The outcome of strabismus surgery in childhood exotropia

Postoperative outcome and influencing factors of strabismus surgery in infants aged 1-6 years

PURPOSE

To evaluate the postoperative outcome of strabismus surgery performed in children aged 1-6 years by investigating the change of the preoperative angle of deviation (AOD), elevation in adduction, best-corrected visual acuity (BCVA) and refractive error.

METHODS

Retrospective chart review of 62 children who received strabismus surgery between January 2018 and December 2021 at the Department of Ophthalmology and Optometry of the Medical University of Vienna. Age, sex, type of strabismus, AOD, BCVA, refractive error and visual acuity were evaluated with respect to the postoperative outcome.

RESULTS

Mean follow-up was 13.55 ± 11.38 months with a mean age of 3.94 ± 1.97 years (range: 1.0-6.0) at time of surgery. 74.19% of patients (n = 46) had isolated or combined esotropia, 12.90% (n = 8) had isolated or combined exotropia and 12.90% (n = 8) had isolated strabismus sursoadductorius. Mean preoperative AOD of 15.69 ± 16.91°/15.02 ± 14.88° (near/distance) decreased to 4.00 ± 9.18°/4.83 ± 7.32° (near/distance) at final follow-up (p < 0.001). BCVA improved from 0.26 ± 0.26/0.25 ± 0.23 (left/right) to 0.21 ± 0.25/0.20 ± 0.23 (left/right) (p = 0.038). There was no significant change regarding refractive error (p = 0.109) or elevation in adduction (p = 0.212). Success rate which was defined as a residual AOD of less than 10° was 74.19% (n = 46). In 3.23% (n = 2) retreatment was necessary.

CONCLUSION

Strabismus surgery in infants was shown to have a satisfactory outcome with a low retreatment rate. Surgical success rate was not linked to age, sex, type of strabismus or the preoperative parameters AOD, refractive error and visual acuity in this study.

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.

Analysis of Postoperative Outcomes in Patients with Intermittent Exotropia According to Preoperative Change of Angle of Deviation

Purpose

The correlation between the existence of the preoperative condition of ≥10 prism diopters (PD) in patients with basic type of intermittent exotropia (IXT) and postoperative outcomes was analyzed.

Methods

The medical records of patients that underwent surgery for IXT were analyzed retrospectively. The analysis was conducted by dividing the patients into a group with change of <10 PD (group 1) and ≥10 PD (group 2) before the time of the surgery. Patients who received at least 6 months of follow-up after surgery were included. The age, sex, angle of deviation and stereoacuity of the patients were studied. Surgical success was defined as exodeviation of <10 PD or esodeviation of <4 PD at the final visit after the surgery. The correlation between clinical factors and surgical success rate was analyzed by using correlative analysis.

Results

A total of 129 patients participated in the study. There were 108 (83.7%) and 21 (16.3%) patients in groups 1 and 2, respectively. There were 89 (82.4%) and 17 (80.1%) patients with surgical successes in groups 1 and 2, respectively (p = 0.18). Moreover, 13 (12.0%) patients in group 1 and three (14.3%) patients in group 2 required reoperation, showing no significant difference (p = 0.12). There was no statistically significant correlation between surgical success and preoperative change of angle of deviation <10 PD (odds ratio, 1.78; p = 0.17).

Conclusions

Among the patients with basic type of IXT subjected to the analysis, 16.3% had a change of ≥10 PD before surgery, and there was no significant correlation between surgical success and preoperative change of angle of deviation.

Surgical outcomes of intermittent exotropia according to exotropia type based on distance/near differences

We compare the surgical outcomes of intermittent exotropia of the basic, pseudo-divergence excess (pseudo-DE) and true divergence excess (true DE) types. A study was performed with 342 patients who had undergone surgery for intermittent exotropia of the basic, pseudo-DE or true DE type with a postoperative follow-up period of 6 months or more. The main outcome measures were postoperative angles of deviation at distance and near, and surgical success rates. Surgical success was defined as alignment between exodeviation of 10 PD and esodeviation of 5 PD at distance and near. Additionally, survival curves of recurrence were analyzed by the Kaplan-Meier method. The postoperative angles of deviation at both distance and near in pseudo-DE type were significantly smaller than those in basic type at the final examination (p = 0.003, <0.001). The final surgical success rate in pseudo-DE (70.2%) was better than in basic (46.3%) or true DE (28.6%) (p = 0.003, 0.01). Reoperation for recurrent exotropia was performed in 27% of the basic, 17% of the pseudo-DE, and 35.7% of the true DE cases. According to a survival analysis for recurrence, patients with pseudo-DE showed lower incidence of recurrence than did patients with basic and true DE (p = 0.003, 0.02). In conclusion, the patients with intermittent exotropia of the pseudo-DE type showed better surgical outcomes than those with the basic or true DE type. Pseudo-DE also showed a lower recurrence rate than did the other 2 groups.

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

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

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

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.

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.

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

Purpose

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

Methods

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

Results

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

Conclusions

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

Outcome of unilateral lateral rectus recession and medial rectus resection in primary exotropia

BACKGROUND

The purpose of this study was to measure the success rate of unilateral lateral rectus recession and medial rectus resection in primary exotropia.

METHODS

This is an interventional case series of 55 patients with primary exotropia (degree of deviation 15-85 PD), above the age of 5 years. Patients were treated in the Department of Ophthalmology, Jinnah Postgraduate Medical Center, Karachi, Pakistan, during the period of July 2009 to March 2010. All the patients underwent surgical procedure i.e., lateral rectus muscle recession (maximum up to 10 mm) and medial rectus muscle resection (up to 6 mm) of one eye, according to the Park's method. Surgery was done based on prism cover test measurements obtained at 6 m with appropriate optical correction in place. Patients were re evaluated at one day, one month, two months and six months post operatively. Final outcome was considered at the end of six months at which achievement of ≤10 PD of exotropia was the success. Data was analyzed on SPSS version 17.0.

RESULTS

We obtained success (≤10 PD) in 42 out of 55 patients (76.4%) and 13 out of 55 patients (23.6%) did not meet our criteria for surgical success (>10 PD). Analysis of success with the type of primary exotropia showed that success was achieved in 22 out of 24 cases of intermittent type (91.6%) and 20 out of 31 cases of constant type (64.5%)(P Value 0.019). The highest percentage of success was achieved in patients with the pre-operative deviation of ≤70 PD i.e., 93.3% (42 out of 45 cases), while none of the patients with the pre-operative deviation of >70 PD (10 out of 10 cases) achieved the criteria for success.

CONCLUSION

We conclude that pre-operative deviation is one of the strongest predictor for favorable surgical outcome. Therefore, eliminating the factors causing error in the correct determination of pre-operative deviation should improve the success and predictability of the surgical outcome. Despite the obstacles in the surgical management of strabismus, our results are encouraging.

Postoperative outcomes of patients initially overcorrected for intermittent exotropia

BACKGROUND

Esotropic overcorrection on postoperative day 1 after surgery for intermittent exotropia is generally thought to increase the likelihood of long-term satisfactory alignment; however, it is unclear why some patients who are initially overcorrected demonstrate recurrent intermittent exotropia whereas others maintain esotropic to orthotropic alignment.

METHODS

The records of all patients who underwent primary surgical correction of intermittent exotropia were reviewed; those with any degree of esotropia on postoperative day 1 were included. The status at the last visit was categorized as orthotropic to <8(Δ) exotropia or having recurrent exotropia >8(Δ), monofixational esotropia <10(Δ), or esotropia >10(Δ).

RESULTS

A total of 63 patients met the inclusion criteria. The mean postoperative day 1 alignment was 6(Δ) ± 3(Δ) esotropia at distance and 5(Δ) ± 3(Δ) esotropia at near. At the last visit, 31 (49%) were orthotropic to <8(Δ) exotropia, 26 (41%) had recurrence of exotropia >8(Δ), and 6 (10%) had monofixational esotropia <10(Δ). There was no significant difference between outcome groups in onset age, age at surgery, stereopsis, deviation (preoperatively or on postoperative day 1), or follow-up length. Risk factor analysis revealed no association between exotropia type, surgical approach, or postoperative day 1 alignment and risk of recurrent intermittent exotropia or monofixational esotropia, although there was a trend toward recurrent intermittent exotropia in those least overcorrected.

CONCLUSIONS

Recommended overcorrection on postoperative day 1 for intermittent exotropia can result in esotropia, intermittent exotropia, or orthotropia. The results of overcorrection for exotropia are variable and unpredictable. We were unable to determine associations with the recurrence of exotropia or secondary esotropia.

Large-angle strabismus: can a single surgical procedure achieve a successful outcome?

PURPOSE

Large-angle strabismus is a gray zone for surgeons with various advocates for one, two-, three-, or even four-muscle surgeries. Very frequently, reoperations are required in these cases in order to achieve a successful outcome. In this article, the authors evaluate the outcome of concomitant large-angle strabismus after a single surgical procedure.

METHODS

A retrospective analysis of all operated cases of concomitant large-angle strabismus (50 prism diopters or more) during a 1.5-year period was performed from patient's case files. A successful outcome of surgery was defined as deviation within 10 prism diopters of orthophoria/tropia for both distance and near.

RESULTS

Fifty patients met the inclusion criteria. The overall success rate was 60%, with the esotropia group having a higher success rate (68.75%) than the exotropia group (44.45%). Ten patients underwent recess-resect procedure, 20 had bimedial rectus recession, and 3 had bilateral lateral rectus recession, while 17 patients had surgery on 3 horizontal rectus muscles. Thirty-three patients had two-muscle surgery with a success rate of 57.58%, while 17 patients had three-muscle surgery with a success rate of 64.71%, the difference being statistically insignificant. There was no statistically significant difference between the various age groups analyzed for overall success rate, suggesting that age group is not a factor for positive outcome in large-angle strabismus surgery. A total of 12 patients were amblyopic at the time of strabismus surgery and they had a success rate of 33.33%, which was much poorer than the success rate (68.42%) of the remaining 38 patients who did not have amblyopia at the time of surgery.

CONCLUSIONS

A good surgical outcome can be obtained in large-angle strabismus with a single surgical procedure, though a randomized controlled study needs to be done to establish whether three-muscle surgeries give better results than two-muscle surgeries.

Timing of Surgery for Primary Exotropia in Children

OBJECTIVE

To compare postoperative alignment and sensory functions in children with primary exotropia who were operated at an early age (< 7 years) with patients who were operated at an older age (> 7 years).

METHODS

In a consecutive retrospective cohort study, 112 patients who had a surgical intervention for primary exotropia between 1997 and 2003 were evaluated for postoperative results. After applying criteria for eligibility, the group of patients was divided into two groups: those who had surgical intervention before the age of seven years (n = 24) and those who had surgery after the age of seven years (n = 36). Age at surgery, preoperative alignment and sensory functions were correlated with the postoperative status. The follow-up was at least one year (1.0 year to 7 years; median: 2.3 and 3.5 years, respectively).

RESULTS

Children who had surgery before the age of seven had significantly better alignment and sensory functions. The univariate logistic regression model confirmed a statistically significant association between motor outcome (exodeviation less than 10 prism-diopters) and age at the time of surgery (before or after the age of seven; p = 0.002). In the multivariate model, the association between age at time of surgery and motor outcome was even stronger. The number of reoperations in the group operated before the age of 7 years was significantly less than in the group operated after the age of seven (2 versus 12, p = 0.023).

CONCLUSION

The postoperative alignment and sensory functions in patients with primary exotropia who had surgical intervention before the age of seven years were, in this study, better than in patients who had surgery after the age of seven years.

Factors affecting the surgical outcome of primary exotropia

AIMS

To identify the predictors for motor outcome and response to surgical treatment of primary exotropia.

SETTING

Taunton and Somerset Hospital, Somerset, United Kingdom.

STUDY TYPE

Retrospective analysis of the surgical treatment of primary exotropia performed in our department over a period of 12 years from April 1991 to May 2003.

METHODS

Case-notes of the patients who had surgical treatment for primary exotropia for the specified period were identified by a hospital computer database (MDI coding). All case-notes were reviewed and the following data were recorded and used for statistical analysis: age at the time of surgery, type and severity of exotropia, presence of amblyopia, AV pattern and vertical deviation, the level of stereopsis, type of surgery, and motor and cosmetic results. The surgical outcome was determined as good motor outcome if tropia was within 10 PD of orthotropia. The response to surgery was derived from the difference between the preoperative and postoperative angle of deviation for distance per amount of muscle surgery in millimetres.

RESULTS

A total of 124 cases were included in the study. Good motor outcome was achieved in 83 (67%) cases. There was a positive correlation between the preoperative angle of deviation at distance and dose response to surgery (r = 0.6 and p < 0.001) and a negative correlation between average corrected visual acuity and response (r = -0.21 and p = 0.025). There was a statistically significant negative relationship between preoperative stereopsis and response to surgery (p = 0.02).

CONCLUSIONS

Surgical treatment for exotropia is effective and the dose response is correlated to the preoperative angle of deviation and average visual acuity. Poor or no preoperative stereopsis was associated with better response to surgery.

Timing of surgery for primary exotropia in children

OBJECTIVE

To compare the postoperative alignment and sensory functions in patients with primary exotropia who had been operated at an early age (< 7 years) with those in patients who had been operated at an older age (> 7 years).

METHODS

In a consecutive retrospective cohort study, 112 patients who had had a surgical intervention for primary exotropia between 1997 and 2003 were evaluated for postoperative results. After applying criteria for eligibility, the group of patients was divided into two groups: those who had had surgery before the age of seven years (n = 24) and those who had had surgery after the age of seven years (n = 36). Age at surgery, preoperative alignment and sensory functions were correlated with the postoperative status. The follow-up was at least one year (1.0 year to 7 years; median: 2.3 and 3.5 years, respectively).

RESULTS

Patients who had had surgery before the age of seven had significantly better alignment and sensory functions. The univariate logistic regression model confirmed a statistically significant association between motor outcome (exodeviation less than 10 diopters) and age at the time of surgery (before or after the age of seven; p = 0.002). In the multivariate model, the association between age at time of surgery and motor outcome was even stronger. The number of re-operations in the group operated before the age of 7 years was significantly less than in the group operated after the age of seven (2 versus 12, p = 0.023).

CONCLUSION

The postoperative alignment and sensory functions for patients with primary exotropia who had had a surgical intervention before the age of seven years were, in this study, better than those in patients who had had surgery after the age of seven years.

[Surgical results in childhood primary comitant large-angle exotropia]

INTRODUCTION

The purpose of this study was to evaluate the surgical results in childhood primary comitant large-angle exotropia (>30Delta) after a single operation and to analyze the factors that could influence these results.

PATIENTS AND METHODS

We carried out a retrospective study in all children presenting with comitant primitive exotropia at an angle greater than 30Delta, who were operated on in our department from January 1996 to December 2000 by various surgeons. One hundred thirty-eight (138) cases were reviewed. The children with a substantial A or V phenomenon, retraction syndromes, nystagmus, those presenting with a neurological disease and those who had had previous eye surgery were excluded. The postoperative results were classified in three categories: residual exotropia over 10Delta, good postoperative result (esotropia<10Delta, orthotropia or exotropia<10Delta), and consecutive esotropia over 10Delta.

RESULTS

Ninety-seven children fulfilled the study criteria. Forty (41.2%) were boys and 57 (58.8%) girls. The average age at the time of surgery was 6.5 years (SD 3.1). Sixty-eight of 97 (70.1%) had intermittent exotropia. Twenty-six children (26.8%) underwent a bilateral recession of the lateral rectus, 67 (69.1%) a unilateral operation, recession of a lateral rectus/resection of a medial rectus, and four (4.1%) an operation on three horizontal muscles. Sixty-nine percent of the children operated on had a good postoperative result, according to criteria defined in our study, 1 year after surgery.

DISCUSSION/CONCLUSION

Childhood primary comitant large-angle exotropia can be corrected with a single surgical procedure, unilateral or bilateral, with a success rate which, in our study, reached 69%.

Surgical outcomes of intermittent exotropia as a function of strabismic angle

Purpose

To analyze postoperative results of intermittent exotropia as a function of the difference in strabismic angles measured immediately and another time prior to the surgery.

Methods

We reviewed the clinical records of intermittent exotropia patients who received surgery and had differences greater than or equal to 10 prism diopters (PD) between the last preoperative measurement of strabismic angle and another previous measurement. After applying various exclusion criteria, 66 patients were entered into our study. At the last follow-up visit after surgery, we divided postoperative results into 3 categories: (1) poor; with greater than 10 PD of esotropia or angle of exodeviation of 20 PD or more (2) moderate; with 6-10 PD of esophoria/tropia or 10-19 PD exodeviation, or (3) good; with 1-5 PD of esophoria / tropia or an angle of exodeviation less than 10 PD, or orthophoria.

Results

Good results were higher in patients where the difference in strabismic angle was 10 PD or greater between the last measurement and any other earlier measurement.

Conclusions

In cases of Intermittent exotropia where the last preoperative value of strabismic angle was greater than any previous preoperative measurement, surgical dosage based on the last preoperative measurement yielded better results.

Clinical study for the undercorrection factor in intermittent exotropia

Purpose

The surgical technique for intermittent exotropia 「X(T)」 is quite simple. However, in many cases, the condition recurs due to any one of a number of causes, including undercorrection. This study examined the factors associated with undercorrection on X(T) patients.

Methods

The study examined 199 X(T) patients who underwent bilateral recession of the lateral rectus muscle or unilateral recession of the lateral rectus muscle and resection of the medial rectus muscle, and who were followed-up for more than a year. Patients whose near and far distance angles of deviation were 9 prism diopters (PD) or more at one year after surgery were designated as group 1. Those whose PD was 8 or below or who had orthophoria were assigned to group 2. Various factors were compared and analyzed.

Results

One day after surgery, group 1 showed an average overcorrection of 1.9 and 4.1 PD at near and far, respectively, and group 2 showed an average overcorrection of 6.3 and 7.6 PD at near and far, respectively. A statistically significant difference was observed between the two groups (p<0.05). Factors such as the age of onset of strabismus, age at the time of surgery, the interval from the onset of strabismus to surgery, the preoperative angle of deviation, the dissociated vertical deviation, amblyopia, anisometropia and vertical strabismus had no influence on the undercorrection of X(T) patients (p>0.05).

Conclusions

Of the many factors that might influence the surgical results of X(T) patients, the angle of deviation during the initial postoperative period is the most important factor.

Conversion of intermittent exotropia types subsequent to part-time occlusion therapy and its sustainability

PURPOSE

To evaluate the effects of part-time occlusion therapy on types of intermittent exotropia and sustainability of converted types.

METHODS

Forty-four and 26 children with basic-type and convergence-insufficiency-type intermittent exotropia, respectively, were evaluated in this study. Upon initial examination, we obtained both distant and near deviating angles using prism cover tests, after correcting for refractive errors. We conducted occlusion of the nondeviating eye for 3 months at 3 h/day and assessed the changes in types of intermittent exotropia. We also observed the changes of deviating angles and sustainability of types after 3 months of cessation of part-time occlusion in patients who did not undergo surgery.

RESULTS

Preocclusion deviating angles (mean +/- SD) were determined to be 27.1+/-7.46 prism diopters (PD) on distant measurements and 30.6+/-7.92 PD on near measurements. After 3 months of occlusion, the deviating angles were 25.9+/-9.10 PD on distant measurements and 21.4+/-11.00 PD on near measurements, corresponding to a significant reduction (p=0.005 and p<0.001, respectively). Fourteen patients (32%) suffering from basic type of intermittent exotropia converted to the pseudodivergence excess type. In patients suffering from the basic type who exhibited no changes in type, 9 patients (20%) exhibited reductions on both near and distant angle measurements. Among the convergence insufficiency type of patients, 18 (69%) converted to basic type and 2 patients (7%) converted to the pseudodivergence excess type. In the 15 patients who did not undergo surgery, the converted types were maintained in 6 patients, though the other 9 patients showed regression to the prepatching types after cessation of patching for 3 months.

CONCLUSION

Part-time occlusion therapy resulted in the conversion of the basic and convergence insufficiency types to pseudodivergence excess and basic types in more than half of the intermittent exotropes. Future studies on correlation between type conversion and surgical outcome would be necessary.

The clinical course of recurrent exotropia after reoperation for exodeviation

PURPOSE

To determine the clinical course of recurrent exotropia after a secondary operation for exotropia.

METHODS

The surgical results in 58 patients who had undergone reoperation for recurrent exotropia (reoperation group) were retrospectively investigated and compared with those of 100 patients who had undergone primary strabismus surgery only (primary operation group) using survival analysis.

RESULTS

In the reoperation group, recurrence occurred in 19 of the 58 patients (33%). Survival analysis revealed that the recurrence rates in the reoperation group were significantly lower than those in the primary operation group at the same follow-up period after the corresponding strabismus surgery (p=0.018). The distant esodeviation at the postoperative 1st week after reoperation was the only significant factor associated with the recurrence after reoperation (p=0.01).

CONCLUSIONS

Exotropia did recur after a secondary operation, although the recurrence rate was lower than that after a primary operation only.

Factors influencing the outcome of strabismus surgery in patients with exotropia

PURPOSE

To determine the factors associated with favorable and less favorable outcomes in strabismus surgery for treatment of exotropia and to show the factors influencing the efficacy of the surgical procedure.

METHODS

Case files of 225 patients with a diagnosis of primary exotropia were evaluated. Information about patient age at onset of deviation, patient age at surgery, interval between onset and surgery, preoperative deviation, refractive errors, degree of anisometropia, visual acuity, presence of amblyopia, presence of an A- or a V-pattern, amount of surgery performed, type of exotropia (intermittent or constant), and existence of binocular single vision before surgery were obtained and evaluated using multiple regression analysis.

RESULTS

Preoperative deviation and refractive errors were proved to be significant factors influencing a favorable outcome in patients with surgically treated exotropia (r(2) = 0.12, P <.001, and r(2) = 0.07, P <.001 respectively). Preoperative deviation, amount of surgery performed, and refractive errors shifting toward myopia significantly influenced the efficacy of the surgery performed (r(2) = 0.31, 0.06, and 0.025, respectively).

CONCLUSION

Special care should be paid to refractive errors in patients with exotropia before determining the amount of surgical intervention.

Measurements for horizontal extraocular muscle surgery from the suture site: outcome and influencing factors

BACKGROUND

Measurement of recession in strabismus surgery is performed either from the limbus or from the muscle insertion. These measurement methods may result in inaccuracies that may influence the outcome of the procedure. We prospectively evaluated the outcome of recessions measured from the extraocular muscle suture site to its insertion in an incidence cohort.

METHODS

Thirty-six consecutive surgical procedures for infantile esotropia and 23 for constant exotropia were performed in which measurements were performed from the suture site. A successful surgery for esotropia was defined as an orthophoria of up to +10 prism dioptres of deviation for non-accommodative targets at a distance of 20 feet, measured by cover and prism test. A successful surgery for exotropia was defined as a residual deviation between -10 and +10 prism dioptres. The statistical significance of the outcome influencing factors was assessed by chi-square test.

RESULTS

Six weeks following surgery, 28 procedures (78%) for infantile and non-accommodative esotropia and 19 procedures (83%) for exotropia were successful. At the end of the follow-up period (mean 13.7 months +/- 9.4 for esotropia and 11.6 months +/- 12.8 for exotropia), the success rate was 77% for esotropia and 75% for exotropia. Prematurity and mental retardation in esotropia, exotropia with pre-operative deviations larger than -45 prism dioptres and amblyopia in exotropia were related to unfavourable outcome (p < 0.05).

CONCLUSIONS

Measurement for muscle recession can be performed from the suture site. The outcome is comparable to the outcome when measurements are performed from the limbus or the insertion, probably due to the incidence cohort. Refinement of the technique and defining other factors influencing the outcome of strabismus surgery may improve the outcome.

Botulinum toxin management of childhood intermittent exotropia

OBJECTIVE

Intermittent exotropia is a common form of childhood strabismus that has a late onset and presents a difficult and frustrating management dilemma. Surgical treatments have a high recurrence rate, and multiple surgeries often are required to achieve a desirable motor outcome. This study presents long-term observations on the use of botulinum toxin for the treatment of intermittent exotropia in children.

DESIGN

This study is a nonrandomized, case-controlled study of consecutive pediatric patients who had intermittent exotropia.

PARTICIPANTS

Thirty-two neurologically normal children ranging from 3 to 144 months in age were diagnosed with intermittent exotropia with a minimum distance deviation of 15 prism diopters (PD).

INTERVENTION

Simultaneous bilateral injections of 2.5 units botulinum toxin type A were made into the lateral rectus muscles with the patient receiving nitrous oxide-ethrane inhalation anesthesia. Patients were observed for 12 to 44 months after the initial injection.

MAIN OUTCOME MEASURES

A satisfactory outcome was considered to be stable binocular alignment of the eyes to an orthophoric range of +/-10 PD.

RESULTS

Bilateral lateral rectus muscle injections of botulinum toxin were effective in reducing the mean preinjection deviation of -29 PD to an average exotropic angle of -6 PD. Stable orthophoria (+/-10 PD) was achieved in 22 patients (69%). Overall, male patients required significantly fewer injections than did female patients. All patients between 24 and 56 months of age, irrespective of gender, required only a single bilateral injection to achieve a favorable motor outcome.

CONCLUSIONS

Botulinum toxin is at least as effective as surgical outcomes reported previously for the treatment of intermittent exotropia in children. This treatment method is particularly effective in children between 2 and 4.5 years of age irrespective of the initial strabismic angle and is not associated with any secondary abnormalities.