: Supervision; Conceptualization; Project administration; Writing – review & editing; Critical revision for intellectual content. Funding This study received no external funding. All analyses and data collection were performed within the institutional framework of the Department of Pediatric Ophthalmology, Faculty of Medicine, Comenius University and National Institute of Children’s Diseases, Bratislava. Data Availability All data supporting the findings of this study are available from the corresponding author upon reasonable request. Acknowledgments The authors sincerely thank the clinical and nursing staff of the Department of Pediatric Ophthalmology, National Institute of Children’s Diseases, Bratislava, for their valuable assistance in patient care and follow-up examinations. Special thanks go to Martin Mocko for providing statistical advice and methodological guidance during data analysis. We are grateful for his support and expertise. Use of Generative Artificial Intelligence Portions of this manuscript were refined using generative artificial intelligence tools for language editing, grammar correction, and improvement of scientific phrasing. The software was also used to assist in the design and formatting of tables and figures. The authors confirm that all intellectual content, analysis, interpretation of data, and final approval of the text are entirely their own, and that the AI tools were used solely to enhance clarity and presentation in accordance with ethical publication standards. Conflict of Interest The authors declare that they have no competing interests. Human Ethics and Consent to Participate declarations The study protocol was approved on January 17, 2023 by the Institutional Ethics Committee of the National Institute of Children’s Diseases, Bratislava (Ref. No. EK1/4/2023). Written informed consent was obtained from all participants’ legal guardians in accordance with the Declaration of Helsinki. Clinical Trial Registration Clinical trial number: not applicable. References von Noorden GK, Campos EC. Binocular Vision and Ocular Motility. 6th ed. Mosby; 2002. Ing MR. Outcome study of surgical alignment before and after 24 months of age in congenital esotropia. Ophthalmology. 1995;102(12):2044–2049. Mohney BG. Common forms of childhood strabismus in an incidence cohort. Am J Ophthalmol. 2007;144(3):465–467. Chew E, Remaley NA, Tamboli A, et al. Risk factors for esotropia and exotropia. Arch Ophthalmol. 1994;112(10):1349–1355. Birch EE. Amblyopia and binocular vision. Prog Retin Eye Res. 2013;33:67–84. Simonsz HJ, et al. Early surgery for congenital esotropia improves stereopsis outcomes: a meta-analysis. Strabismus. 2011;19(4):158–166. Castro PD, et al. Congenital esotropia: epidemiology and clinical features. MEDICC Rev. 2011;13(1):18–22. Choi MY, Kushner BJ. The surgical management of large-angle congenital esotropia. Am Orthopt J. 1999;49:67–72. Helveston EM. Surgical management of infantile esotropia. J Pediatr Ophthalmol Strabismus. 1993;30(4):215–232. Mehner L, Ng SM, Singh J. Interventions for infantile esotropia. Cochrane Database Syst Rev. 2023;(1):CD004917. Bhate M, et al. Surgical timing in essential infantile esotropia: a review. Indian J Ophthalmol. 2022;70(7):2563–2568. Kushner BJ. Does overcorrection of congenital esotropia improve sensory outcomes? Arch Ophthalmol. 2000;118(8):1034–1037. Greenberg AE, Mohney BG. Predictive factors for favorable sensory outcomes following early surgery for congenital esotropia. J AAPOS. 2006;10(1):20–23. Birch EE, Stager DR. Long-term stability of alignment and sensory outcomes after early surgery for infantile esotropia. J AAPOS. 2006;10(5):409–413. Simons K. Early Visual Development: Normal and Abnormal. Oxford University Press; 1993. Wright KW, Spiegel PH, Thompson LS. Handbook of Pediatric Strabismus and Amblyopia. Springer; 2006. Lambert SR, Plager DA, Lynn MJ. Long-term results of early surgery for congenital esotropia. Ophthalmology. 1999;106(11):2096–2101. Ing MR. Outcome study of very early surgery for congenital esotropia. J Pediatr Ophthalmol Strabismus. 1995;32(3):145–148. Kekunnaya R, Mendonca T, Sachdeva V. Timing of surgery in infantile esotropia: a meta-analysis of long-term motor and sensory outcomes. J AAPOS. 2015;19(2):123–127. Lee SY, Kim SH. Long-term outcomes of surgery for congenital esotropia. Korean J Ophthalmol. 2012;26(3):177–181. Thomas S, Guha S. Large-angle strabismus: can a single surgical procedure achieve a successful outcome? Strabismus. 2010;18(4):129–136. Fawcett SL, Birch EE. Motion VEPs, stereopsis, and bifoveal fusion in children with strabismus. Invest Ophthalmol Vis Sci. 2000;41(2):411–416. Zimmermann A, et al. Visual development in children aged 0 to 6 years. Arq Bras Oftalmol. 2019;82(3):173–175. von Noorden GK. A hypothesis on the development of infantile esotropia. Br J Ophthalmol. 1988;72(2):160–165. Repka MX. Surgery for congenital esotropia: a dilemma. J AAPOS. 2002;6(1):2–3. Adams WE, Leske DA, Hatt SR, Holmes JM. Defining real change in measures of stereoacuity. Ophthalmology. 2009;116(2):281–285. Hunter DG, Kelly JB. Neurosensory consequences of strabismus surgery. J AAPOS. 2010;14(4):326–331. Wright KW. Essential infantile esotropia: surgical strategies. Ophthalmol Clin North Am. 2001;14(3):389–395. Chart 1 Chart 1 is available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files Flowchart1.patientselectionandinclusioninthestudy..jpg Flowchart 1. Patient selection and inclusion in the study. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 20 Nov, 2025 Reviews received at journal 20 Nov, 2025 Reviewers agreed at journal 17 Nov, 2025 Reviewers invited by journal 21 Oct, 2025 Editor assigned by journal 15 Oct, 2025 Submission checks completed at journal 15 Oct, 2025 First submitted to journal 13 Oct, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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07:01:10","extension":"jpg","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":113472,"visible":true,"origin":"","legend":"","description":"","filename":"Figure3.Horizontaldeviationovertimebyagegroup..jpg","url":"https://assets-eu.researchsquare.com/files/rs-7851132/v1/10538e2c479ccf511e5d57ea.jpg"},{"id":94875199,"identity":"eaed0d49-ddde-43f9-9b22-9836d6bb1d69","added_by":"auto","created_at":"2025-10-31 15:35:37","extension":"jpg","order_by":12,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":157663,"visible":true,"origin":"","legend":"","description":"","filename":"Flowchart1.patientselectionandinclusioninthestudy..jpg","url":"https://assets-eu.researchsquare.com/files/rs-7851132/v1/27e3a03ae82ff516d688e54f.jpg"},{"id":94985738,"identity":"c3e5bff8-7fa5-4f4b-8a10-5882d0ed7072","added_by":"auto","created_at":"2025-11-03 06:58:49","extension":"png","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":19610,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFigure1.Meanbinocularfunctionscorebyagegroup..png","url":"https://assets-eu.researchsquare.com/files/rs-7851132/v1/9b57011c272edefb43c8378c.png"},{"id":94986652,"identity":"5d77ee99-10f2-4aed-b657-c5e730dc06d9","added_by":"auto","created_at":"2025-11-03 07:00:31","extension":"png","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":21040,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFigure2.Presenceofstereopsisinindividualagegroups..png","url":"https://assets-eu.researchsquare.com/files/rs-7851132/v1/e3ebd1660348b58fba53b65b.png"},{"id":94875207,"identity":"f951a518-1921-47f7-82bb-ed2bb3982d23","added_by":"auto","created_at":"2025-10-31 15:35:37","extension":"png","order_by":15,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":28116,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFigure3.Horizontaldeviationovertimebyagegroup..png","url":"https://assets-eu.researchsquare.com/files/rs-7851132/v1/c83f41c3516af4b460a5c27c.png"},{"id":94875209,"identity":"bba36f79-2035-4c94-8a27-4045db00dcaf","added_by":"auto","created_at":"2025-10-31 15:35:37","extension":"png","order_by":16,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":35683,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFlowchart1.patientselectionandinclusioninthestudy..png","url":"https://assets-eu.researchsquare.com/files/rs-7851132/v1/d479adea164a94fcc97c812c.png"},{"id":94986456,"identity":"43e576ce-107d-4c9d-a744-5c93d7d2cc68","added_by":"auto","created_at":"2025-11-03 07:00:19","extension":"xml","order_by":17,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":75061,"visible":true,"origin":"","legend":"","description":"","filename":"83666a41d9a14e89b5605bca350e5d941structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7851132/v1/a4dbf2fd1a028cfd9422d293.xml"},{"id":94875210,"identity":"d6eac3ce-7f02-4e44-a400-3530e317632e","added_by":"auto","created_at":"2025-10-31 15:35:37","extension":"html","order_by":18,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":87359,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7851132/v1/ff3664ecf54cbeaff1bac897.html"},{"id":94875188,"identity":"d170d11d-5ddf-429a-82d7-9c5bf4701b01","added_by":"auto","created_at":"2025-10-31 15:35:37","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":88953,"visible":true,"origin":"","legend":"\u003cp\u003eMean binocular function score by age group. The 12–18 month group achieved the highest mean binocular function (3.07).\u003c/p\u003e","description":"","filename":"Figure1.Meanbinocularfunctionscorebyagegroup..jpg","url":"https://assets-eu.researchsquare.com/files/rs-7851132/v1/30b0fa3029d00605ec085be6.jpg"},{"id":94875190,"identity":"7923e1f2-435c-4bec-a29e-a26e0904f96a","added_by":"auto","created_at":"2025-10-31 15:35:37","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":88779,"visible":true,"origin":"","legend":"\u003cp\u003eIncidence of stereopsis in individual age groups. The highest proportion of stereopsis (16.7%) was observed in the 12–18 month group.\u003c/p\u003e","description":"","filename":"Figure2.Presenceofstereopsisinindividualagegroups..jpg","url":"https://assets-eu.researchsquare.com/files/rs-7851132/v1/3a246ee53798ff3d08cf0a3e.jpg"},{"id":94986411,"identity":"b537b2b1-573d-46bc-a6b4-b82c5906c46c","added_by":"auto","created_at":"2025-11-03 07:00:17","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":113472,"visible":true,"origin":"","legend":"\u003cp\u003eMean residual horizontal deviation one year after the first surgery and three or more years after the last surgery, by age group. The smallest deviation was observed in the 12–18 month group.\u003c/p\u003e","description":"","filename":"Figure3.Horizontaldeviationovertimebyagegroup..jpg","url":"https://assets-eu.researchsquare.com/files/rs-7851132/v1/f8127cf8ed12d67b9f834c51.jpg"},{"id":94990525,"identity":"af2c23f6-b9c2-4deb-ab72-c45bd701aab5","added_by":"auto","created_at":"2025-11-03 07:17:41","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1365222,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7851132/v1/873891f4-046c-4399-8e18-56fa7a12c7af.pdf"},{"id":94875194,"identity":"70e0cb10-83f5-40fc-8d76-7ea360119949","added_by":"auto","created_at":"2025-10-31 15:35:37","extension":"jpg","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":157663,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFlowchart 1.\u003c/strong\u003e Patient selection and inclusion in the study.\u003c/p\u003e","description":"","filename":"Flowchart1.patientselectionandinclusioninthestudy..jpg","url":"https://assets-eu.researchsquare.com/files/rs-7851132/v1/22421a14fd32c0237bfa11cf.jpg"}],"financialInterests":"No competing interests reported.","formattedTitle":"Optimal Timing of Surgical Correction for Congenital Esotropia: A Retrospective Cohort Analysis of 86 Patients","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eCongenital esotropia is a form of convergent strabismus characterized by a large, constant ocular deviation that typically appears within the first six months of life. It is rarely present immediately after birth but develops over several weeks [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. The reported incidence varies from 0.2% to 2% across populations [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The etiology of congenital esotropia is multifactorial. It is believed to result from cortical fusion dysfunction secondary to severe motor imbalance. Asymmetry in the myelination process of the oculomotor nerves innervating the medial and lateral rectus muscles may play an important role [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Risk factors include a positive family history of strabismus, low birth weight, prematurity, and neurological comorbidities such as cerebral palsy or hydrocephalus [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Clinically, congenital esotropia presents with a large-angle convergent deviation (often\u0026thinsp;\u0026gt;\u0026thinsp;30 prism diopters), usually equal at distance and near fixation, accompanied by hypermetropia up to +\u0026thinsp;3 diopters, which is physiologic in infancy [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Common findings include alternating fixation, cross-fixation, and latent nystagmus. Differential diagnosis encompasses sixth-nerve palsy, accommodative esotropia, Duane retraction syndrome, and congenital fibrosis of the extraocular muscles [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. The treatment of congenital esotropia is primarily surgical. The objective is to achieve stable ocular alignment and create conditions for monofixation or at least partial binocular function [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The timing of surgery has a decisive impact on outcomes. Operations performed before two years of age increase the probability of restoring fusional mechanisms and, in exceptional cases, stereopsis [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Despite well-established surgical approaches, the optimal timing of intervention remains controversial. A recent Cochrane systematic review (2023) emphasized that current evidence is insufficient to define the ideal age for surgery and called for additional high-quality studies [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. A comprehensive review by Bhate et al. (2022) confirmed that earlier operations (before 12 months) improve stereopsis development but also highlighted the practical limitations of such early interventions [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Similarly, the retrospective analysis by Castro et al. (2011) showed that most surgeries were performed before two years of age, with orthotropia achieved in more than 60% of cases [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. The aim of the present study was to retrospectively analyze clinical outcomes in 86 patients with congenital esotropia and to verify the hypothesis that surgery performed between 12 and 18 months of age provides the optimal balance between functional and anatomical results, while remaining feasible in standard clinical practice.\u003c/p\u003e"},{"header":"2 Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1 Study Design and Patient Cohort\u003c/h2\u003e\u003cp\u003eThis retrospective cohort study analyzed data from 86 patients with congenital esotropia who underwent surgical correction at the Department of Pediatric Ophthalmology, National Institute of Children\u0026rsquo;s Diseases, between January 1, 2010, and December 31, 2021.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2 Inclusion and Exclusion Criteria\u003c/h2\u003e\u003cp\u003ePatients were included if they met the following criteria:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eComplete medical documentation;\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eManifestation of strabismus before six months of age;\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003ePreoperative deviation\u0026thinsp;\u0026ge;\u0026thinsp;20 prism diopters;\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eAbsence of severe neurological disease (e.g., cerebral palsy, hydrocephalus);\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eParticipation in follow-up ophthalmologic examinations at least three years after the final operation, including assessment of binocular function.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003eEach record was required to contain detailed anamnesis, data on the duration and onset of deviation, associated symptoms, ophthalmologic findings in both eyes (including uncorrected and best-corrected visual acuity, ocular motility, and angle of deviation), anterior segment examination, and complete surgical reports.\u003c/p\u003e\u003cp\u003eThe following parameters were analyzed before and after surgery:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eAge at first surgery,\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eMagnitude of deviation (preoperatively, one year after the first surgery, and \u0026ge;\u0026thinsp;3 years after the last surgery),\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eDegree of binocular function after all surgeries,\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eNumber of operations per patient,\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003ePresence of associated conditions,\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eType of surgical procedure performed,\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eVisual acuity,\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eDegree of refractive error, and\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eSeverity of amblyopia.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003ePatients with incomplete records or neurological comorbidities were excluded.\u003c/p\u003e\u003cp\u003eDuring the study period, 108 patients underwent their first operation for congenital esotropia. Eleven lacked complete documentation, five did not attend postoperative follow-ups, and six were excluded due to severe neurological complications. Ultimately, 86 patients met all inclusion criteria and were analyzed (\u003cspan type=\"ItalicUnderline\" class=\"ItalicUnderline\" name=\"Emphasis\"\u003esee Flowchart 1\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.3 Patient Stratification\u003c/h2\u003e\u003cp\u003ePatients were divided into four age groups according to age at first surgery (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e: \u003cspan type=\"ItalicUnderline\" class=\"ItalicUnderline\" name=\"Emphasis\"\u003eBasic characteristics of the cohort\u003c/span\u003e):\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eBasic characteristics of the patient cohort\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge group\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNumber of patients (n)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSex ratio (M:F)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePrematurity (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eMean number of surgeries\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;12 months\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5:4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e22.2%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1.33\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e12\u0026ndash;18 months\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e16:14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e20.0%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1.23\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e18\u0026ndash;24 months\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e15:13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e17.9%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1.46\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;24 months\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10:9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e15.8%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1.58\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e\u0026lt;\u0026thinsp;12 months (n\u0026thinsp;=\u0026thinsp;9),\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e12\u0026ndash;18 months (n\u0026thinsp;=\u0026thinsp;30),\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e18\u0026ndash;24 months (n\u0026thinsp;=\u0026thinsp;28),\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e24 months (n\u0026thinsp;=\u0026thinsp;19).\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003e2.4 Examination Methods\u003c/h2\u003e\u003cp\u003eIn addition to the retrospective review of medical records, all patients underwent standardized ophthalmologic evaluation focused on binocular function at least three years after the first surgery.\u003c/p\u003e\u003cp\u003eThe examination included:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eAssessment of simultaneous macular perception, fusion, and stereopsis using a synoptophore,\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eEvaluation of stereopsis with the Titmus and Lang tests, and\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eMeasurement of residual horizontal deviation (in degrees) using a synoptophore.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003e2.5 Outcome Measures\u003c/h2\u003e\u003cp\u003eThe \u003cb\u003eprimary outcome\u003c/b\u003e was the degree of binocular function, rated on a six-point scale:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e0\u0026thinsp;=\u0026thinsp;no binocular function\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e1\u0026thinsp;=\u0026thinsp;simultaneous macular perception\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e2\u0026thinsp;=\u0026thinsp;first-degree fusion\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e3\u0026thinsp;=\u0026thinsp;second-degree fusion\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e4\u0026thinsp;=\u0026thinsp;third-degree fusion\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e5\u0026thinsp;=\u0026thinsp;stereopsis\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003eThe \u003cb\u003esecondary outcome\u003c/b\u003e was residual horizontal deviation following surgery.\u003c/p\u003e\u003cp\u003eAdditional variables analyzed included age at surgery, sex, prematurity, and number of surgical procedures.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003e2.6 Statistical Analysis\u003c/h2\u003e\u003cp\u003eStatistical analyses were performed using the following methods:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eKruskal\u0026ndash;Wallis test\u003c/b\u003e to compare differences among groups,\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eMann\u0026ndash;Whitney U test\u003c/b\u003e with Bonferroni correction for pairwise comparisons,\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eSpearman correlation\u003c/b\u003e to evaluate relationships between the number of operations and binocular function, and\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e\u003cb\u003eOrdinal logistic regression\u003c/b\u003e for multivariate analysis of predictors affecting outcomes.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003eA p-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e\u003c/div\u003e"},{"header":"3 Results","content":"\u003cp\u003eA total of 86 patients with congenital esotropia who underwent surgical treatment between January 1, 2010, and December 31, 2021, were included in the retrospective analysis. Patients were divided into four age groups according to age at the first surgery:\u003c/p\u003e\u003cp\u003e\u0026lt;\u0026thinsp;12 months (n\u0026thinsp;=\u0026thinsp;9), 12\u0026ndash;18 months (n\u0026thinsp;=\u0026thinsp;30), 18\u0026ndash;24 months (n\u0026thinsp;=\u0026thinsp;28), and \u0026gt;\u0026thinsp;24 months (n\u0026thinsp;=\u0026thinsp;19).\u003c/p\u003e\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003e3.1 Binocular Function\u003c/h2\u003e\u003cp\u003eThe mean degree of binocular function was highest in the group operated between 12 and 18 months (mean\u0026thinsp;=\u0026thinsp;3.07), corresponding to advanced binocular fusion or stereopsis. The lowest mean score was observed in the group operated after 24 months (mean\u0026thinsp;=\u0026thinsp;1.67) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e: \u003cspan type=\"ItalicUnderline\" class=\"ItalicUnderline\" name=\"Emphasis\"\u003eResults of binocular function\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eResults of binocular function\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge group\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eMean binocular function score\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eKruskal-Wallis significance (p)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eSignificant pairwise differences (Mann\u0026ndash;Whitney U test)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;12 months\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e2.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.0042\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNo significant differences\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e12\u0026ndash;18 months\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e3.07\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.0042\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eBetter than 18\u0026ndash;24 months (p\u0026thinsp;=\u0026thinsp;0.0019),\u003c/p\u003e\u003cp\u003e\u0026gt;\u0026thinsp;24 months (p\u0026thinsp;=\u0026thinsp;0.0017)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e18\u0026ndash;24 months\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e2.04\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.0042\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eWorse than 12\u0026ndash;18 months\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;24 months\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.0042\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eWorse than 12\u0026ndash;18 months\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe Kruskal\u0026ndash;Wallis test demonstrated a statistically significant difference between groups (H\u0026thinsp;=\u0026thinsp;13.235, p\u0026thinsp;=\u0026thinsp;0.0042). Pairwise comparisons using the Mann\u0026ndash;Whitney U test with Bonferroni correction (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e: \u003cspan type=\"ItalicUnderline\" class=\"ItalicUnderline\" name=\"Emphasis\"\u003eBinocular function by age group\u003c/span\u003e) revealed:\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eSignificantly better functional outcomes in the 12\u0026ndash;18 month group compared with the 18\u0026ndash;24 month group (p\u0026thinsp;=\u0026thinsp;0.0019);\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eSignificantly better outcomes compared with the \u0026gt;\u0026thinsp;24 month group (p\u0026thinsp;=\u0026thinsp;0.0017).\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003eDifferences between the \u0026lt;\u0026thinsp;12 month group and other age groups were not statistically significant (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05), likely due to the smaller sample size and a higher proportion of patients with the cross-fixation subtype (6 of 9 patients), in whom earlier intervention (around 6 months of age) is generally recommended [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Surgical age in this subgroup ranged from 7 to 13 months, which may explain the lower functional results compared with expectations.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003e3.2 Recovery of Stereopsis\u003c/h2\u003e\u003cp\u003eStereopsis (score 5) was achieved in seven patients (8.1% of the total cohort). Of these, five (71.4%) belonged to the group operated between 12 and 18 months, representing 16.7% of all patients in that age category (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e: \u003cspan type=\"ItalicUnderline\" class=\"ItalicUnderline\" name=\"Emphasis\"\u003eStereopsis distribution by age group\u003c/span\u003e):\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e\u0026lt;\u0026thinsp;12 months: 1 patient (11.1%),\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e12\u0026ndash;18 months: 5 patients (16.7%),\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e18\u0026ndash;24 months: 1 patient (3.6%),\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e24 months: 0 patients (0%).\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003e3.3 Residual Horizontal Deviation\u003c/h2\u003e\u003cp\u003eThe mean residual horizontal deviation was lowest in the 12\u0026ndash;18 month group both one year after the first operation (mean\u0026thinsp;=\u0026thinsp;5.38\u0026deg;, SD\u0026thinsp;=\u0026thinsp;2.97\u0026deg;) and at the final follow-up (\u0026ge;\u0026thinsp;3 years after the last operation; mean\u0026thinsp;=\u0026thinsp;3.89\u0026deg;, SD\u0026thinsp;=\u0026thinsp;2.21\u0026deg;).\u003c/p\u003e\u003cp\u003e\u003cb\u003eMean residual horizontal deviation one year after the first operation\u003c/b\u003e:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e\u0026lt;\u0026thinsp;12 months: 7.22\u0026deg; (SD\u0026thinsp;=\u0026thinsp;3.41\u0026deg;)\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e12\u0026ndash;18 months: 5.38\u0026deg; (SD\u0026thinsp;=\u0026thinsp;2.97\u0026deg;)\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e18\u0026ndash;24 months: 7.71\u0026deg; (SD\u0026thinsp;=\u0026thinsp;3.86\u0026deg;)\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e24 months: 8.15\u0026deg; (SD\u0026thinsp;=\u0026thinsp;4.09\u0026deg;)\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eMean residual horizontal deviation three or more years after the final operation\u003c/b\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e: \u003cspan type=\"ItalicUnderline\" class=\"ItalicUnderline\" name=\"Emphasis\"\u003eResidual horizontal deviation over time\u003c/span\u003e):\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003e\u0026lt;\u0026thinsp;12 months: 5.56\u0026deg; (SD\u0026thinsp;=\u0026thinsp;2.68\u0026deg;)\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e12\u0026ndash;18 months: 3.89\u0026deg; (SD\u0026thinsp;=\u0026thinsp;2.21\u0026deg;)\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e18\u0026ndash;24 months: 6.14\u0026deg; (SD\u0026thinsp;=\u0026thinsp;2.97\u0026deg;)\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003e24 months: 7.12\u0026deg; (SD\u0026thinsp;=\u0026thinsp;3.05\u0026deg;)\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003eThe Kruskal–Wallis test (final evaluation) showed a statistically significant difference between groups (H = 11.04, p = 0.0115). Pairwise Mann–Whitney U tests with Bonferroni correction (Table\u0026nbsp;3: Residual horizontal deviation ≥ 3 years after last operation) confirmed:\u003c/p\u003e\n\u003cdiv\u003e\n \u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 3\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eHorizontal deviation results (≥ 3 years after last surgery)\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eAge group\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMean deviation (°)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cdiv\u003e\n \u003cp\u003eKruskal–Wallis significance (p)\u003c/p\u003e\n \u003ctable id=\"Taba\" border=\"1\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSignificant pairwise differences (Mann–Whitney U test)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026lt; 12 months\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.0115\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv\u003e\n \u003cp\u003eWorse than 12–18 months (p = 0.048)\u003c/p\u003e\n \u003ctable id=\"Tabb\" border=\"1\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12–18 months\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.0115\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBetter than 18–24 months (p = 0.034); \u0026gt;24 months (p = 0.008)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e18–24 months\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.0115\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWorse than 12–18 months\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026gt; 24 months\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.0115\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWorse than 12–18 months\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cul\u003e\n \u003cli\u003e\n \u003cp\u003eSignificantly lower residual deviation in the 12–18 month group vs. the 18–24 month group (p = 0.034);\u003c/p\u003e\n \u003c/li\u003e\n \u003cli\u003e\n \u003cp\u003eSignificantly lower deviation vs. the \u0026gt; 24 month group (p = 0.008);\u003c/p\u003e\n \u003c/li\u003e\n \u003cli\u003e\n \u003cp\u003eA significant difference also compared with the \u0026lt; 12 month group (p = 0.048).\u003c/p\u003e\n \u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003eSummary\u003c/strong\u003e:\u003c/p\u003e\n\u003cp\u003eThe lowest mean deviation was achieved in patients operated between 12 and 18 months. These results suggest that surgery during this age window is associated with the highest likelihood of parallel ocular alignment and stable functional outcomes.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.4 Influence of Additional Factors\u003c/strong\u003e\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003e\n \u003cp\u003eSex: No statistically significant effect on binocular function (p = 0.96) or residual deviation (p = 0.89).\u003c/p\u003e\n \u003c/li\u003e\n \u003cli\u003e\n \u003cp\u003ePrematurity: No significant influence on binocular function (p = 0.14) or residual deviation (p = 0.21).\u003c/p\u003e\n \u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003eNumber of operations\u003c/strong\u003e:\u003c/p\u003e\n\u003cp\u003eSpearman correlation analysis revealed a weak but statistically significant negative correlation between the number of surgeries and final binocular function (ρ = − 0.237, p = 0.029) and a positive correlation with residual deviation (ρ = 0.264, p = 0.018).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMultivariate analysis (Ordinal logistic regression)\u003c/strong\u003e:\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003e\n \u003cp\u003eSurgery at 18–24 months (β = − 1.34, p = 0.007) and \u0026gt; 24 months (β = − 1.36, p = 0.011) was significantly associated with poorer functional outcomes compared with the reference group (12–18 months).\u003c/p\u003e\n \u003c/li\u003e\n \u003cli\u003e\n \u003cp\u003eThe number of operations was an independent negative predictor of functional outcome (β = − 0.65, p = 0.012).\u003c/p\u003e\n \u003c/li\u003e\n \u003cli\u003e\n \u003cp\u003eSex and prematurity had no statistically significant impact (Table\u0026nbsp;4: Ordinal logistic regression results).\u003c/p\u003e\n \u003c/li\u003e\n\u003c/ul\u003e\n\u003cdiv\u003e\n \u003ctable id=\"Tab4\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 4\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eResults of ordinal logistic regression\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFactor\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eBeta coefficient (β)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSignificance (p)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSurgery at 18–24 months\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-1.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.007\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSurgery after 24 months\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-1.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.011\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNumber of surgeries\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-0.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.012\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSex\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003en.s.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u0026gt; 0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePrematurity\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003en.s.\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u0026gt; 0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e"},{"header":"4 Discussion","content":"\u003cp\u003eThe results of this retrospective cohort study confirm that surgical correction of congenital esotropia performed between 12 and 18 months of age leads to superior functional and anatomical outcomes. Patients operated within this age range achieved the highest mean degree of binocular function (3.07 out of 5) and the lowest residual horizontal deviation at long-term follow-up (mean 3.89\u0026deg; after \u0026ge;\u0026thinsp;3 years). These differences were statistically significant compared with patients operated after 18 months (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Our findings support the existence of a \u0026ldquo;critical period\u0026rdquo; for surgical intervention in congenital esotropia, occurring approximately between 6 and 24 months of age [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. During this period, the neuroplastic potential of the visual pathways is greatest, enabling the most effective development of binocular vision [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. According to the most recent Cochrane systematic review (Mehner et al., 2023), current evidence remains insufficient to define the ideal age for surgical correction, and further high-quality studies are required [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The present work directly addresses this research gap by providing new clinical data supporting intervention between 12 and 18 months of age. Bhate et al. (2022) analyzed 28 studies and also recommended surgery within the 12\u0026ndash;18-month window, emphasizing that interventions before 6 months are technically challenging and often impractical [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Our results corroborate this view: the 12\u0026ndash;18-month group achieved the best functional and anatomical outcomes. Similarly, the retrospective analysis by Castro et al. (2011) demonstrated that most successful realignments occurred in children operated before two years of age [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Our findings are consistent with those of von Noorden and Campos, who described higher success rates in patients operated before 24 months [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Mohney\u0026rsquo;s population-based study also confirmed the positive influence of early alignment on binocular outcomes [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Moreover, the meta-analysis by Simonsz et al. showed that early surgery significantly improves the likelihood of achieving stereopsis [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The study further demonstrated a negative association between the number of operations and binocular outcomes. Spearman correlation analysis revealed that more surgical procedures were linked to poorer binocular function (ρ = \u0026minus;\u0026thinsp;0.237, p\u0026thinsp;=\u0026thinsp;0.029) and greater residual deviation (ρ\u0026thinsp;=\u0026thinsp;0.264, p\u0026thinsp;=\u0026thinsp;0.018), consistent with previous research [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Sex and prematurity showed no significant influence, in agreement with other published studies [\u003cspan additionalcitationids=\"CR12 CR13 CR14 CR15\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. From a clinical perspective, these results have important implications. When planning surgical treatment for congenital esotropia, priority should be given to performing the procedure between 12 and 18 months of age whenever feasible. Surgery within this window not only optimizes functional recovery but also reduces the likelihood of repeated interventions, which are associated with poorer prognosis [\u003cspan additionalcitationids=\"CR19\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. The main limitation of this study lies in its retrospective, single-center design, which may limit generalizability. However, the uniform follow-up of patients by one specialized department and standardized surgical and assessment protocols strengthen the internal validity of the results. In summary, our findings align with current international recommendations and underline the importance of timely surgical intervention. Future research should focus on prospective, multicenter studies to confirm these observations and further refine the optimal age range for surgery [\u003cspan additionalcitationids=\"CR22 CR23 CR24 CR25 CR26 CR27\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e"},{"header":"5 Conclusion","content":"\u003cp\u003eBased on our retrospective cohort analysis, we conclude that \u003cb\u003eperforming the first surgical correction for congenital esotropia between 12 and 18 months of age represents the optimal timing in terms of functional outcome, including the potential restoration of stereopsis.\u003c/b\u003e This period offers the best balance between developmental benefit, surgical feasibility, and organizational practicality. From the standpoint of binocular vision development and ocular alignment, this interval constitutes a critical window that should be the target for clinical management. Our results emphasize the necessity of an efficient system for early diagnosis and coordinated surgical care. The presented data respond directly to the call of the latest Cochrane review (2023) for observational studies investigating optimal surgical timing in congenital esotropia.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDaniel Havalda: Conceptualization; Methodology; Investigation; Data curation; Formal analysis; Writing \u0026ndash; original draft; Visualization;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eKl\u0026aacute;ra Hod\u0026aacute;lov\u0026aacute;: Methodology; Data validation; Writing \u0026ndash; original draft; Writing \u0026ndash; review \u0026amp; editing;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eVeronika Popova: Investigation; Resources; Data curation; Writing \u0026ndash; review \u0026amp; editing;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAnton Gerinec: Supervision; Conceptualization; Project administration; Writing \u0026ndash; review \u0026amp; editing; Critical revision for intellectual content.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study received no external funding. All analyses and data collection were performed within the institutional framework of the Department of Pediatric Ophthalmology, Faculty of Medicine, Comenius University and National Institute of Children\u0026rsquo;s Diseases, Bratislava.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eAvailability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data supporting the findings of this study are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors sincerely thank the clinical and nursing staff of the Department of Pediatric Ophthalmology, National Institute of Children\u0026rsquo;s Diseases, Bratislava, for their valuable assistance in patient care and follow-up examinations.\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;Special thanks go to Martin Mocko for providing statistical advice and methodological guidance during data analysis. We are grateful for his support and expertise.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eUse of Generative Artificial Intelligence\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePortions of this manuscript were refined using generative artificial intelligence tools for language editing, grammar correction, and improvement of scientific phrasing. The software was also used to assist in the design and formatting of tables and figures. The authors confirm that all intellectual content, analysis, interpretation of data, and final approval of the text are entirely their own, and that the AI tools were used solely to enhance clarity and presentation in accordance with ethical publication standards.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of Interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eHuman Ethics and Consent to Participate declarations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study protocol was approved on January 17, 2023 by the Institutional Ethics Committee of the National Institute of Children\u0026rsquo;s Diseases, Bratislava (Ref. No. EK1/4/2023). Written informed consent was obtained from all participants\u0026rsquo; legal guardians in accordance with the Declaration of Helsinki.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical Trial Registration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eClinical trial number: not applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003evon Noorden GK, Campos EC. \u003cem\u003eBinocular Vision and Ocular Motility.\u003c/em\u003e 6th ed. Mosby; 2002.\u003c/li\u003e\n\u003cli\u003eIng MR. Outcome study of surgical alignment before and after 24 months of age in congenital esotropia. \u003cem\u003eOphthalmology.\u003c/em\u003e 1995;102(12):2044\u0026ndash;2049.\u003c/li\u003e\n\u003cli\u003eMohney BG. Common forms of childhood strabismus in an incidence cohort. \u003cem\u003eAm J Ophthalmol.\u003c/em\u003e 2007;144(3):465\u0026ndash;467.\u003c/li\u003e\n\u003cli\u003eChew E, Remaley NA, Tamboli A, et al. Risk factors for esotropia and exotropia. \u003cem\u003eArch Ophthalmol.\u003c/em\u003e 1994;112(10):1349\u0026ndash;1355.\u003c/li\u003e\n\u003cli\u003eBirch EE. Amblyopia and binocular vision. \u003cem\u003eProg Retin Eye Res.\u003c/em\u003e 2013;33:67\u0026ndash;84.\u003c/li\u003e\n\u003cli\u003eSimonsz HJ, et al. Early surgery for congenital esotropia improves stereopsis outcomes: a meta-analysis. \u003cem\u003eStrabismus.\u003c/em\u003e 2011;19(4):158\u0026ndash;166.\u003c/li\u003e\n\u003cli\u003eCastro PD, et al. Congenital esotropia: epidemiology and clinical features. \u003cem\u003eMEDICC Rev.\u003c/em\u003e 2011;13(1):18\u0026ndash;22.\u003c/li\u003e\n\u003cli\u003eChoi MY, Kushner BJ. The surgical management of large-angle congenital esotropia. \u003cem\u003eAm Orthopt J.\u003c/em\u003e 1999;49:67\u0026ndash;72.\u003c/li\u003e\n\u003cli\u003eHelveston EM. Surgical management of infantile esotropia. \u003cem\u003eJ Pediatr Ophthalmol Strabismus.\u003c/em\u003e 1993;30(4):215\u0026ndash;232.\u003c/li\u003e\n\u003cli\u003eMehner L, Ng SM, Singh J. Interventions for infantile esotropia. \u003cem\u003eCochrane Database Syst Rev.\u003c/em\u003e 2023;(1):CD004917.\u003c/li\u003e\n\u003cli\u003eBhate M, et al. Surgical timing in essential infantile esotropia: a review. \u003cem\u003eIndian J Ophthalmol.\u003c/em\u003e 2022;70(7):2563\u0026ndash;2568.\u003c/li\u003e\n\u003cli\u003eKushner BJ. Does overcorrection of congenital esotropia improve sensory outcomes? \u003cem\u003eArch Ophthalmol.\u003c/em\u003e 2000;118(8):1034\u0026ndash;1037.\u003c/li\u003e\n\u003cli\u003eGreenberg AE, Mohney BG. Predictive factors for favorable sensory outcomes following early surgery for congenital esotropia. \u003cem\u003eJ AAPOS.\u003c/em\u003e 2006;10(1):20\u0026ndash;23.\u003c/li\u003e\n\u003cli\u003eBirch EE, Stager DR. Long-term stability of alignment and sensory outcomes after early surgery for infantile esotropia. \u003cem\u003eJ AAPOS.\u003c/em\u003e 2006;10(5):409\u0026ndash;413.\u003c/li\u003e\n\u003cli\u003eSimons K. \u003cem\u003eEarly Visual Development: Normal and Abnormal.\u003c/em\u003e Oxford University Press; 1993.\u003c/li\u003e\n\u003cli\u003eWright KW, Spiegel PH, Thompson LS. \u003cem\u003eHandbook of Pediatric Strabismus and Amblyopia.\u003c/em\u003e Springer; 2006.\u003c/li\u003e\n\u003cli\u003eLambert SR, Plager DA, Lynn MJ. Long-term results of early surgery for congenital esotropia. \u003cem\u003eOphthalmology.\u003c/em\u003e 1999;106(11):2096\u0026ndash;2101.\u003c/li\u003e\n\u003cli\u003eIng MR. Outcome study of very early surgery for congenital esotropia. \u003cem\u003eJ Pediatr Ophthalmol Strabismus.\u003c/em\u003e 1995;32(3):145\u0026ndash;148.\u003c/li\u003e\n\u003cli\u003eKekunnaya R, Mendonca T, Sachdeva V. Timing of surgery in infantile esotropia: a meta-analysis of long-term motor and sensory outcomes. \u003cem\u003eJ AAPOS.\u003c/em\u003e 2015;19(2):123\u0026ndash;127.\u003c/li\u003e\n\u003cli\u003eLee SY, Kim SH. Long-term outcomes of surgery for congenital esotropia. \u003cem\u003eKorean J Ophthalmol.\u003c/em\u003e 2012;26(3):177\u0026ndash;181.\u003c/li\u003e\n\u003cli\u003eThomas S, Guha S. Large-angle strabismus: can a single surgical procedure achieve a successful outcome? \u003cem\u003eStrabismus.\u003c/em\u003e 2010;18(4):129\u0026ndash;136.\u003c/li\u003e\n\u003cli\u003eFawcett SL, Birch EE. Motion VEPs, stereopsis, and bifoveal fusion in children with strabismus. \u003cem\u003eInvest Ophthalmol Vis Sci.\u003c/em\u003e 2000;41(2):411\u0026ndash;416.\u003c/li\u003e\n\u003cli\u003eZimmermann A, et al. Visual development in children aged 0 to 6 years. \u003cem\u003eArq Bras Oftalmol.\u003c/em\u003e 2019;82(3):173\u0026ndash;175.\u003c/li\u003e\n\u003cli\u003evon Noorden GK. A hypothesis on the development of infantile esotropia. \u003cem\u003eBr J Ophthalmol.\u003c/em\u003e 1988;72(2):160\u0026ndash;165.\u003c/li\u003e\n\u003cli\u003eRepka MX. Surgery for congenital esotropia: a dilemma. \u003cem\u003eJ AAPOS.\u003c/em\u003e 2002;6(1):2\u0026ndash;3.\u003c/li\u003e\n\u003cli\u003eAdams WE, Leske DA, Hatt SR, Holmes JM. Defining real change in measures of stereoacuity. \u003cem\u003eOphthalmology.\u003c/em\u003e 2009;116(2):281\u0026ndash;285.\u003c/li\u003e\n\u003cli\u003eHunter DG, Kelly JB. Neurosensory consequences of strabismus surgery. \u003cem\u003eJ AAPOS.\u003c/em\u003e 2010;14(4):326\u0026ndash;331.\u003c/li\u003e\n\u003cli\u003eWright KW. Essential infantile esotropia: surgical strategies. \u003cem\u003eOphthalmol Clin North Am.\u003c/em\u003e 2001;14(3):389\u0026ndash;395.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Chart 1","content":"\u003cp\u003eChart 1 is available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bratislava-medical-journal","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Bratislava Medical Journal](https://link.springer.com/journal/44411)","snPcode":"44411","submissionUrl":"https://submission.springernature.com/new-submission/44411/3","title":"Bratislava Medical Journal","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"congenital esotropia, binocular vision, stereopsis, strabismus, surgical treatment","lastPublishedDoi":"10.21203/rs.3.rs-7851132/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7851132/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eThe timing of surgical intervention for congenital esotropia is crucial for the restoration of binocular vision. Published data provide diverse recommendations, most frequently indicating an optimal age for the first surgery before 24 months, with some authors advocating intervention before one year of age. The goal of early surgery is to maximize the potential for normal binocular development. However, very early operations (6\u0026ndash;12 months) raise concerns about technical difficulty, anesthetic safety, and healthcare system constraints. This study aimed to determine whether surgery performed between 12 and 18 months yields better functional and anatomical outcomes compared with other age groups.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eWe conducted a retrospective cohort analysis of 86 patients with congenital esotropia operated between January 2010 and December 2021. Patients were categorized by age at first surgery into four groups: \u0026lt; 12 months, 12\u0026ndash;18 months, 18\u0026ndash;24 months, and \u0026gt;\u0026thinsp;24 months. The primary outcome was the degree of binocular function; the secondary outcome was residual horizontal deviation. Statistical analyses included Kruskal\u0026ndash;Wallis, Mann\u0026ndash;Whitney U tests with Bonferroni correction, Spearman correlation, and ordinal logistic regression.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eThe group operated at 12\u0026ndash;18 months achieved the highest mean level of binocular function and the highest proportion of patients with stereopsis (16.7%). Age at surgery and the number of procedures were significant predictors of outcome (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Poorer results in the \u0026lt;\u0026thinsp;12 months group may partly reflect a higher prevalence of the cross-fixation subtype.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eBased on our findings, surgery for congenital esotropia performed between 12 and 18 months of age provides the optimal balance between functional and anatomical outcomes and practical feasibility within real-world clinical settings.\u003c/p\u003e","manuscriptTitle":"Optimal Timing of Surgical Correction for Congenital Esotropia: A Retrospective Cohort Analysis of 86 Patients","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-31 15:35:32","doi":"10.21203/rs.3.rs-7851132/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-11-20T09:34:37+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-20T08:34:48+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"1852978398590674685063842235846363744","date":"2025-11-17T05:57:12+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-10-21T18:08:15+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-10-15T05:07:53+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-10-15T05:07:44+00:00","index":"","fulltext":""},{"type":"submitted","content":"Bratislava Medical Journal","date":"2025-10-13T16:38:34+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bratislava-medical-journal","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Bratislava Medical Journal](https://link.springer.com/journal/44411)","snPcode":"44411","submissionUrl":"https://submission.springernature.com/new-submission/44411/3","title":"Bratislava Medical Journal","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"126a775a-551c-4a9b-ae40-77cddea4de75","owner":[],"postedDate":"October 31st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-11-27T20:53:07+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-31 15:35:32","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7851132","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7851132","identity":"rs-7851132","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}