Binocular status after surgery for constant and intermittent exotropia

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.

Effect of surgery on sensory eye balance in patients with intermittent exotropia: An observational study

To evaluate the impact of strabismus surgery on sensory eye balance in patients with intermittent exotropia (IXT). In total, 112 IXT patients with ocular alignment at the first strabismus surgery and 34 controls were enrolled from January 2015 to December 2016 in this retrospective study. The effective contrast ratio (ECR) of non-dominant eyes was measured by binocular phase combination paradigm before and 3 months after surgery, and the degree of sensory eye balance was quantitatively evaluated and compared between IXT patients and controls. The preoperative and postoperative mean ECRs of IXT patients were 0.492 ± 0.182 and 0.684 ± 0.198, respectively, which were significantly lower than those of the control group (0.896 ± 0.214, both P < .001). In addition, the postoperative ECR was significantly higher than the preoperative ECR (P < .001). The ECR change was not correlated with age orstrabismus degree measured with a6 m accommodative target (both P > .05), while significant negative correlation was observed between the ECR change and strabismus degree measured with a 33 cm accommodative target (P = .002). Strabismus surgery can significantly reduce the degree of sensory eye imbalance in patients with IXT, while further treatment aimed at rebalancing the ocular dominance might be necessary for more efficient binocular visual processing in the long-term.

The Effects of Orthoptic Therapy on the Surgical Outcome in Children with Intermittent Exotropia: Randomised Controlled Clinical Trial

BACKGROUND

To assess the clinical effectiveness of orthoptic therapy in the postoperative stabilisation and rehabilitation of binocular function in children with intermittent exotropia (IXT) after surgery.

METHODS

This was a prospective, parallel, randomised controlled trial. A total of 136 IXT patients (aged from 7 to 17 years) who had been successfully corrected at 1 month after surgery were enrolled in this study, and 117 patients (58 controls) completed the 12-month follow-up visit. The primary outcome was established as the proportion of patients with suboptimal surgical outcomes, which were defined as: (1) exodeviation ≥10 prism diopters (PD) at distance or near using the simultaneous prism and cover test (SPCT), or (2) constant esotropia ≥6 PD at distance or near using SPCT, or (3) loss of 2 or more octaves of stereopsis from baseline. The secondary outcomes were the exodeviation at distance and near using the prism and alternate cover test (PACT), stereopsis, fusional exotropia control and convergence amplitude.

RESULTS

The cumulative probability of suboptimal surgical outcome by 12 months was 20.5% (14/68) in the orthoptic therapy group and 42.6% (29/68) in the control group. There was a significant difference between these two groups (χ² = 7.402, p = 0.007). Improvements in stereopsis, fusional exotropia control and fusional convergence amplitude were found in the orthoptic therapy group. A smaller exodrift was found in the orthoptic therapy group at near fixation (t = 2.26, p = 0.025).

CONCLUSIONS

Early postoperative orthoptic therapy can effectively improve the surgical outcome as well as stereopsis and fusional amplitude.

Indications and results of exotropia surgical management

AIM

To study the clinical particularities and the surgical management of the different forms of exotropia, and to analyze the prognostic factors influencing the surgical result.

METHODS

Medical records of 132 patients who underwent exotropia surgery from 1995 to 2015, were retrospectively reviewed. Ophthalmological examination and a complete sensorimotor assessment were performed for each patient. All surgeries were performed by the same surgeon.

RESULTS

We had 57 cases of intermittent exotropia (IE), 22 cases of infantile exotropia (IfE), 43 cases of sensory exotropia (SE) and 10 cases of concecutive exotropia (CE). The average age of onset of exotropia was 6.8 years +/- 8 SD. Amblyopia was noted in 36.4% of cases  of  IfE.  The mean deviation angle was  36.5  DP in (IE),  39.6  DP in (IfE)  and  44.5  DP  in  (SE). A vertical syndrome was frequently found in (IfE) patients. Bilateral recession of  lateral  rectus  was  the  most  performed  surgery  type.  The overall success rate after a  single  surgery  was  72%.  A multivariate logistic regression analysis  showed  that good prognosis  factors  were  the absence  of  amblyopia, the intermittent form of the strabismus,  a low  preoperative deviation angle and the ocular alignment on day one postoperatively.

CONCLUSIONS

IE is the most common divergent strabismus.  Surgery resulted in successful alignment in most of the cases.  Early management and rigorous analysis of  patients sensorimotor status are the best guarantors of long-term success.

Longitudinal Rehabilitation of Binocular Function in Adolescent Intermittent Exotropia After Successful Corrective Surgery

PURPOSE

To study the longitudinal rehabilitation of binocular visual function in adolescent intermittent exotropia (IXT) after successful surgery and compare the results with those of a normal population. The role of binocular function in ocular alignment stability was also evaluated postoperatively.

METHODS

In this prospective study, 30 adolescents with IXT successfully corrected after 1 month were followed for 12 months, and 30 children with normal vision were enrolled as controls. Stereopsis, the fusional vergence amplitude, sensory fusion, and accommodative flexibility were measured to assess binocular function at baseline and 6 and 12 months postoperatively. The controls were tested once when they were enrolled in the study.

RESULTS

The deviation was -32.00 ± 8.60 prism diopters (PD) at distance fixation and -36.0 ± 9.10 PD at near fixation preoperatively with an average correction of 28.53 ± 3.79 PD and 30.67 ± 1.34 PD at 1 month postoperatively. Distance stereoacuity and near stereoacuity improved from 1 to 12 months postoperatively (p = 0.025 and p = 0.041, respectively). Compared with the controls, the fusional convergence reserve at distance (p = 0.025) and near (p = 0.033) fixations and fusion reserve ratio at distance (p = 0.000) and near (p = 0.000) fixations remained subnormal, whereas sensory fusion (p = 0.237), distance stereopsis (p = 0.120), and the fusional divergence amplitude at a distance (p = 0.168) were normal. However, no significant correlations were found between binocular functions at 1 month postoperatively and the postoperative drift.

CONCLUSION

Binocular function significantly improved from before to after successful corrective surgery and continued to improve from 1 to 12 months postoperatively in adolescents with IXT. No significant correlations were found between binocular functions at 1 month postoperatively and ocular alignment stability.

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.].

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.

Factors Associated with the Prognosis after Operation in Children with Recurrent Intermittent Exotropia

BACKGROUND

To describe factors affecting the prognosis after operation for recurrent intermittent exotropia (X[T]) in children.

METHODS

Clinical records of 50 patients who underwent operation for recurrent X(T) by a single surgeon were reviewed. The age at diagnosis of X(T), and first and second operations, deviation angle at distance and near, surgical method, concurrent vertical strabismus, stereoacuity, and Worth's Four Dot (W4D) examination before reoperation were analyzed, along with the postoperative deviation angle. A successful surgical outcome was defined as orthophoria, esodeviation ≤ 5 prism diopters, or exodeviation ≤ 10 prism diopters at distance.

RESULTS

Among the 50 recurrent exotropes who underwent surgery and were followed up for more than 1 year postoperatively, 13 showed recurrent exotropia and 1 showed consecutive esotropia. The mean age at reoperation was 8.49 ± 2.19 years, and the mean duration of postoperative follow-up was 27.78 ± 12.02 months. Good near fusion before reoperation was a significant factor in the success of surgery (P = 0.006). Smaller postoperative deviation angle measured immediately and 2 months after surgery were related to smaller final deviation angle (P = 0.027 and P = 0.022, respectively).

CONCLUSION

Peripheral suppression lowers the success rate of operation for recurrent X(T) in children. Overcorrection rather than orthotropia should be the target of immediate postoperative deviation angle. Peripheral suppression status and immediate and 2-month postoperative deviation angle may be important clues for predicting the final result of operation for recurrent X(T).

[Intermittent exotropia]

Intermittent exotropia (IXT) is the most common type of divergent strabismus. It is the consequence of passive mechanisms due to the anatomy of the globes and orbits or due to active innervational mechanisms, resulting in divergence of the visual axes, which is compensated by fusional convergence. Intermittent insufficiency in this compensation gives this form of exotropia its intermittent nature. The most common symptoms of IXT are closure of one eye, asthenopia and diplopia, but they are often absent. The clinical classification of IXT (according to Burian) is based on the difference between the distant and the near angles of deviation. It defines 4 types: true divergence excess (at distance), pseudo-divergence excess, the basic form (distance and near angles are equal) and convergence insufficiency (near angle greater than distance angle). One of the main difficulties in examination of IXT is neutralizing the fusional convergence in order to classify the strabismus. For this purpose, the monocular occlusion test, a near addition, or a prism adaptation test can be used. IXT is also characterised by the quality of control of the deviation by the patient, which is taken in account for therapeutic decision. Tools for measurement of this control have recently been developed and are not commonly used. The natural history of IXT is not well understood. Treatment relies mainly on optical correction, binocular visual training therapy and surgery, but their indications are not well defined, nor are outcomes analysis criteria. In the case of surgery, it aims to treat the maximum measured distance angle; the medium- and long-term angular results of surgery are often disappointing, although it probably improves control of the strabismus in most cases.

Clinical study of the influence of preoperative wearing time on postoperative effects in children with partially accommodative esotropia

The aim of this study was to evaluate the influence of the preoperative wearing time on the postoperative effect in children with partially accommodative esotropia.Sixty children with partially accommodative esotropia who visited our hospital were placed in full cycloplegic refraction by using 1% Atropine eye gel and then wore full hyperopic correction glasses. Children were divided into groups A and B according to the preoperative wearing time. The visual acuity, eye position, and results of the synoptophore and Titmus stereoacuity tests were recorded before and half a year after the surgery in each group, and appropriate statistical analyses were conducted.Half a year after the operation, 54 cases achieved orthotropia when wearing full hyperopic correction glasses. One case was overcorrected. Five cases were undercorrected. The results of the synoptophore and Titmus stereoacuity test showed that there was no significant difference between postoperative outcomes for patients who wore glasses for half a year and for 1 year before the operation.For children with partially accommodative esotropia, surgery should be used to correct the eye position after wearing full hyperopic correction glasses for half a year to improve the eye position and binocular vision as early as possible. If the operation cannot be completed after the patient wears full hyperopic correction glasses for half a year due to various subjective and objective factors, a good postoperative effect can be obtained if the patients receive surgery after wearing full hyperopic correction glasses for 1 year.

Reduction of Consecutive Esotropia Using Modified Contralateral Recession and Resection for Recurrent Intermittent Exotropia

PURPOSE

To report consecutive esotropia in contralateral lateral rectus recession and medial rectus resection for recurrent intermittent exotropia after unilateral lateral rectus recession and medial rectus resection and to evaluate the surgical outcome of modified contralateral lateral rectus recession and medial rectus resection for exotropia after unilateral lateral rectus recession and medial rectus resection.

METHODS

A total of 36 patients were included in this retrospective study. As a primary surgery for exotropia, all patients underwent unilateral lateral rectus recession and medial rectus resection on the non-dominant eye. Patients were subsequently assigned to either conventional contralateral lateral rectus recession and medial rectus resection (surgical dosages based on Wright's surgical table) (n = 19; conventional group) or modified contralateral lateral rectus recession and medial rectus resection (surgical dosages reduced by 5 prism diopters on Wright's surgical table) (n = 17; modified group) for recurrent exotropia. Surgical success rates were evaluated. Reoperation or prism glasses prescription rates due to consecutive esotropia were evaluated.

RESULTS

The mean follow-up durations after reoperation were 25.8 and 24.0 months in the conventional and modified groups, respectively. The surgical success rates were 73.7% and 82.4% (P = .538, Fisher's exact test) and the recurrence rates were 0% and 17.6% (P = .059, Fisher's exact test), respectively. The reoperation or prism glasses prescription rates due to consecutive esotropia were 26.3% and 0%, respectively (P = .025, Fisher's exact test).

CONCLUSIONS

Final outcomes were better in the modified group compared to the conventional group. Consecutive esotropia was significantly more frequent in the conventional group than in the modified group. In surgery for recurrent exotropia, a reduction of the surgical dosage will reduce the incidence of consecutive esotropia. [J Pediatr Ophthalmol Strabismus. 2018;55(1):53-58.].

Variability of preoperative measurements in intermittent exotropia and its effect on surgical outcome

PURPOSE

To investigate the variability of preoperative measurements in patients with intermittent exotropia and to compare surgical outcomes according to the variability.

METHODS

Patients who underwent unilateral lateral rectus recession and medial rectus resection and had 24 months' postoperative follow-up were enrolled. Patients were divided into three groups according to variability, which was defined as the largest angle minus the smallest angle ever measured during the preoperative visits; group C comprised patients with consistent exodeviation; group V_L, patients with less variability (<10^Δ); and group V_M, patients with more variability (≥10^Δ). Surgical outcomes of the three groups were compared.

RESULTS

A total of 344 patients were included: 128 in group C, 155 in group V_L, and 61 in group V_M. The largest variability was 20^Δ and 62.8% (216/344, group V_L + group V_M) of the patients showed variable angles of deviation during the preoperative measurements. The postoperative exodeviation increased in all groups over the 24-month follow-up; however, the postoperative exodeviation of group V_M was lower than that of both groups C and V_L (repeated-measure ANOVA, P = 0.032). There was a trend toward decreased rates of reoperation from group V_M compared with groups V_L and C (linear by linear association, P = 0.004).

CONCLUSIONS

More than half of patients with intermittent exotropia showed variable angles of deviation during the preoperative measurements. The surgical outcomes were better in those with variable preoperative measurements than in those with consistent preoperative measurements.

Post-operative strabismus control and motor alignment for basic intermittent exotropia

AIM

To assess strabismus control and motor ocular alignment for basic exotropia surgery at 5y follow-up.

METHODS

The medical records of 80 consecutive patients aged less than 17 years of age, who underwent surgery for basic exotropia by a single surgeon between years 2000 to 2009 and completed a minimum of 5y follow-up post-operatively were reviewed. Pre- and post-operative characteristics were documented at 1wk, 6mo, 1, 3 and 5y follow-up. Subjects at 5-year follow-up were assigned to the success group if they had a post-operative angle of deviation within 10 prism diopters of exotropia or within 5 prism diopters of esotropia for distance on prism cover test, and had moderate to good strabismus control. The remaining subjects were assigned to the failure group.

RESULTS

Post-operative surgical success at one week was 75%, which decreased to 41% at 5y follow-up. The success group was noted to have more patching pre-operatively (P=0.003). The duration of patching a day (P=0.020) and total duration of patching pre-operatively (P=0.030) was higher in the success group. Surgical success at 1y (P=0.004) and 3y (P=0.002) were associated with higher surgical success at 5y follow-up.

CONCLUSION

Post-operative motor alignment and strabismus control for basic exotropia surgery at 1y and beyond is associated with higher exotropia surgery success at 5-year follow-up. There is an association between pre-operative patching and 5-year surgical success of basic intermittent exotropia surgery.

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.

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.

Sensory eye balance in surgically corrected intermittent exotropes with normal stereopsis

Surgery to align a deviated or strabismic eye is often done for both functional as well as cosmetic reasons. Although amblyopia is often an impediment to regaining full binocularity in strabismics in general, intermittent exotropes, because their deviation is intermittent, have no amblyopia and some degree of stereopsis. Binocular function, including a balanced ocular dominance, could be expected to be normal after surgical correction if normal levels of stereopsis and visual acuity are postsurgically achieved. Here we used a binocular phase combination paradigm to quantitatively assess the ocular dominance in a group of surgically corrected intermittent exotropes who have normal stereo and visual acuity as defined clinically. Interestingly, we found significant interocular imbalance (balance point < 0.9) in most of the surgically treated patients (8 out 10) but in none of the controls. We conclude that the two eyes may still have a residual sensory imbalance in surgically corrected strabismus even if stereopsis is within normal limits. Our study opens the possibility that a further treatment aimed at re-balancing the ocular dominance might be necessary in surgically treated intermittent exotropia to provide more efficient binocular processing in the long term.

Outcomes of 3 or 4 Horizontal Muscles Surgery in Large-Angle Exotropia

PURPOSE

To evaluate motor and sensory outcomes of 3 or 4 horizontal muscles surgery for the treatment of large-angle exotropia and to evaluate factors influencing the success rate and the relationship between initial postoperative and final motor outcomes.

DESIGN

A retrospective analytical study.

METHODS

Medical records of patients with primary large-angle exotropia [>50 prism diopters (PD)] who had 3 or 4 horizontal muscles surgery were reviewed. Motor outcomes were categorized as successful (esotropia 1-8 PD, orthotropia or exotropia 1-10 PD), acceptable (exotropia 11-20 PD), and poor (esotropia >8 PD or exotropia >20 PD). Results were evaluated only at the last follow-up visit if patients were followed up for less than 2 years. Those who were followed up for more than 2 years were evaluated at both the 2-year and final follow-up visits. Factors influencing the success rate and the relationship between initial postoperative and final motor outcomes were analyzed.

RESULTS

A total of 36 patients were enrolled in this study. The median follow-up time was 18 months (range, 3-60 months). The success rate was 69% at the last follow-up and 75% at the follow-up at 2 years, respectively. Stereopsis improved in 43% at the last follow-up and 56% at 2 years. Initial postoperative deviation was found to correlate with the success rate at the last follow-up (P = 0.018). Initial postoperative overcorrection of 8 to 14 PD had the highest possibility of gaining successful final motor outcomes.

CONCLUSIONS

Three or 4 horizontal muscles surgery in large-angle exotropia can achieve successful motor outcomes and improve stereopsis. Surgeons should aim for initial overcorrection in order to maximize long-term success.

Persistent binocular diplopia in childhood following successful treatment for esotropia: a case series

INTRODUCTION

Diplopia is rare in children with nonpathological esotropia because facultative suppression develops prior to visual maturation. Our aim is to present five cases of children with binocular diplopia following treatment of childhood esotropia, exploring possible mechanisms for the development of diplopia based upon the patient's history and findings, and discussing treatment for diplopia in this setting.

METHODS

A retrospective chart review of five sequential patients presenting with binocular diplopia following treatment of esotropia was performed. Treatment of esotropia included correction of hyperopic error, correction of anisometropic amblyopia to 20/30 or better, and strabismus surgery as indicated.

RESULTS

Diplopia developed in two children with accommodative esotropia, one child with infantile esotropia and partially accommodative esotropia, and two children with a history of infantile esotropia and consecutive exotropia following surgical correction. Diplopia onset occurred between ages 7 and 11. Four of the five children experienced resolution of diplopia with prism glasses.

CONCLUSION

Children with esotropia before visual maturation may develop persistent diplopia. Clinical features of the children with diplopia in our case series include poor fusion, poor stereopsis, consecutive exotropia, refractive changes, onset of diplopia after 7 years of age, and occlusion therapy for amblyopia. Prisms may be beneficial in controlling the diplopia.

Factors associated with the angle of exodeviation in patients with recurrent exotropia

AIMS

To compare preoperative and postoperative distance deviation angle in recurrent exotropes, and to determine factors associated with large-angle recurrent exotropia.

METHODS

In recurrent exotropes who were followed-up more than 2 years postoperatively, the largest angle after recurrence (LAAR) was compared with the preoperative deviation angle (PA). Patients were classified into those who had LAAR<PA and LAAR≥PA. Differences in clinical factors between groups were examined.

RESULTS

Among 242 exotropes who underwent surgery, and followed-up for more than 2 years postoperatively, 83 showed recurrent exotropia. Mean age at surgery was 5.7 ± 2.4 years, and mean postoperative follow-up was 36.2 ± 11.3 months. The bigger the preoperative angle, the bigger the angle of recurrence is. However, the smaller the preoperative angle, the angle of recurrence grows closer to the preoperative one. Only six showed bigger recurrence (LAAR≥PA), and these patients had a smaller mean preoperative angle (p=0.01) compared to patients whose angle of recurrence was smaller than the preoperative one. Among the patients with LAAR<PA, type of exotropia (p=0.03) and preoperative constant deviation (p=0.02) was associated with PA-LAAR≤5(Δ).

CONCLUSIONS

Although the overall incidence of recurrent exotropia with a relatively large angle (LAAR≥PA) is low among patients who underwent surgery for exotropia (2.5%), the possibility of this phenomenon should be noted. The ratio of relatively large angle recurrence was higher in patients with a small preoperative exodeviation and basic type exotropia.

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.

Contralateral lateral rectus recession versus recess-resect for recurrent exotropia after unilateral recess-resect

BACKGROUND

To compare outcomes following contralateral lateral rectus (LR) recession and recess-resect (RR) procedures for recurrent exotropia of 20-25 prism dioptres (PD) after unilateral RR.

METHODS

39 subjects were included in this retrospective study. All underwent, as a primary surgery for intermittent exotropia, unilateral RR on the non-dominant eye. They were assigned to the subsequent contralateral LR recession (LR, n=19) or RR (n=20) group for recurrent exotropia of 20-25 PD. Surgical success was defined as alignment between 5 PD esodeviation and 10 PD exodeviation.

RESULTS

The mean follow-up duration after the reoperation was 32.3±26.4 months in the LR group and 30.5±26.8 in the RR group (p=0.945). The mean deviation angles at postoperative 1 day were -0.7 PD (overcorrection) in the LR group and -4.3 PD in the RR group (p=0.047). The deviation angles at 3 and 6 months postoperatively were not significant (p=0.771, p=0.923). The final successful outcome was achieved in 63.2% of patients in the LR group and in 65% of patients in the RR group (p=0.905).

CONCLUSIONS

Contralateral LR recession was found to be a safe and effective procedure for the treatment of recurrent exotropia of 20-25 PD after unilateral RR for intermittent exotropia. With LR recession, the intentional overcorrection in the immediate postoperative period could be avoided.

Postoperative stabilization of the strabismic angle in intermittent exotropia

Purpose

To analyze the postoperative strabismic angle for five years or more and to investigate when the angle stabilized in intermittent exotropia.

Methods

We retrospectively reviewed the clinical records of 89 patients who had undergone surgery for intermittent exotropia. The postoperative strabismic angles measured were analyzed at one-year intervals up to five years postoperatively. We divided them into two groups according to their age at the time of surgery. Group 1 was less than 5 years of age, while Group 2 participants were 5 years of age or older.

Results

For our 89 total patients, average exo-angles were 7.8 ± 7.26, 7.9 ± 7.51, 9.5 ± 7.05, 10.1 ± 6.87, and 9.4 ± 6.90 prism diopters at one, two, three, four, and five years postoperatively, respectively. Average exo-angles between postoperative year one and year three, as well as between postoperative year two and year three, were statistically significant (p = 0.015, 0.022). However, the angles were not statistically significant between postoperative year three and year four or between years three and five, respectively (p = 0.707, p = 0.948). The stabilization characteristics of the angle were somewhat different according to age group. In Group 1, the average exo-angle in postoperative years one and three were statistically significant (p = 0.016), but the angle in the same period was not statistically significant in Group 2 (p = 0.203).

Conclusions

There was no significant interval change after three years postoperatively in intermittent exotropia, but if the patient's age at surgery was 5 years or higher, no significant change of exo-angle was found following postoperative year one in this study.

Long-term results of the surgical management of intermittent exotropia

PURPOSE

To examine long-term surgical success rates (>10 years) for patients with intermittent exotropia and the risk factors for failure of surgery in these patients.

METHODS

An attempt was made to contact all patients who underwent surgical treatment for intermittent exotropia between the years of 1970 to 1998 with a minimum postoperative follow-up of 10 years. Each patient underwent a detailed sensory and motor examination, including measurements of near and distance stereoacuity, cover testing, and ocular rotations. Patients were classified as achieving an excellent, fair, or poor outcome on the basis of motor and sensory outcomes. Risk factor analysis was performed to evaluate associations with a poor outcome and reoperations.

RESULTS

Of 197 patients identified, 50 were reevaluated. When combined motor/sensory criteria for surgical success were used, we found that 38% of patients achieved an excellent outcome, whereas 34% and 28% achieved a fair or poor outcome, respectively. When only the motor criteria were used, we found that 64% had an excellent outcome, whereas the remaining patients achieved either a fair (18%) or a poor (18%) outcome. During the follow-up period, 60% of patients required at least one reoperation. Multivariate risk factor analysis determined that anisometropia (p = 0.03) was associated with a poor outcome, whereas postoperative undercorrection (p = 0.04) and lateral incomitance (p = 0.06) were associated with reoperations.

CONCLUSIONS

Long-term surgical results in intermittent exotropia are less encouraging when sensory status is added to the evaluation. Patients with anisometropia, lateral incomitance, and immediate postoperative undercorrection are at increased risk for poor outcomes and to require reoperations.

Evaluation of distance and near stereoacuity and fusional vergence in intermittent exotropia

AIM

To evaluate the role of distance and near stereoacuity and fusional vergence in patients with intermittent exotropia [X(T)] and their change after surgery.

MATERIALS AND METHODS

This prospective interventional institution-based clinical study included 31 cases of X(T) requiring surgery and 33 age, sex-matched controls. All subjects underwent complete orthoptic assessment including near stereopsis (Randot stereogram) and distance stereopsis by polaroid stereo-projector apparatus using special paired slides and fusional vergence assessment at distance and near prism bar at baseline and one week, one month, three months and six months after surgery in X(T).

RESULTS

The successful surgical alignment rate was 74.2%. Preoperatively, cases demonstrated significantly poor distance and near stereoacuity, compared to controls ( P < 0.001). Mean distance stereoacuity (sec of arc) in normals, (X)T preoperatively and postoperatively was 344.8 +/- 139.5, 1149.2 +/- 789.4 and 450.1 +/- 259 while mean near stereoacuity was 34.7 +/- 9.5, 68.7 +/- 31.1 and 47.4 +/- 22.6 respectively. Postoperatively at six months, significant improvement in stereoacuity was observed both at near and distance ( P < 0.05). Mean distance fusional convergence (in prism diopter) in normals, X(T) preoperatively and postoperatively was 20.7 +/- 4.7, 18.0 +/- 3.3 and 21.4 +/- 3.6 respectively, mean near fusional convergence was 27.8 +/- 6.3, 24.1 +/- 5.5 and 29.1 +/- 5.5 respectively. There was good correlation between fusional vergence amplitudes for distance and near indicating any one would suffice.

CONCLUSION

Early detection of abnormal stereoacuity (near and if possible distance) and near fusional vergence amplitudes may help to decide proper timing of surgery in X(T).

Postoperative outcomes in children with intermittent exotropia from a population-based cohort

PURPOSE

To describe the long-term surgical outcomes in a population-based cohort of children with intermittent exotropia.

METHODS

The medical records of all children (<19 years) who were diagnosed with intermittent exotropia as residents of Olmsted County Minnesota, from January 1, 1975, through December 31, 1994, and managed with surgery were retrospectively reviewed.

RESULTS

Of 184 patients with intermittent exotropia, 61 (33%) underwent surgery at a mean age of 7.6 years (range, 3.2 to 23 years). Twelve of the 61 children (19.7%) underwent a second surgery (10 for recurrent exotropia and 2 for consecutive esotropia), and no patient received 3 or more surgeries during a mean follow-up of 10 years from the first surgery. The final postoperative measurements were recorded in 56 of 61 patients (92%) at a mean of 7.4 years (range, 0 to 18 years) after the first surgery: 31 of the 56 (55%) were within 9(Delta) of orthotropia at distance and 25 of 55 (45%) had better than 60 seconds of stereopsis. The Kaplan-Meier rate of developing >/=10(Delta) of misalignment after the first surgery was 54% by 5 years, 76% by 10 years, and 86% by 15 years.

CONCLUSIONS

In this population-based study of surgery in children with intermittent exotropia, although only 1 in 5 received a second surgery, after a mean follow-up of 8 years, approximately half were successfully aligned and 45% had high-grade stereopsis.