The long-term survival analysis of bilateral lateral rectus recession versus unilateral recession-resection for intermittent exotropia

Symmetric versus asymmetric surgery for the treatment of intermittent exotropia with equal dominance

PURPOSE

Long-term surgical outcomes were compared between bilateral lateral rectus recession (BLR) and unilateral lateral rectus recession combined with medial rectus resection in the same eye (R&R) for therapy of basic type intermittent exotropia (IXT) with equal dominance.

METHODS

Two hundred and sixty-eight subjects (3-11 years old) with basic IXT with equal dominance who underwent BLR or R&R surgery were enrolled to this study, and with a minimum follow-up period of 18 months. One hundred and fourteen patients underwent BLR surgery and 144 underwent R&R surgery at a single centre. Surgical outcomes between groups were compared. Surgery results were divided into 3 categories: undercorrection/recurrence (exotropia/phoriaå 10PD), success(esotropia/phoria ≤5PD to exotropia/phoria≤10PD), and overcorrection (esotropia/phoriaå 5 PD) according to postoperative deviation angle.

RESULTS

No statistical difference was detected between BLR group and R&R group at all intervals with the exception of the last examination, demonstrating a higher success rate and a lower recurrence rate in the BLR group than R&R group at last visit (P = 0.04). Additionally, the BLR group demonstrated a smaller exodrift than the R&R group at distance and near fixation (P = 0.01; P = 0.03). Stereoacuity and exotropia control showed overall improvement following both surgeries, and this improvement had no statistical difference between groups(P > 0.05).

CONCLUSIONS

BLR showed better long-term results than R&R in the treatment of basic type intermittent exotropia with equal dominance given its low recurrence rate. Both BLR and R&R surgeries could improve stereoacuity function and exotropia control, and to same extents.

Analysis of postoperative exodrift according to surgical methods for intermittent exotropia

PURPOSE

This study aimed to compare the periods for exodrift stabilization and the long-term surgical outcomes among different surgical methods in intermittent exotropia.

METHODS

The medical records of 350 patients who had undergone intermittent exotropia correcting surgery [unilateral lateral rectus recession-medial rectus resection (R&R, n = 221), bilateral lateral rectus recession (BLR, n = 51) and unilateral lateral rectus recession (ULR, n = 78)] with a postoperative follow-up period of 1.5 years or more were retrospectively reviewed. The deviation angles every 6 months after surgery, periods of exodrift stabilization and surgical outcomes were analysed. The period of postoperative exodrift stabilization was defined as when exodrift was no longer significantly different from that at the next visit (p > 0.05). An alignment of 5 PD (prism diopters) esotropia to 10 PD exotropia at a distance and near fixation was considered surgical success.

RESULTS

The mean angle of exodeviation was significantly different among surgical procedures at postoperative 1 month (BLR > ULR > R&R, p < 0.001); however, there were no differences among the procedures at 6 months (p = 0.088). The periods of exodrift stabilization were 6 months after ULR, 1 year after BLR and 4.5 years after R&R. The surgical success and reoperation rates did not show significant differences among procedures at the final follow-up.

CONCLUSION

Patients undergoing R&R showed smaller exodeviation shortly after surgery but required a longer period to stabilize the exodrift. Following ULR, exodeviation was larger in the early postoperative period, but the exodrift was stabilized earlier. Therefore, the long-term surgical outcomes were similar among ULR, BLR and R&R.

Outcomes for maximal bilateral lateral rectus recession in large-angle exotropia

BACKGROUND

Surgical treatment for large-angle exotropia can be challenging. The aim of this study was to evaluate short-term surgical outcomes of patients with large-angle exotropia (≥50Δ) undergoing maximal bilateral lateral rectus muscle recession of 10 mm.

METHODS

This was a retrospective study of consecutive patients at our institution who underwent maximal bilateral lateral rectus muscle recession for exodeviation ≥50Δ from January 1, 2008, to July 22, 2022. We subdivided the cohort into large-angle exotropia (largest amount of exodeviation at near and/or distance ≥50Δ and <65Δ) and very large-angle exotropia (largest exodeviation ≥65Δ). Patients with a history of prior eye muscle surgery, neurologic deficits, and three- or four-muscle surgery were excluded.

RESULTS

A total of 22 patients were included. Mean preoperative exodeviation at distance was 51.9Δ in the large-angle group and 67.5Δ in the very-large-angle group (P = 0.001). Outcomes for the large-angle and very-large angle groups were, respectively, as follows: mean follow-up, 31.1 weeks and 11.8 weeks (P = 0.97); success, 75.0% and 16.7% (P = 0.02); undercorrection rates, 18.7% and 83.3% (P = 0.01); and mean postoperative exodeviation at distance, 3.7Δ ± 6.3Δ and 28.0Δ ± 13.5Δ (P = 0.001).

CONCLUSIONS

Our study identified good surgical outcomes (75%) with maximal bilateral lateral rectus muscle recession of 10 mm in treating patients with large-angle exotropia between 50Δ and <65Δ. Other surgical techniques such as recession-resection and three- or four-muscle surgery may result in better outcomes when treating patients with exotropia ≥65Δ.

Efficacy of part-time patching in preventing recurrence after bilateral lateral rectus recession in children with intermittent exotropia

BACKGROUND

This study evaluate the efficacy of part-time patching in preventing recurrence after bilateral lateral rectus recession (BLR) in patients with intermittent exotropia (IXT).

METHODS

A total of 190 children aged 3-13 years who experienced recurrence after BLR for IXT and received part-time patching were retrospectively reviewed. The patching was prescribed for 2 h per day for more than 6 months. Patients who had a recurrence of 18 PD or more underwent reoperation. Changes in exodeviation and reoperation ratio after part-time patching were analyzed.

RESULTS

A total of 34 patients (17.9%) received reoperation after part-time patching, and the reoperation ratio after 2 years was 20.3% as per the Kaplan-Meier survival analysis. Patients with a recurrence of 7 to 10 PD showed a significantly better effect compared to those with a recurrence of more than 10 PD (p < 0.001), and the reoperation ratio was also lower in the survival analysis (p = 0.004). The factor associated with reoperation in patients with part-time patching was the duration between the operation and the initiation of part-time patching (hazard ratio [HR] = 1.006, p = 0.002).

CONCLUSIONS

Part-time patching was effective in maintaining the efficacy of surgery and delaying the need of reoperation after BLR. This effect was better in patients with a recurrence of ≤ 10 PD.

Treatment of intermittent exotropia in children using a lateral rectus fenestration technique

PURPOSE

To report the results of bilateral fenestration of the lateral rectus muscle in cases of intermittent exotropia in pediatric patients.

METHODS

Children <12 years of age with basic and pseudo-divergence excess type intermittent exotropia who underwent bilateral lateral rectus muscle fenestration were prospectively enrolled in this study. Success was defined as postoperative alignment within 8Δ of orthotropia in the primary position at the last follow-up.

RESULTS

A total of 36 children were included. The mean preoperative angle of deviation at distance improved from 33.1Δ ± 3.8Δ (range, 25Δ-40Δ) preoperatively to 4.5Δ ± 5.7Δ (range, 0-16Δ) postoperatively (P < 0.001). The near angle was reduced from 32.0Δ ± 4.2Δ (range, 25Δ-35Δ) to 2.8Δ ± 4.5Δ (range, 0Δ-14 Δ) postoperatively (P < 0.001). Successful outcome was achieved in 81% of the cases at the 6-month follow-up. There were no reported intra- or postoperative complications.

CONCLUSIONS

In our study cohort, bilateral fenestration of the lateral rectus muscle resulted in successful outcomes in the majority of patients, resulting in a significant reduction in angle of deviation in primary position at both distance and near fixation.

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.

Preoperative and postoperative clinical factors in predicting the early recurrence risk of intermittent exotropia after surgery

PURPOSE

Preoperative and postoperative identification of early recurrence risk factors in intermittent exotropia (IXT) patients after surgery.

DESIGN

Prospective clinical cohort study.

METHODS

We included 210 basic-type IXT patients who underwent either the bilateral rectus recession or unilateral recession and resection procedure and had complete follow-up until recurrence or for more than 24 months postoperatively. The primary outcome was early recurrence, defined as postoperative exodeviation over 11 prism diopters at any time beyond postoperative 1 month and within 24 months. Survival was estimated by the Kaplan-Meier method. Preoperative and postoperative clinical characteristics were collected from patients, and preoperative and postoperative Cox proportional hazards regression analyses were performed. Preoperative model was fit with nine preoperative clinical factors (sex, onset age of exotropia, duration of disease, spherical equivalent of the more myopic eye, preoperative distant exodeviation, near stereoacuity, distant stereoacuity, near control and distant control). Postoperative model was fit by adding two factors relevant to surgery (surgery type and immediate postoperative deviation). Corresponding nomograms were constructed and evaluated using the concordance indexes (C-indexes) and calibration curves. Decision curve analysis (DCA) was used to determine the clinical utility.

RESULTS

The recurrence rate was 8.10% for 6 months, 11.90% for 12 months, 17.14% for 18 months, and 27.14% for 24 months after surgery. Younger onset age, larger preoperative angle and less immediate postoperative overcorrection were found to increase the risk for recurrence. Though onset age and age at surgery were strongly correlated in this study, age at surgery was not significantly associated with IXT recurrence. The C-indexes for the preoperative and postoperative nomograms were 0.66 (95% confidence interval [CI]: 0.60-0.73) and 0.74 (95% CI: 0.68, 0.79), respectively. Calibration plots between predicted and actual observed 6-, 12-, 18-, and 24-month overall survival using the two nomograms revealed high consistency. The DCA indicated that both models yielded great clinical benefits.

CONCLUSIONS

By relatively accurate weighing of each risk factor, the nomograms offer good prediction for early recurrence in IXT patients and may help clinicians and individualized patients make appropriate intervention plans.

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.

Correlation between Frisby-Davis Distance Stereoacuity Scores and Long-term Surgical Outcomes in Intermittent Exotropia

Purpose: We analyzed postoperative Frisby-Davis distance (FD2) stereotest scores and changes in the angle of deviation, and the correlation between postoperative FD2 stereotest scores and long-term surgical outcomes, in patients with intermittent exotropia.Methods: This retrospective study included patients aged less than 12 years with intermittent exotropia who underwent at least 28 months of postoperative follow-up. We analyzed the changes in the postoperative angle of deviation and preoperative and postoperative Titmus and FD2 stereotest scores. Surgical success rates at 28 months postoperatively were compared between the good (FD2 at 10 months postoperatively ≤ 10 arcsec) and bad (FD2 at 10 months postoperatively ≥ 15 arcsec) stereotest groups. Surgical success was defined as a horizontal deviation on distance measurement of 5 prism diopter (PD) esodeviation to 10 PD exodeviation at 1 year postoperatively.Results: This study included 101 patients. No significant difference was identified between preoperative and postoperative Titmus test scores. However, the FD2 stereotest scores were significantly improved at 10 months postoperatively (p = 0.001). A significant, positive correlation was observed between FD2 stereotest scores at 10 months postoperatively and the angles of deviation at distance at 10, 16, 22, and 28 months postoperatively (p ≤ 0.001 for all). The surgical success rates at 28 months postoperatively were 73.1% and 43.5% in the good and bad stereotest groups, respectively (p = 0.008).Conclusions: Distance stereoacuity within 1 year postoperatively correlated with the postoperative angle of deviation at distance. Good distance stereoacuity (i.e., < 10 arcsec) within 1 year postoperatively correlated with a higher surgical success rate compared to bad distance stereoacuity.

A Novel Method Ensuring an Immediate Target Angle After Horizontal Strabismus Surgery in Children

Purpose

Pediatric strabismus surgery has low success rates and high reoperation rates because of difficult alignment measurements and the nature of different strabismus types. Furthermore, adjustable sutures are not easily employed in children on an OPD basis.

Methods

This was a retrospective comparative case study of children less than 12 years old who underwent strabismus surgery and were followed up at least 6 months postoperatively. We proposed a novel method that combines adjustable sutures and corneal light reflexes in regular strabismus surgery to improve surgical results. Efficacy and safety were evaluated and compared with those in a regular fixed-suture group.

Results

In total, 128 children (88: exotropia and 41: esotropia) in the novel method group (Group 1) and 109 (71: exotropia and 38: esotropia) in the regular fixed-suture group (Group 2) were enrolled. The primary outcome was the immediate target angle (for esotropia within 4 PD of orthotropia and exotropia within 8 PD of esotropia within the first week postoperatively); the secondary outcome was success at the 6-month visit (angle of deviation < 10 PD). Consequently, there was a significantly higher proportion of achieving the immediate target range and success rate in both exotropic and esotropic patients in Group 1 than in Group 2. A significantly lower reoperation rate was also demonstrated in Group 1. No complications were noted in either group.

Conclusions: The novel method enabled a higher proportion of subjects to achieve an immediate target range and success rate and a lower chance of reoperation among both esotropic and exotropic patients.

Longitudinal course of consecutive esotropia in children following surgery for basic-type intermittent exotropia

PURPOSE

To evaluate the longitudinal course of consecutive esotropia following surgery for basic-type intermittent exotropia.

METHODS

Patients who underwent surgery (bilateral lateral rectus muscle recession [BLR] or unilateral lateral rectus muscle recession-medial rectus muscle resection [RR]) for the treatment of intermittent exotropia between 2011 and 2017 with a minimum follow-up period of 2 years were retrospectively reviewed. When esodeviation occurred later in patients with orthotropia or exodeviation at postoperative month 1, it was defined as delayed-onset consecutive esotropia. The number of patients with esodeviation at every follow-up and characteristics of patients were evaluated.

RESULTS

A total of 336 patients (6.2 ± 2.1 years; 236 in the BLR group and 100 in the RR group) were included. After surgery, postoperative esodeviation decreased mostly during the 1st postoperative month in both groups. At postoperative year 2, there were 28 patients (8.3%) with consecutive esotropia: six in the RR group and 22 in the BLR group. Among the 284 patients with orthotropia or exodeviation at postoperative month 1, there were 13 patients with delayed-onset consecutive esotropia; they presented larger preoperative angle of exodeviation, poorer stereopsis, younger at the time of surgery and associated with the types of surgeries for exotropia.

CONCLUSIONS

In patients with consecutive esotropia, the angle of esodeviation decreased and patching/prismatic correction helped achieve the good surgical outcomes. However, delayed-onset consecutive esotropia and persistent esotropia also presented, requiring the reoperation. Therefore, postoperative alignment should be carefully monitored after surgery for intermittent exotropia.

Efficacy of bilateral lateral rectus recession versus unilateral recession and resection for basic-type intermittent exotropia: a meta-analysis

PURPOSE

To investigate the efficacy of bilateral lateral rectus recession (BLR) versus unilateral recession and resection (RR) for the treatment of patients with basic-type intermittent exotropia (IXT).

METHODS

We systematically searched the EMBASE, PubMed, Web of Science and Cochrane Library databases for relevant studies published before April 2020 with no language restrictions. Related studies meeting the eligibility criteria were included. The primary outcomes were success rate and mean postoperative deviation. Odds ratios (ORs) and weighted mean differences (MDs) with 95% confidence intervals (CIs) were calculated.

RESULTS

From 1243 screened articles, a total of 10 studies involving 967 patients were included in the analysis. No differences were observed in success rates between the BLR and RR groups at 1-day to 1-week postoperatively (OR: 0.9, 95% CI: 0.53 to 1.53, p = 0.69), or at 6-month postoperatively (OR: 1.11, 95% CI: 0.59 to 2.11, p = 0.74), or at the last follow-up visit (OR: 0.76, 95% CI: 0.44 to 1.34, p = 0.34). The unsatisfactory effects (the overcorrection and undercorrection rates) between the two groups were comparable. In addition, there were no significant differences between the two groups in postoperative deviation at 1-day to 1-week postoperatively (MD: 0.03, 95% CI: -1.32 to 1.27, p = 0.97), or at 6-month postoperatively (MD: 1.42, 95% CI: -0.43 to 3.27, p = 0.13) or at the last follow-up visit (MD: 0.29, 95% CI: -1.39 to 1.97, p = 0.74).

CONCLUSION

This meta-analysis provides evidence that both the BLR and RR procedures have similar efficacy for the treatment of basic-type IXT.

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).

Initial overcorrection after surgery for intermittent exotropia in children less than 4 years old: Comparison with older children

PURPOSE

While initial overcorrection after exotropia-correcting surgery is widely accepted for a favorable long-term outcome, some have not advocated such overcorrection in younger children owing to concerns regarding rapid deterioration of bifixation ability. This study aimed to evaluate the relationship between initial overcorrection after intermittent exotropia surgery and the surgical outcome in patients aged <4 years.

METHODS

In this retrospective study, 391 patients who had undergone surgery for intermittent exotropia were classified into two groups according to the age at surgery: <4 years old (group Y [young], 130 patients) and 4-16 years old (group O [old], 261). The patients were subdivided into three groups according to the angle of deviation at postoperative 1 week: esophoria-tropia (ET) ≥10 prism diopters (PD) (subgroup I), ET 1-9 PD (II), and orthotropia or exophoria-tropia (XT) (III). We compared the surgical outcomes between the two groups and among subgroups; then, we analyzed consecutive esotropia patients.

RESULTS

The mean exodeviation was smaller in the order of subgroup I, II, and III at every postoperative visit (p<0.05) in group Y but showed no difference among subgroups after 2 years in group O. Consecutive esotropia occurred at 1 month, postoperatively, in 6.9% and 2.6% of the patients in groups Y and O (p = 0.133), respectively. However, it persisted in two and one patient in groups Y and O, respectively, until the last visit.

CONCLUSION

Early overcorrection after intermittent exotropia surgery was a safe and desirable result in terms of motor outcome in children aged under 4 years, as well as for children aged between 4-16 years.

Evaluation of Efficacy and Lateral Gaze Incomitance in Symmetrical and Asymmetrical Surgery for Concomitant Esotropia and Exotropia

Purpose

Evaluation of asymmetrical and symmetrical horizontal strabismus surgery as regards efficacy and postoperative lateral gaze incomitance.

Patients and Methods

This prospective comparative interventional case series study included 40 patients of age more than 3 years with alternating horizontal strabismus. Patients were divided according to the type of horizontal deviation into esotropia and exotropia groups, which were further subdivided into asymmetrical and symmetrical subgroups in each type. The surgery was defined as symmetrical procedure if the surgery was done on the same muscle in the two eyes and it was defined as asymmetric in recess-resect procedures in one eye, and three horizontal muscles surgery. Preoperative and postoperative measurements were done in primary position, right, and left gaze using alternate prism cover test and hand-held orthopedic goniometer.

Results

At the end of follow-up period, a statistically insignificant difference (P value = 0.8057) was present in the success rate between the asymmetrical and symmetrical subgroups of esotropia (90 and 86.67%, respectively) and it was 100% in both exotropia subgroups. Lateral gaze incomitance results were different between esotropia and exotropia subgroups. In esotropia, a statistically significant difference was reported at 1 month (0.009), which became insignificant at 6 months (0.077) and 12 months (0.077) between asymmetrical and symmetrical subgroups. In exotropia subgroups, there was a statistically insignificant difference in lateral gaze incomitance at 1, 6, and 12 months (P = 1).

Conclusion

Asymmetrical procedure had the same efficacy and success rate of symmetrical procedure for the correction of concomitant horizontal deviations in primary gaze without persistent postoperative lateral gaze incomitance, especially in exotropia.

Clinical Trial Registration

NCT04199286.

Quantitative Analysis of Eyeball Rotation During Lateral Gaze in Intermittent Exotropia: A Magnetic Resonance Imaging Study

Purpose

To evaluate the eyeball rotation during lateral gaze in patients with intermittent exotropia (IXT) using three-dimensional magnetic resonance imaging (MRI).

Methods

In this prospective observational study, patients with IXT (n = 29) underwent orbital MRI during central, right, and left gazes. Fixation targets were placed at a 40° angle for lateral gaze. After acquisition of MR images, the position of the static tissues other than the eyeball in the MR images were matched three-dimensionally. The optical axis was defined as the perpendicular line to its lens passing through the corneal vertex. The rotation angle was measured as the angle between optical axes in central gaze and lateral gaze using ImageJ. A difference of 3° or more in the rotational angle between both eyes was considered a significant difference.

Results

Eight patients (26.7%) had a larger adduction angle than the abduction angle of the fellow eye and six patients (20.0%) showed a smaller adduction angle during lateral gaze on at least one side. There was no significant factor associated with the pattern of rotation.

Conclusions

Almost one-half of the patients with IXT had significant difference in the rotation angle between both eyes during lateral gaze. Measurement of the rotation angle during lateral gaze using MRI showed that IXT is not a perfectly comitant disturbance of gaze in some subjects.

Translational Relevance

Quantitative analysis for eye movements using MRI can provide useful information for physiologic mechanism and proper surgical planning in patients with IXT.

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.

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.].

Risk factors for excessive postoperative exo-drift after unilateral lateral rectus muscle recession and medial rectus muscle resection for intermittent exotropia

BACKGROUND

To detect significant factors associated with excessive postoperative exo-drift in young patients with intermittent exotropia who had undergone unilateral lateral rectus muscle recession and medial rectus muscle resection.

METHODS

We retrospectively examined the records of 64 consecutive patients < 18 years old who underwent surgery between April 2004 and December 2011. We sought risk factors for excessive postoperative exo-drift among patients' demographic and clinical characteristics using univariate and multivariable linear regression analysis.

RESULTS

Younger patients (P = 0.007), and those with larger preoperative exo-deviation at distance (P = 0.033), a lower incidence of peripheral fusion at distance (P = 0.021) or a greater postoperative initial eso-deviation (P = 0.001), were significantly more likely to have an excessive postoperative exo-drift (> 20 prism diopters). Univariate analysis revealed significant associations between excessive postoperative exo-drift and age at surgery (P = 0.004), preoperative exo-deviation at distance (P = 0.017) and postoperative initial eso-deviation at distance (P < 0.001). Multivariable linear regression analysis showed that postoperative initial eso-deviation at distance (P = 0.008) was significantly associated with postoperative exo-drift.

CONCLUSIONS

Postoperative exodrift in unilateral RR is predicted by the initial postoperative eso-deviation, which may offset the overcorrection. However, the exo-drift is greater in cases with a large preoperative exo-deviation and/or at a younger age, and should be followed carefully.

The stability of horizontal ocular alignment of triad exotropia after one-step triple surgery

PURPOSE

A-pattern exotropia, superior oblique muscle overaction, and dissociated vertical deviation may coexist and are referred to as triad exotropia. The present study evaluated the postoperative stability of horizontal ocular alignment of triad exotropia and possible prognostic factors.

METHODS

Medical records of patients with triad exotropia who had one-step triple surgery of superior oblique muscle weakening, superior rectus muscle recession, and lateral rectus muscle recession were reviewed. The horizontal alignment and postoperative drift of triad exotropia were analyzed and compared with constant exotropia.

RESULTS

The triad exotropia showed a mean of 7.7^△ (± 8.5^△) eso-drift, while the constant exotropia was (3.5^△ ± 3.4^△) exo-drift. Multiple linear regression analysis showed that the degree of superior oblique muscle overaction after surgery (P = 0.011) was the only factor associated with horizontal drift. Patients with superior oblique muscle underaction showed larger eso-drift when compared to patients without superior oblique muscle underaction (- 18.0^△ ± 11.1^△ vs. - 5.1^△ ± 5.7^△; P = 0.024). The final success rates of the triad exotropia and constant exotropia groups were 53.3% and 69.2%, respectively, and the overcorrection rates were 26.7% and 2.6% (P = 0.035).

CONCLUSIONS

An overall trend of eso-drift in primary position occurred in triad exotropia after triple surgery up to a follow-up of 25 months. Patients presenting superior oblique muscle underaction after surgery seemed to have large angles of eso-drift, which might be taken into account in surgical planning and follow-up.

Risk factors associated with poor outcome after medial rectus resection for recurrent intermittent exotropia

PURPOSE

To describe characteristics of recurrent intermittent exotropia after bilateral lateral rectus (BLR) recession, and identify factors associated with poor outcome after unilateral medial rectus (MR) resection for recurrent intermittent exotropia.

METHODS

We retrospectively reviewed 124 patients who have undergone unilateral MR resection for recurrent intermittent exotropia after BLR recession. Patients were followed for at least 2 years after MR resection. Clinical characteristics and risk factors associated with poor outcome after unilateral MR resection were evaluated. Successful outcome was defined as distant deviation within the range of 4 prism diopters (PD) esotropia and 10 PD exotropia at last visit after MR resection.

RESULTS

Among 124 patients, 50 patients (41.1%) were male, and the mean age at the time of MR resection was 9.5 ± 3.1 years. The average follow-up period after MR resection was 43.8 ± 23.7 months. Forty-seven patients (37.9%) were classified to have poor outcome at last visit, and 29 patients (23.4%) underwent third operation. None of the patients was overcorrected after MR resection. Multiple logistic regression analyses showed that distant deviation at post-operative 3 months and male gender were associated with poor outcome (OR 1.49; 95% CI 1.27-1.73; P < 0.001, and OR 5.19; 95% CI 1.42-18.98; P = 0.013, respectively).

CONCLUSION

Ocular deviation at 3 months after unilateral MR resection for recurrent intermittent exotropia may play a valuable role in anticipating poor outcome. Patients whose exotropia exceeded 9 PD at distance at 3 months' follow-up tended to recur while those whose exotropia remained below 9 PD at distance showed a stable disease course.

Do the primary surgical options for basic-type exotropia cause differences in distance-near discrepancy of recurrent exotropia after surgery?

Purpose

Most ophthalmologists appear to have no distinct preference between unilateral recess-resect (R&R) and bilateral lateral rectus (BLR) recessions to treat basic-type exotropia. This study aimed to determine whether differences in distance-near discrepancy and resultant exotropia types of recurrent exotropia following surgery for primary basic-type exotropia exist between the two surgical options.

Methods

Ninety-three patients with recurrent exotropia following BLR recessions for basic-type exotropia (BLR group) and 95 following R&R for basic-type exotropia (R&R group) were included in this retrospective study. The exotropia types in recurrent exotropia were classified into three types according to distance-near discrepancy: basic, divergence-excess, and convergence-insufficiency. The BLR and R&R groups were compared.

Results

After surgery for basic-type exotropia, the type composition changed differently in each group (p < 0.001). The basic-type of primary exotropia was more often maintained in recurrent exotropia in the R&R group than in the BLR group. The incidence of postoperative convergence-insufficiency type exotropia in the BLR group was 28.0% and 8.4% in the R&R group (p = 0.001). Postoperative near stereopsis and fusion control grade of distance deviation did not differ between the two groups (p > 0.05).

Conclusions

Convergence-insufficiency type recurrent exotropia occurred more frequently after BLR recessions than after R&R for basic-type exotropia. The high rate of secondary convergence-insufficiency type exotropia after BLR recessions should be considered when clinicians select a surgical option to treat exotropia.

Long-term outcomes following resection-recession versus plication-recession in children with intermittent exotropia

Background/Aims

To compare the long-term surgical outcomes between unilateral lateral rectus recession-medial rectus resection (RR) and lateral rectus recession-medial rectus plication (RP) in children with intermittent exotropia.

Methods

Children who underwent RR or RP for intermittent exotropia between January 2008 and July 2016, with a minimum follow-up period of 2 years were retrospectively reviewed. Postoperative angle of deviations and clinical factors including sex, age, refractive errors, preoperative angle of deviation, types of exotropia and stereopsis were investigated. Based on the angle of deviation at year 2, surgical outcomes were classified into two groups as follows: success (esodeviation ≤5 prism dioptres (PD) to exodeviation ≤10 PD) and failure (overcorrection (esodeviation >5 PD) and undercorrection or recurrence (exodeviation >10 PD)).

Results

Of the 186 patients, 114 underwent RR and 72 underwent RP. The angle of exodeviation steadily increased over time in both groups after surgery. The durations of exodrift were longer in the RP group than in the RR group. The surgical success at postoperative year 2 was 55.3% in the RR group and 27.8% in the RP group (p<0.001). The amount of overcorrection was associated with successful outcomes in both groups.

Conclusions

In children with intermittent exotropia, RR group presented better surgical outcomes than RP group. The amount of initial overcorrection was important to achieve favourable outcomes in children with intermittent exotropia.

Long-term outcomes of bilateral lateral rectus recession versus unilateral lateral rectus recession-medial rectus plication in children with basic type intermittent exotropia

PURPOSE

To compare the long-term surgical outcomes between bilateral lateral rectus recession (BLR) and unilateral lateral rectus recession-medial rectus plication (RP) in intermittent exotropia.

METHODS

Children who underwent BLR or RP for basic type intermittent exotropia between 2015 and 2016 with a minimum follow-up period of 2 years were retrospectively reviewed. Surgical outcomes were classified based on postoperative angle of deviation as follows: success (esodeviation ≤ 5 prism diopters [PD] to exodeviation ≤ 10 PD), and failure (overcorrection [esodeviation > 5 PD] and undercorrection or recurrence [exodeviation > 10 PD]).

RESULTS

Of 144 patients, 90 underwent BLR and 54 underwent RP. The angle of exodeviation of the RP group steadily increased over time after the surgery. The BLR group showed an earlier exodrift and a more stable course compared to the RP group. Kaplan-Meier survival analysis showed a better survival in the BLR group, with final success rates of 48.9% in the BLR group and 25.9% in the RP group after a mean follow-up of 2.2 years. Patients with a successful outcome had greater esodeviation at 1 week postoperatively (at distance 7.6 PD in the BLR group, 11.4 in the RP group).

CONCLUSIONS

Surgical outcomes were better in the BLR group than in the RP group. The RP group showed higher rates of recurrence of exodeviation, while the BLR group presented a more stable course. Establishing more esodeviation at postoperative week 1 in the RP group compared to the BLR group would be required to achieve successful results.

Comparison of surgical outcomes between bilateral recession and unilateral recession-resection in moderate-angle intermittent exotropia

PURPOSE

To compare postoperative drift after bilateral lateral rectus recession (BLR) and after unilateral recession combined with medial rectus resection (R&R) in children with primary moderate-angle intermittent exotropia.

METHODS

The medical records of children with intermittent exotropia in the range of 25^Δ-50^Δ who underwent BLR or R&R from July 2015 to September 2016 were reviewed retrospectively. Outcomes were classified according to postoperative angle of deviation at distance as overcorrection (esophoria or -tropia of >5^Δ), success (esophoria or -tropia of ≤5^Δ to exophoria/tropia of ≤10^Δ), or recurrence (exophoria or -tropia of >10^Δ). Patients were examined on postoperative day 1 and at 6 weeks, 6 months, and 12 months. Sensory status was evaluated using the Titmus stereoacuity test.

RESULTS

A total of 330 children were included (BLR, 175; R&R, 155). Exotropic drift was greater in the R&R group in the period between day 1 and 6 weeks and from 6 to 12 months (P <0.05). Surgical successful rates in each group were comparable: 57.7% in the BLR group and 60.6% in the R&R group (P > 0.05). However, higher overcorrection rates were noted in the BLR group at 6 and 12 months (16.6% vs 6.5 % at 12 months [P = 0.003]). There were more patients with deteriorated stereopsis after surgery in the BLR group (P = 0.025).

CONCLUSIONS

In our study cohort, BLR was associated with more stable long-term ocular alignment and a higher rate of overcorrection than R&R. Postoperative day 1 overcorrection of <16^Δ following R&R and of <10^Δ following BLR were associated with relatively good results.

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.

Comparison of bilateral/unilateral lateral rectus recession and unilateral recession-resection for intermittent exotropia: a Meta-analysis

AIM

To compare the effectiveness of unilateral recession-resection (R&R) and bilateral/unilateral recession (BLR/ULR) for treatment of basic type of intermittent exotropia [IX(T)].

METHODS

A comprehensive literature search was performed using PubMed, EMBASE, and the Cochrane Library, to identify randomized controlled trials and comparative studies regarding the effectiveness of R&R and BLR/ULR for IX(T). Based on which, a Meta-analysis was then performed in terms of long-term success rate, overcorrection rate, and recurrence rate.

RESULTS

Nine studies in total satisfy the specified eligibility criteria. BLR is at disadvantage to R&R at a short-term follow-up [<2y, OR 0.56 (0.33-0.94) for success rate; OR 2.11 (1.17, 3.81) for undercorrection rate]. However, BLR achieved a higher success rate [OR 2.49 (1.61, 3.86)] and a lower undercorrection rate [OR 0.40 (0.23, 0.71)], compared to that of R&R at a long-term follow-up (>2y). There is no significant difference was found in overcorrection rate, regardless of the length of follow-up time [OR 0.85 (0.41, 1.75)]. In the treatment for small-angle IX(T), the final outcome was significantly different between the groups, demonstrating a more successful alignment [OR 0.37 (0.18, 0.74)] and a lower undercorrection [OR 3.50 (1.28, 7.26)] in the R&R group than in the ULR group. While for moderate-angle IX(T) (20 PD-25 PD), the effectiveness of R&R and ULR is quite equivalent with similar success rate [OR 1.08 (0.65, 1.79)] and undercorrection rate [OR 0.89 (0.54, 1.48)].

CONCLUSION

As regard to the effect of BLR and R&R, R&R shows an advantage over BLR at short term. But, BLR is more effective in the long term for the basic type IX(T) in children. R&R surgery should be a better choice for the treatment of small-angle IX(T) of ≤20 PD than ULR. However, both of ULR and R&R are recommended for moderate-angle IX(T) from 20 PD to 25 PD.

Outcomes of bilateral lateral rectus recession in treatment of recurrent exotropia after bilateral medial rectus resection

PURPOSE

To report the results of bilateral lateral rectus muscle recession for recurrent exotropia in cases where the primary surgery was a bilateral medial rectus resection.

METHODS

Retrospective chart review of 15 subjects who completed 6 months of follow-up. Data collected included patients' demographics and pre- and post-operative measurements of ocular alignment and motility. Surgical nomogram used was the same nomogram we use for primary cases of exotropia.

RESULTS

At 6-month follow-up, 73.3% of cases had a successful surgical outcome (defined as 8 PD of esotropia to 10 PD of exotropia). In addition, recession of lateral rectus muscles against the previously resected medial recti did not result in a significant increase in the limitation of abduction.

CONCLUSION

Bilateral lateral rectus recession using standard surgical tables is a safe and effective method for treating recurrent exotropia following bilateral medial rectus resection. Even large primary resections up to 12 mm do not seem to affect the results of bilateral lateral rectus recession.

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.

Long-term outcomes of augmented unilateral recess-resect procedure in children with intermittent exotropia

BACKGROUND

Initial overcorrection after exotropia surgery has been considered as a desirable result. Recently, there had been several studies that reported better surgical results of augmented bilateral lateral rectus muscle recession procedure over the conventional procedure.

OBJECTIVES

To compare the long-term results of augmented unilateral lateral rectus recession-medial rectus resection procedure (RR) with the original surgery in exotropic children.

DATA EXTRACTION

A retrospective cohort study was performed on a total of 121 children with exotropia who underwent RR from February 2005 to December 2012 and were followed-up for at least 24 months. In 64 patients, RR was performed based on the original surgical table (original RR group). In 57 patients, the amount of medial rectus muscle resection was increased by 1 mm (augmented RR group).

RESULTS

In the original RR group, 47 of 64 patients (73.4%) had a successful outcome, 13 patients (20.3%) had recurrence, and 4 patients (6.3%) had overcorrection at 2 years after surgery. In the augmented RR group, 45 of 57 patients (79.0%) were successful, 4 patients (7.0%) had recurrence and 8 patients (14.0%) had overcorrection at 2 years after surgery. The recurrence rate was significantly lower in the augmented RR group than the original RR group, whereas the overcorrection rate was not significantly different between two groups at 2 years after surgery (P = 0.036 and P = 0.153, respectively). The cumulative probability of recurrence was lower in the augmented group at 36 months after surgery (P = 0.046, log rank test).

CONCLUSIONS

The long-term success rate of augmented RR in exotropic children was 79.0% and the recurrence rate was significantly lower than original RR with comparable overcorrection rates. Augmented RR can be considered as an alternative procedure in children with basic and convergence insufficiency type 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.

Factors affecting residual exotropia after two muscle surgery for intermittent exotropia

AIM

To study the factors affecting residual exotropia (>10 PD) at 4-6wk postoperative visit following two rectus muscle surgery for intermittent exotropia [bilateral lateral rectus (LR) recession or unilateral recess resect procedure].

METHODS

A retrospective chart review of patients with intermittent exotropia ≤50 PD who underwent two rectus muscle surgery in between Jan. 2011 to Dec. 2013 was performed. Possible factors were compared between patients with residual exotropia (>10 PD) and successful outcome (within 10 PD of orthotropia) at the 4-6wk postoperative visit. Effect/dose ratio was calculated by dividing the effect of surgery by the total amount (mm) of muscle surgery done.

RESULTS

One hundred and fifty-seven patients with mean age of 14y (range 3-53y) were included. Twenty-seven patients (17.2%) had residual exotropia at 4-6wk postoperative follow up. Age at surgery (P=0.009) and preoperative deviation for distance (P≤0.001) and near (P=0.001) were identified as important predictors of unsuccessful outcome. The occurrence of residual exotropia was not affected by amblyopia, anisometropia, lateral incomitance, pattern deviation, vertical deviation, type of exotropia or type of surgery done (recess-resect or bilateral LR recession). The effect/dose ratio was more in deviations >40 PD in the both recess-resect and bilateral LR recession type of surgery. The effect/dose ratio was less in patients with residual exotropia as compared to the successful outcome group (1.36 PD/mm vs 2.05 PD/mm in the bilateral LR recession surgery and 1.93 PD/mm vs 2.63 PD/mm in the unilateral recess-resect surgery).

CONCLUSION

Residual exotropia is seen in 17% of patients after two muscle surgery for intermittent exotropia. Patients with older age and larger preoperative deviation have greater chances of developing failure of two muscle strabismus surgery for intermittent exotropia.

Patient Characteristics and Surgical Approach Impacting Simultaneous to Alternate Prism Cover Test Disparity After Exotropia Surgery: A Quantitative Look at the Difference in Motor Outcomes

PURPOSE

To investigate the relationship between simultaneous prism and cover test (SPCT) and alternate prism and cover test (APCT) outcomes after exotropia surgery, and to identify characteristics associated with significant disparity between them.

METHODS

Review of sensorimotor outcomes 2 to 6 months after exotropia surgery identified patients with alignment documented by both SPCT and APCT at the same examination. Two hundred seventy-four and 319 patients had both measurements recorded at distance and near, respectively. Correlation between the SPCT and APCT and range of APCT when the SPCT measurement was zero were determined. Patient characteristics studied for association with a difference between the SPCT and APCT exceeding known APCT test-retest variability included age, visual acuity, fusion, intermittency, pattern, preoperative and postoperative angle, and treatment with or without medial rectus resection.

RESULTS

SPCT and APCT outcomes were strongly correlated (P < .001), significantly different (P < .001), and linearly related. The percentage of patients who were orthotropic (SPCT = 0) was 76% at distance and 80% at near. Misalignment of 10 prism diopters (PD) or less by the APCT was present in 92% of orthotropic patients at distance and 84% at near. Surgery without medial rectus resection (P = .015), larger preoperative angle (P = .003), intermittent exotropia (P = .028), and postoperative exotropia rather than esotropia (P < .001) were associated with a significant SPCT-APCT difference.

CONCLUSIONS

Although a greater postoperative SPCT-APCT disparity was confirmed for patients with intermittent exotropia, it also independently associated with a larger preoperative deviation and surgery without medial rectus resection. Performing medial rectus resection, a surgeon's prerogative, provides more apparently consistent postoperative alignment characterized by less SPCT-APCT disparity. [J Pediatr Ophthalmol Strabismus. 2017;54(4):222-230.].

Comparison of Long-term Surgical Outcomes of Two-muscle Surgery in Basic-type Intermittent Exotropia: Bilateral versus Unilateral

Purpose

To compare long-term surgical outcomes after bilateral lateral rectus recession (BLR) and unilateral lateral rectus recession-medial rectus resection (RR) for the treatment of basic-type intermittent exotropia.

Methods

Consecutive patients who underwent BLR or RR for treatment of intermittent exotropia between 1999 and 2010 and underwent ≥5 years of follow-up were recruited for this study. Surgical outcomes were grouped according to postoperative angle of deviation: overcorrection (esophoria/tropia >8 prism diopters [Δ]), success (esophoria/tropia ≤8Δ to exophoria/tropia ≤8Δ), and undercorrection/recurrence (exophoria/tropia >8Δ). Outcomes were compared between the BLR group and the RR group at postoperative week 1, months 1 and 6, and years 1, 2, 3, 4, and 5.

Results

Of 99 patients, 37 underwent BLR and 62 underwent RR. At postoperative month 6 (97.3% vs. 82.3%, p = 0.045) and year 1 (91.9% vs. 74.2%, p = 0.040), the surgical success rates in the BLR group were significantly higher than in the RR group. Recurrence of exophoria/tropia most commonly occurred between 2 and 3 years after surgery in the BLR group, but continuous recurrences were found in the RR group. At postoperative year 5, the surgical success rate was 54.1% in the BLR group and 41.9% in the RR group (p = 0.403). The reoperation rate was 24.3% in the BLR group and 33.9% in the RR group (p = 0.317).

Conclusions

Surgical outcomes 5 years after surgery for intermittent exotropia were comparable between the BLR and RR groups. The surgical success rate and the reoperation rate were not significantly different between the BLR and RR 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.

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.

Type of the recurrent exotropia after bilateral rectus recession for intermittent exotropia

Background

The aim of this study was to investigate the type of exotropia (XT) based on the distance-near (D/N) difference in recurrent XT after bilateral lateral rectus (BLR) recession to treat intermittent XT (IXT) to look into the possibility of secondary convergence insufficiency (CI)-type strabismus.

Methods

A total of 121 patients with recurrent XT after BLR recession for basic-type and divergence excess (DE)-type IXT were retrospectively enrolled at a single institution. The distributions in the XT types were compared according to the D/N difference between primary and recurrent XT.

Results

Preoperatively, the population comprised 14 divergence excess (DE) types and 107 basic types. After the BLR recession, the XT-type composition changed to 59 basic types, 33 CI types, and 29 DE types. In one of the 14 preoperatively identified DE-type XT cases, the XT type changed to CI type, it changed to basic type in four cases, and the remaining nine cases showed no change in the DE type. The 107 preoperatively identified basic-type XT cases postoperatively became 55 basic-type, 32 CI-type, and 20 DE-type recurrent XT cases, and their postoperative distance XT control grades and near stereoacuity values did not significantly differ.

Conclusion

The XT type composition changed after the BLR recession. The XT types in recurrent XT after BLR recession showed an increasing proportion of CI-type. We suspect that an individual fusion mechanism might also influence the XT-type in recurrent XT in view of the somewhat increased DE-type in recurrent XT.

Outcome of two-muscle surgery for large-angle intermittent exotropia in children

BACKGROUND/AIMS

To evaluate the surgical outcomes of two-muscle surgery for childhood intermittent exotropia comparing large angles with moderate angles.

METHODS

We retrospectively reviewed the medical records of 178 children who had undergone bilateral lateral rectus recession (BLR) or unilateral recess-resect (RR) for large-angle (≥40 prism dioptres (PD); group A) or moderate-angle (≥20 and <30 PD; group B) intermittent exotropia with a postoperative follow-up period of 6 months or more. The main outcome measures were postoperative deviation angle and surgical success rate, and the secondary outcome measure was effect/dose ratio. The effect/dose ratio was defined as the corrected angle of deviation at postoperative 6 months divided by the sum of the amount of lateral rectus recession in each eye in BLR and by the sum of the amount of lateral rectus recession and medial rectus resection in RR. Surgical success was defined as alignment between 10 PD of exodeviation and 5 PD of esodeviation both at distance and at near.

RESULTS

There was a significant difference in mean angle of deviation at distance throughout the postoperative period (p<0.05). The final surgical success rate was significantly lower in group A than in group B (p<0.05). The effect/dose ratio for both BLR and unilateral RR was significantly greater in group A than in group B (p<0.05).

CONCLUSIONS

The patients with childhood intermittent exotropia with large angles showed significantly higher rates of undercorrection, though they also showed greater effects of BLR or RR per millimetre (the effect/dose ratio), compared with moderate-angle exotropia.

Clinical analysis of childhood intermittent exotropia with surgical success at postoperative 2 years

PURPOSE

To analyse the characteristics of children who had maintained the successful outcome at 2 years after surgery for intermittent exotropia.

METHODS

A retrospective study was performed in 216 patients who had undergone intermittent exotropia surgery and had had at least 2 years of follow-up. Surgical outcomes were grouped, according to the angle of deviation at postoperative 2 years, as success (esophoria/tropia ≤ 5 prism dioptres (PD) to exophoria/tropia ≤ 10PD), recurrence (exotropia > 10PD or reoperation within 2 years) or overcorrection (esophoria/tropia > 5PD). We investigated various clinical factors for their possible associations with the surgical outcomes.

RESULTS

Of the 216 patients, 128 (59%) were assigned to the success group, and 84 (39%) to the recurrence group. According to a univariate analysis, surgical method and the angle of deviation at the postoperative day 1 showed statistically significant associations with the surgical outcome for intermittent exotropia. However, in the results of a logistic regression test, the angle of deviation at distance at postoperative day 1 was the only factor showing a significant association (p = 0.023).

CONCLUSIONS

Early postoperative overcorrection was significantly associated with the maintenance of successful surgical outcome of intermittent exotropia at postoperative 2 years.

Long-Term Surgical Outcomes of Augmented Bilateral Lateral Rectus Recession in Children With Intermittent Exotropia

PURPOSE

To compare the long-term surgical outcomes of augmented bilateral lateral rectus (LR) recession with original surgery.

DESIGN

Retrospective, nonrandomized clinical study.

METHODS

A total of 447 children with ≤35 prism diopters (PD) of basic and divergence excess-type intermittent exotropia, who underwent original bilateral LR recession based on the largest angle measured at distance and near, or augmentation surgery with the surgical dosage augmented by 1.0-1.5 mm more than the original formula were included. Patients were observed for at least 2 years. Success rates, cumulative probabilities of success, factors related to recurrence, and overcorrection were evaluated.

RESULTS

At a mean follow-up of 4.0 years, 48 of 101 patients (48%) undergoing original surgery maintained successful alignment within 10 PD of exophoria/tropia and 5 PD of esophoria/tropia; 49 (49%) had recurrence, and 3 (3%) had overcorrection. After augmented surgery, 203 of 346 patients (59%) were successfully aligned, 129 (37%) had recurrence, and 14 (4%) had overcorrection. Augmented surgery showed higher long-term successful alignment rates (P= .047) and lower recurrence rates compared to original surgery (P = .042) and the overcorrection rate was similar between the 2 groups (P= .774). Patients with divergence excess type showed higher cumulative success rates compared to that of the basic type (P = .010) after augmented surgery.

CONCLUSION

Augmented bilateral LR recession resulted in more successful alignment and lower recurrence without higher overcorrection compared to the original surgery for the children with intermittent exotropia. Augmentation of the original table should be considered when planning bilateral LR recession, especially in patients with divergence excess-type 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.

The Stabilization of Postoperative Exo-drift in Intermittent Exotropia after Surgical Treatment

PURPOSE

To investigate the long-term clinical course of intermittent exotropia after surgical treatment to determine whether and when postoperative exo-drift stabilizes, and the required postsurgery follow-up duration in cases of intermittent exotropia.

METHODS

We retrospectively reviewed the medical records of patients diagnosed with intermittent exotropia who underwent surgical treatment between January 1992 and January 2006 at Yeungnam University Hospital and postoperatively performed regular follow-up examinations for up to 7 years. We also analyzed the difference in exo-drift stabilization, according to surgical procedure.

RESULTS

A total of 101 patients were enrolled in the study. Thirty-one patients underwent lateral rectus recession and medial rectus resection (R&R) and 70 patients underwent bilateral lateral rectus recession (BLR). The postoperative angles of deviation increased significantly during the initial 36 months, but no subsequent significant changes were observed for up to 84 months. Follow-ups for 7 years revealed that more than 50% of the total amount of exo-drift was observed within the first postoperative year. In addition, the angles of deviation at 1 year correlated with those at 7 years postoperatively (Pearson correlation coefficient r = 0.517, p < 0.001). No significant exo-drift was observed after 36 months in patients who underwent BLR, whereas after 18 months in patients who underwent R&R.

CONCLUSIONS

The minimum postoperative follow-up required after surgical treatment to ensure stable results is 36 months. In particular, careful follow-up is necessary during the first postoperative year to detect rapid exo-drift. Patients who underwent BLR required a longer follow-up than those who underwent R&R to ensure stable postoperative alignment.

Comparative study of lateral rectus recession versus recession-resection in unilateral surgery for intermittent exotropia

PURPOSE

To compare the outcomes of unilateral lateral rectus recession to unilateral recession-resection in the treatment of patients with intermittent exotropia.

METHODS

The medical records of patients with intermittent exotropia with exodeviation of 20(Δ) to 25(Δ) who underwent unilateral lateral rectus recession or recession-resection at a single center from 2002 to 2010 were retrospectively reviewed, and surgical outcomes between groups were compared.

RESULTS

Of 70 patients, 37 underwent lateral rectus recession; 33, recession-resection. The mean preoperative exodeviation was 22.2(Δ) ± 2.1(Δ) at distance and 22.3(Δ) ± 3.3(Δ) at near in the lateral rectus group and 24.5(Δ) ± 1.4(Δ) at distance and 26.4(Δ) ± 3.6(Δ) at near in the recession-resection group. Successful surgical outcome was defined as esodeviation of ≤5(Δ) to exodeviation of ≤10(Δ) at distance in primary position. The mean follow-up period was 37.1 months in the lateral rectus group and 44.6 months in the recession-resection group (P = 0.078). The surgical success did not differ significantly between groups at the final follow-up (45.9% in the lateral rectus group and 39.4% in the recession-resection group; P = 0.215). However, posteroperative overcorrection was less common in the lateral rectus group through 12 months' follow-up.

CONCLUSIONS

Surgical outcomes at a mean of 3.4 years did not differ significantly between groups. In our study cohort, unilateral lateral rectus recession showed a low risk of overcorrection in the treatment of mild to moderate angle exotropia.