Initial postoperative deviation as a predictor of long-term outcome after surgery for intermittent exotropia

Divergence excess and basic exotropia types of intermittent exotropia: a major review. Part 2: non-surgical and surgical treatment options

INTRODUCTION

Currently, there is no consensus regarding the management of intermittent exotropia (IXT), which includes both surgical and non-surgical treatment options. Nonsurgical management of IXT has been suggested and includes watchful observation, patching, overminus lenses, prism, and vision therapy/orthoptics. While a significant portion of IXT patients are treated by surgery, it is reported that there is a substantial tendency for reoperation or recurrence of IXT. This paper provides a comprehensive review of non-surgical and surgical treatment options for the IXT.

METHODS

Search strategies involving combination of keywords including intermittent exotropia, divergence excess, basic exotropia, refractive error, glasses, spectacles, natural history, untreated, observe, occlusion, patch, overminus, overcorrecting minus, prism, vision therapy, orthoptic, anti-suppression, fusion exercise, and surgery were used in Medline. All English articles from 01/01/1900 to 01/09/2020 were reviewed. The reference list of the identified articles was also checked for additional relevant articles. Studies focused on animal models or strabismus associated with neurologic disorders or injury were excluded. The following filters were used for surgical management due to the abundance of reports: full text, randomized controlled trial, review, in the last 5 years.

RESULTS

Appropriate optical correction of refractive error is generally the starting point for all management approaches, but there is a lack of randomized clinical trial data regarding this treatment modality. Randomized clinical trial data indicate that both observation and occlusion are reasonable management options for children 3-10 years old, and there were insufficient data to recommend occlusion for children 12-35 months old. While overminus lenses were found to improve the control of IXT when assessed wearing overminus spectacles, this improvement did not persist after the treatment ended. The result of the only randomized clinical trial on the effectiveness of base-in prism indicated that this treatment is no more effective than nonprism spectacles for improving control. A recent randomized clinical trial showed that vision therapy/orthoptics is effective in improving the control of IXT when compared to observation alone. Surgery was found to alter a number of clinical characteristics of IXT, including reducing the distance and near angle of deviation, reducing photophobia, improving health-related quality of life, stereopsis, and the Newcastle Control Score. However, there are no randomized clinical trial data comparing surgery with a control group such as placebo or a no treatment observation group.

DISCUSSION

Rigorously designed clinical trials to investigate the effectiveness of non-surgical and surgical treatments for intermittent exotropia are needed.

Stability of the angle of deviation in basic intermittent exotropia (IXT) following surgical correction: a retrospective observational study from southern India

Introduction: Intermittent exotropia (IXT) is commonly seen in areas with more sunlight, females and Asians. Surgical alignment is recommended to improve binocular function, but a high recurrence rate has been reported. This study aimed to assess the stability of ocular alignment and factors contributing to exodrift post-surgery for IXT over 6-month follow-up. Methods: We retrospectively reviewed the medical records of patients with IXT who underwent unilateral recess resect procedures and attended follow-up examinations for at least six months post-surgery. A significant exodrift was defined as exodrift of more than 10PD at distance and near. Ocular deviation, binocularity, and stereopsis at one and six-month post-operative visits were studied to assess the incidence of exodrift post-surgery and the probable factors causing such drift. Results: Of the 50 patients studied, 26 (52%) were males, 42 (84%) were <20 years. The median age at surgery was 10 years (range 6-14), and the median preoperative angle of deviation was 37 PD. Majority of patients (62%) had exodrift within six months of surgery, and about a quarter of the study population had significant exodrift >10 PD. No clinical factors were found to contribute significantly to exodrift in this study.16 (61.5%) patients attained near and distance BSV post-surgery (p-value: <0.001). Six (12%) and 10 (20%) patients with subnormal near and distance stereopsis, respectively, attained normal stereopsis post-surgery. Conclusion: Over half of the patients operated for IXT had some Exodrift, and one-fourth had significant exodrift within six months post-surgery. Despite improved BSV, many patients failed to attain normal stereopsis with just motor alignment.

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.

Early post-operative angle as a predictor of surgical success in adult patients with intermittent exotropia

Purpose: Intermittent exotropia is a condition where divergent strabismus is present at certain times or fixation distances and is surgically treated with bilateral lateral rectus recession or unilateral lateral rectus recession with medial rectus resection. The main purpose of our study is to assess the relationship between the initial post-operative deviation and surgical outcomes in adult exotropes undergoing recess-resect surgery. Methods: A retrospective chart review was performed on adult patients who underwent unilateral recess-resect surgery for intermittent exotropia between March 2010 and February 2022 at a single institution with at least 3 months of follow-up. Based on their motor alignment at 2 weeks following surgery, they were categorized as having exodeviation, esodeviation within 10 PD and esodeviation exceeding 10 PD. Surgical success was defined as motor alignment within 10 PD of exotropia and 5 PD of esotropia at distance and near at final follow-up. Results: 93 patients were included, 55% female and average age was 37 years. At postoperative week 2, 26 patients demonstrated residual exodeviation (Group A), 53 patients demonstrated an esodeviation of within 10 PD (Group B) and 14 patients demonstrated an esodeviation greater than 10 PD (Group C). There were no significant differences in pre-operative and demographic factors between the group. At the final follow-up, surgical success was observed in 57 patients: 12 in Group A, 41 in Group B and 4 in Group C (P < .01). Conclusion: Overcorrection of within 10 PD at 2 weeks following surgery showed a more favorable surgical outcome compared to exodeviation or esodeviation exceeding 10 PD.

Initial postoperative plasticity as a predictor of mid-term stereoacuity outcome after surgery for intermittent exotropia

BACKGROUND

Intermittent exotropia (IXT) would cause different degrees of damage to stereopsis. We aimed to introduce a visual perception plasticity score (VPPS) that reflects initial postoperative plasticity and evaluate its effectiveness in predicting the mid-term surgical outcome in IXT patients.

METHODS

A total of 149 patients with intermittent exotropia who underwent surgery in November 2018 and October 2019 were recruited. All subjects underwent detailed ocular examinations before and after surgery. VPPS were calculated based on visual perception examination system at one week postoperatively. Demographic, angle of deviation and stereopsis were collected and analyzed with regard to the VPPSs preoperatively and at one week, one month, three months, six months postoperatively. Predictive performances of VPPS were assessed using receiver operating characteristic (ROC) curves, the area under the curve (AUC) and cut-offs were obtained.

RESULTS

Of the 149 patients, the average deviation was 43^Δ at distance and 46^Δ at near. The average rate of normal stereopsis before surgery was 22.81% at distance and 29.53% at near. Higher VPPS was associated with preoperative better near stereoacuity (r = 0.362, p = 0.000), less angle of deviation at distance (r=-0.164, p = 0.046), and better near (r = 0.400, p = 0.000) and distant stereoacuity (r = 0.321, p = 0.000) during the early postoperative period (1 week). The areas under the curves suggested that VPPS could be an effective predictor of sensory outcome(AUC>0.6). Cut-off values of 50 and 80 were calculated for VPPS using ROC curve analysis.

CONCLUSION

Higher VPPSs were associated with a greater possibility of stereopsis improvement in patients with IXT. VPPS is a potentially promising indicator to predict the mid-term surgical outcome of intermittent exotropia.

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.

Risk of consecutive esotropia after surgery for intermittent exotropia according to passive duction force

PURPOSE

To determine the relationship between consecutive esotropia (ET) and passive duction force (PDF) in patients with intermittent exotropia (XT).

METHODS

The study enrolled 70 patients in whom PDF was measured under general anesthesia prior to XT surgery. The preferred eye for fixation (PE) and the nonpreferred eye for fixation (NPE) were determined using a cover-uncover test. The patients were subdivided into two groups according to the angle of deviation at 1 month postoperation: (1) consecutive ET (CET group), >10 prism diopters (PD) of ET; and (2) non-CET (NCET group), ≤10 ET or residual exodeviation. The relative PDF of the medial rectus muscle (MRM) was obtained by subtracting the ipsilateral PDF of the lateral rectus muscle (LRM) from the PDF of the MRM.

RESULTS

The PDFs for the LRM in the PE in the CET and NCET groups were 47.28 g and 58.59 g, respectively (p = 0.147), and 56.18 g and 46.59 g for the MRM (p = 0.11), and in the NPE were 59.84 g and 55.25 g, respectively, for the LRM (p = 0.993), and 49.12 g and 50.53 g, respectively, for the MRM (p = 0.81). However, in the PE, the PDF in the MRM was larger in the CET group than in the NCET group (p = 0.045), which was positively associated with the postoperatively overcorrected angle of deviation (p = 0.017).

CONCLUSIONS

An increased relative PDF in the MRM in the PE was a risk factor for consecutive ET after XT surgery. Quantitative evaluation of the PDF could be considered when planning strabismus surgery to achieve the desired surgical outcome.

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

Purpose

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

Methods

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

Results

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

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

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.

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.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Consecutive Esotropia with and without Abduction Limitation - Risk Factors and Surgical Outcomes of Lateral Rectus Advancement

Purpose: To identify risk factors for abduction limitation in consecutive esotropia following surgical correction of exotropia. To study outcomes of lateral rectus advancement for consecutive esotropia correction.Methods: Patients with consecutive esotropia (>10PD) operated between 2007 and 2019 with a minimum follow-up of 2 months were reviewed retrospectively. Preoperative and postoperative alignment and ocular motility were recorded. Patients were classified into those with full abduction (group-A) and with abduction limitation (group-B). Success was defined as deviation ≤10 PD of esotropia or exotropia in the primary position.Results: Forty-cases fulfilled the inclusion criteria (group-A = 28 and group-B = 12). Median age at surgery was five years, median consecutive esotropia was 20PD and follow-up was 29.18 months. Abduction limitation (group-B) was associated with constant exotropia (p = .01) and larger bilateral lateral rectus recession (group-A = 13 mm, group-B = 15 mm; p = .04). Nineteen patients underwent lateral rectus advancement (group-A = 12, group-B = 7), one underwent medial-rectus recession and two were excluded due to lack of postoperative follow-up. Five patients had spontaneous resolution with good alignment (group-A = 3, group-B = 2), two refused surgery, three were observed and eight were lost to follow-up. Success following second surgery was similar in both groups (group-A = 86%, group-B = 77%)(p = 1).Conclusion: Constant exotropia and larger lateral rectus recession were associated with abduction limitation in consecutive esotropia. Lateral rectus advancement produced good outcomes irrespective of abduction limitation.

Clinical factors affecting the rate of exodrift after surgery in patients with basic intermittent exotropia

We investigated the period of postoperative exodrift during follow-up and clinical factors that affect the rate of exodrift after surgery in the patients with intermittent exotropia (IXT). A retrospective review of medical records of patients with exodrift who underwent bilateral rectus recession for IXT was performed. Exodrift was defined as angle of deviation greater than 10 prism diopters (PD) at distance and near. The median survival period of postoperative exodrift was analyzed using Kaplan Meier survival analysis. The patients were divided into two groups according to the median period of postoperative exodrift (early and late group). The weighted Cox’s proportional hazards regression analysis to investigate the risk factors that affect rate of postoperative exodrift was performed. A total of 108 patients was included. The preoperative angle of deviation at distance and near were 30.3 ± 7.2 PD and 29.5 ± 8.6 PD, respectively. The median survival period of postoperative exodrift was 24 months (range, 6–48 months).The angle of deviation at postoperative day 1 in early and late group were − 3.8 ± 5.5 PD (range, − 16–8 PD) and − 7.7 ± 4.6 PD (range, − 16–4 PD) (p < 0.01). Minus value means esodeviation. In regression analysis, the angle of deviation at postoperative day 1 was the significantly related with rate of exodrift (p < 0.01). The median period of exodrift after surgery was 24 months, angle of deviation at postoperative day 1 could affect the rate of exodrift in patients with IXT.

Can Clinical Measures of Postoperative Binocular Function Predict the Long-Term Stability of Postoperative Alignment in Intermittent Exotropia?

Purpose

To evaluate whether clinical measures of postoperative binocular functions could predict the long-term stability of postoperative ocular alignment in children with intermittent exotropia.

Methods

A retrospective study was performed in thirty-nine children (median: 7 years) who have been surgically treated from intermittent exotropia without overcorrection (less than 10 prism diopters [pd] of exodeviation at 1 month postoperatively). Angles of deviation and binocular functions were measured preoperatively and at 1 month, 6 months, and the final follow-up visit (≥24 months) postoperatively. We examined the relationships between postoperative drift (change of ocular alignment) and binocular functions (sensory fusion, fusional convergence amplitude, and stereoacuity).

Results

The surgical success rate (esophoria/tropia ≤5 pd to exophoria/tropia ≤10 pd) dropped to 76.9% at 6 months after surgery and to 53.8% at individuals' last visit (mean: 37 months). The mean exodrift was 7.7 ± 9.2 pd from the postoperative month 1 to the final visit (p < 0.001) on distance fixation. Distance stereoacuity, central fusion, and fusional convergence amplitude significantly improved following surgery (p < 0.05). However, no significant correlation was found between their binocular functions measured at the beginning of each follow-up period and the postoperative drift (all p > 0.13).

Conclusion

Our findings suggest that the clinical measures of sensory fusion, fusional convergence amplitude, and stereoacuity cannot serve as a robust predictor for the long-term stability of postoperative ocular alignment in patients who underwent successful surgery without overcorrection at 1 month postoperatively.

Lateral rectus advancement versus medial rectus recession for consecutive esotropia

PURPOSE

To compare lateral rectus advancement with medial rectus recession for patients with consecutive esotropia without abduction limitation.

METHODS

Forty-three patients who developed consecutive esotropia following bilateral lateral rectus recession for intermittent exotropia were reviewed retrospectively. Twenty-two patients underwent lateral rectus advancement (lateral rectus advancement group) and medial rectus recession was performed in 21 patients (medial rectus recession group). Success rate of the surgery was based on the percentage of postoperative esophoria or exophoria of less than 8 PD, which did not require a third surgery. Mean follow-up after second surgery was 23.5 ± 8.7 months.

RESULTS

Mean consecutive esotropia in the lateral rectus advancement group was 24.8 ± 9.0 PD. Eight patients were orthophoric after second surgery; mean postoperative esophoria and exophoria/tropia was 5.4 ± 3.4 PD and 6.5 ± 5 PD, respectively. Postoperative success rate in this group was 90.9%. Mean consecutive esotropia in the medial rectus recession group was 21 ± 98.4 PD. Three patients were orthophoric after second surgery; mean postoperative esotropia/phoria and exophoria was 9.5 ± 5.0 PD and 5.2 ± 1.3 PD, respectively. Postoperative success rate in this group was 71.4%. Postoperative undercorrection rate of 4.5% in lateral rectus advancement group was significantly less than the similar measure of 28.6% in medial rectus recession group (chi-square, P = 0.03).

CONCLUSION

Advancement of the previously recessed lateral rectus has improved consecutive esotropia better than medial rectus recession.

Model of a Support Vector Machine to Assess the Functional Cure for Surgery of Intermittent Exotropia

In this paper the optimum timing for the postoperative functional cure of basic intermittent exotropia is explored based on support vector machine (SVM). One hundred and thirty-two patients were recruited in this prospective cross-sectional study with 6 months of follow-up. Examinations included angle of deviation, central and peripheral fusion, controllability, and near and distance stereopsis. Influencing factors of postoperative alignment and stereopsis were analyzed with a chi-squared test and univariate and multivariate logistic regression analyses. At 6 months post-operation, there were 84 successful procedures for the angle of deviation, with 4 overcorrections and 44 undercorrections. The success rate was 63.6%. The angle of deviation on postoperative day 1 was the only significant associated factor. One hundred and thirty patients had normal near stereoacuity, 60 had normal distance stereoacuity according to a Functional Visual Analyzer assessment, and 108 had normal stereoacuity as assessed by the Frisby Davis Distance (FD2) stereotest. The age of onset and preoperative distance stereoacuity with FD2 were the influencing factors of postoperative distance stereopsis restoration. The accuracy of this method of SVM was 82.1%. The angle of deviation for distance on postoperative day 1 was the only significant factor that correlated with alignment at 6 months post-operation, and the model of SVM was useful to determine the optimal time of the postoperative functional cure.

Surgical management of intermittent exotropia: do we have an answer for all?

Intermittent exotropia (X(T)) is one of the most common form of strabismus with surgery being the mainstay of treatment. The main goal of surgery is to preserve binocular vision and stereopsis and to prevent its further loss. The decision to operate is mainly based on four aspects: increasing angle of exodeviation, deteriorating control of X(T), decrease in stereopsis for near or distance and quality of life. Bilateral lateral rectus muscle recession and unilateral lateral rectus recession with medial rectus resection, are the two most common surgical procedures performed and have been studied extensively in basic, divergence excess and convergence insufficiency types of X(T). However, there is no consensus over the relative efficacy of the two procedures in terms of postoperative alignment, residual or recurrent exotropia and consecutive esotropia with widely variable results, which can be attributed to poor understanding of the natural course of the disease. Multiple demographic, clinical and anatomic features that may influence the surgical outcomes have been studied to explain this variability. Moreover, most of the evidence regarding surgical outcomes of X(T) is from retrospective studies and the ongoing randomised prospective trials can shed light on long-term efficacy of these procedures. The goal of this review is to give a comprehensive overview of the outcomes of various surgical techniques in the management of different types of X(T), the preoperative and postoperative factors that may affect the surgical outcomes and to discuss the dilemmas faced by the treating surgeons including the effective management of overcorrection and undercorrection.

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.

Immediate Postoperative Alignment Following Bimedial Rectus Recession for Esotropia in Children Compared to Adults

PURPOSE

To determine whether the immediate postoperative alignment among patients undergoing successful bilateral weakening surgery for esotropia is different in children compared to adults.

METHODS

The medical records of all patients undergoing surgery for esotropia by a single surgeon at a major academic referral center between January 1, 2002, and July 1, 2014 (n = 544), were retrospectively reviewed. Exclusion criteria included those with prior strabismus surgery, unilateral surgery, strengthening procedures, vertical or superior oblique surgery, and those wearing hyperopic spectacles for accommodative esotropia. Additionally, all patients had to have a 1- and 6-week postoperative examination and 8 prism diopters (PD) or less of deviation at their 6-week examination.

RESULTS

Ninety-five (17.5%) of the 544 patients met the inclusion criteria. Surgery was performed at a median age of 3.7 years (range: 7 months to 86 years) for a median esodeviation of 35 PD (range: 12 to 70 PD). Among the 73 patients younger than 11 years, the immediate mean postoperative alignment was 9 PD of exotropia (range: 14 PD esotropia to 30 PD exotropia) compared to 2 PD of exotropia (range: 9 PD esotropia to 30 PD exotropia) in the 22 patients 11 years or older (P = .001). Seventy-one percent of successfully aligned patients younger than 11 years were exotropic in the immediate postoperative week compared to 23% of those 11 years or older (P < .001). Twenty-four (32.8%) of the younger cohort had an immediate overcorrection of 15 PD or more compared to 1 (4.5%) in the older cohort (P = .006).

CONCLUSIONS

Successful bilateral strabismus surgery for children with esotropia results in a significantly greater overcorrection, compared to adults, in the immediate postoperative period. [J Pediatr Ophthalmol Strabismus. 2018;55(5):299-305.].

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.

Characteristics of Patients Who Are Not Responsive to Alternate Patching for Overcorrected Intermittent Exotropia

Purpose

To compare the characteristics of patients with surgically overcorrected intermittent exotropia treated with alternate patching.

Methods

The medical records of 51 patients who underwent bilateral lateral rectus muscle recession for intermittent exotropia and required alternate patching to correct postoperative overcorrection were retrospectively reviewed. Patients with postoperative esodeviation ≥18 prism diopters (PD) were started on alternate patching on postoperative day 1, whereas those with postoperative esodeviation of 10 to 17 PD were started after 2 weeks. Postoperative esodeviation <10 PD was considered as slight intentional overcorrection after exotropia surgery. Patients not responsive to alternate patching treatment were defined as those with postoperative esodeviation ≥10 PD after 3 months of treatment. Sex, family history, age, refractive error, amblyopia, stereopsis, suppression, type of exotropia, surgical method, preoperative and postoperative angle of deviation, and start time of alternate patching were compared.

Results

Among 51 patients, 29 patients responded to alternate patching and 22 patients did not respond. Female sex (p = 0.04), larger preoperative exodeviation at distance (p = 0.04), late onset of postoperative maximal esodeviation (p < 0.01), larger postoperative maximal esodeviation at near (p = 0.02), and late initiation of alternate patching (p = 0.01) were associated with patients in the non-responsive group. Although postoperative angle of deviation was similar for 2 weeks, the angle of postoperative esodeviation was significantly larger in the non-responsive group than in the responsive group, beginning at 1 month postoperatively.

Conclusions

Female sex, large preoperative exodeviation, late initiation of alternate patching, and large esodeviation 1-month postoperative predisposed patients to be resistant to alternate patching for postoperative overcorrection.

The difference of surgical outcomes between manifest exotropia and esotropia

PURPOSE

To determine the factors that affect ocular alignment and binocular sensory functions after strabismus surgery and compare surgical outcomes between manifest exotropia (XT) and esotropia (ET).

METHODS

In a retrospective study, 41 XT and 17 ET patients who had undergone strabismus surgery were recruited. Information on type and duration of strabismus, age at onset of deviation and surgery, pre- and postoperative strabismus deviation angles, and binocular sensory functions including stereoacuity and macular fusion capacity was recorded.

RESULTS

In all patients, the ocular alignment and binocular sensory functions improved with time following surgery. Residue strabismus deviation angles (≦ 10 prism diopters) at postoperative 1 month determined the final successful ocular alignment. In patients with final excellent binocular sensory functions, XT group restored macular fusion capacity and stereoacuity at postoperative 1 month, but ET group regained macular fusion capacity at postoperative 1 month and then restored stereoacuity at postoperative 3 months. Though XT patients showed better pre- and postoperative stereoacuity than ET patients, patients with successful ocular alignment had an odd of 4.5 in XT group and 22.5 in ET group to achieve excellent and fair binocular sensory functions.

CONCLUSION

Surgical correction of strabismus could improve ocular alignment and binocular sensory functions in patients with manifest strabismus, regardless of onset age, strabismus duration, or type. Postoperative 1-month status may help to predict the final motor and sensory outcomes. ET patients would benefit more final successful ocular alignment and excellent binocular sensory functions from early surgery and maintaining postoperative small deviation angle than XT patients.

The fast exodrift after the first surgical treatment of exotropia and its correlation with surgical outcome of second surgery

Background

To compare the rate of exodrift after a second surgery for recurrent exotropia, in patients grouped to fast versus slow exodrift after their first surgery. To determine whether there is a correlation with surgical outcome, and to evaluate the factors associated with fast exodrift.

Methods

Patients with recurrent intermittent exotropia, who underwent contralateral lateral rectus recession and medial rectus resection as the second surgery and were followed up for 24 months postoperatively between January 1991 and January 2013, were reviewed retrospectively. The patients were divided into two groups according to the rate of exodrift after the first surgery: Group F, patients exhibiting fast exodrift after the first surgery (> 10 prism diopters [PD] before postoperative month 6); and Group S, patients exhibiting slow exodrift after the first surgery (≤10 PD before postoperative month 6). The difference in the clinical course over the 24 months after the second surgery between the two groups and factors associated with fast exodrift were analyzed.

Results

In total, 106 patients with recurrent exotropia were enrolled in this study. Of these, 68 (64.2%) and 38 (35.8%) patients were included in group F and S, respectively. Group F showed more exodrift compared with groups S over the 24-month postoperative period; however, there was no significant difference in the clinical course between the two groups during that time (p = 0.54, repeated-measure ANOVA). In logistic analysis, immediate postoperative deviation after the first surgery was associated with fast exodrift (p <  0.001).

Conclusion

Although patients with recurrent exotropia had shown fast exodrift after the first surgery, no significant difference in the surgical outcome was observed after the second surgery according to the rate of exodrift after the first surgery.

Factors affecting surgical outcome of intermittent exotropia

PURPOSE

The purpose of this study was to investigate the factors affecting surgical outcome in intermittent exotropia.

DESIGNS

This was a retrospective interventional study.

METHODS

Intermittent exotropic patients who had undergone surgical correction with a postoperative follow-up period of 1 month or more were included in the study. Surgical success was defined as an alignment between 10 prism diopters (PD) of exotropia or 5 PD of esotropia at 1 month. After data collection, data were analyzed in SPSS version 23 software. The main outcome measures were the factors affecting surgical outcome.

RESULTS

We included 101 patients, including 52 (51.5%) male and 49 (48.5%) female. Among them, 62 (61.4%) patients achieved surgical success. Undercorrection was the primary reason of surgical failure. Multivariate regression analysis showed that a larger preoperative angle of deviation was associated with unfavorable surgical outcome (P = 0.053, odds ratio [OR] =0.97, 95% confidence interval [CI] = 0.94-1.00), and the presence of postoperative day 1 (POD 1) diplopia correlated significantly with higher surgical success (P = 0.001, OR = 4.54, 95% CI = 1.80-11.43). The presence of POD 1 diplopia was highly associated with POD 1 esotropia (P = 0.005, OR = 7.26, 95% CI = 1.84-28.58).

CONCLUSION

In intermittent exotropia, larger preoperative angle of deviation may predict a lower surgical success rate. Despite a worrisome issue, the presence of diplopia on first POD is associated with immediate postoperative alignment of esotropia and predicts a higher surgical success.

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

BACKGROUND

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

OBJECTIVES

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

DATA EXTRACTION

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

RESULTS

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

CONCLUSIONS

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

Combined Surgery for Simultaneous Treatment of Congenital Ptosis and Coexisting Strabismus

PURPOSE

To evaluate the clinical outcomes of single-stage surgery for treatment of patients with congenital ptosis and coexisting strabismus.

METHODS

A retrospective analysis was performed on 10 patients (17 eyes) with congenital ptosis and coexisting strabismus. Patients were treated with levator resection or frontalis suspension for ptosis and ocular muscle surgery for strabismus, performed as a single-stage procedure. Levator resection was performed in 9 patients (15 eyes) and frontalis muscle flap suspension was performed in 1 patient (2 eyes) with blepharophimosis. Seven patients (11 eyes) simultaneously underwent exotropia correction, and inferior oblique myectomy was performed in 3 patients (3 eyes) with congenital superior oblique palsy.

RESULTS

Satisfactory efficacy of single-stage surgery for correction of congenital ptosis and coexisting strabismus was achieved without complications.

CONCLUSIONS

Comprehensive preoperative examination is vital to determine the appropriate diagnosis and guide surgical decision-making. Single-stage surgery for congenital ptosis and coexisting strabismus is effective and a shortened treatment period is beneficial to patients. [J Pediatr Ophthalmol Strabismus. 2017;54(5):288-294.].

Factors affecting residual exotropia after two muscle surgery for intermittent exotropia

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

Clinical Characteristics and Surgical Outcomes in Patients With Intermittent Exotropia: A Large Sample Study in South China

The clinical characteristics and surgical outcomes in a large sample of patients with intermittent exotropia (IXT) as well as an analysis of risk factors associated with surgical failures are presented in this article. Data from IXT patients who received surgical management at the Eye Hospital, in the Zhongshan Ophthalmic Center, of Sun Yat-Sen University, China from January 2009 to December 2013 were reviewed retrospectively. Included within this analysis were data from pre- and postoperative ocular motility, primary alignment, and binocular vision.A total of 1228 patients with IXT were reviewed. Males (50.4%) and females (49.6%) were nearly equally represented in this sample. Thirty-two patients (2.6%) had a family history of strabismus. The mean age at onset was 6.77  ±  6.43 years (range 7 months -48.5 years), mean duration at presentation was 7.35  ±  6.68 years (range 6 months-47 years), and mean age at surgery was 13.7  ±  8.8 years (range 3-49 years). The mean refractive error was -0.84  ±  2.69 diopter in the right eye and -0.72  ±  2.58 diopter in the left eye. Amblyopia (4.2%), oblique muscle dysfunction (7.0%), and dissociated vertical deviation (4.7%) were also present in these patients. The most common subtype of IXT was the basic type (88.1%). Orthophoria was observed in 80.5% of patients and the ratios of surgical undercorrection and overcorrection were 14.7% and 4.8%, respectively, as determined with a mean follow-up time of 7.8  ±  3.7 months. When combining ocular alignment with binocular vision as the success criteria, the success rate decreased to 35.6%. Multivariate risk factor analysis showed that only the loss of stereoacuity (P = 0.002) was associated with a poor outcome. There were no differences in the long-term results between bilateral lateral rectus recession and unilateral lateral rectus recession with medial rectus resection.Most IXT patients displayed normal vision, with few having positive family histories, amblyopia, oblique muscle dysfunction, and dissociated vertical deviation. The most common subtype of IXT was the basic type. Long-term surgical results were less favorable when sensory status was included in the criteria for success. Patients with stereoacuity loss were at an increased risk for poor outcomes.

The Effect of Achieving Immediate Target Angle on Success of Strabismus Surgery in Children

PURPOSE

To determine if achieving the ideal postoperative target range increases the long-term success of pediatric strabismus surgery.

DESIGN

Interventional case series.

METHODS

Children below 12 years old with horizontal strabismus who underwent surgical correction by recession, resection, advancement, or a combination of both between 1996 and 2011 were included. Alignment was measured within 1 week and at a minimum of 6 months after surgery. The ideal postoperative target range was defined as 0-8 prism diopters (PD) of esotropia in exotropic patients and within 4 PD of orthotropia in esotropic patients measured within 1 week after the surgery. Success was defined as a measurement within 10 PD of orthotropia at the latest postoperative visit. The main outcome measures were surgical success rate and the factors affecting it.

RESULTS

We included 352 patients with mean follow-up of 18 months. Overall, patients within the target range had a higher success rate than those outside it (75.6% vs 57% P = .0004). This was highly significant for exotropia (P = .0002) but not for esotropia (P = .4). Multiple regression analysis revealed that being within target range was the strongest predictor of long-term success (odds ratio [OR] = 2.3, range 1.4-3.7). Overall, surgeries on patients with esotropia were more likely to be successful than on those with exotropia (OR = 1.9, range 1.2-3), and premature patients had poorer outcomes (OR = 0.2, range 0.1-0.8).

CONCLUSION

Achieving the ideal target range within 1 week after surgery is associated with a high rate of long-term success in exotropia surgery in children.

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.

Surgical treatment for residual or recurrent strabismus

Although the surgical treatment is a relatively effective and predictable method for correcting residual or recurrent strabismus, such as posterior fixation sutures, medial rectus marginal myotomy, unilateral or bilateral rectus re-recession and resection, unilateral lateral rectus recession and adjustable suture, no standard protocol is established for the surgical style. Different surgical approaches have been recommended for correcting residual or recurrent strabismus. The choice of the surgical procedure depends on the former operation pattern and the surgical dosages applied on the patients, residual or recurrent angle of deviation and the operator's preference and experience. This review attempts to outline recent publications and current opinion in the management of residual or recurrent esotropia and exotropia.

Early postoperative alignment as a predictor of 6-month alignment after intermittent exotropia surgery

PURPOSE

The angle of postoperative deviation changes over time in patients undergoing surgery for intermittent exotropia. The aim of the current study was to assess the relationship between the motor alignment at 1 week and 6 months after exotropia surgery.

METHODS

The records of 81 patients who underwent surgery for intermittent exotropia from 2002 to 2012 at Imam Hussein Medical Center and had at least 6 months of postoperative follow-up were retrospectively reviewed. Each patient underwent complete eye examination and had surgery for orthophoria. Patients were divided into three groups according to their 1-week postoperative alignment (undercorrection [exotropia > 10 prism diopters (PD)], orthophoria [exotropia ≤ 10 PD and esotropia ≤ 5 PD], and overcorrection [esotropia > 5 PD]).

RESULTS

The postoperative success rates for 1 week and 6 months were 75.3% and 76.5% respectively. Of 61 orthophoric, 13 undercorrected, and 7 overcorrected patients at 1 week postoperatively, 51 (83.6%), 7 (53.8%), and 2 (28.6%) patients, respectively, preserved their initial alignment at 6 months (P = .024 for orthophoria). The type of surgery had no effect on the results at 6 months. Reoperation was needed in 10 (12.3%) of our patients at the 6-month follow-up (7 undercorrected and 3 orthophoric patients).

CONCLUSIONS

Early postoperative alignment of intermittent exotropia at 1 week can be considered a predictor of orthophoria at 6 months, whereas fewer cases in other groups made predicting their alignment at 6 months statistically difficult. Reoperation was needed in 12.3% of cases at the 6-month follow-up.

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.

Augmented surgical amounts for intermittent exotropia to prevent recurrence

Purpose:

The purpose was to evaluate the results of bilateral lateral rectus (BLR) recession which is based on augmented surgical amounts of classical surgical table of Parks’ for basic and pseudo-divergence excess type intermittent exotropia [X(T)].

Materials and Methods:

Patients with X(T) operated by the same surgeon and followed-up for at least 6 months were included. Patients with prior surgery, neurobehavioral and musculoskeletal conditions, strabismus different from that mentioned above X(T) were excluded. All the patients received BLR only. The amount of the recession was increased by the amount needed to correct 5 prism diopters (PD) more X(T) than what was measured. After the operation, 1^st week, 2^nd and 6 months measurements were recorded. The patients were grouped according to their 1^st week (3–7 days) postoperative examination as: >10 PD esotropia (Group 1), ≤10 PD esotropia (Group 2), exotropia (Group 3), and orthotropic (Group 4), respectively. Final surgical outcomes were classified as “good” (≤10 PD exotropia and ≤5 PD esotropia), “recurrence” (>10 PD exotropia) and “overcorrected” (>5 esotropia).

Results:

Thirty-seven patients were included. The mean age was 6.78 ± 2.87 years (range: 2–12 years). Mean preoperative deviation was 29.72 ± 8.07 PD (range: 15–45 PD) at distance and 20.94 ± 11.65 PD (range: 10–45 PD) at near (P < 0.0001). There were 21 (56.8%) patients in Group 1, 9 (24.3%) patients in Group 2, 1 (2.7%) patient in Group 3 and 6 (16.2%) patients in Group 4. Initial esotropia was achieved in 30 (30/37) of the patients. Twenty-eight of them had good results at the end of the 6 months. Overall “motor surgical” success rate was found to be 89.2% (33/37 patients), with 1 (2.7%) overcorrection and 3 (8.1%) recurrences at the end of the 6 months.

Conclusion:

This study demonstrated that early overcorrection of 10–20 PD after X(T) surgery can achieve acceptable motor outcomes in the first 6 months postoperative period.

Botulinum toxin a treatment of consecutive esotropia in children

OBJECTIVE

To assess the outcome of botulinum A toxin (BTXA) to treat surgically overcorrected intermittent exotropia in children.

METHODS

A retrospective analysis was performed on a series of children with consecutive esotropia treated with BTXA.

RESULTS

Six children with a mean consecutive esotropia of 21 prism diopters (PD) were treated with BTXA at a mean of 19.8 months following strabismus surgery. Two patients underwent a single injection, three patients 2 injections, and one patient 3 injections. Complications included transient ptosis and a vertical deviation. Mean follow-up from last BTXA injection was 16 months. At last follow-up, 4 of the 6 patients were orthotropic and stereopsis was present in 4 of 5 patients old enough to cooperate with testing. One patient was treated with strabismus surgery following a single BTXA injection.

CONCLUSIONS

BTXA is an efficacious treatment for consecutive esotropia in children. However, in our series, two-thirds of patients required multiple injections to achieve the desired outcome and one ultimately had an additional strabismus surgery.

Postoperative minimal overcorrection in the surgical management of intermittent exotropia

PURPOSE

To investigate the effect of initial postoperative minimal overcorrection on the result of the surgical management of intermittent exotropia based on long-term follow-up results.

METHODS

111 patients who underwent surgery for intermittent exotropia and were followed up for at least 5 years after surgery were retrospectively reviewed. The outcome was judged to be successful when there was 10 prism dioptres (PD) or less of exodeviation and less than 5 PD of esodeviation without any reoperation at the final follow-up visit. We evaluated the success, recurrence, overcorrection rate and the duration of diplopia according to their initial deviation.

RESULTS

We divided patients into four groups based on their initial deviation: orthophoria or undercorrection (Ortho group, 31 patients), minimally overcorrected at 5 PD or less (MO group, 20 patients), usually overcorrected between 6 PD and 10 PD (UO group, 35 patients), and highly overcorrected at more than 10 PD (HO group, 25 patients). The success rate was 43-60% between the four groups (p=0.52). The recurrence rate was 28-57% (p=0.105), but post hoc analysis showed borderline p values between the Ortho and HO group (p=0.024). No overcorrection was noted in the Ortho and MO groups (p=0.04). The duration of diplopia was 0-2.5 weeks, showing statistically significant difference among groups (p<0.001).

CONCLUSIONS

The amount of initial postoperative overcorrection may not predict the long-term success rate. However, the MO group showed a lower recurrence rate than the Ortho group and also showed no overcorrection and a shorter duration of postoperative diplopia than the UO and HO groups.

Clinical characteristics of patients that experience different rates of exodrift after strabismus surgery for intermittent exotropia and the effect of the rate of exodrift on final ocular alignment

PURPOSE

To evaluate the ocular motility factors associated with the rate of exodrift after surgical correction of intermittent exotropia and to determine whether the rate had an effect on the subsequent postoperative ocular alignment.

METHODS

Consecutive patients who underwent surgical correction of intermittent exotropia between 2009 and 2010 were observed for 12 months. Patients were divided into two groups, according to the averaged value of the rate of exodrift (fast vs slow). The ocular motility characteristics of the patients in each group were compared with identify factors that correlated with the speed of postoperative exodrift and to determine whether the rate had an effect on the final ocular alignment at 12 months after surgery.

RESULTS

A total of 159 patients underwent strabismus surgery during the study period. Of these, 130 experienced postoperative drift. The preoperative deviation at near and distance differed significantly between the fast and slow groups (P < 0.05) and was correlated to the rate of exodrift (near r = 0.427, distance r = 0.378): fast group, 32.09(Δ) ± 10.07(Δ), 27.60(Δ) ± 6.65(Δ); slow group, 31.74(Δ) ±10.34(Δ), 27.21(Δ) ± 6.03(Δ). The deviation at the first day after the surgery differed significantly between groups (P < 0.05) and was correlated to the rate of drift (r = 0.381): fast group, 4.72(Δ) ± 5.46(Δ) esotropia; slow group, 1.87(Δ) ± 4.40(Δ) esotropia. The two groups did not differ significantly in other factors. There were no differences in ocular alignment at 12 months' follow-up.

CONCLUSIONS

The rate of exodrift correlated with the size of the preoperative deviation and the amount of the initial postoperative overcorrection. It had no affect on the ocular alignment at 12 months after surgery.

Prismatic correction of consecutive esotropia in children after a unilateral recession and resection procedure

PURPOSE

To determine the long-term efficacy of prismatic correction in consecutive esotropia after a unilateral recession and resection (RR) procedure for primary exotropia.

DESIGN

Retrospective cohort study.

PARTICIPANTS

A total of 110 patients with esodeviation of 5 prism diopters (PD) or more at 4 weeks after the unilateral RR procedure for primary exotropia who were fitted with prism glasses and were followed up for a minimum of 2 years after primary surgery.

METHODS

Patients were divided into 2 groups based on whether they were weaned off the prism glasses within 1 year: (1) the prism-weaned group whose esotropia decreased enough for them to be weaned off the prism within 1 year; (2) the prism-wearing group who wore prism glasses for more than 1 year. Clinical characteristics and changes in deviation angle were compared between groups.

MAIN OUTCOME MEASURES

The period of prism wearing, the rate of decline in deviation angle after prismatic correction, and preoperative and postoperative motor and sensory outcomes.

RESULTS

The average age of patients was 4.7 years. Overall, the average period of prism wearing was 20.9 months, and the rate of decrease in the deviation angle was 2.9 PD per 6 months. Thirty-four patients (32%) were weaned off the prism glasses within 1 year. The prism-weaned group showed more preoperative constant deviation and anisometropia compared with the prism-wearing group. Overall, successful motor outcome was achieved in 71% of patients. The rate of recurrence during follow-up was higher in the prism-weaned group, and the rate of overcorrection was higher in the prism-wearing group (P = 0.003). No patients demonstrated new onset amblyopia, and 1 of the 105 patients (0.95%) demonstrated loss of stereoacuity as a result of overcorrection. At the final visit, stereoacuity was improved or was maintained in 92% of patients compared with preoperative values.

CONCLUSIONS

Prismatic correction can lead to good motor outcomes while maintaining favorable sensory status in most patients with consecutive esotropia. Patients showed different clinical manifestations and outcome according to the period of prismatic correction. Patients in the prism-weaned group showed a faster change in esodeviation after prismatic correction and more exotropic drift after prism weaning, resulting in a higher rate of recurrence of exotropia.

Long-term ocular alignment after bilateral lateral rectus recession in children with infantile and intermittent exotropia

PURPOSE

To compare postoperative drift after bilateral lateral rectus recession for infantile exotropia (XT) and for intermittent XT and to compare initial postoperative alignment with long-term motor outcome.

METHODS

Medical records of all patients with infantile exotropia or intermittent exotropia who had undergone bilateral lateral rectus muscle recession surgery with a follow-up longer than 3 years were reviewed. The pre- and postoperative angles of deviation at distance and at near and postoperative drift at distance were compared. Surgical outcome was categorized as "success" (esotropia <6(Δ) or exotropia <11(Δ)), "recurrence" (>10(Δ) exotropia), or "overcorrection" (>5(Δ) of esotropia).

RESULTS

The overall mean postoperative exotropic drift at 3 years was 10.4(Δ) in the infantile XT group and 7.2(Δ) in the intermittent XT group (P = 0.05). Both groups had a low success rate at 3 years: 41% in the infantile XT group and 51% in the intermittent XT group (P = 0.270). For patients with an initial esotropia of 0(Δ) to 10(Δ), the success rate at 3 years was 86% in the infantile XT group (12 of 14) and 65% in the intermittent XT group (28 of 43).

CONCLUSIONS

Postoperative exotropic drift is clinically similar in patients with intermittent versus infantile exotropia. Esotropia of 0(Δ) to 10(Δ) during the early postoperative period may be associated with the best long-term ocular alignment.