Interventions for intermittent exotropia

Surgical outcomes and etiological considerations in intermittent exotropia: a systematic narrative review

Introduction: Is Intermittent Exotropia being conceived and treated as an ocular-mechanical problem? Is etiology taken into account when planning for intervention? Which success criteria are used? Are they based on alignment or do they also consider visual function? In order to answer these questions, a review of studies assessing the outcomes of strabismus surgery in Intermittent Exotropia has been conducted. Methods: published between January 2003 and December 2023 were included. The database searched was MEDLINE following a predefined protocol. In addition to electronic database searches, manual searches were carried out and experts contacted. A total of 102 studies comprising 12 974 participants were included in this review. Results: Possible strabismus etiology was not stated in 91.2% of the studies. The underlying causes of the deviation were not taken into account for treatment consideration in any of the studies. Criteria for surgical success was based solely on ocular alignment (82.4%) and only 10 studies (9.8%) defined successful surgery with both motor and sensory criteria. Thirty-four different definitions of successful ocular alignment were identified. Discussion: In conclusion, Intermittent exotropia etiology is omitted in studies assessing surgical outcomes. The possible causes of the deviation are not taken into account when deciding on the type of surgery and are rarely mentioned. In most studies, the criteria for surgical success is based solely on eye alignment, independently of visual function and control.

An artificial intelligence platform for the screening and managing of strabismus

OBJECTIVES

Considering the escalating incidence of strabismus and its consequential jeopardy to binocular vision, there is an imperative demand for expeditious and precise screening methods. This study was to develop an artificial intelligence (AI) platform in the form of an applet that facilitates the screening and management of strabismus on any mobile device.

METHODS

The Visual Transformer (VIT_16_224) was developed using primary gaze photos from two datasets covering different ages. The AI model was evaluated by 5-fold cross-validation set and tested on an independent test set. The diagnostic performance of the AI model was assessed by calculating the Accuracy, Precision, Specificity, Sensitivity, F1-Score and Area Under the Curve (AUC).

RESULTS

A total of 6194 photos with corneal light-reflection (with 2938 Exotropia, 1415 Esotropia, 739 Vertical Deviation and 1562 Orthotropy) were included. In the internal validation set, the AI model achieved an Accuracy of 0.980, Precision of 0.941, Specificity of 0.979, Sensitivity of 0.958, F1-Score of 0.951 and AUC of 0.994. In the independent test set, the AI model achieved an Accuracy of 0.967, Precision of 0.980, Specificity of 0.970, Sensitivity of 0.960, F1-Score of 0.975 and AUC of 0.993.

CONCLUSIONS

Our study presents an advanced AI model for strabismus screening which integrates electronic archives for comprehensive patient histories. Additionally, it includes a patient-physician interaction module for streamlined communication. This innovative platform offers a complete solution for strabismus care, from screening to long-term follow-up, advancing ophthalmology through AI technology for improved patient outcomes and eye care quality.

Relationships between fusional convergence, suppression depth, and exotropia control in intermittent exotropia

Purpose: To assess the correlation between the contribution rates of fusional convergence from the dominant and non-dominant eye and suppression depth and exotropia control. Study design: Cross-sectional prospective study. Methods: The fusional convergence of 25 participants with intermittent exotropia (mean age 10.8 ± 3.4; range 6-18 years) was measured with an eye-tracking system. The contribution rate was defined based on the amplitude of fusional convergence during refusion relative to the exo-deviation angle. The suppression depth was assessed, and exotropia control was evaluated using the intermittent exotropia Office Control Score. We analyzed the correlations between the contribution rate from the dominant and non-dominant eyes and the suppression depth or control score. Results: There was a negative correlation between the dominant eye's contribution rate and the suppression depth in both eyes (r =  -0.85, 95% confidence interval [CI]: -0.97 to - 0.20 in the fixated dominant eye and r =  -0.91, 95%CI: -0.95 to - 0.40 in the fixated non-dominant eye). There was a negative correlation between the dominant eye's contribution rate and the control score at a 4-meter distance (r =  -0.53, 95%CI: -0.76 to - 0.17). Conclusion: Suppression in intermittent exotropia patients could affect the fusional convergence in the dominant eye.

Impact of Online Video Game-Based Dichoptic Training on Binocular Vision Rehabilitation in Post-surgical Patients with Intermittent Exotropia

INTRODUCTION

Dichoptic training has emerged as a promising rehabilitation approach for improving binocular visual function in patients with strabismus. A prospective observational study design was employed to assess the effectiveness of online video game-based dichoptic training in rehabilitating binocular visual function in patients who had undergone an operation for intermittent exotropia.

METHODS

A total of 64 patients who had undergone an operation for intermittent exotropia were recruited and divided into the training group and the control group based on whether they would receive the dichoptic training. The dichoptic training was conducted for 3 months in the training group and the control group would not accept any form of orthoptic therapy. Assessments of binocular visual functions and deviation were conducted at baseline, 3-month and 6-month follow-up.

RESULTS

Twenty-nine participants in the training group (mean 9.69 ± 2.66 years old) and 26 participants in the control group (mean 8.41 ± 2.64 years old) completed follow-up. At both 3- and 6-month follow-ups, the training group showed superior distance stereopsis compared to the control group, with near stereopsis only showing significant difference at the 6-month follow-up. Additionally, the training group exhibited significantly less distance exo-deviation drift than the control group at these times, and no significant difference was observed in near exo-deviation drift between the groups. The control group had a significantly higher rate of suboptimal surgical outcomes at both the 3- and 6-month follow-up. However, no significant differences were observed in simultaneous perception and fusion functions between the two groups.

CONCLUSIONS

Online video game-based dichoptic training has the potential to become a novel postoperative rehabilitation strategy for patients with intermittent exotropia.

Outcomes for Intermittent Exotropia Using Three Common Surgical Approaches

PURPOSE

To compare a single surgeon's surgical outcomes for treating intermittent exotropia using bilateral lateral rectus recession (BLR), unilateral lateral rectus recession and medial rectus resection (RR), and unilateral lateral rectus recession and medial rectus plication (RP).

METHODS

A retrospective review of all surgeries for basic intermittent exotropia between 2015 and 2023 was performed. Only patients with initial correction using BLR, RR, or RP were included. Exclusion criteria included age older than 18 years, vertical deviation, any nonrefractive ocular diagnoses, prior ocular surgery, and inadequate follow-up.

RESULTS

There were 460 patients identified; 123 met inclusion criteria with 54 in the BLR group, 41 in the RR group, and 28 in the RP group. The average pre-operative distance alignment (and standard error) values for the BLR, RR, and RP groups were 25.07 (7.35), 22.44 (5.95), and 23.84 (6.42) prism diopters (PD), respectively. At 1 year, the postoperative distance alignment values for the BLR, RR, and RP groups were 8.72 (7.89), 7.46 (6.31), and 12.83 (6.82) PD, respectively (P = .03). A subanalysis found a significant difference between the BLR and RP (P = .02) and RR and RP (P = .02) groups. There was no difference between the BLR and RR groups (P = .57).

CONCLUSIONS

This study of three surgical approaches for intermittent exotropia found RP had a significantly larger angle of exodeviation compared to BLR and RR at 1 year of follow-up. Both BLR and RR were equally effective approaches for treating intermittent exotropia. [J Pediatr Ophthalmol Strabismus. 2024;61(4):287-290.].

Experience with Strabologic Surgery on Pediatric Patients with Divergence Excess Exotropia

AIM

This retrospective clinical study evaluates the results of surgical treatment of patients diagnosed with intermittent exotropia of the divergence excess type. The study compares the results of surgery delayed due to the Covid-19 pandemic (patients underwent the surgery after the age of eight), versus a group of younger children.

MATERIALS AND METHODS

The objective angle of deviation and quality of binocular functions were examined. The follow-up period was six months after surgery. The patients were divided into two groups according to age: 4-7 years and 8-13 years. Each group included 20 patients. The second group comprised patients whose surgery was postponed due to restrictions on elective surgery during the ongoing pandemic. The surgery took place at the University Hospital in Pilsen. Angle of deviation and binocular functions were examined before surgery, postoperatively, and three and six months after surgery. Data were collected retrospectively and statistically processed. The main values were plotted in charts.

RESULTS

Accordance between the angle of deviation before surgery in both groups was statistically demonstrated. During the six-month follow-up period, the median angle of deviation was statistically without proof of disparity between the groups. Six months after surgery, an objective angle of deviation within the limit ±5 degrees was achieved in 65% of patients from the first group and in 75% from the second group. Binocular vision before surgery was statistically without proof of difference between both groups. However the statistical processing demonstrated a difference between the two groups six months after the surgery. Better binocular functions were achieved by the younger children in the first group.

CONCLUSION

The objective deviation angle was comparable in both study groups prior to surgery as well as six months after the surgery. The first group of younger patients attained a higher quality of binocular functions within the six-month follow-up period compared to children operated on after the age of eight. This claim was statistically verified.

Surgical Approach and Reoperation Risk in Intermittent Exotropia in the IRIS Registry

Importance

There is no consensus on the optimal surgical treatment for children with intermittent exotropia (IXT).

Objective

To compare the 5-year reoperation rates for children with IXT treated with horizontal muscle strabismus surgery using bilateral lateral rectus recession (BLR) vs unilateral lateral rectus recession with medial rectus resection (RR).

Design, Setting, and Participants

This cohort study examined data obtained from the Intelligent Research in Sight (IRIS) Registry on 7482 children (age, <18 years) with IXT who underwent horizontal eye muscle strabismus surgery between January 1, 2013, and December 31, 2017. Children undergoing initial surgeries involving 3 or more horizontal muscles, vertical muscles, or reoperations were excluded.

Main Outcomes and Measures

The primary outcome was the adjusted cumulative incidence of repeat horizontal muscle surgery within 5 years after the initial surgery. Reoperation risk was analyzed using adjusted hazard ratios (AHRs) derived from multivariable Cox regression models, adjusting for individual demographic and surgical factors (age, sex, race and ethnicity, US Census region, and surgeon subspecialty). Data were analyzed between January 16 and September 20, 2023.

Results

The study included 7482 children (median [IQR] age at initial surgery, 6 [4-9] years; 3945 females [53%]) with IXT treated with horizontal muscle strabismus surgery. Bilateral lateral rectus recession was performed more frequently than RR (85.3% vs 14.7%, P < .001), especially in younger children (rates of BLR vs RR by age: age 0 to ≤4 years, 88.4% vs 11.6%; age 5 to ≤11 years, 84.7% vs 15.3%; age 12 to ≤17 years, 78.1% vs 21.9%; P < 0.001). After data adjustment, the 5-year cumulative incidence of reoperation was 21.3% (95% CI, 20.1%-22.5%). The adjusted 5-year cumulative incidence of reoperation was higher for BLR than for RR (22.2% vs 17.2%; difference, 4.9%; 95% CI, 1.9%-8.0%). Unilateral lateral rectus recession with medial rectus resection was associated with a lower 5-year reoperation risk compared with BLR (AHR, 0.77; 95% CI, 0.64-0.93). Younger age at time of initial surgery was associated with a higher reoperation risk (AHR per 1-year decrease, 1.09; 95% CI, 1.07-1.11) after adjusting for all other covariates.

Conclusions and Relevance

In this nationwide registry, approximately 1 in 5 children with IXT underwent reoperation within 5 years after the initial surgery. Children treated with RR were less likely to require a reoperation within 5 years compared with those treated with BLR. Further efforts to identify modifiable risk factors for reoperation are needed to reduce the surgical burden and improve outcomes for children with IXT.

Effect of visual perception training on binocular visual function reconstruction in patients after strabismus surgery

AIM

To explore the effect of visual perception learning software training (VPT) on binocular visual function reconstruction in children with intermittent exotropia after strabismus surgery.

METHODS

Ninety children with intermittent exotropia admitted to our hospital from June 2018 to December 2018 were included, and randomly divided into VPT and control groups. Children in the control group received basic binocular vision training, while those in the VPT group received VPT after strabismus surgery. Tertiary visual function, visual perception function, Newcastle Control Score (NCS), and ocular position retraction rate were compared at 3 and 12mo after the surgery.

RESULTS

At 3 and 12mo after the surgery, the proportion of simultaneous perception, binocular fusion version and binocular stereo vision in the VPT group was conspicuously higher than that in the control group (P<0.05). After the vision training, the binocular visual perception functions of children in both groups were significantly improved compared with that before training (P<0.05). Interestingly, the grating sharpness, texture perception and texture motion perception in the VPT group were dramatically better than control group (P<0.01). The NCS in the VPT group was significantly lower than that in the control group (P<0.05). The ocular position retraction rate in the VPT group was significantly lower than that in the control group at 12mo (8.89% vs 26.67%, P=0.03).

CONCLUSION

VPT effectively promotes binocular visual function reconstruction in intermittent exotropia children after strabismus surgery and reduces the strabismus severity and ocular position retraction rate.

A pilot randomized clinical trial comparing muscle transplant versus hang back recession in extra-large angle exotropia

PURPOSE

For extra-large angle exotropia (>60 prism diopters, PD), single-setting surgical alternatives are scarce; frequently, more than two muscle or two eye procedures are indicated. To evaluate the viability of single eye surgery, a current randomized comparative trial is undertaken.

METHODS

Twenty adult patients with extra-large angle exotropia underwent a thorough orthoptic evaluation before being divided into two groups at random. Ten patients in group 1 underwent medial rectus resection (5.5-7.5 mm), followed by transplant-aided lateral rectus recession (effective length: 4-5.5 mm) (9 mm). In group two, ten different patients underwent medial rectus resection (5.5-7 mm), but this time, the lateral rectus recession (9 mm) was aided with a hang-back suture (5-7 mm). The two procedures were compared at baseline and six months post-operatively.

RESULTS

There was no significant difference in the groups' median ages (P = .95). In groups one and two, the median corrections achieved were 81.00 (79.50-85.50) PD and 81.00 (79.75-86.50) PD, respectively. The differences in corrections were statistically insignificant (p = .99). In all patients, abduction limitation was frequently noted in the immediate post-operative period, which improved over time. In each group, there were two patients (>90 prisms) with residual deviation of at least 30 PD, for which the contralateral eyes were operated.

CONCLUSIONS

The hang-back recession was as successful as muscle transplant procedure in correcting 80-90 PD of exotropia with notable clinical benefits and ease.

Systemic evaluation of the risk of reoperations in pediatric populations with exotropia and esotropia: nested case-control study

The study aimed to assess the risk of reoperations for strabismus in the pediatric population and to identify high-risk groups. This was a nationwide population-based study that used data from the Korean National Health Claims Database from 2008 to 2020. Two major cohorts were established based on initial strabismus: age-, sex-, and recruitment year-matched controls were randomly selected. Patients aged ≤ 9 years who underwent initial strabismus surgery for exotropia and esotropia were included, resulting in a total of 24,816 patients included to this study. The cumulative incidence of reoperations was 843 per 10,000 persons for exotropia, 1559 per 10,000 persons for esotropia. To assess the significant exposure factors, conditional logistic regression was performed to obtain odds ratio (OR) in each cohort. In patients with exotropia, the OR of reoperations was 4.26 times higher when the initial surgery is performed at younger age (earlier than 3-year-old) and 6.49 times higher when only one eye underwent than two eye. Similarly, in patients with esotropia, younger age (6.57 times) and unilateral surgery (7.20 times) were identified as common factors that increase the risk of reoperations. Based on the findings, special attention is recommended for patients younger than 3 years, especially those performed unilateral surgery as initial intervention in practical settings.

The Influence of Part-Time Occlusion Therapy on Control of Intermittent Exotropia: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Intermittent exotropia is the most prevalent subtype of exotropia in children. Part-time occlusion (PTO) as an anti-suppression therapy was applied for nonsurgical management of intermittent exotropia.

OBJECTIVE

The aim of the study was to compare the effectiveness of PTO therapy and observation in the treatment of intermittent exotropia.

METHOD

An exhaustive search of the literature from PubMed, Embase, Web of Science, and Cochrane Library databases was carried out until July 2022. No language restrictions were applied. The literature was rigorously screened against eligibility criteria. Weighted mean differences and 95% confidence interval (CI) were calculated.

RESULTS

A total of 4 articles with 617 participants were included in this meta-analysis. Our pooled results showed that PTO exhibited superior effects compared to observation, with greater decrease in exotropia control at distance and near (MD = -0.38, 95% CI: -0.57 to -0.20, p < 0.001; MD = -0.36, 95% CI: -0.54 to -0.18, p < 0.001); patients subjected to PTO therapy had greater decrease in distance deviations (MD = -1.95, 95% CI: -3.13 to -0.76, p = 0.001), and there was greater improvement in near stereoacuity among the PTO group in comparison with the observation group (p < 0.001).

CONCLUSIONS

The present meta-analysis indicated that PTO therapy showed a better effect in improving control and near stereopsis and decreasing distance exodeviation angle of children with intermittent exotropia in comparison with observation.