Outcome study of unilateral lateral rectus recession for small to moderate angle intermittent exotropia in children

Long-term surgical outcomes of one-muscle vs. two-muscle horizontal strabismus surgery

PURPOSE

While horizontal strabismus surgery is generally considered to have favorable outcomes, success rates can vary by type of procedure. Our purpose is to compare the long-term outcomes of patients who underwent one-muscle vs. two-muscle horizontal strabismus surgery.

METHODS

This is a retrospective study comparing one-muscle to two-muscle strabismus surgery for small to moderate angle horizontal strabismus. Demographic data and eye exam parameters were compared at baseline and postoperatively (6 months up to 6 years). Surgical success was defined as a post-operative angle of 10 PD or less. We also compared outcomes by strabismus type: esotropia vs exotropia and adjusted the analysis for previous strabismus surgery.

RESULTS

Out of 89 patients with moderate angle horizontal strabismus (25 PD or less), 17 patients had a one-muscle operation, and 72 patients had two-muscle surgery. The mean age was 14.12 ± 9.30 years and 11.70 ± 11.30 years for the one-muscle and two-muscle groups, respectively (p = .74). The baseline characteristics of both groups were comparable. Follow-up time was 32.82 ± 26.93 months in one-muscle and 37.67 ± 23.81 in two-muscle groups (p = .29). Success rate was 70.6% for the one-muscle group and 68.10% for the two-muscle group (p = .69). Outcomes were similar when divided into esotropia and exotropia. The success rate was not affected by previous strabismus surgeries nor by the initial angle of deviation.

CONCLUSION

One-muscle and two-muscle horizontal strabismus surgery had similar long-term outcomes and did not differ by strabismus type nor by angle of deviation.

Results of Unilateral Lateral Rectus Recession Surgery in 15 - 30 PD Intermittent Exotropia

PURPOSE

To evaluate the surgical outcomes of unilateral lateral rectus muscle recession (ULR) with low surgical dosage in patients with intermittent exotropia (IXT) of 15 - 30 prism dioptres (PD).

METHODS

We retrospectively analysed 92 eyes of 92 patients who underwent ULR surgery with the diagnosis of IXT of 15 - 30 PD at distance fixation between January 2017 and June 2019. ULR surgery of 6.5 mm was performed for exotropia of 15 - 20 PD, 7.5 mm for that of 20 - 25 PD, and 8.5 mm for that of 25 - 30 PD and postoperative results were evaluated at the 1st week, 1st month, 6th month, and the 2nd year. Orthophoria or IXT less than 10 PD was accepted as successful.

RESULTS

The mean preoperative deviation angle at distance was 22.3 ± 4.4 PD. Mean postoperative deviation angles at distance were 2.5 ± 1.7, 3.9 ± 2.4, 6.5 ± 3.0, and 8.7 ± 3.1 at 1 week, 1 month, 6 months, and 2 years, respectively. The surgical success rate of ULR was 100, 96.7, 84.7, and 77.1% at the 1st week, 1st month, 6th month, and the 2nd year, respectively. In the long-term results, there were no complications such as lateral gaze incomitance, overcorrection, or deterioration in stereopsis.

CONCLUSION

Using the ULR technique, we were able to obtain effective surgical results in IXT with less surgical dosage and without any serious complications. ULR surgery can be used as an effective method in patients with IXT of 15 - 30 PD.

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.

Comparison of Unilateral Versus Bilateral Lateral Rectus Recession for Small Angle Intermittent Exotropia: Outcomes and Surgical Dose-Responses

PURPOSE

To compare the surgical outcomes of unilateral lateral rectus recession to bilateral lateral rectus recession for small angle intermittent exotropia.

METHODS

This was a retrospective cohort study of pediatric patients with an intermittent exotropia between 16 and 20 prism diopters (PD) who underwent unilateral lateral rectus recession or bilateral lateral rectus recession at a single tertiary care pediatric hospital. The primary outcome was success (exotropia < 10 PD of esotropia < 5 PD, no decrease in stereopsis > 0.6 log arcsec, and no reoperation) at 12 months postoperatively. Secondary outcomes included survival analysis of time to surgical failure, surgical dose-response, and improvement in central fusion or stereopsis.

RESULTS

At 12 months, successful outcomes were achieved in 13 of 27 patients (46%) in the bilateral lateral rectus recession group and 19 of 28 patients (70%) in the unilateral lateral rectus recession group, which was not a statistically significant difference (P = .10). Survival analysis showed a trend toward a higher rate of failure in the bilateral lateral rectus recession group compared to the unilateral lateral rectus recession group (P = .04). The mean surgical dose-response was 1.7 PD/mm at 1 week and 1.0 PD/mm at 12 months for the bilateral lateral rectus recession group, and 2.0 PD/mm at 1 week postoperatively and 1.4 PD/mm at 12 months postoperatively for the unilateral lateral rectus recession group. There were no cases of long-term postoperative lateral incomitance in either group.

CONCLUSIONS

Unilateral lateral rectus recession and bilateral lateral rectus recession have similar success rates for small angle intermittent exotropia after at least 12 months of follow-up. Randomized controlled trials in surgical management of intermittent exotropia should consider unilateral lateral rectus recession as a treatment arm. [J Pediatr Ophthalmol Strabismus. 2022;59(5):350-355.].

A Prospective Study of One-Muscle Surgery in 15-25 Prism Diopters Horizontal Comitant Strabismus in Adults

Purpose

To prospectively evaluate the results of one-muscle surgery in 15-25 prism diopters (PD) horizontal comitant strabismus in adults.

Patients and Methods

15-25 PD horizontal strabismus patients, comprising 25 exotropic (XT) patients and 11 esotropic (ET) patients, who underwent one-muscle recession by a single surgeon with a fixed surgical dosage were included in the study with a minimum follow-up of 3 months. The main outcome was a surgical success, which is defined as a residual deviation of <8 PD at the last examination. Other parameters include postoperative lateral incomitance and patient satisfaction. Postoperative lateral incomitance indicated a difference in deviation of >5 PD between the primary position and lateral gaze, or duction limitation at any visit. Patient satisfaction regarding cosmetic and functional outcomes was assessed by using a 5-point Likert scale.

Results

Successful alignment was obtained in 19 (76%) and 9 (81.81%) XT and ET patients (p = 1.00), with a median and interquartile range (IQR) of follow-up time of 3, 3-3 months and 3, 3-7 months, respectively. Postoperative lateral incomitance was observed in 8 (32%) XT patients and in 1 (9.09%) ET patient (p = 0.22). One XT patient and one ET patient who developed incomitance reported diplopia, which disappeared 3 months after surgery. One XT patient reported diplopia while gazing towards the operated eye whilst one ET patient reported diplopia occasionally which was unrelated to gaze direction. Patient satisfaction was based on Likert scale scores with 4.12 ± 0.97 in XT patients and 4.73 ± 0.65 in ET patients (p = 0.07).

Conclusion

One-muscle recession with a fixed surgical dosage was effective for treating small angle horizontal strabismus with a high rate of surgical success and patient satisfaction. Although postoperative lateral incomitance occurred, only a few patients developed symptomatic diplopia, which completely resolved 3 months after surgery.

Stepped Strabismus Surgery

Purpose

To present stepped strabismus surgery as a novel technique in cases of small to moderate angle strabismus.

Methods

Retrospective chart review of cases of stepped strabismus surgery from 2010 untill 2018. In stepped surgery, the first muscle is operated on under rapid induction-recovery IV propofol infusion. Patient is assessed in the OR. If deemed necessary, other muscles are operated on under general anesthesia. No adjustable sutures are used.

Results

The technique was used in 22 cases of superior oblique palsy (SOP) (primary position hypertropia in the range of 12–25 prism diopters) and 29 horizontal strabismus cases (angles in the range 12–20 prism diopters). The first step was an inferior oblique myectomy in the SOP cases and a single rectus recession in the horizontal cases. After intraoperative assessment, 31% (16/51) needed additional muscle surgery. After 6 months of follow up, the overall reoperation rate was 9%. The technique was well tolerated by all patients.

Conclusion

Stepped strabismus surgery is a useful technique for small to moderate angle strabismus cases with the potential for reducing the number of extraocular muscles operated on without compromising the surgical outcome.

Association between esodeviation and primary open-angle glaucoma: the 2010-2011 Korea National Health and Nutrition Examination Survey

BACKGROUND/AIMS

To evaluate the association between strabismus and primary open-angle glaucoma (POAG) in a representative Korean population.

METHODS

A total of 11 114 participants aged 20 years or older in the Korea National Health and Nutrition Examination Survey database for the years 2010 through 2011 were reviewed. A standardised protocol was used to interview every participant and to perform comprehensive ophthalmic examinations. Glaucoma diagnosis was based on fundus photography and frequency-doubling technology perimetry results, according to the International Society of Geographical and Epidemiological Ophthalmology criteria. Ocular alignment was evaluated using the alternate prism and cover test, and clinically significant horizontal strabismus was defined as exodeviation of ≥15 prism dioptres (PD) and esodeviation of ≥10 PD. Univariate and multivariate regression analyses were used to evaluate the potential risk factors for POAG.

RESULTS

In the Korean population, subjects with clinically significant esodeviation had a much higher prevalence of POAG (12.32%) than those without clinically significant esodeviation (3.14%, p=0.016). After adjusting for age and intraocular pressure, clinically significant esodeviation was independently associated with POAG (OR 7.61, p=0.002).

CONCLUSION

Esodeviation was independently associated with POAG in the Korean population. This could be the result of, at least in part, ocular-adduction-induced greater strain on the temporal optic nerve head and peripapillary tissues, which makes eyes with esodeviation more vulnerable to POAG.

Surgical outcomes related to degree of unilateral lateral rectus muscle recession in intermittent exotropia of 20 prism diopters

PURPOSE

We compared the surgical results of different degrees of unilateral lateral rectus muscle recession (ULR) and investigated the surgical outcomes and factors related to recurrence of intermittent exotropia of 20 prism diopters (PD).

STUDY DESIGN

Retrospective study.

METHODS

The study comprised 163 patients with intermittent exotropia of 20 PD who underwent ULR between January 2010 and May 2015 and at least 2 years of follow-up after the initial surgery. The patients were divided into 3 groups according to the extent of ULR (8.0, 8.5, or 9.0 mm), and the surgical results were compared. We investigated the surgical outcomes and factors related to recurrence.

RESULTS

The mean postoperative follow-up period was 3.89 ± 1.82 years. The rate of recurrence within 2 years differed clinically (8.0 mm: 25.7%; 8.5 mm: 19.0%; 9.0 mm: 8.6%). However, other factors did not significantly differ among the groups. The comparison of the recurrence and the nonrecurrence groups showed that the age at the time of surgery varied significantly (recurring: 6.5 years, nonrecurring: 8 years; P = 0.012). A younger age at the time of surgery and a ULR of 8.0 mm were significant risk factors for the recurrence of ULR in intermittent exotropia of 20 PD.

CONCLUSION

We suggest that a surgical dose of 9.0 mm ULR is preferable to 8.0 mm ULR for intermittent exotropia of 20 PD.

Comparison of surgery versus observation for small angle intermittent exotropia

In young children with small angle exotropia, making decisions for the individual patient whether to perform surgery or not, and choosing the optimal time for surgical intervention are quite difficult. We aimed to compare the long-term outcomes of small angle intermittent exotropia of 20 prism diopters (PD) or less after observation versus strabismus surgery. A retrospective study was performed on 164 patients aged 3 to 13 who underwent surgical intervention or observation with or without conservative management for intermittent exotropia of 14 to 20 PD. The minimum follow-up period was 2 years. The average follow-up period was 3.9 ± 2.2 years in the observation group and 4.5 ± 2.3 years in the surgery group. At the final examination, the mean angle of deviation at distance was 11.1 ± 8.9 PD in the observation group and 9.0 ± 7.5 PD in the surgery group, which was not significantly different (P = 0.121). Changes in sensory outcome and fusional control were not significantly different between both groups (P = 0.748 and P = 0.968). Subgroup analysis including patients with poor fusional control also showed similar results. By multivariate analysis, the type of surgery, unilateral recess-resect procedure, was the only predictive factor of good motor outcome in the surgery group. In conclusion, long-term surgical outcomes in small angle exotropia did not appear to be more satisfying than observation in terms of motor and sensory outcomes.

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.

One-Muscle Strabismus Surgery: A Review

Proper management of a patient with small to moderate horizontal deviations continues to be challenging for the strabismus surgeon. The use of one-muscle surgery for comitant strabismus has been controversial because of concerns that it may result in a significant number of undercorrections and/or ocular incomitance. Recent literature on unilateral rectus muscle surgery has shown that this surgery is a safe and effective procedure for small and moderate angle horizontal deviations. It has the advantage of limiting surgery to one eye, reducing operative time and possible cost to the family, and leaving other muscles untouched in case repeat surgery is necessary. Larger studies need to be done in the future; however, this surgery should be considered as a primary approach in the treatment of small to moderate angle esotropia. [J Pediatr Ophthalmol Strabismus. 2018;55(5):288-292.].

The use of one muscle recession for horizontal strabismus

Purpose

To evaluate the outcomes of one muscle recession for horizontal comitant strabismus at a major referral hospital in the Middle East.

Method

Retrospective charts review of postoperative outcomes of 90 patients who had undergone one muscle recession for small to moderate angle esotropia or exotropia. Data were collected for age, vision, amblyopia, previous surgery or botulinum toxin injection, preoperative deviation, amount and type of one muscle surgery, and postoperative deviation at the initial and last (six months or more) postoperative visit. Successful alignment was defined as ±10 prism diopters (PD) of orthophoria.

Results

Sixty patients underwent medial rectus recession and 30 patients underwent lateral rectus recession. The average preoperative and last follow up deviation -respectively- was 24 ± 6.1 PD (15–35) PD and 14.62 ± 8.91 PD in the medial rectus recession group and 21.3 ± 5.1 PD (12–30) and 12.60 ± 8.74 in the lateral rectus recession group. The final success rates were 63.3% in both groups.

Conclusion

Single muscle strabismus surgery to correct horizontal strabismus had a variable outcome. Larger recession may help in achieving better outcomes. Properly designed prospective studies may help in identifying the factors affecting the outcomes of single muscle strabismus surgeries.

Prevalence and risk factors of strabismus in children and adolescents in South Korea: Korea National Health and Nutrition Examination Survey, 2008-2011

Purpose

To evaluate the prevalence and risk factors associated with horizontal strabismus in children and adolescents in South Korea.

Methods

A total of 5,935 children and adolescents 5–18 years of age who participated in the fourth and fifth Korean National Health and Nutrition Examination Survey (KNHANES IV-V) from July 2008 to December 2011 were evaluated and the prevalence of horizontal strabismus was estimated. Univariate and multivariate logistic regression analyses were conducted to determine the association between demographic, socioeconomic and clinical risk factors and clinically significant exodeviation (≥15 prism diopters [PD]) and esodeviation (≥10 PD).

Results

Among 5,935 eligible subjects, 84 subjects had clinically significant exodeviation and 13 had clinically significant esodeviation. The overall prevalence of clinically significant horizontal strabismus was 1.6% (95% confidence interval [CI], 1.2–2.1): 1.3% (95% CI, 1.0–1.7) for clinically significant exodeviation and 0.3% (95% CI, 0.1–0.6) for clinically significant esodeviation. Clinically significant exodeviation was associated with amblyopia (adjusted odds ratio [aOR], 6.45; 95% CI, 2.14–19.44), family history of strabismus (aOR, 4.91; 95% CI, 1.71–14.08) and astigmatism ≥1.0 D (aOR, 1.84; 95% CI, 1.13–2.98). Clinically significant esodeviation was associated with hyperopia (aOR, 12.16; 95% CI, 1.31–113.04) and amblyopia (aOR, 4.70; 95% CI, 1.12–19.81). Other demographic, socioeconomic, and clinical variables were not associated with strabismus.

Conclusion

This study provides data on the prevalence and independent risk factors for clinically significant exodeviation and esodeviation in a representative population of children and adolescents in South Korea.

Surgical outcomes according to distance between preplaced suture and muscle insertion in lateral rectus recession

PURPOSE

To compare surgical outcomes according to the distance between the preplaced suture and the muscle insertion in lateral rectus (LR) recession for exotropia.

METHODS

We retrospectively reviewed 64 patients who had undergone unilateral LR recession by one right-handed surgeon and divided the patients into 2 groups: right LR recession (R group, 26 patients) and left LR recession (L group, 38 patients). In the R group, the preplaced suture was behind the hook, far from the insertion; in the L group, the suture was in front of the hook, near the insertion. The main outcome measures were postoperative alignment and surgical success rate and the secondary outcome measure was effect/dose ratio. Surgical success was defined as an alignment between 10 prism diopters (PD) of exodeviation and 5 PD of esodeviation both at distance and at near. The effect/dose ratio was defined as the corrected angle of deviation at postoperative 6 months divided by the amount of LR recession.

RESULTS

The mean angle of deviation at distance showed a significant difference between the groups at postoperative 3 months (p = 0.022), but not at final follow-up (p = 0.163). There was no difference between the groups in the mean angle of deviation at near postoperatively. Surgical success was achieved in 73.1% of the R group and 71.1% of the L group at final follow-up, which was not significant (p = 0.860).

CONCLUSIONS

The distance between the preplaced suture and the muscle insertion in LR recession did not affect the surgical success rate or the postoperative alignment at final follow-up.

Prognostic preoperative factors for successful outcome of surgery in horizontal strabismus

CONTEXT

Surgery for horizontal strabismus reportedly has a success rate of 60%-80%. However, which preoperative factors are predictive of this success is not clear.

AIMS

To identify prognostic factors those are predictive of successful outcome in horizontal strabismus surgery.

SETTINGS AND DESIGN

Observational analytical study using multiple logistic regression (MLR).

SUBJECTS AND METHODS

We assessed the medical records of patients who had undergone first-time horizontal muscle strabismus surgery between 2002 and 2013, where complete follow-up data were available for ≥6 weeks, and also, we collected data prospectively on patients operated between January 2014 and September 2015. Successful outcome was defined as a postoperative angle of deviation within 10 prism diopter of orthophoria at ≥6 weeks postoperatively. Independent variables considered were age at onset, age at surgery, duration, gender, deviation - type and amount, logMAR visual acuity (VA) - mean and of the poorer eye, mean refractive error, amount of anisometropia, and presence of dense amblyopia. Only those with P < 0.2 on univariate analyses (UAs) were included in the MLR, with significance set at P ≤ 0.05.

STATISTICAL ANALYSES

UA (Chi-square for categorical variables and t-tests for continuous variables), followed by logistic regression analysis.

RESULTS

Of 113 patients, on UA, type of deviation (P = 0.01), age at surgery (P = 0.16), absence of dense amblyopia (P = 0.002), and logMAR VA of the poorer eye (P = 0.005) qualified for the inclusion in MLR. On MLR, esotropia (ET) (odds ratio [OR]: 4.46) and absence of dense amblyopia (OR: 5.90) were associated with success.

CONCLUSIONS

With an overall success rate of 83%, ET and absence of dense amblyopia were significantly predictive of surgical success.

Comparison of Long-term Surgical Outcomes Between Unilateral Recession and Unilateral Recession-Resection in Small-Angle Exotropia

PURPOSE

To compare the surgical outcomes of unilateral lateral rectus recession-medial rectus resection (RR) and unilateral lateral rectus recession (ULR) for intermittent exotropia of ≤20 prism diopters (PD).

DESIGN

Retrospective, nonrandomized clinical study.

METHODS

A total of 130 children with intermittent exotropia of ≤20 PD who underwent unilateral RR or ULR of 10 mm were included. Patients were observed for at least 2 years. Success rates, cumulative probabilities of success, and factors related to recurrence and overcorrection were evaluated.

RESULTS

The mean follow-up duration after surgery was 3.1 ± 1.0 years in the RR group and 3.6 ± 1.6 years in the ULR group. In the RR group, 38 of 61 patients (62%) had ocular alignment within 10 PD of exophoria/tropia and 5 PD of esophoria/tropia; 18 patients (30%) had recurrence, and 5 (8%) had overcorrection. In the ULR group, 26 of 69 patients (38%) had successful alignment, 41 patients (59%) had recurrence, and 2 patients (3%) were overcorrected. At 6 months after surgery, the success rate was significantly higher in the ULR group (RR 61%; ULR 78%, P = .039), but it became comparable after 2 years (RR 60%; ULR 52%, P = .370). At the final examination after a mean duration of 3 years, the recurrence rates were lower in the RR group (30% vs 59%, P = .001), and the overcorrection rates were comparable (8% vs 3%, P = .252).

CONCLUSION

Unilateral RR resulted in more successful alignment and lower recurrence compared to ULR for the treatment of small-angle intermittent exotropia of ≤20 PD.

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.

Comparison of Postoperative Exodrift after First Unilateral and Second Contralateral Lateral Rectus Recession in Recurrent Exotropia

Purpose

To compare postoperative exodrift of the first unilateral lateral rectus (ULR) muscle recession with the exodrift of the second contralateral ULR muscle recession in patients with recurrent small-angle exotropia (XT).

Methods

We evaluated the results of a second ULR muscle recession in 19 patients with recurrent XT with deviation angles under 25 prism diopter (PD), following a first procedure of ULR muscle recession for small-angle XT. Recession of the lateral rectus muscle ranged from 8 to 9 mm. The postoperative motor alignment and degree of exodrift were investigated after the first ULR muscle recession and the second ULR muscle recession in the same patients.

Results

Observed differences in postoperative ocular alignment between the first ULR muscle recession and the second ULR muscle recession were statistically significant at follow-up periods of six months (7.84 ± 4.43 vs. 3.89 ± 3.47 PD), one year (9.58 ± 4.97 vs. 5.21 ± 4.94 PD), and at a final follow-up (21.11 ± 2.98 vs. 7.52 ± 4.06 PD) after surgery (p = 0.006, 0.013, and 0.000). Postoperative exodrift was statistically different between the first and second ULR muscle recessions at three to six months (2.89 ±3.75 vs. 0.63 ± 3.45 PD) and one year to final follow-up (11.52 ± 5.50 vs. 2.32 ± 3.53 PD) (p = 0.034 and 0.000). All of the first ULR muscle recession patients showed XT with deviation angles of more than 15 PD at the final follow-up. Regardless, the surgical success rate (<8 PD) after the second ULR recession was 63.16% (12 patients) among the total amount of patients with recurrent XT.

Conclusions

This study shows that changes in exodrift after a second ULR muscle recession are less than changes after the first URL muscle recession among patients with recurrent XT. A second ULR muscle recession may be a useful surgery for small-angle XT patients with deviation angles of 25 PD or less after a first ULR muscle recession.

Long-term surgical outcomes and factors for recurrence after unilateral lateral rectus muscle recession

AIM

To evaluate long-term surgical outcomes and risk factors for recurrence after unilateral lateral rectus muscle recession (ULR) in children with small to moderate angle intermittent exotropia (IXT).

METHODS

214 patients with basic type IXT of 15-24 prism dioptres (PD) who underwent ULR were included. The main outcome measure was success rate at 2 years after surgery and at final follow-up. The risk factors related to recurrence were evaluated using univariable and multivariable logistic regression analyses.

RESULTS

Success rate at postoperative 2 years was 92.5% and at final examination after a mean follow-up of 3.9 years was 83.2%. No overcorrection was observed. Preoperative exodeviation of 20-24 PD was the significant risk factor for recurrence according to both univariable (OR=3.577, p=0.022) and multivariable analysis (OR=3.265, p=0.034).

CONCLUSIONS

The overall long-term successful alignment rate of ULR for 15-24 PD of IXT was good. However, patients with 20-24 PD of IXT showed worse prognosis compared with 15-19 PD of IXT.

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.

Predictive Factors Affecting Long-Term Outcome of Unilateral Lateral Rectus Recession

Background

There are few long-term outcome reports of unilateral lateral rectus (LR) recession for exotropia including a large number of subjects. Previous reports on unilateral LR recession commonly show extremely low rates of initial overcorrection and large exodrifts after surgery suggesting that the surgical dose may be increased. However, little is known of the long-term outcome of a large unilateral LR recession for exotropia.

Objectives

To determine long-term outcomes and predictive factors of recurrence after a large unilateral LR recession in patients with exotropia.

Data Extraction

Retrospective analysis was performed on 92 patients aged 3 to 17 years who underwent 10 mm unilateral LR recession for exotropia of ≤ 25 prism diopters (Δ) with prism and alternate cover testing and were followed up for more than 2 years after surgery. Final success rates within 10Δ of exophoria/tropia and 5Δ of esophoria/tropia at distance in the primary position, improvement in stereopsis and the predictive factors for recurrence were evaluated.

Results

At 24 months after surgery, 54% of patients had ocular alignment meeting the defined criteria of success, 45% had recurrence and 1% had overcorrection. After a mean follow-up of 39 months, 36% showed success, 63% showed recurrence and 1% resulted in overcorrection. The average time of recurrence was 23.4±14.7 months (range, 1–60 months) and the rate of recurrence per person-year was 23% after unilateral LR recession. Predictive factors of recurrence were a larger preoperative near angle of deviation (>16Δ) and larger initial postoperative exodeviation (>5Δ) at distance.

Conclusions

Long-term outcome of unilateral LR recession for exotropia showed low success rates with high recurrence, thus should be reserved for patients with a small preoperative near angle of exodeviation.

Unilateral strabismus surgery in patients with exotropia results in postoperative lateral incomitance

PURPOSE

To determine whether unilateral strabismus surgery creates lateral incomitance in patients with exotropia.

METHODS

Patients >7 years of age with intermittent or constant exotropia who underwent unilateral horizontal rectus muscle surgery between December 2009 and January 2012 were prospectively evaluated. Prism and alternate cover testing was performed with distance fixation in primary position, right gaze, and left gaze after 1 hour of monocular occlusion. Measurements were obtained within 1 month prior to surgery, within 1 week after surgery, and >3 months after surgery. The surgical procedure varied according to the surgeon's discretion. The change in deviation induced by strabismus surgery in lateral gaze was expressed as a percentage of the change in deviation induced in primary position.

RESULTS

A total of 12 patients met inclusion criteria. Of the 11 patients with postoperative examinations within 1 week after surgery, 10 (91%) had greater surgical effect with gaze toward the operated eye (P = 0.007). All 9 patients with >3 months' follow-up had greater surgical effect with gaze toward the operated eye (P = 0.003). On average, the surgical effect in gaze toward the operated eye was 120% of that achieved in primary position; in gaze away from the operated eye, 75% (P < 0.001). Three patients had diplopia in lateral gaze toward the operated eye that remained >6 months after surgery.

CONCLUSIONS

Unilateral strabismus surgery induces lateral incomitance that may cause diplopia >6 months after surgery in patients with exotropia. This should be considered when planning strabismus surgery and counseling patients.

Long-term outcomes of unilateral lateral rectus recession versus recess-resect for intermittent exotropia of 20-25 prism diopters

Background

The purpose of this study was to compare surgical outcomes of unilateral lateral rectus recession (ULR) and unilateral recess-resect (RR) for intermittent exotropia of 20-25 prism diopters (PD).

Methods

In this retrospective study, ULR was performed on 82 patients and RR on 98 patients for the treatment of intermittent exotropia of 20-25 PD with a follow-up period of 24 months or more. The main outcome measures were postoperative exodeviation angles and final success rates. A surgical success was considered to be an alignment within 10 PD.

Results

The mean follow-up duration after the surgery was 53.8 ± 26.4 months in the ULR group and 52.5 ± 27.4 months in the RR group (p = 0.482). The mean deviation angles at postoperative 1 day were -0.49 PD (esodeviation) in the ULR group and -1.98 PD in the RR group. Subsequently, at postoperative 1 week, 1 and 3 months, the deviations became more exotropic in the ULR group than in the RR group (p < 0.05). However, the mean deviation angles at 6 months, 1 and 2 years and at the final follow-up did not significantly differ between the two groups. Surgical success at the final follow-up was achieved for 50 patients (60.9%) in the ULR group and 55 patients (56.1%) in the RR group (p = 0.511).

Conclusions

ULR is an effective surgical method for treatment of moderate-angle intermittent exotropia of 20-25 PD, showing results similar to those of RR.