Comparison of bilateral lateral rectus recession and unilateral recession resection for basic type intermittent exotropia in children

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.

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.

Revisiting the surgical table: An analysis of surgical dose-response in Asian exotropia

BACKGROUND

Previous research on the factors associated with surgical dose-response in strabismus surgery for exotropia has yielded inconsistent results. This study determined the factors influencing surgical dose-response in exotropia patients who underwent recession and resection (R&R).

METHODS

Exotropia patients who underwent unilateral R&R at the National Taiwan University Hospital between 2006 and 2021 were evaluated. Deviation-angle differences in prism diopters (PD) were measured preoperatively and at 1 month postoperatively. Surgical dose-response (PD/mm) was defined as the difference in deviation angle (in PD) divided by the surgical dose in millimeters. Linear and non-linear regression models were used to evaluate the influence of variables including age, sex, axial length, and preoperative deviation on surgical dose-response.

RESULTS

Overall, 295 patients (162 children; 133 adults) were included. Average surgical dose-response in the pediatric and adult groups was 2.82 ± 0.60 PD/mm and 3.02 ± 0.62 PD/mm, respectively. Male sex was negatively correlated with surgical dose-response in children. The surgical dose-response was larger in adults with longer axial length (>25.64 mm) and patients with larger preoperative deviation (>42.6 PD and >38.7 PD in pediatric and adult groups, respectively). Surgical dose-responses peaked at 35.1 years.

CONCLUSION

Age, axial length, and preoperative deviation have a nonlinear effect on surgical dose-responses in exotropia patients undergoing R&R. Surgical dose-responses were larger in patients in young adulthood, with longer axial length and larger preoperative deviation angle. A table with fitted values for surgical dose-response based on age, axial length, and preoperative deviation was established for clinical reference.

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.

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.

Effects of orthoptic therapy in children with intermittent exotropia after surgery: study protocol for a randomized controlled trial

Background

Intermittent exotropia (IXT) is the most common type of exotropia in China. Surgery is usually required to align the eye deviation to maintain or obtain better binocular visual function. However, there is a high rate of exodrift or recurrence in surgically treated patients. Orthoptic therapy is sometimes recommended for IXT patients after surgery. However, there is a lack of high-quality randomized controlled trials to prove that orthoptic therapy could be an effective supplement to surgical treatment for IXT patients. The main purpose of this study is to test the clinical effectiveness of orthoptic therapy in long-term stabilization of postoperative IXT patient. This report describes the design and methodology of the Intermittent Exotropia Postoperative Treatment Clinical Trial, which is the first large-sample, blank-controlled, randomized clinical trial.

Methods

A total of 136 IXT patients (aged 7 to 17 years) will be enrolled and assigned to the orthoptic therapy group or blank control group according to a simple randomization scheme. Patients in the orthoptic therapy group will receive at least 2 months of orthoptic therapy, such as anti-suppression, vergence, and accommodation training. Patients in the blank control group will receive only refractive correction. All enrolled patients will need regular follow-up observation until 24 months after surgery. The primary outcome will be the proportion of participants meeting suboptimal surgical outcomes in this 24-month follow-up, which is defined as (1) exodeviation of 10 prism diopters (PD) at distance or near using the simultaneous prism and cover test (SPCT) or (2) loss of 2 or more octaves of stereoacuity from baseline, at any masked follow-up visit examination. The secondary outcomes will be the exodeviation at distance and near using the simultaneous prism and alternate cover test (PACT), magnitude of fusional convergence, stereoacuity, and accommodation. Measurements will be taken at baseline and at the 6-, 12-, 18-, and 24-month follow-ups.

Discussion

To the best of our knowledge, this will be the first prospective, randomized controlled study of orthoptic training in IXT patients after surgery. The aim of this work is to confirm the efficacy of orthoptic therapy in reducing the proportion of recurrence among IXT patients after surgery and improving binocular vision function.

Trial registration

Chinese Clinical Trial Registry ChiCTR1900026891. Registered on 25 October 2019.

Dose-Response of Primary Bilateral Medial Rectus Resection in Infantile Exotropia

PURPOSE

To evaluate the dose-response relationship for primary bilateral medial rectus resection in children with exotropia, based on outcomes with this procedure.

METHODS

Dose-response at both distance and near were calculated as prism diopters correction per millimeter (PD/mm) of rectus resection. All surgeries were performed under general anesthesia through a fornix incision, using doubled-armed 6-0 polyglactin sutures. The resection amount ranged from 5 to 8 mm in each eye, according to the surgical dosage based on the largest angle of preoperative deviation.

RESULTS

The mean surgical dose-response for all procedures was 2.83 ± 1.03 PD/mm of resection at distance and near. The overall success rate was 53% at the final examination after a mean follow-up of 21.9 months. Patients with moderate angles (25 to 45 PD) had a higher success rate than those with 50 PD or greater deviation.

CONCLUSIONS

Primary bilateral medial rectus resection should be considered as a surgical alternative in childhood exotropia, particularly for moderate and constant deviations. [J Pediatr Ophthalmol Strabismus. 2022;59(1):24-27.].

Binocular Summation Is Intact in Intermittent Exotropia After Surgery

Purpose: To determine binocular summation of surgically treated intermittent exotropia (IXT) patients by measuring the contrast threshold.

Methods: We recruited 38 surgically treated IXT patients aged 8–24 years and 20 age-matched healthy controls. All participants had normal or corrected-to-normal visual acuity (Snellen ≥ 20/20) in both eyes. The IXT patients had undergone the surgery at least a year prior to the study. Twenty-one of them obtained good alignment and 17 experienced a recurrence of exotropia. We measured the observers' monocular and binocular contrast sensitivities (CS) at six spatial frequencies (1.5, 3, 6, 12, 18, 24 cycles/degree) as an index of visual information processing at the threshold level. Binocular summation was evaluated against a baseline model of simple probability summation based on the CS at each spatial frequency and the area under the log contrast sensitivity function (AULCSF).

Results: The exo-deviation of IXTs with good alignment was −6.38 ± 3.61 prism diopters (pd) at 33 cm and −5.14 ± 4.07 pd at 5 m. For the patients with recurrence, it was −23.47 ± 5.53 pd and −21.12 ± 4.28 pd, respectively. There was no significant difference in the binocular summation ratio (BSR) between the surgically treated IXT patients, including those with good alignment and recurrence, and normal controls at each spatial frequency [F_(2,55) = 0.416, P = 0.662] and AULCSF [F_(2,55) = 0.469, P = 0.628]. In addition, the BSR was not associated with stereopsis (r = −0.151, P = 0.365).

Conclusion: Our findings of normal contrast sensitivity binocular summation ratio in IXT after surgical treatment suggest that the ability of the visual cortex in processing binocular information is intact at the contrast threshold level.

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).

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.].

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.].

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.

Transient Increase of Wavefront Aberrations after Horizontal Rectus Muscle Surgery in Exotropia

Aims: Wavefront aberration (WA) has become one of the important indicators for measuring the visual quality. Whether strabismus surgery affects the WA remain controversial. This study aims to investigate the postoperative alterations of WA in patients who underwent horizontal rectus muscle surgery.Methods: A total of 34 patients were enrolled and divided into two groups: bilateral lateral rectus recession (BLR) group and unilateral lateral rectus recession and medial rectus resection (R&R) group. The WA was examined 1 day before surgery, 3 days, and 6 weeks after surgery using the iTrace Visual Function Analyzer (Tracey Technologies).Results: Significant increases in total WA, lower-order aberration (LOA) and higher-order aberration (HOA) of both groups were detected in 3 days after surgery (P < 0.05), while no significant differences in 6 weeks after surgery. Significant increases in astigmatism, secondary astigmatism, and trefoil of both groups were detected in 3 days after surgery (P < 0.05), while no significant differences in individual order of LOA and HOA in 6 weeks postoperatively. Z₂², Z₃³, and Z₄² of both groups increased significantly 3 days after surgery (P < 0.05) and returned to baseline level 6 weeks after surgery, while the rest Zernike coefficients remained the same postoperatively. When comparing the differences between the two groups, there were no statistically significant differences in these parameters between baseline and each follow-up visit postoperatively.Conclusions: The increase of WA restored to pre-operative level in 6 weeks after surgery, indicating the influences of horizontal rectus muscle surgery to WA were transient and reversible.

The Stereoacuity-Dependent Concordance between Preferred Fixating Eye and Sighting Dominant Eye in Paediatric Intermittent Exotropia

Objective: To investigate if the concordance between sighting dominance and fixation preference depends on stereoacuity in children with intermittent exotropia (IXT). Methods: A total of 160 children (aged 7.24 ± 2.14 years, range 4-13 years) with the basic type of IXT at distance participated in the study. Binocular fusion and vergence were evaluated with synoptophore. Stereoacuity was assessed using the Titmus stereo test. The hole-in-the-card test was used to determine sighting dominance, while the eye of fixation preference was determined by the cover-uncover test. The chi-squared test was used to evaluate whether a distribution was different from the chance distribution. The Kappa value was computed to quantify the concordance between fixation preference and sighting dominance. Results: The mean deviations were 19 ± 4.58 prism diopters (PD) and 18.9 ± 4.47 PD for at distance and near, respectively. The mean amplitude of divergence was 5.34 ± 1.89 PD, and the mean amplitude of convergence was 14.08 ± 4.96 PD. Subjects were categorized as having either good (40-60 seconds of arc, n = 41), moderate (80-140 seconds of arc, n = 46), poor (≥ 200 seconds of arc, n = 45), or having no measurable stereoacuity (n = 28). The concordance between sighting dominance and fixation preference was high in subjects with good (Kappa = 0.858) or moderate (kappa = 0.812) stereoacuity, but it decreased quickly in subjects with poor stereoacuity (kappa = 0.496) or no stereopsis (kappa = 0.563). Conclusions: In pediatric patients with IXT, the concordance between sighting dominance and fixation preference depends on stereoacuity. The results from these two tests become increasingly incongruent as stereoacuity deteriorated.

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.

Changes in refractive error and axial length after horizontal muscle surgery for strabismus

PURPOSE

To investigate changes in refractive error following horizontal muscle surgery and to analyze the relationship between these changes and axial length.

METHODS

Patients with intermittent exotropia who underwent bilateral lateral rectus recession (LR group) or unilateral lateral rectus recession with medial rectus resection (RR group) were investigated prospectively. The patients were followed for at least 3 months postoperatively; refractive error, axial length, mean corneal astigmatism, anterior chamber depth, corneal thickness, and intraocular pressure were evaluated at each examination. Postoperative changes in both groups were compared.

RESULTS

A total of 64 eyes of 47 patients were included-34 eyes in the LR group and 30 eyes in the RR group. In both groups refractive error, axial length, and mean corneal astigmatism significantly increased 1 day postoperatively, although the changes in all three parameters returned to their preoperative values within 1 month of surgery and remained stable thereafter for the duration of the follow-up period. There was a negative correlation between changes in axial length and refractive error toward myopia in the 64 eyes on postoperative day 1 (partial correlation coefficient r = -0.637; P < 0.001). Changes in refractive error and axial length were significantly larger in the RR than in the LR group 1 day postoperatively (P < 0.001 and P < 0.001, resp.).

CONCLUSIONS

Horizontal muscle surgery induces a transient myopic shift. This is thought to be due to axial length elongation as well as changes in corneal astigmatism.

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.

Bilateral lateral rectus recession versus unilateral recession/resection for basic intermittent exotropia

INTRODUCTION

Intermittent exotropia requires surgical resolution under some clinical circumstances. The main techniques are bilateral lateral rectus recession and unilateral recess/resection. Although bilateral recession is the most widely used, it is not clear whether it leads to better results.

METHODS

To answer this question we used Epistemonikos, the largest database of systematic reviews in health, which is maintained by screening multiple information sources, including MEDLINE, EMBASE, Cochrane, among others. We extracted data from the systematic reviews, reanalyzed data of primary studies, conducted a meta-analysis and generated a summary of findings table using the GRADE approach.

RESULTS AND CONCLUSIONS

We identified five systematic reviews including seven studies overall, of which three were randomized trials. We concluded unilateral recess/resection might achieve greater surgical success and probably decrease the rate of undercorrection/recurrence when compared to bilateral lateral rectus recession.

Relation between early postoperative deviation and long-term outcome after unilateral lateral rectus recession and medial rectus resection for adult exotropia

AIM

To evaluate the relationship between early postoperative deviation and long-term outcome after unilateral recession and resection surgery for adult exotropia, and to evaluate exotropic shift after surgery.

METHODS

This was a retroprospective study involving adult patients with exotropia who underwent unilateral recession and resection surgery and were followed up for at least 2y. The results were evaluated at 2y and the final visit. Factors influencing a successful outcome were analyzed. Early postoperative deviation at 1wk was used to evaluate relationship with long-term outcome. The long-term outcome was classified into 3 groups: successful, acceptable, and poor. Successful outcome was defined as a distance deviation between esodeviation 8 prism diopters (PD) and exodeviation 10 PD.

RESULTS

Forty-two patients were enrolled. The mean age at surgery was 26y (range, 15-49y). The median follow-up period was 30mo (range, 24-108mo). Successful outcome was found in 81% of patients at 2y and in 71% at the final visit. Overcorrection at 1wk postoperatively was associated with a successful outcome at 2y. Initial postoperative alignment between orthotropia and esodeviation of 8 PD had the highest chance of a successful outcome (RR=2.2). The mean postoperative exotropic drift was 4.7 PD at the first month and 9.3 PD at 2y.

CONCLUSION

Initial postoperative deviation can predict long-term outcome after unilateral recession and resection surgery for adult exotropia. The most desirable outcome at 1wk post-operatively was orthotropia to small esodeviation. Most patients have exotropic drift at a subsequent follow-up, especially in the first month after surgery.

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.

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.

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.

Long-term postoperative outcomes of bilateral lateral rectus recession vs unilateral recession-resection for intermittent exotropia

AIM

To discuss the long-term postoperative results of bilateral lateral rectus recession (BLR) and unilateral lateral rectus recession-medial rectus resection (RR) in therapy of intermittent exotropia.

METHODS

We retrospectively analyzed 213 cases of intermittent exotropia who underwent surgery between 2008 and 2010. The patients were grouped into BLR group and RR group. Motor outcomes were divided into three groups on the basis of the angle of deviation after surgery: overcorrection (esotropia/phoria >5(Δ)), orthophoria (esotropia/phoria ≤5(Δ) to exotropia/phoria ≤10(Δ)), and undercorrection/recurrence (exotropia/phoria >10(Δ)). Titmus test was used to evaluate stereoacuity, the stereoacuity <800s of arc meaned the patients had stereopsis. Surgical outcome including motor criteria and sensory status were compared at postoperative 6, 12, 24mo and at 36mo examination between groups.

RESULTS

At 12, 24mo after surgery, the motor outcomes had no difference (P>0.05) between groups. However, the motor outcomes at 6, 36mo were signally different in each group, indicating the success rate in RR group at 6mo was higher than that in BLR group (83.02% vs 82.24%, P<0.05) but the result was contrary at the 3y examination (60.75% vs 43.40%, P<0.05). No statistical significance were found in the sensory outcomes between the groups at mean of 3.7y follow-up.

CONCLUSION

The motor outcomes in RR group were better than in BLR group at 6mo after surgery, while the 3y outcomes were better in BLR group. This may be due to the recurrence rate of the BLR was lower than the RR group's.