Timely surgery in intermittent and constant exotropia for superior sensory outcome

Divergence excess and basic exotropia types of intermittent exotropia: a major review. Part 2: non-surgical and surgical treatment options

INTRODUCTION

Currently, there is no consensus regarding the management of intermittent exotropia (IXT), which includes both surgical and non-surgical treatment options. Nonsurgical management of IXT has been suggested and includes watchful observation, patching, overminus lenses, prism, and vision therapy/orthoptics. While a significant portion of IXT patients are treated by surgery, it is reported that there is a substantial tendency for reoperation or recurrence of IXT. This paper provides a comprehensive review of non-surgical and surgical treatment options for the IXT.

METHODS

Search strategies involving combination of keywords including intermittent exotropia, divergence excess, basic exotropia, refractive error, glasses, spectacles, natural history, untreated, observe, occlusion, patch, overminus, overcorrecting minus, prism, vision therapy, orthoptic, anti-suppression, fusion exercise, and surgery were used in Medline. All English articles from 01/01/1900 to 01/09/2020 were reviewed. The reference list of the identified articles was also checked for additional relevant articles. Studies focused on animal models or strabismus associated with neurologic disorders or injury were excluded. The following filters were used for surgical management due to the abundance of reports: full text, randomized controlled trial, review, in the last 5 years.

RESULTS

Appropriate optical correction of refractive error is generally the starting point for all management approaches, but there is a lack of randomized clinical trial data regarding this treatment modality. Randomized clinical trial data indicate that both observation and occlusion are reasonable management options for children 3-10 years old, and there were insufficient data to recommend occlusion for children 12-35 months old. While overminus lenses were found to improve the control of IXT when assessed wearing overminus spectacles, this improvement did not persist after the treatment ended. The result of the only randomized clinical trial on the effectiveness of base-in prism indicated that this treatment is no more effective than nonprism spectacles for improving control. A recent randomized clinical trial showed that vision therapy/orthoptics is effective in improving the control of IXT when compared to observation alone. Surgery was found to alter a number of clinical characteristics of IXT, including reducing the distance and near angle of deviation, reducing photophobia, improving health-related quality of life, stereopsis, and the Newcastle Control Score. However, there are no randomized clinical trial data comparing surgery with a control group such as placebo or a no treatment observation group.

DISCUSSION

Rigorously designed clinical trials to investigate the effectiveness of non-surgical and surgical treatments for intermittent exotropia are needed.

Prevalence of strabismus in premature infants in an age-related perspective

THE AIM

was to investigate the prevalence of strabismus in premature infants; to identify diagnostic indicators for predicting strabismus at the age of 3-8 years.

METHODS

The material was the data of 84 premature infants who underwent ophthalmological examination at the age of 6 months - 3 years and again - at 3-8 years. All children underwent ophthalmic examination for retinopathy of prematurity (ROP) in infancy.

RESULTS

An increase in the frequency of strabismus occurrence among preterm infants was observed in 3-8 years compared to the data from 6 months - 3 years - from 13.3% to 20.0% in children without ROP, from 5.9% to 23.5% in children with self-resolving ROP, from 22.7% to 45.5% in children with ROP after laser retinal photocoagulation. The presence of strabismus and structural changes of eye at ages 6 months - 3 years increase the risk of strabismus at ages 3-8 years, OR = 6.5 (95% CI 3.8-11.3), (p < 0.001); OR = 4.2 (95% CI 2.8-6.2), (p = 0.005). The increase in the risk of developing strabismus at ages 3-8 years is associated with the presence of anisometropia, (p = 0.047), amblyopia, (p < 0.05). Children with higher visual acuity at ages 3-8 years have a decreased risk of strabismus, (p < 0.05).

CONCLUSIONS

The frequency of strabismus occurrence among preterm infants has increased by ages 3-8 years. Strabismus, structural changes of eye at ages 6 months - 3 years increases the risk of strabismus at ages 3-8 years. Anisometropia and amblyopia increase in the risk of strabismus, higher visual acuity decreases risk of strabismus.

Demographic and clinical characteristics and risk factors of stereoacuity in convergence insufficiency-type intermittent exotropia

Purpose

To investigate characteristics and risk factors of poor stereoacuity of Convergence insufficiency-type Intermittent Exotropia (CI-type X(T)).

Design

Observational, cross-sectional study.

Methods

The medical records of 615 CI-type X(T) and 222 basic-type intermittent exotropia (X(T)) were enrolled from January 2018 to January 2022. The characteristics were compared between the two types, and the associations between clinical factors and poor stereoacuity were examined using logistic regression.

Results

Compared with basic-type X(T), earlier surgery age, shorter misalignment duration, and the smaller distance exodeviation were observed in CI-type X(T). The CI-type X(T) demonstrated better sensory status and lower incidence of ocular muscle dysfunction than did the basic-type X(T). The surgery age between 6 and 12 years (odds ratio [OR], 0.595; compared with ≤6 years) was inversely associated with poor near stereoacuity, whereas duration more than 4 years (OR, 2.474), amblyopia (OR, 4.057), large distance exodeviation (>60PD: OR, 2.462) and anisometropia (>2.00D: OR, 3.874) were positively associated with poor near stereoacuity. The onset age older than 6 years (6-9 years: OR, 0.397; >9 years: OR, 0.317) was associated with better distance stereoacuity, whereas large distance exodeviation (>60PD: OR, 23.513), and dominant eye best corrected visual acuity (BCVA) worsen than 0.20 (OR, 2.987) were positively associated with poor distance stereoacuity.

Conclusion

CI-type X(T) declined surgery early, with small distance exodeviation, better sensory status, and low incidence of ocular muscle dysfunction. A strong dose-dependent link between early onset age, long misalignment duration, worse dominant eye BCVA, distance exodeviation, amblyopia, anisometropia, and poor stereoacuity was confirmed.

The distribution characteristics of strabismus surgery types in a tertiary hospital in the Central Plains region during the COVID-19 epidemic

OBJECTIVE

This study aimed to analyze the distribution of different types of strabismus surgery in a tertiary hospital in Central China during the three-year period of the COVID-19 pandemic.

METHODS

A retrospective analysis was conducted on the clinical data of strabismus patients who underwent surgery and were admitted to the Department of Strabismus and Pediatric Ophthalmology at the First Affiliated Hospital of Zhengzhou University between January 2020 and December 2022.

RESULTS

A total of 3939 strabismus surgery patients were collected, including 1357 in 2020, 1451 in 2021, and 1131 in 2022. The number of surgeries decreased significantly in February 2020, August 2021, and November and December 2022. Patients aged 0-6 years accounted for 37% of the total number of strabismus surgery patientsr. The majority (60%) of all strabismus surgery patients were diagnosed with exotropia, with intermittent exotropia accounting for the highest proportion (53%). There was no statistically significant difference in the proportion of intermittent exotropia and constant exotropia during the three-year period (χ2 = 2.642, P = 0.267 and χ2 = 3.012, P = 0.221, respectively). Among patients with intermittent exotropia, insufficient convergence type was the most common form of strabismus (accounting for over 70%). Non-accommodative esotropia accounted for more than 50% of all internal strabismus cases.

CONCLUSION

During the period from 2020 to 2022, the total number of strabismus surgeries in our hospital did not show significant fluctuations, but there was a noticeable decrease in the number of surgeries during months affected by the pandemic. Exotropia accounted for the highest proportion among strabismus surgery patients. Intermittent exotropia was the most common type among patients undergoing surgery for exotropia, and the most prevalent subtype was the insufficient convergence type. The age distribution of patients varied in different months, with a concentration of surgeries for strabismus patients in the 7-12 years old age group during the months of July and August each year.

Incidence, Risk Factors and Management of Postoperative Complications in Horizontal Strabismus Surgery

OBJECTIVE

To report the incidence, risk factors and management of postoperative complications after horizontal strabismus surgery.

DESIGN

Retrospective Cohort study.

PARTICIPANTS

The study assessed 1,273 patients with 1,035 cases of exotropia and 238 cases of esotropia, with a minimum 18-month follow-up.

METHODS

Retrospective review of strabismus operation patients' medical records included baseline demographics, age at surgery, pre/postoperative visual acuity, and deviation. Complications were categorized as surgical site (infection, scarring, cyst, granuloma, ischemia) and strabismus-related (recurrence, diplopia), with analysis of incidence, risk factors, and management.

RESULTS

Among surgical site complications, the incidence of infection, pyogenic granuloma, and anterior segment ischemia were similar between the exotropia (0.3%, 0.3%, 0.2%) and esotropia (0.8%, 0%, 0.4%) groups (p = .221, 0.406, 0.515). In contrast, the esotropia group presented a higher risk of conjunctival inclusion cyst and conjunctival scar than the exotropia group, with incidences of 5.0% vs 2.2% and 6.3% vs 1.3%, respectively (p = .004, <0.001). Regarding strabismus complications, the incidence of early recurrence was not significant between the two groups, with 10.0% in the exotropia group and 10.5% in the esotropia group (p = .553). Older age and poor initial visual acuity were associated with early recurrence (p < .001). The esotropia group had a higher risk of persistent diplopia than the exotropia group, with incidences of 4.2% vs 2.0%, respectively (p = .003).

CONCLUSION

Esotropia carries a higher risk of conjunctival inclusion cysts, conjunctival scarring, and persistent diplopia compared to the exotropia group, while both groups exhibit similar rates of early recurrence and other surgical site complications.

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.

Divergence excess and basic exotropia types of intermittent exotropia: a major review. Part 1: prevalence, classification, risk factors, natural history and clinical characteristics

INTRODUCTION

Intermittent exotropia (IXT) is a common form of strabismus. It is an outward deviation of one eye typically when viewing at distance. Symptoms include, but are not limited to double vision, eyes feeling tired, excessive blinking, and reduced quality of life. Its clinical characteristics are distinctive from other types of strabismus. This paper provides a comprehensive review of prevalence, classification, risk factors, natural history and clinical characteristics of the divergence excess and basic exotropia types of IXT.

METHODS

Search strategies involving combination of keywords including intermittent exotropia, exotropia, divergences excess, basic exotropia, prevalence, incidence, classification, terminology, risk factor, natural history, observation, angle of deviation, control, control score, symptom, quality of life, suppression, anomalous retinal correspondence, AC/A, accommodative convergence/accommodation, accommodative convergence, convergence, accommodation, vergence, incomitance and vertical were used in Medline. All English articles from 1900/01/01 to 2020/09/01 were reviewed. The reference list of the identified article was also checked for additional relevant article. Studies focused on animal model or strabismus associated with neurologic disorder or injury were excluded.

RESULTS

The estimated prevalence of IXT in children ranges from 0.1% to 3.7%. Hypoxia at birth and being female are potential risk factors of IXT. Using validated measures of control, multicenter prospective studies showed that the rate of conversion from IXT to constant exotropia is low. The angle of deviation is the most reported outcome measure in studies of IXT. It is often used to represent the severity of the condition and has been suggested as one of the four core outcomes for studies of the surgical management of IXT. Control of exodeviation is one of the four suggested core outcomes for study of surgery of IXT and is considered the main parameter of disease severity. Several validated tools for quality of life score are available to evaluate the subjective severity of IXT.

DISCUSSION

We reviewed the prevalence, classification, risk factors, natural history and clinical characteristics of the divergence excess and basic exotropia types of IXT. Further research into these areas, especially its clinical characteristics (e.g. suppression, dual retinal correspondence), will increase our understanding of this condition and potentially lead to better management of this common form of strabismus.

Ambulatory Monitoring With Eye Tracking Glasses to Assess the Severity of Intermittent Exotropia

PURPOSE

To explore the utility of eye tracking glasses in patients with intermittent exotropia as a means for quantifying the occurrence of exotropia, defined as the percentage of time that the eyes are misaligned.

DESIGN

Prospective observational study.

METHODS

Eye tracking glasses were used to obtain 68 recordings in 44 ambulatory patients with a history of intermittent exotropia. Vergence angle was monitored for up to 12 hours to document the occurrence of exotropia.

RESULTS

Intermittent exotropia was present in 31 of 44 patients. They had a mean exotropia of 19.3 ± 5.3° and a mean occurrence of 40% (range 3-99%). There was a moderate correlation between the magnitude of exotropia and its occurrence (r = 0.59). In 13 patients the occurrence of exotropia was <1%; they were deemed to have an exophoria only. In 35 of 44 cases, families reported an occurrence of intermittent exotropia greater than that measured by the eye tracking glasses.

CONCLUSIONS

Eye tracking glasses may be a useful tool for quantifying the severity of intermittent exotropia and for defining more precisely its clinical features.

How to Better Treat Patients with Intermittent Exotropia: A Review of Surgical Treatment of Intermittent Exotropia

Intermittent exotropia (X(T)) is the most common form of strabismus, especially in Asians. Treatment of X(T) includes occlusion, overminus lens, and surgery, of which, surgery is the mainstay of treatment. Commonly performed surgical procedures for X(T) are bilateral lateral rectus muscle recession or unilateral lateral rectus recession with medial rectus resection; however, it is unclear which of the two surgeries is more effective. The purpose of this review is to provide an insight on the surgical treatment of X(T). Randomized controlled trials, comparative observational studies, and case series with a large number of patients as well as a long follow-up period of over a year were included.

Effect of age on reoperation rate in children undergoing exotropia surgery

PURPOSE

To determine the effect of age on the reoperation rate in children undergoing exotropia surgery.

METHODS

This was a population-based retrospective cohort study using claims data that included children ≤ 12 years who had undergone exotropia surgery as the first strabismus operation and had ≥ 3 years of continuous enrolment were selected from the Optum de-identified Clinformatics Data Mart Database (2003-2019). Patient age at the first exotropia surgery was grouped into three categories; 0-3, 4-6, and 7-12 years. We assessed the sex, race, age, surgical methods, continuous enrolment period after the first surgery, and the time between the first surgery and reoperation. Cox regression analysis was used to estimate the risk of reoperation at different ages. The hazard ratio of reoperation in children undergoing exotropia surgery according to the age at the first exotropia surgery.

RESULTS

Among 2015 children, 312 (15.5%) underwent one or more reoperations. A reoperation was more often performed for recurrent exotropia (n = 231) than for consecutive esotropia (n = 81). The time between the first surgery and reoperation was shorter for reoperation for consecutive esotropia (376 days) than for recurrent exotropia (672 days) (p < 0.001). Younger children showed a higher reoperation hazard ratio than older children (p < 0.001). In reoperation for consecutive esotropia, the patients aged 0-3 years showed a high hazard ratio (2.82; 95% CI, 1.59-5.01).

CONCLUSION

Children undergoing exotropia surgery at a younger age have a higher reoperation rate than those undergoing surgery at an older age.

Long term surgical outcomes of unilateral recession-resection versus bilateral lateral rectus recession in basic-type intermittent exotropia in children

The long-term results of surgical treatment of intermittent exotropia (X(T)) according to the type of surgery are controversial. We conducted a retrospective cohort study to compare the long-term results between unilateral recession-resection (RR) and bilateral lateral rectus recession (BLR) with an average follow-up of 9.5 years in children with basic-type X(T). Patients with basic-type X(T), who underwent RR (RR group) or BLR (BLR group) and were followed-up for more than 5 years postoperatively, were analyzed. Of the 560 patients, 363 patients received BLR and 197 patients underwent RR. There was no significant difference in the success rates between the two groups until postoperative 3 years. At an average of 9.5 ± 2.6 years after surgery, the success rate of the RR group was significantly higher than that of the BLR group starting from the fourth post-operative year until the last follow-up examination (64.5% vs 43.3%, P < 0.001). By multivariate analysis, preoperative hyperopia of more than + 2.00 diopters, younger age of onset, younger age at surgery, larger exodeviation at near than at distance of > 5 prism diopters, and the type of surgery (BLR) were risk factors of recurrence. In conclusion, RR was more successful than BLR with a lower recurrence rate in the long-term follow-up of patients with basic-type X(T).

Interventions for intermittent exotropia

BACKGROUND

The clinical management of intermittent exotropia (X(T)) has been discussed extensively in the literature, yet there remains a lack of clarity regarding indications for intervention, the most effective form of treatment, and whether there is an optimal time in the evolution of the disease at which any given treatment should be carried out.

OBJECTIVES

The objective of this review was to analyze the effects of various surgical and non-surgical treatments in randomized controlled trials (RCTs) of participants with intermittent exotropia, and to report intervention criteria and determine whether the treatment effect varies by age and subtype of X(T).

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2021, Issue 1), which contains the Cochrane Eyes and Vision Trials Register; Ovid MEDLINE; Ovid Embase; Latin American and Caribbean Health Science Information database (LILACS); the ISRCTN registry; ClinicalTrials.gov, and the WHO ICTRP. The date of the search was 20 January 2021. We performed manual searches of the British Orthoptic Journal up to 2002, and the proceedings of the European Strabismological Association (ESA), International Strabismological Association (ISA), and American Association for Pediatric Ophthalmology and Strabismus meeting (AAPOS) up to 2001.

SELECTION CRITERIA

We included RCTs of any surgical or non-surgical treatment for intermittent exotropia.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology.

MAIN RESULTS

We included six RCTs, four of which took place in the United States, and the remaining two in Asia (Turkey, India). A total of 890 participants with basic or distance X(T) were included, most of whom were children aged 12 months to 10 years. Three of these six studies were from the 2013 version of this review. Overall, the included studies had a high risk of performance bias as masking of participants and personnel administering treatment was not possible. Two RCTs compared bilateral lateral rectus recession versus unilateral lateral rectus recession with medial rectus resection, but only one RCT (n = 197) reported on the primary outcomes of this review. Bilateral lateral rectus recession likely results in little difference in motor alignment at near (MD 1.00, 95% CI -2.69 to 4.69) and distance (MD 2.00, 95% CI -1.22 to 5.22) fixation as measured in pupillary distance using PACT (moderate-certainty evidence). Bilateral lateral rectus recession may result in little to no difference in stereoacuity at near fixation (risk ratio (RR) 0.77, 95% CI 0.35 to 1.71), adverse events (RR 7.36, 95% CI 0.39 to 140.65), or quality of life measures (low-certainty evidence). We conducted a meta-analysis of two RCTs comparing patching (n = 249) with active observation (n = 252), but were unable to conduct further meta-analyses due to the clinical and methodological heterogeneity in the remaining trials. We found evidence that patching was clinically more effective than active observation in improving motor alignment at near (mean difference (MD) -2.23, 95% confidence interval (CI) -4.02 to -0.44) and distance (MD -2.00, 95% CI -3.40 to -0.61) fixation as measured by prism and alternate cover test (PACT) at six months (high-certainty evidence). The evidence suggests that patching results in little to no difference in stereoacuity at near fixation (MD 0.00, 95% CI -0.07 to 0.07) (low-certainty evidence). Stereoacuity at distance, motor fusion test, and quality of life measures were not reported. Adverse events were also not reported, but study authors explained that they were not anticipated due to the non-surgical nature of patching. One RCT (n = 38) compared prism adaptation test with eye muscle surgery versus eye muscle surgery alone. No review outcomes were reported. One RCT (n = 60) compared lateral rectus recession and medial rectus plication versus lateral rectus recession and medial rectus resection. Lateral rectus recession and medial rectus plication may not improve motor alignment at distance (MD 0.66, 95% CI -1.06 to 2.38) (low-certainty evidence). The evidence for the effect of lateral rectus recession and medial rectus plication on motor fusion test performance is very uncertain (RR 0.92, 95% CI 0.48 to 1.74) (very low-certainty evidence).

AUTHORS' CONCLUSIONS

Patching confers a clinical benefit in children aged 12 months to 10 years of age with basic- or distance-type X(T) compared with active observation. There is insufficient evidence to determine whether interventions such as bilateral lateral rectus recession versus unilateral lateral rectus recession with medial rectus resection; lateral rectus recession and medial rectus plication versus lateral rectus recession and medial rectus resection; and prism adaptation test prior to eye muscle surgery versus eye muscle surgery alone may confer any benefit.

Short-Term Near Stereoacuity Improvements Following Favorable Surgical Alignment in Exotropic and Esotropic Patients

PURPOSE

Surgical treatment for strabismus is to promote binocular vision, and the study is to evaluate the effect of surgical realignment on near stereopsis in exotropic and esotropic patients.

METHODS

The records of patients who underwent strabismus surgery were retrospectively reviewed. Visual acuity, ocular deviations, fusion control, ocular motility, strabismus subtype and duration, surgery procedures, and stereopsis at before and at one month after surgery were collected. RMANOVA was performed to analyze stereopsis improvement by surgery. A logistic analysis was used to investigate the factors for stereopsis improvement.

RESULTS

143 exotropic and 40 esotropic patients were enrolled. The stereopsis was not significantly improved in patients with exotropia (p > .05), but not in esotropic patients (p < .01). Small degree of near deviation (β = 0.01), without vertical surgery (β = 0.11), and the high pre-surgery Titmus (β = -0.44) were related factors for stereopsis improvement in exotropia patients; male (β = 0.21) and the high pre-surgery Titmus (β = -0.36) were related factors for stereopsis improvement in esotropia patients.

CONCLUSION

The loss of stereopsis was significantly restored by surgery in esotropia patients and the extent of stereopsis recovery by surgery depends on the deviation at near distance, vertical surgery, and pre-surgery stereopsis in exotropes and on sex and pre-surgery Titmus in esotropes.

Outcomes of intermittent exotropia surgery

PURPOSE

To study the epidemiological and clinical characteristics of intermittent exotropia and to describe our therapeutic choices as well as their results and prognostic factors.

MATERIALS AND METHODS

This was a retrospective study including 57 cases of intermittent exotropia. All patients underwent a complete ophthalmological examination with a sensory-motor assessment. Surgery was performed by the same surgeon, and the vertical component was addressed surgically at the same time as the exotropia. Statistical analysis was performed using SPSS software version 21.0.

RESULTS

Our patients were classified as basic exotropia in 46 cases (80.7%), divergence excess in eight cases (14.1%), and convergence insufficiency in three cases (5.2%). Amblyopia was found in 26% of cases. The preoperative maximum angle of deviation was 36.5DP±9.1DS and a vertical component was found in 16 patients (28%). The most common was V pattern (8 patients). The mean age at the time of surgery was 14.8 years old. After a single surgery, we obtained motor success in 78.9% of the patients. Three patients were re-operated, with an overall motor success of 84.2%.

CONCLUSIONS

Motor and sensory success may be achieved in intermittent exotropia. Rigorous, early management is necessary, even if tropic episodes are still rare. The rate of early consultation among children is still low in our country; thus, a national strabismus screening program must be established to obtain the best results.

Predictive factors of stereopsis outcomes following strabismus surgery

Purpose:

To determine the predictive factors of post-operative stereopsis in patients with strabismus.

Method:

In this retrospective study, records of patients who received surgical treatment for strabismus were reviewed. All types of strabismus were included. Pre- and post-treatment stereoacuity were measured using the Titmus Stereo Fly test, and predictive factors of stereopsis were evaluated.

Results:

A total of 194 patients (132 females and 62 males) with a mean age of 14.8 ± 8.4 years were included. There was a statistically significant improvement in stereopsis following surgery (p value < 0.001). Patients with a higher amount of deviation at baseline had poorer stereopsis on the final examination (p value < 0.001). Stereopsis improvement was more prominent in the pure horizontal strabismus group, compared to combined horizontal and vertical deviations. Baseline and the final stereopsis were higher in the “exotropia” group as compared to the “esotropia” group (p value = 0.003 and 0.0155, respectively); however, the within group change of stereopsis was not significantly different between these two groups (p value = 0.144). Post surgical residual deviation was associated with a poorer stereopsis (p value = 0.002, r = 0.251). A longer duration of strabismus before surgery was associated with poorer final stereopsis levels (p value = 0.026). The presence of amblyopia before surgery was associated with poorer stereopsis on last examination (p value < 0.001 for both correlations).

Conclusion:

Based on the result of this study, final stereopsis after strabismus surgery could be affected by the type, duration, and the amount of deviation before surgery, amblyopia, and post operative ocular deviation.

The Success of Unilateral Surgery for Constant and Intermittent Exotropia and Factors Affecting It in a Large Scandinavian Case Series

PURPOSE

To compare the results of surgery for constant and intermittent exotropia, to determine factors affecting surgical success, and to evaluate the effect of horizontal rectus muscle surgery on distance-near incomitance.

METHODS

In this retrospective study of 291 Scandinavian patients, inclusion criteria were surgery for constant (n = 101) or intermittent (n = 190) exotropia with no vertical deviation, no previous strabismus surgery, and available postoperative follow-up data. Medical records of patients (age: 3 to 85 years) undergoing surgery were reviewed. Surgical success was defined as postoperative esodeviation of less than 5 prism diopters (PD) to exodeviation of 10 PD or less.

RESULTS

Surgical success was 70% in constant exotropia and 80% in intermittent exotropia (P > .05). At follow-up 1.5 years after surgery, a significant drift was found in intermittent exotropia (P < .05). Different surgeons, spherical equivalents, anisometropia, amblyopia, gender, and age had no effect on surgical success (P > .05). The surgical success rate increased with decreasing preoperative angle (P < .05). Resection of the medial rectus muscle had a greater effect on the near deviation, whereas recession of the lateral rectus muscle had a greater effect on the distance deviation (P < .05).

CONCLUSIONS

Surgical success was equally good in constant and intermittent exotropia, but better long-term stability was observed following surgery for constant exotropia. The only factor affecting surgical success was the preoperative deviation, with smaller deviations having a better outcome. A distance-near incomitance may be an important consideration in choosing the magnitude of medial versus lateral rectus muscle surgery. [J Pediatr Ophthalmol Strabismus. 2021;58(1):34-41.].

Recurrence of Intermittent Exotropia after Bilateral Lateral Rectus Recession

PURPOSE:

The purpose of this study was to evaluate predictive factors for intermittent exotropia (XT) recurrence after bilateral lateral rectus (BLR) recession.

METHODS:

This is a retrospective chart review of patients with XT who underwent BLR recession surgery between January 2007 and March 2017 with at least one postsurgical follow-up. Forty-one medical records were reviewed. Information collected included age, gender, systemic diseases, history of prematurity, family history of eye diseases, visual acuity, refraction, ocular alignment and control, stereoacuity, slit-lamp examination, fundoscopy, and amount of BLR recession. Successful alignment was defined as ≤8 prism diopters of esotropia or exotropia postoperatively.

RESULTS:

The mean age of patients at the time of surgery and follow-up time was 9.2 ± 12.3 years (y) and 23.6 ± 36.5 months (m), respectively. The mean amount of BLR recession was 6.5 ± 1.0 mm. Recurrence rate was 43.9% on the last follow-up. Age at surgery and at the time of last follow-up were significantly higher in the recurring group (P = 0.04 and P = 0.05, respectively). Postoperative angle of misalignment during the first 3 months was correlated with exotropia recurrence. No statistical significance was found among the remaining factors studied.

CONCLUSIONS:

The recurrence rate of XT in our study was 43.9%; it was increased in patients operated at older age and amid those with significant exotropia detected in the early postoperative period (within 3 months of surgery).

Long-term Motor and Sensory Outcomes After Unilateral Lateral Rectus Recession-Medial Rectus Resection for Basic Intermittent Exotropia

PURPOSE

To report long-term motor and sensory outcomes after unilateral lateral rectus recession-medial rectus resection for basic intermittent exotropia.

METHODS

The medical records of patients who had undergone unilateral lateral rectus recession-medial rectus resection for basic intermittent exotropia and were observed postoperatively for a minimum of 10 years were reviewed retrospectively.

RESULTS

A total of 41 patients were included (mean age: 6.07 ± 2.96 years; range: 3 to 17 years). The mean postoperative follow-up was 13.28 ± 3.27 years (range: 10 to 23 years). Overall, 19 patients (46%) had surgical success at their most recent follow-up visit. Age at onset of strabismus, age at surgery, strabismus duration, preoperative size of near and distance deviation, presence of stereopsis, and initial postoperative overcorrection did not predict motor outcome after surgery. Twenty-five patients (74%) achieved stereopsis. None of the 4 patients without binocular single vision preoperatively achieved stereopsis, compared to 3 of 7 patients (43%) with peripheral binocular single vision (P = .02). Five of 7 patients (71%) with a preoperative stereoacuity of 120 to 240 seconds of arc improved to 60 seconds of arc. Age at surgery did not predict stereopsis. Patients with a strabismus duration of 5 years or less achieved a better stereopsis.

CONCLUSIONS

Fewer than half of the patients with basic intermittent exotropia achieved a successful long-term surgical outcome. Age at surgery, strabismus duration, preoperative stereopsis, and an initial postoperative overcorrection did not predict motor outcome. A pre-operative absence of binocular single vision indicated a poor prognosis for stereopsis. A shorter duration of strabismus predicted a better stereopsis after surgery. [J Pediatr Ophthalmol Strabismus. 2020;57(5):326-332.].

The Relationship of Age and Other Baseline Factors to Outcome of Initial Surgery for Intermittent Exotropia

PURPOSE

To determine whether age at surgery is associated with surgical outcome of intermittent exotropia (IXT) at 3 years.

DESIGN

Secondary analysis of pooled data from a randomized trial.

METHODS

A total of 197 children 3 to <11 years of age with basic-type IXT of 15-40 prism diopters (Δ) were randomly assigned to 1 of 2 surgical procedures for treatment of intermittent exotropia. Masked examinations were conducted every 6 months for 3 years. The primary outcome was suboptimal surgical outcome by 3 years, defined as constant or intermittent exotropia of ≥10 Δ at distance or near by simultaneous prism and cover test (SPCT); constant esotropia of ≥6 Δ at distance or near by SPCT; or decrease in near stereoacuity of ≥2 octaves, at any masked examination; or reoperation without meeting any of these criteria.

RESULTS

The cumulative probability of a suboptimal surgical outcome by 3 years was 28% (19 of 72) for children 3 to <5 years of age, compared with 50% (57 of 125) for children 5 to <11 years of age (adjusted hazard ratio = 2.05; 95% confidence interval = 1.16 to 3.60). No statistically significant associations were found between suboptimal outcome and other baseline factors (magnitude of deviation, control score, fixation preference, or near stereoacuity) (P values ≥ .20).

CONCLUSIONS

This analysis suggests that in children with IXT, younger age at surgery (3 to <5 years) is associated with better surgical outcomes; however, further evidence from a randomized trial comparing immediate with delayed surgery is needed for confirmation.

Recovery From Suppression With Successful Motor Alignment After Surgery for Intermittent Exotropia

PURPOSE

To investigate recovery from suppression when the target motor alignment is achieved following surgery for intermittent exotropia.

METHODS

The medical records of 237 patients who underwent surgery for exotropia were retrospectively reviewed. The age at surgery, sex, preoperative angle of deviation, suppression status, and near stereopsis were investigated. Suppression status was classified as no, alternate, or constant suppression. Target motor alignment was defined as 10 prism diopters (PD) or less of exodeviation or 2 PD of esodeviation at the final visit.

RESULTS

The mean age at surgery was 8.2 ± 3.2 years and 115 (48.5%) patients were male. The preoperative angle of deviation was 26.3 ± 5.9 PD and the follow-up postoperative period was 21.6 ± 7.6 months. The preoperative suppression status included 23 (9.7%), 55 (23.2%), and 159 (67.1%) patients who showed no, alternate, or constant suppression, respectively. Two hundred fifteen (90.7%) patients obtained the target motor alignment by the final visit. Of the 144 patients who demonstrated constant suppression preoperatively but achieved the target motor alignment postoperatively, 12 (8.3%) patients demonstrated residual suppression. All 12 of these patients had a preoperative angle of exotropia of greater than 20 PD.

CONCLUSIONS

Most patients undergoing surgery for intermittent exotropia obtained both successful motor alignment and fusion postoperatively. However, successful motor alignment did not guarantee recovery of suppression when the preoperative angle of exotropia was greater than 20 PD. The preoperative factors and functional implications underlying this finding are unclear and merit further study. [J Pediatr Ophthalmol Strabismus. 2020;57(1):21-26.].

Different surgical outcomes in infantile exotropia according to onset time

PURPOSE

To determine whether age of onset influences surgical outcomes in infantile exotropia.

METHODS

The medical records of patients at our tertiary care facility who underwent bilateral lateral rectus recession for infantile exotropia during the period 2004-2013 were reviewed retrospectively. Patients were grouped by onset age: 6 months or earlier (E6 group) or later than 6 months (L6 group). Motor outcomes, near stereoacuity, and distance fusional status in both groups were evaluated.

RESULTS

A total of 134 patients were included: 35 in the E6 group and 99 in the L6 group. At a mean follow-up of 4.6 years, recurrence occurred in 12 (34%) of the E6 group and 38 (38%) of the L6 group (P = 0.496). Overcorrection occurred in 3 (9%) of the E6 group and in 4 (4%) of the L6 group (P = 0.341). In the analysis of 109 patients eligible for sensory examinations, the E6 group demonstrated a higher proportion of patients with reduced stereoacuity of 80 arcsec or worse (54% vs 25% [P = 0.007]) and suppression (46% vs 12% [P < 0.001]) compared with those in the L6 group. In logistic regression analyses, onset of ≤6 months was significantly associated with reduced stereoacuity (OR = 6.42) and suppression (OR = 37.67) but not with recurrence or overcorrection.

CONCLUSIONS

In our study cohort, age of onset ≤6 months was associated with worse sensory prognosis for children with infantile exotropia but not with a difference in motor outcomes.

Characterization of Intelligence in Children with Exotropia

The effect of exotropia on the intelligence of children is unknown. This study aimed to assess the intelligence in children with exotropia and investigate the influence of the main clinical indexes of strabismus on intelligence. Eighty-four participants aged 8–12 years were enrolled, including 37 patients with exotropia (exotropia group) and 47 normal individuals (normal group). Intelligence was assessed by the Wechsler Intelligence Scale for Children—Fourth Edition (WISC-IV), including the Verbal Comprehension Index (VCI), Perceptual Reasoning Index (PRI), Working Memory Index (WMI), Processing Speed Index (PSI), and Full-Scale Intelligence Quotient (FSIQ). The exotropia group had a significantly lower PRI score but a higher PSI score than the normal group. However, there was no significant difference in the WMI, VCI, and FSIQ between groups. Multiple linear regression showed that PRI–WMI and PRI–PSI differences were significantly lower in the exotropia group. Inter-subscale correlations analysis showed that the pattern of intelligence structure was different between groups. The type of exotropia, angle of deviation, duration of symptoms, and stereoacuity had no effect on the intelligence of children with exotropia. Children with exotropia had a relatively worse performance in the perceptual reasoning skill but a better processing speed and a different pattern of intelligence structure.

Does successful surgical correction of childhood large angle exotropia in adults make any difference to binocularity and quality of life?

Background/Aim: Strabismus surgery could achieve motor alignment and improve health-related quality of life (HRQOL) in adults with large angle exotropia, but whether it could improve binocularity and whether the binocularity is associated with HRQOL are unknown. The aim of this study is to evaluate the binocularity and HRQOL following successful surgical correction of childhood large angle exotropia in adults. Methods: Consecutive adults with childhood large angle exotropia (≥90 prism diopters) who underwent strabismus surgery in the Department of Ophthalmology and Vision Science, Eye and ENT Hospital, Shanghai Medical School, Fudan University were enrolled. Static and dynamic stereopsis tests were performed before surgery and 1 month after surgery. At the same time, Adult Strabismus-20 (AS-20), and Amblyopia and Strabismus questionnaire (A&SQ) were investigated. Results: A total of 29 adults achieved successful alignment: 18 intermittent exotropes (IXT) and 11 constant exotropes (CXT). One month after surgery, stereopsis was demonstrated better in all types of tests (p < .05 for all comparisons). Twelve patients gained normal stereopsis. More patients in IXT group gained normal stereopsis than in CXT group (x² = 7.62 p = .008). All HRQOL scores showed statistically significant improvement after surgery (p < .05 for all comparisons). IXT group had more changes of the composite score (t = 2.24, p = .03) and the functional score (t = 2.92, p = .007) of AS-20, and the functional score (t = 3.06, p= .005) of A&SQ than CXT group. Only the change of the functional score of A&SQ was demonstrated a statistically significant correlation with the normal stereopsis (t = 2.67, p = .02). Conclusions: The stereopsis and HRQOL in adults with childhood large angle exotropia can be improved after successful surgical correction. More patients in IXT group gained normal stereopsis correlated with better functional aspects of HRQOL.

Surgical management of intermittent exotropia: do we have an answer for all?

Intermittent exotropia (X(T)) is one of the most common form of strabismus with surgery being the mainstay of treatment. The main goal of surgery is to preserve binocular vision and stereopsis and to prevent its further loss. The decision to operate is mainly based on four aspects: increasing angle of exodeviation, deteriorating control of X(T), decrease in stereopsis for near or distance and quality of life. Bilateral lateral rectus muscle recession and unilateral lateral rectus recession with medial rectus resection, are the two most common surgical procedures performed and have been studied extensively in basic, divergence excess and convergence insufficiency types of X(T). However, there is no consensus over the relative efficacy of the two procedures in terms of postoperative alignment, residual or recurrent exotropia and consecutive esotropia with widely variable results, which can be attributed to poor understanding of the natural course of the disease. Multiple demographic, clinical and anatomic features that may influence the surgical outcomes have been studied to explain this variability. Moreover, most of the evidence regarding surgical outcomes of X(T) is from retrospective studies and the ongoing randomised prospective trials can shed light on long-term efficacy of these procedures. The goal of this review is to give a comprehensive overview of the outcomes of various surgical techniques in the management of different types of X(T), the preoperative and postoperative factors that may affect the surgical outcomes and to discuss the dilemmas faced by the treating surgeons including the effective management of overcorrection and undercorrection.

Survival analysis of adult and children intermittent exotropia using a matched case-control design

To compare the surgical outcomes of adult intermittent exotropia (X(T)) patients and matched control children X(T) patients including survival analysis. Fifty-two adult X(T) patients and 129 matched control children X(T) patients were included. Clinical characteristics, survival analysis, and surgical dose-response curves were evaluated and compared between the two groups. The weighted Cox proportional hazards regression analysis was used in order to find risk factors for the recurrence. Using Kaplan-Meier survival analysis, the cumulative probability of survival rate considering recurrence as event of Adult group were 93.97% for one year, and maintained at 88.44% for two, three. four, and five years after surgery. In contrast, those of the Child group were 83.6%, 76.5%, 65.6%, 56.23%, and 40.16% for one, two, three, four, and five years after surgery, respectively. The Adult group had a better event-free survival curve than the Child group as analyzed by a Log-rank test (p = 0.020). According to multivariate weighted Cox regression analysis, the younger age at operation and the larger preoperative angle were significant risk factors for recurrence.

Evaluation of dynamic stereopsis in intermittent exotropia patients

AIM

To delineate the characteristics of the dynamic stereopsis test and analyze related parameters in intermittent exotropia [X(T)] patients.

METHODS

Fifty-seven X(T) patients and 55 normal subjects were enrolled in this study. The normal and X(T) groups were used to test the reproducibility and reliability of the dynamic stereopsis test, and Bangerter filters with densities of 0.2 were then used to simulate suppression to test for traditional and dynamic stereopsis. In the X(T) group, the measurements included 1) dynamic stereopsis test comprising three parts: motion+disparity, motion only and disparity only; 2) ocular deviation angle; 3) Bagolini striated lens test; 4) disease course; and 5) Titmus stereopsis test.

RESULTS

The test-retest reliability of the dynamic stereopsis method was 0.901 in the normal and X(T) groups, and none of the X(T) patients were able to pass the static and dynamic stereopsis tests after using the 0.2 Bangerter filter. The accuracy rate was greater than 80% in the normal group and 31.81%, 36.36%, and 45.45% for the motion+disparity, motion-only and disparity-only components of the traditional test for X(T) patients diagnosed with stereoblindness via traditional tests, respectively. Patients with a long disease course (>1y) had worse dynamic stereopsis than those with a short disease course (<1y; P<0.05, Chi-square test). The deviation angle was not correlated with the motion+disparity, disparity-only, or the motion-only test components (all P>0.05, Chi-square test).

CONCLUSION

Dynamic stereopsis is preserved in certain X(T) patients diagnosed with stereoblindness via traditional tests. A long disease course was shown to be a negative factor for dynamic stereopsis in X(T) patients which might be associated with worse progression, and provide good references clinically.

Long-term Outcomes After Same Amount of Bilateral Rectus Muscle Recession for Intermittent Exotropia With the Same Angle of Deviation

PURPOSE

To evaluate long-term outcomes of homogenous bilateral rectus recession in patients with the same preoperative angle of deviation in intermittent exotropia and investigate factors associated with surgical outcomes.

METHODS

In this retrospective review, patients with the same preoperative angle of deviation who underwent bilateral 6-mm lateral rectus recession between January 2008 and January 2014 were observed for 2 or more years. Patients were classified into two groups based on deviation angle: success (orthophoria or exodeviation < 10 prism diopters [PD]) or recurrence (exodeviation ≥ 10 PD). Preoperative and postoperative ophthalmologic factors were compared between groups.

RESULTS

The success and recurrence groups contained 50 and 49 patients, respectively. Preoperative maximum angle of deviation was 29.0 ± 1.8 PD at distance in the success group and 28.9 ± 1.8 PD in the recurrence group. Deviation at the 2-year follow-up was 3.7 ± 3.7 and 18.3 ± 5.3 PD in the success and recurrence groups, respectively (P < .001). Preoperative factors were not significantly different between groups except for presence of lateral incomitance; success group patients presented more lateral incomitance (P = .035). The success group also presented more esodeviation just after the operation and showed a more stable course during follow-up. Surgical outcomes of patients with 10 PD or more of esodeviation 1 week postoperatively were significantly more favorable than patients with less than 10 PD of esodeviation (P = .027, log-rank test).

CONCLUSIONS

Presence of lateral incomitance and early postoperative overcorrection were significantly associated with favorable surgical outcome and should be considered when planning intermittent exotropia surgery. [J Pediatr Ophthalmol Strabismus. 2018;55(5):319-325.].

The difference of surgical outcomes between manifest exotropia and esotropia

PURPOSE

To determine the factors that affect ocular alignment and binocular sensory functions after strabismus surgery and compare surgical outcomes between manifest exotropia (XT) and esotropia (ET).

METHODS

In a retrospective study, 41 XT and 17 ET patients who had undergone strabismus surgery were recruited. Information on type and duration of strabismus, age at onset of deviation and surgery, pre- and postoperative strabismus deviation angles, and binocular sensory functions including stereoacuity and macular fusion capacity was recorded.

RESULTS

In all patients, the ocular alignment and binocular sensory functions improved with time following surgery. Residue strabismus deviation angles (≦ 10 prism diopters) at postoperative 1 month determined the final successful ocular alignment. In patients with final excellent binocular sensory functions, XT group restored macular fusion capacity and stereoacuity at postoperative 1 month, but ET group regained macular fusion capacity at postoperative 1 month and then restored stereoacuity at postoperative 3 months. Though XT patients showed better pre- and postoperative stereoacuity than ET patients, patients with successful ocular alignment had an odd of 4.5 in XT group and 22.5 in ET group to achieve excellent and fair binocular sensory functions.

CONCLUSION

Surgical correction of strabismus could improve ocular alignment and binocular sensory functions in patients with manifest strabismus, regardless of onset age, strabismus duration, or type. Postoperative 1-month status may help to predict the final motor and sensory outcomes. ET patients would benefit more final successful ocular alignment and excellent binocular sensory functions from early surgery and maintaining postoperative small deviation angle than XT patients.

The pursuit of stereopsis

BACKGROUND

Pediatric ophthalmologists are increasingly expected to promote, preserve, and restore binocular vision.

METHODS

Clinical studies on restoring alignment and stereopsis in the management of amblyopia, esotropia, exotropia, and complex strabismus are reviewed from the perspective of the author's published work and personal experiences.

RESULTS

Treatment of amblyopia by means of optical rehabilitation, occlusion, or penalization has been reinforced by medical treatment and perceptual training with monocular or binocular video games. Studies indicate that early management of esotropia and alignment within 8^Δ is required for regaining stereopsis. In the surgical management of intermittent exotropia, distance stereopsis by Frisby Davis Distance stereotest can predict better stereopsis, with patients having preoperative distance stereopsis of <70 arcsec less likely to improve after surgery. The surgeon's armamentarium for correcting alignment and restoring binocular vision include procedures such as adjustable, partial vertical rectus muscle transposition in cases of exotropic Duane syndrome and lateral rectus palsy, periosteal fixation of the globe or of the lateral rectus muscle, and medial transposition of the split lateral rectus muscle.

CONCLUSIONS

The goal for present-day strabismologists is not merely to correct strabismus but also to achieve alignment of eyes in time to ensure normal development of stereopsis in children and to restore alignment and stereopsis in adults.

Expression of schizophrenia biomarkers in extraocular muscles from patients with strabismus: an explanation for the link between exotropia and schizophrenia?

Recent studies have implicated exotropia as a risk factor for schizophrenia. We determined whether schizophrenia biomarkers have abnormal levels of expression in extraocular muscles from patients with strabismus and explored whether differences in gene expression between medial and lateral rectus muscles may explain the specific association of schizophrenia with exotropia but not esotropia. Samples from horizontal extraocular muscles were obtained during strabismus surgery and compared with age- and muscle type-matched normal muscles from organ donors. We used PCR arrays to identify differences in gene expression among 417 signaling molecules. We then focused on established schizophrenia-related growth factors, cytokines, and regulators of the extracellular matrix. Among 36 genes with significantly altered gene expression in dysfunctional horizontal rectus muscles, over one third were schizophrenia-related: CTGF, CXCR4, IL1B, IL10RA, MIF, MMP2, NPY1R, NRG1, NTRK2, SERPINA3, TIMP1, TIMP2, and TNF (adjusted p value ≤ 0.016667). By PCR array, expression of three of these genes was significantly different in medial rectus muscles, while eleven were significantly altered in lateral rectus muscles. Comparing baseline levels between muscle types, three schizophrenia-related genes (NPY1R, NTRK2, TIMP2) had lower levels of expression in medial rectus muscles. Despite the surprisingly large number of schizophrenia-related genes with altered gene expression levels in dysfunctional muscles, the lack of specificity for medial rectus muscles undermines a model of shared, region-specific gene expression abnormalities between exotropia and schizophrenia, but rather suggests consideration of the alternative model: that exotropia-induced aberrant early visual experiences may enable and/or contribute as a causative factor to the development of schizophrenia.

Intermittent Divergent Squint in Prematurity and Its Neurophysiological Aspects

Intermittent distance exotropia is a deviation characterized by an exophoria at near fixation and manifest exotropia at distance fixation. There is normal binocular fusional vergence and stereoacuity at near fixation, but the eyes tend to diverge in bright sunlight, tiredness, day dreaming and the patient may close one eye in such circumstances. Prematurity is associated with numerous eye pathology, besides retinopathy of prematurity, amblyopia, refractive errors, it is also associated with a higher risk esotropia and exotropia. We report a case of a 5-year-old girl (preterm and very low birth weight) with an intermittent deviation of both eyes since three years. On her detailed ocular examination diagnosis of divergence excess intermittent exotropia with normal accommodative convergence to accommodation ratio was made. Bilateral lateral rectus recession was done using hang back technique. Postoperatively, the eyes were aligned normally thereby achieving orthotropia. This article reviews various neurophysiological aspects of intermittent divergent squint delineating the etiopathogenesis, classification system, and management options in intermittent exotropia.

Long-Term Surgical Outcomes of Early Surgery for Intermittent Exotropia in Children Less than 4 Years of Age

PURPOSE

To investigate the long-term outcomes of intermittent exotropia surgery for children less than 4 years of age.

MATERIALS AND METHODS

Consecutive patients who underwent surgery for intermittent exotropia and had follow-up durations longer than 2 years were recruited. The patients were classified according to age at surgery-the patients of group 1 had undergone surgery before 4 years of age and those of group 2 at or after 4 years of age. Motor success was defined by exodeviation < 10 prism diopters (PD) and esodeviation < 5 PD at distance at 2 years postoperatively. Stereoacuity was considered as success at a value ≤ 60 arc seconds. The motor and sensory success rates as well as the surgical complications were compared.

RESULTS

Of the 73 patients, 36 were allocated to group 1 and 37 to group 2. At 2 years after surgery, 13 of the 36 (36.1%) patients in group 1 and 12 of the 37 (32.4%) in group 2 had achieved successful alignment; 32 (88.9%) patients in group 1 and 35 (94.6%) in group 2 achieved normal stereoacuity. No significant differences in the motor or sensory success rates were observed between the two groups (p = 0.46 and 0.32, respectively).

CONCLUSIONS

The surgical success rates for intermittent exotropia were comparable between the patients operated upon before 4 years of age and those operated upon after 4 years of age. The incidence of postsurgical complications was low and not significantly different between the two study groups.

Intermittent exotropia: Surgical treatment strategies

Surgical management of intermittent exotropias (IXTs) is ambiguous, with techniques of management varying widely between institutions. This review aims to examine available literature on the surgical management of IXT. A literature search was performed using PubMed, Web of Knowledge, LILACS, and the University of Liverpool Orthoptic Journals and Conference Transactions Database. All English-language papers published between 1958 and the present day were considered.

Factors associated with surgical success in adult patients with exotropia

PURPOSE

To report the results of surgical treatment for intermittent or constant comitant exotropia in adults and to examine the factors associated with the surgical outcome.

METHODS

The medical records of consecutive patients older than 18 years of age at the time of surgery for intermittent or constant comitant exotropia and with at least 1 year's follow-up were retrospectively reviewed. Surgical success was defined as postoperative esodeviation of <5^Δ, orthotropia, or exodeviation of <10^Δ. Overcorrection (defined as esodeviation >5^Δ) and recurrence (exodeviation of >10^Δ) were considered surgical failure. Preoperative patient characteristics, surgical procedures performed, and early postoperative ocular alignment were evaluated as potential factors associated with the surgical outcome.

RESULTS

A total of 39 patients were included, of whom 28 (72%) achieved surgical success, 7 (18%) showed overcorrection, and 4 (10%) had recurrence. Alignment at postoperative week 1 was the only significant factor correlated with surgical results. Surgical outcome was best with early postoperative alignment of <10^Δ of esotropia.

CONCLUSIONS

Early postoperative overcorrection of <10^Δ resulted in more favorable surgical outcomes in adults undergoing surgery to treat exotropia.

An external pilot study to test the feasibility of a randomised controlled trial comparing eye muscle surgery against active monitoring for childhood intermittent exotropia [X(T)]

INTRODUCTION

The evidence base for the treatment of strabismus (squint) is poor. Our main aim is to improve this evidence base for the treatment of a common type of childhood squint {intermittent exotropia, [X(T)]}. We conducted an external pilot study in order to inform the design and conduct of a future full randomised controlled trial (RCT).

METHODS

Children of between 6 months and 16 years with a recent diagnosis of X(T) were eligible for recruitment. Participants were recruited from secondary care at the ophthalmology departments at four UK NHS foundation trusts. Participants were randomised to either active monitoring or surgery. This report describes the findings of the Pilot Rehearsal Trial and Qualitative Study, and assesses the success against the objectives proposed.

RECRUITMENT AND RETENTION

The experience gained during the Pilot Rehearsal Trial demonstrates the ability to recruit and retain sites that are willing to randomise children to both trial arms, and for parents to agree to randomisation of their children to such a study. One child declined the group allocation. A total of 231 children were screened (expected 240), of whom 138 (60%) were eligible (expected 228: 95%) and 49 (35% of eligible) children were recruited (expected 144: 63% of eligible). Strategies that improved recruitment over the course of the trial are discussed, together with the reasons why fewer children were eligible for recruitment than initially anticipated. Attrition was low. Outcome data were obtained for 47 of 49 randomised children.

TRIAL PROCESSES AND DATA COLLECTION

The Trial Management processes proved effective. There were high levels of completion on all of the data collection forms. However, the feedback from the treatment orthoptists revealed that some modifications should be made to the length and frequency of the health service assessment and travel assessment questionnaires, thus reducing the burden on participants in the main trial. Modifications to the wording of the questions also need to be made.

MONITORING OF BIAS

Children who recruited to the trial were older and had more severe strabismus than those children eligible but declining participation. Strategies to account for this in a full trial are proposed.

REASONS FOR PARTICIPATION OR DECLINING STUDY

These were identified using qualitative interviews. The principal reasons for declining entry into the study were strong preferences for and against surgical treatment.

HARMS

There were no serious unexpected adverse events. Two children had overcorrection of their X(T) with reduction in binocular vision following surgery, which is in line with previous studies. No children in the active monitoring arm developed a constant strabismus although two showed some reduction in control.

CONCLUSIONS

The SamExo study has demonstrated that it is possible to recruit and retain participants to a randomised trial of surgery compared with active monitoring for X(T). For longer-term full RCTs, in order to maximise the generalisability of future studies, consideration needs to be given to planning more time and clinic appointments to assess eligibility and to allow consideration of participation; the greater use of research nurses for recruitment; and accommodating the strong preferences of some parents both for and against surgical intervention.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN44114892.

FUNDING

This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 19, No. 39. See the NIHR Journals Library website for further project information.

Clinical Characteristics and Surgical Outcomes in Patients With Intermittent Exotropia: A Large Sample Study in South China

The clinical characteristics and surgical outcomes in a large sample of patients with intermittent exotropia (IXT) as well as an analysis of risk factors associated with surgical failures are presented in this article. Data from IXT patients who received surgical management at the Eye Hospital, in the Zhongshan Ophthalmic Center, of Sun Yat-Sen University, China from January 2009 to December 2013 were reviewed retrospectively. Included within this analysis were data from pre- and postoperative ocular motility, primary alignment, and binocular vision.A total of 1228 patients with IXT were reviewed. Males (50.4%) and females (49.6%) were nearly equally represented in this sample. Thirty-two patients (2.6%) had a family history of strabismus. The mean age at onset was 6.77  ±  6.43 years (range 7 months -48.5 years), mean duration at presentation was 7.35  ±  6.68 years (range 6 months-47 years), and mean age at surgery was 13.7  ±  8.8 years (range 3-49 years). The mean refractive error was -0.84  ±  2.69 diopter in the right eye and -0.72  ±  2.58 diopter in the left eye. Amblyopia (4.2%), oblique muscle dysfunction (7.0%), and dissociated vertical deviation (4.7%) were also present in these patients. The most common subtype of IXT was the basic type (88.1%). Orthophoria was observed in 80.5% of patients and the ratios of surgical undercorrection and overcorrection were 14.7% and 4.8%, respectively, as determined with a mean follow-up time of 7.8  ±  3.7 months. When combining ocular alignment with binocular vision as the success criteria, the success rate decreased to 35.6%. Multivariate risk factor analysis showed that only the loss of stereoacuity (P = 0.002) was associated with a poor outcome. There were no differences in the long-term results between bilateral lateral rectus recession and unilateral lateral rectus recession with medial rectus resection.Most IXT patients displayed normal vision, with few having positive family histories, amblyopia, oblique muscle dysfunction, and dissociated vertical deviation. The most common subtype of IXT was the basic type. Long-term surgical results were less favorable when sensory status was included in the criteria for success. Patients with stereoacuity loss were at an increased risk for poor outcomes.

Clinical Preoperative and Postoperative Symptoms of Exotropia

PURPOSE

To examine clinical preoperative and postoperative symptoms and changes in exotropia according to constancy and age.

METHODS

A survey was conducted of 50 patients on the day before and 1 month after exotropia surgery. Survey results were analyzed by type of exotropia at presentation and age. Changes in subjective symptoms from preoperatively to postoperatively were examined for stereopsis (5 items), asthenopia (5 items), and appearance (5 items). Each item was rated on a 5-point scale ranging from 0 to 4.

RESULTS

The mean age of the 50 patients was 10.6 ± 7.75 years, and there were 21 (41.2%) males and 29 (56.9%) females. Thirty-two patients with intermittent exotropia had no significant improvement in the stereopsis or asthenopia symptoms. However, they showed significant (P < .05) improvement in the appearance symptoms of squint and out of focus. Eighteen patients with constant exotropia showed significant improvements in the symptoms of tripping over objects or running into a wall in stereopsis and of squint and out of focus in appearance (P < .05). Postoperatively, all patients had significant improvement in appearance-related symptoms regardless of age (P < .05).

CONCLUSIONS

Patients with constant exotropia had improved symptoms in stereopsis, asthenopia, and appearance after surgery. Appearance was improved regardless of the type of exotropia or age.

Comparison of Surgical Outcomes with Unilateral Recession and Resection According to Angle of Deviation in Basic Intermittent Exotropia

Purpose

The purpose of this study is to compare the surgical outcomes and near stereoacuities after unilateral medial rectus (MR) muscle resection and lateral rectus (LR) recession according to deviation angle in basic intermittent exotropia, X(T).

Methods

Ninety patients with basic type X(T) were included in this study. They underwent unilateral recession of the LR and resection of the MR and were followed postoperatively for at least 12 months. Patients were divided into three groups according to their preoperative deviation angle: group 1 ≤20 prism diopter (PD), 20 PD< group 2 <40 PD, and group 3 ≥40 PD. Surgical outcomes and near stereoacuities one year after surgery were evaluated. Surgical success was defined as having a deviation angle range within ±10 PD for both near and distance fixation.

Results

Among 90 patients, groups 1, 2, and 3 included 30 patients each. The mean age in groups 1, 2, and 3 was 9.4 years, 9.4 years, and 11.0 years, respectively. The surgical success rates one year after surgery for groups 1, 2, and 3 were 80.0%, 73.3%, and 73.3% (chi-square test, p = 0.769), respectively. The undercorrection rates for groups 1, 2, and 3 were 16.7%, 23.3%, and 26.7%, and the overcorrection rates were 3.3%, 3.3%, and 0%, respectively. The mean preoperative near stereoacuities for groups 1, 2, and 3 were 224.3 arcsec, 302.0 arcsec, and 1,107.3 arcsec, and the mean postoperative near stereoacuities were 218.3 arcsec, 214.7 arcsec, and 743.0 arcsec (paired t-test; p = 0.858, p = 0.379, p = 0.083), respectively.

Conclusions

In basic X(T) patients, the amount of angle deviation has no influence on surgical outcomes in unilateral LR recession and MR resection. The near stereoacuities by one year after LR recession and MR resection for intermittent X(T) were not different among patient groups separated by preoperative deviation angle.

Predictors of stereoacuity outcome in visually mature subjects with exotropia

The purpose of this study was to determine the predictors of stereoacuity outcome in visually mature subjects with exotropia following surgical correction. Visually mature subjects who were surgically aligned and had been tested for stereoacuity in the postoperative period were studied retrospectively. Subjects were grouped with respect to their responses to Titmus or TNO stereotests. Characteristics such as amblyopia, anisometropia, and characteristics of the exodeviation such as time of onset, duration, intermittency, presence of an A or V pattern, distance-near disparity, coexisting vertical deviation, and inferior oblique overaction, were compared between the groups. One hundred and four visually mature subjects with exotropia met the inclusion criteria. Stereoacuity was achieved in 77% of the study group and only 9% of these could achieve fine stereoacuity. Negative stereoacuity was more frequently associated with larger deviation angles, higher anisometropia, inferior oblique overaction, pattern strabismus, coexisting vertical strabismus, and distance-near disparity, but not at a statistically significant level. The optimal cutoff for strabismus duration was 20 years for a positive stereoacuity outcome. Any-level visual acuity difference was found to decrease the chance for positive stereoacuity significantly. The odds ratios for the stereoacuity positivity were 4.05 for strabismus duration <20 years, 7.9 for strabismus onset >1 year of age, 3.79 for weaker eye visual acuity >20/25 and 9.85 for intermittency of strabismus. Intermittence of exotropia was the strongest predictor for positive stereoacuity. Exotropia onset after 1 year of age, absence of any-level visual acuity difference, and strabismus duration <20 years were the other predictors with decreasing power.

Improvement in fusion and stereopsis following surgery for intermittent exotropia

PURPOSE

To evaluate fusion stereopsis in patients with intermittent exotropia before and after strabismus surgery.

METHODS

Fifty-three patients (mean age: 11.8 years, range: 5 to 25 years) with intermittent exotropia were enrolled. Fusion was measured with the Worth 4-dot test. Near stereopsis was examined with Titmus and stereoscopic test charts (created in China by Shao-Ming Yan). Distance stereopsis was tested with random-dot stereograms produced by Tianjin Eye Hospital. All patients completed the tests preoperatively and 2 and 6 weeks postoperatively.

RESULTS

There were no statistically significant differences in stereoscopic test charts among groups preoperatively (P > .05) and postoperatively (P > .05) or on Titmus tests preoperatively (P > .05) and postoperatively (P > .05). Among 53 patients, the percentage of distance stereoscopic improvement was 49% after 2 weeks and 77% after 6 weeks compared to 13% preoperatively. Six weeks postoperatively, random-dot stereograms were significantly different in those younger than 7 years and older than 13 years (P < .05), as well as those 7 to 13 years and older than 13 years (P < .05). Fifty (94%) demonstrated peripheral fusion and only 21 (40%) demonstrated central fusion preoperatively. Six weeks postoperatively, all patients exhibited peripheral fusion and 52 (98%) demonstrated central fusion. Central fusion in patients with intermittent exotropia significantly increased after 6 weeks (chi-square = 42.29, P < .01).

CONCLUSIONS

Patients with intermittent exotropia have good near stereoacuity preoperatively and postoperatively. Even if surgery is postponed until adolescence, distance stereopsis can still be recovered. Surgical intervention can restore central fusion and stereoacuity in patients with intermittent exotropia.

Interventions for intermittent exotropia

BACKGROUND

The clinical management of intermittent exotropia has been discussed extensively in the literature, yet there remains a lack of clarity regarding indications for intervention, the most effective form of treatment and whether or not there is an optimal time in the evolution of the disease at which any treatment should be carried out.

OBJECTIVES

The objective of this review was to analyse the effects of various surgical and non-surgical treatments in randomised trials of participants with intermittent exotropia, and to report intervention criteria and determine the significance of factors such as age with respect to outcome.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library, Issue 4, 2012), MEDLINE (January 1966 to May 2012), EMBASE (January 1980 to May 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to May 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 4 May 2012. We are no longer searching the UK Clinical Trials Gateway (UKCTG) for this review. We manually searched the British Orthoptic Journal up to 2002, and the proceedings of the European Strabismological Association (ESA), International Strabismological Association (ISA) and American Academy of Paediatric Ophthalmology and Strabismus meeting (AAPOS) up to 2001. We contacted researchers who are active in the field for information about further published or unpublished studies.

SELECTION CRITERIA

We included randomised controlled trials of any surgical or non-surgical treatment for intermittent exotropia.

DATA COLLECTION AND ANALYSIS

Each review author independently assessed study abstracts identified from the electronic and manual searches. Author analysis was then compared and full papers for appropriate studies were obtained.

MAIN RESULTS

We found one randomised trial that was eligible for inclusion. This trial showed that unilateral surgery was more effective than bilateral surgery for correcting the basic type of intermittent exotropia.

AUTHORS' CONCLUSIONS

The available literature consists mainly of retrospective case reviews, which are difficult to reliably interpret and analyse. The one randomised trial included found unilateral surgery more effective than bilateral surgery for basic intermittent exotropia. However, across all identified studies, measures of severity and thus criteria for intervention are poorly validated, and there appear to be no reliable natural history data. There is therefore a pressing need for improved measures of severity, a better understanding of the natural history and carefully planned clinical trials of treatment to improve the evidence base for the management of this condition.

Binocular vision outcomes following surgery for long-standing large angle exodeviation

INTRODUCTION

One goal of pre-operative sensorimotor testing is to determine fusion potential. Potential for recovery of binocularity following surgical repair of strabismus is inversely correlated to duration of misalignment. The purpose of this study was to determine binocular vision outcomes in long-standing, large-angle, constant exotropia, when the pre-operative sensorimotor exam predicts poor sensory outcome.

METHODS

Patients with constant exotropia >35Δ, present for ≥20 years, and scheduled to undergo strabismus surgery were recruited. Subjects were sorted into 3 groups based on pre-operative sensorimotor results. Group A had evidence of fusion pre-operatively, Group B demonstrated suppression on all tests, and Group C demonstrated paradoxical diplopia on at least one test.

RESULTS

Twenty patients were included: 11 in Group A, 5 in Group B, and 4 in Group C. Binocular vision was regained following surgery by 100% in Group A, 80% in Group B, and 50% in group C.

CONCLUSION

Surgical realignment leads to improvements in binocular vision in most patients, even in the case of very long-standing, large, constant deviations. The presence of paradoxical diplopia or dense suppression pre-operatively does not preclude a good sensory outcome.

Outcomes of surgery in children with early-onset exotropia

OBJECTIVE

To evaluate the clinical characteristics and surgical outcomes of early-onset exotropia and to compare differences between constant and intermittent exotropia at presentation.

METHODS

The medical records of 45 exotropia patients with a reported onset before 1 year of age who were operated on between 2008 and 2011 were reviewed, and the clinical characteristics and surgical outcomes of these patients were analyzed retrospectively. Patients were then divided into two groups according to type of exotropia at presentation: a constant (XT) group and an intermittent (X(T)) group. Clinical features and surgical results of exotropia were then compared between these two groups.

RESULTS

The mean age of onset of exodeviation in 45 patients was 9.3±3.8 months. Mean age at surgery was 4.5±2.4 years, and the mean postoperative follow-up period was 17.3 months (range, 6-37 months). Of the 45 patients, 67% showed alignment of less than±10 prism diopters (PD) at final visit. Gross stereopsis was achieved in all 34 testable patients, and bifixation developed in 10 patients (29%). Eleven patients were included in XT group and 34 patients in X(T) group. No significant intergroup difference was found between surgical success rates and binocularities.

CONCLUSION

Surgical outcomes, both motor and sensory, were not poor in early-onset exotropia patients, even in patients with constant deviation. Good binocular results following surgery can be achieved in children presenting with apparently constant early-onset exotropia.