Consecutive exotropia after surgical treatment of childhood esotropia: a 40-year follow-up study

Strabismus Surgery for Psychosocial Reasons-A Literature Review

Introduction

Strabismus surgery may be undertaken for visual benefit, to improve or eliminate diplopia symptoms, or to restore or improve binocular single vision (BSV). In patients without visual symptoms or expected visual benefit, strabismus surgery may still be undertaken if the presence of strabismus causes the patient psychosocial symptoms. To evaluate strabismus surgery undertaken for psychosocial reasons, evidence of postoperative outcomes in this specific cohort is needed.

Methods

A systematic search of the literature was conducted (1946-2023) to identify evidence where postoperative outcomes were reported for adult patients (age 18 years and above) who had undergone strabismus surgery for psychosocial reasons.

Results

Sixty-nine papers were included in the literature review. Most sources of evidence included patients within heterogeneous cohorts of strabismus surgery outcomes, with a range of symptoms and differing surgical aims.

Discussion

In adults who underwent strabismus surgery for psychosocial reasons, improved postoperative ocular alignment and/or improved health related quality of life (HRQoL) were common. Strabismus surgery outcomes appeared to be measured satisfactorily at three months postoperatively. Additional surgical outcomes, including an expanded field of vision, unexpected BSV, improved binocular summation, improved task performance and improved eye movements have been reported, but not fully investigated. There was a lack of consensus on how postoperative success should be defined and measured. A core outcome set for strabismus has been suggested and there is potential to add to the available evidence by investigating which outcome measures are most relevant to those with strabismus and psychosocial symptoms. There is a growing need for robust evidence in this specific subgroup of patients due to a lack of evidence specifically reporting postoperative outcomes in adults with strabismus and psychosocial symptoms.

Long-term Motor and Sensory Outcomes After Unilateral Medial Rectus Recession-Lateral Rectus Resection for Infantile Esotropia

PURPOSE

To report long-term motor and sensory outcomes after unilateral medial rectus recession-lateral rectus resection for infantile esotropia.

METHODS

The medical records of patients who had undergone unilateral medial rectus recession-lateral rectus resection for infantile esotropia and were followed up postoperatively for a minimum of 10 years were reviewed retrospectively.

RESULTS

A total of 100 patients were included. The mean age at surgery was 2.9 ± 2.2 years (range: 2.5 months to 9.0 years). The mean postoperative follow-up was 15.7 ± 4.4 years (range:10.0 to 27.5 years). Overall, 54 patients (54%) had surgical success at their last follow-up visit. Age at first surgery, strabismus duration, degree of hyperopia, preoperative size of deviation, presence of dissociated vertical deviation, inferior oblique overaction, or both dissociated vertical deviation and inferior oblique overaction, and the number of esotropia surgeries did not predict motor outcome after surgery. Consecutive exotropia developed in 43% of patients (constant in 18% and intermittent in 25%). Residual and recurrent esotropia occurred in 20% and 21% of patients, respectively. Refractive accommodative esotropia developed in 17% of patients and there was a high accommodation convergence/accommodation ratio esotropia in 2%. Peripheral binocular single vision was achieved in 54% of patients and stereopsis in 1%. Patients with 1.5 years or less of strabismus duration had better chances of achieving peripheral binocular single vision.

CONCLUSIONS

Nearly half of the patients with infantile esotropia achieved a successful long-term motor outcome and peripheral binocular single vision. Consecutive exotropia occurred frequently. Recurrent esotropia and refractive accommodative esotropia developed in some patients, and a high accommodation convergence/accommodation ratio esotropia in a few. Stereopsis outcome was extremely poor. [J Pediatr Ophthalmol Strabismus. 2024;61(2):106-113.].

Characteristics and risk factors for spontaneous and postoperative consecutive exotropia in children with esotropia

Background

To investigate the risk factors for the development of consecutive exotropia (CXT) by comparing patients with spontaneous or postoperative CXT during follow-up with another group of patients who had no deviation or less than 10 prism dioptre (PD) esotropia.

Methods

In this retrospective cohort study, 6 patients with spontaneous CXT (group A), 13 patients with postoperative CXT (group B), and 39 patients with no exotropia (group C) were enrolled. Probable risk factors for CXT were evaluated among the groups. Kruskal-Wallis H test was used to determine if any significant differences were present among the groups. Fisher's exact test or Mann-Whitney U test was used for univariate analyses to compare differences between case groups or between case and control groups. The Bonferroni method was used to conduct multiple comparisons.

Results

The follow-up period of spontaneous CXT patients was significantly longer than that of postoperative CXT and nonconsecutive exotropia patients (p = 0.035 and p < 0.001, respectively). The interval between alignment and CXT onset in spontaneous CXT patients was slightly longer than that in postoperative CXT patients, but not significantly difference (6.50 vs. 5.00 years, p = 0.072). Vertical deviation was associated with a high risk of postoperative CXT (p = 0.001). Most [38 (97.44%)] nonconsecutive exotropia patients had fusion; conversely, the absence of fusion function (p < 0.001) as well as stereoacuity (p = 0.029) were associated with a high risk of CXT.

Conclusion

Vertical deviation and poor binocular function are strongly associated with a high risk of CXT. Children with spontaneous CXT are highly recommended to be followed-up long-term, while they maintain long-term ocular alignment before developing consecutive exotropia from comitant esotropia (CE).

Evaluation of Strabocheck® as an objective measurement method of comitant horizontal strabismus in children undergoing surgery

The gold standard of angle measurement is the prism alternating cover test (PCT). This method requires cooperation from the child, experience, and presents a significant inter-observer variability. Strabocheck®(SK) is a new simple tool for objective and semi-automated angle measurement. Our purpose is to evaluate Strabocheck® in children undergoing surgery for comitant horizontal strabismus. The study population was divided into 3 groups: infantile esotropia, partially accommodative esotropia and intermittent exotropia. The primary endpoint was the agreement between Strabocheck®and the PCT. A total of 44 children were included prospectively. The correlation between the angle measured by the PCT and the angle measured by SK was strong (R = 0.87). The mean absolute difference in the angle measured by the two methods was Δ = 11.9+/- 9.8 diopters. The Bland-Altman plot shows a 95% interval limit between -30.0 [-34.4; -25.6] and 31.0 [26.7; 35.4] diopters. SK is an interesting tool to evaluate the angle of strabismus in children. However, the residual discordance between PCT and SK leads us to question the real value of the angle, which can only be approximated. A better clinical experience of this new tool in relation to the clinical condition and the PCT will allow to have a more accurate idea on the true angle and will probably help the surgeon to adapt this procedure.

Routine use of non-absorbable sutures in bi-medial rectus recession as a measure to reduce the incidence of consecutive exotropia

OBJECTIVE

To evaluate the incidence of consecutive exotropia following bilateral medial rectus muscle recession surgery (BMR) for esotropia using non-absorbable compared with absorbable sutures in children undergoing strabismus surgery.

METHODS

A retrospective cohort study of all children with esotropia who underwent BMR by a single surgeon in a tertiary public hospital. As of February 2018, only non-absorbable sutures were used. The primary outcome was the incidence of consecutive exotropia.

RESULTS

A total of 121 children were included in the analysis, 3.66 ± 2.62 years, 53% were male. In 80 children (66%) non-absorbable sutures were used (non-absorbable group) and in 41 children (34%) absorbable sutures were used (absorbable group). Consecutive exotropia (≥ 8 prism dioptres) occurred in ten children (24%) in the absorbable group and in three children (4%) in the non-absorbable group (OR = 8.28, 95% CI = 2.13-32.13; P = 0.002). This difference between groups remained significant after adjustment for potential confounders and follow-up time (HR = 4.98, 95% CI = 1.30-19.05, P = 0.019). Mean follow-up time was 22 and 12 months in the absorbable and non-absorbable groups, respectively (P < 0.001). Two children in the non-absorbable group had pyogenic granuloma that resolved after 3 months of topical steroidal therapy.

CONCLUSION

Routine use of non-absorbable sutures in BMR surgery for esotropia may be a preferable alternative to absorbable sutures for the prevention of consecutive exotropia.

Surgical outcomes of medial Rectus advancement for consecutive exotropia

PURPOSE

To evaluate the surgical results of medial rectus muscle advancement for consecutive exotropia.

METHODS

The medical data of patients that underwent reoperation between the years 2000-2020 were collected and reviewed retrospectively. Patients who underwent medial rectus advancement for consecutive exotropia were included. The exclusion criteria were follow-up period shorter than 6 months, past reoperations and restrictive or paralytic strabismus. Success was defined as alignment within 10 PD of orthophoria at last follow-up. The success group of patients was compared with the failure group.

RESULTS

Twenty patients with mean postoperative follow-up from the second surgery of 34.7  ±  29.2 months were included. On last follow-up examination, 9 (45.0%) patients had a successful result. Nine patients had undercorrection and 2 had overcorrection. The two groups were similar in the preoperative amount of mean exotropia, 23.3  ±  9.9 PD in the success group and 29.8  ±  14.0 PD in the failure group. On last follow-up examination, the amount of mean deviation was 2.7  ±  2.6 PD exotropia in the success group and 13.4  ±  23.6 PD exotropia in the failure group.

CONCLUSION

Medial rectus advancement for the correction of consecutive exotropia was successful in almost half of the cases. Failure was usually due to undercorrection.

Evaluation of the insertion distance of the medial rectus in consecutive exotropia by means of intraoperative measure and optical coherence tomography

PURPOSE

To assess the agreement between the measurements of the distance from the medial rectus muscles insertion to the limbus measured by intra-operative spectral-domain optical coherence tomography (SD-OCT) in consecutive exotropia (cXT).

METHODS

An analysis was performed on total of 14 medial rectus (MR) muscles of 14 patients who underwent surgery for the treatment of cXT. The limbus-insertion distance of the MR muscles was measured using preoperative SD-OCT and intraoperatively using a calliper. The intraclass correlation coefficient (ICC) and Bland Altman plots were calculated to determine the agreement between the two methods, as well as the correlation.

RESULTS

Mean age was 36.3 ± 16.0 years (range 13-60), with 60% being women. Mean preoperative deviation was 38.7 ± 16.9 prismatic dioptres (PD) (range 16-65), being +1.3 ± 6.3 PD (range -12 to +10 PD) after surgery. Intraoperatively the MR insertion was found at 8.7 ± 2.1 mm (range 5.5-12.0) and by OCT at 7.7 ± 1.2 mm (range 5.3-10.0). The ICC showed a moderate to good agreement (0.659; 95% confidence interval: 0.157-0.885; p < 0.001), with a correlation of R = 0.792 (p = 0.011). A better agreement was observed in those MR that were less retro-inserted.

CONCLUSIONS

SD-OCT is able to measure the insertion to the limbus distance of the medial rectus muscles that have been previously operated on, showing moderate to good agreement with intraoperative measurements. However, the agreement was poor in muscles with a large retro-insertion.

Surgical treatment of consecutive exotropia: Comparison of different surgical methods applied to one eye in one session

PURPOSE

To compare the different surgical methods performed on a single eye in a single session and the factors that affect the success of patients having consecutive exotropia (XT) developed after esotropia surgery.

METHODS

The medical data of the patients who underwent surgery for consecutive XT were reviewed retrospectively. Patients with followed of 6 months or more were divided into four groups; patients with medial rectus (MR) advancement (Group 1 = 10), MR advancement and MR resection (Group 2 = 12), MR advancement and lateral rectus (LR) recession (Group 3 = 13), MR advancement, MR resection, and LR recession (Group 4 = 14). Success results and possible risk factors were investigated.

RESULTS

Forty-nine patients with consecutive XT (21 female, 28 male) were enrolled in the study. The mean age of overall patients was 22.97 years at surgery for consecutive XT. The groups did not display significant differences in terms of surgery ages, gender, refraction values, visual acuity, amblyopia, inferior oblique overaction, limitation of adduction, surgical success rates, and follow-up time (p > 0.05). Patients of Group 4 had larger preoperative and postoperative deviation, while Group 1 had smaller (p < 0.05). The surgical success rates of Groups 1, 2, 3, 4 were 90%, 75%, 76.9%, and 50%, respectively (p = 0.192). Statistically, no factor was found to be effective in surgical success rates (p > 0.05).

CONCLUSION

Surgical treatment of consecutive XT is successful in most of the patients with numerous surgical options performed on a single eye in a single session. Patients, particularly with a high amount of deviation should be warned about the possibility of additional surgery.

Bilateral combined resection-recession of the same rectus muscle versus Fadenoperation for treatment of purely tonic esotropias

PURPOSE

To compare the efficiency of bilateral combined resection-recession surgery of the medial rectus muscle versus using a modified Fadenoperation for surgical management of esotropias that totally resolve under general anesthesia, which we called "purely tonic" esotropias.

METHODS

We included 65 unselected consecutive cases of patients with purely tonic esotropias who underwent surgery between October 2017 and 2018. Patients were divided into group I, who underwent a combined resection and recession of medial recti muscles, and group II, who underwent a bilateral medial rectus Fadenoperation using posterior strapping. A satisfactory outcome was defined as deviation ⩽10 prism diopters (PD), at near and distance fixation, between 3 and 6 months postoperatively.

RESULTS

Mean initial deviation was in group I, 19.6 PD and 32.0 PD, in group II, 23.6 PD and 33.5 PD, at distance and near fixation respectively. Postoperatively, in group I, 31 patients (91.2%) showed satisfactory alignment at near and distance fixation. Post-operatively, in group II, 25 patients (80.6%) showed satisfactory alignment at near and distance fixation.

CONCLUSION

Our results suggest both techniques are good options to treat purely tonic esotropias.

Spontaneous consecutive sensory esotropia: a case series

We present the first case series of patients with no systemic neurologic disease who experienced a spontaneous conversion from an initial exotropia to a sensory esotropia in the absence of strabismus surgery or chemodenervation. The patients in this series all were exotropic in the first 2 years of life, with the strabismic eye having decreased vision due to unilateral ocular pathology. All patients demonstrated spontaneous conversion to esotropia between 4 and 8 years of age and thereafter clinically demonstrated a high ratio of accommodative convergence to accommodation. There was no discernible relationship between refractive error and the pattern of spontaneous esotropia. The existence of this rare entity may support delayed surgical correction of strabismus in patients with sensory exotropia.

Medial Rectus Advancement for Secondary Exotropia

PURPOSE

To determine the preoperative characteristics and surgical results after medial rectus advancement in patients with secondary exotropia.

DESIGN

Retrospective, interventional case series.

METHODS

Setting: Tertiary Care University Medical Center. PatientPopulation: 221 patients with a diagnosis of secondary exotropia who underwent medial rectus advancement surgery by a single surgeon.

OBSERVATION

Preoperative demographics, exodeviation and motility, intraoperative findings, and postoperative results were recorded. MainOutcomeMeasure: Success of surgery, defined as Esotropia <15 prism diopters (pd) at postoperative week 1, or any deviation of <8 pd at postoperative month 2 (POM2).

RESULTS

A total of 98 patients underwent unilateral medial rectus advancement (UMRadv), 89 underwent UMRadv with lateral rectus recession (LRc), and 34 underwent bilateral medial rectus advancement (BMRadv). POM2 success rates were 66.7% in UMRadv patients, 62.1% in UMRadv + LRc, and 56% in BMRadv. A total of 117 patients had preoperative adduction deficits, which were significantly associated with the finding of an intraoperative stretched scar (P < .001). Larger preoperative duction deficits were associated with larger stretched scars (P < .001). At POM2, the mean effect of surgery (pd of correction/mm) was 2.3 ± 1.4 pd/mm for UMRadv, 2.5 ± 0.8 pd/mm for UMRadv + LRc, and 2.8 ± 1.1 pd/mm for BMRadv. Patients with a stretched scar had significantly less correction per millimeter (2.2 ± 1.2 pd/mm) compared with those without (2.6 ± 1.2 pd/mm, P < .001). A total of 38.6% of patients experienced exodrift greater than 10 pd. Exodrift was significantly larger in the BMRadv group (P < .005).

DISCUSSION

These results provide guidance for surgical correction based on preoperative deviation and ductions. Adduction deficits indicate a stretched scar, which must be treated with resection and advancement of the medial rectus. A larger amount of surgery is needed in patients with a stretched scar. Exodrift is common, and therefore aiming for approximately 10 pd of overcorrection at postoperative week 1 can improve final outcomes.

CONCLUSION

Medial rectus advancement results in successful surgical results at POM2 for secondary exotropia.

Evaluation of the insertion distance of the medial rectus in consecutive exotropia by means of intraoperative measure and optical coherence tomography

PURPOSE

To assess the agreement between the intraoperative measurements of the distance from the medial rectus muscles insertion to the limbus and preoperative spectral-domain optical coherence tomography (SD-OCT) in consecutive exotropia (cXT).

METHODS

An analysis was performed on total of 14 medial rectus (MR) muscles of 14 patients who underwent surgery for the treatment of cXT. The limbus-insertion distance of the MR muscles was measured using preoperative SD-OCT and intraoperatively using a calliper. The intraclass correlation coefficient (ICC) and Bland Altman plots were calculated to determine the agreement between the two methods, as well as the correlation.

RESULTS

Mean age was 36.3±16.0 years (range 13-60), with 60% being women. Mean preoperative deviation was 38.7±16.9 prismatic dioptres (PD) (range 16 to 65), being +1.3±6.3 PD (range -12 to +10 PD) after surgery. Intraoperatively the MR insertion was found at 8.7±2.1mm (range 5.5 - 12.0) and by OCT at 7.7±1.2mm (range 5.3 - 10.0). The ICC showed a moderate to good agreement (0.659; 95% confidence interval: 0.157-0.885; P<.001), with a correlation of R=0.792 (P=.011). A better agreement was observed in those MR that were less retro-inserted.

CONCLUSIONS

SD-OCT is able to measure the insertion to the limbus distance of the medial rectus muscles that have been previously operated on, showing moderate to good agreement with intraoperative measurements. However, the agreement was poor in muscles with a large retro-insertion.

Comparison of surgical outcomes between lateral rectus recession and medial rectus advancement for postoperative consecutive exotropia

To compare the surgical outcomes of medial rectus advancement and lateral rectus recession in postoperative consecutive exotropia with single-stage adjustable suture surgery.Among 1003 patients who underwent bilateral medial rectus recession between November 1996 and March 2013, the patients who required surgery for consecutive exotopia were retrospectively reviewed. Nineteen patients underwent medial rectus advancement and 15 patients underwent lateral rectus recession. All patients underwent single-stage adjustable surgery under topical anesthesia and were followed up for at least 12 months.The mean follow-up duration was 2.4 years. At final follow-up, a successful surgical outcome was found in 12 patients (63.0%) in the medial rectus advancement group and 14 patients (93.3%) in the lateral rectus recession group (P = .039). The change in ocular deviation was correlated with the amount of recession (P = .008) and preoperative angle (P < .001) in the lateral rectus recession group.Lateral rectus recession showed a higher success rate with predictable and easily performed procedure than medial rectus advancement for the treatment of postoperative consecutive exotropia with adjustable suture.

Consecutive strabismus after infantile nystagmus syndrome surgery and potential risk factors

PURPOSE

The aim of this study is to evaluate the incidence of consecutive strabismus after infantile nystagmus surgery and its potential risk factors.

METHODS

A retrospective study including 89 patients was conducted. Patients presented infantile nystagmus (idiopathic or ocular disease-associated nystagmus) without previous or coincidental strabismus. Sex, age at surgery, amblyopia, botulinum toxin (BT) injection before surgery, spherical equivalent, anisometropia, surgery procedure (Anderson's or retroequatorial recessions of four horizontal recti), and follow-up were analyzed. Kaplan-Meier and univariate Cox regression were performed.

RESULTS

The median age at surgery was 5 years. The median follow-up was 36 months. The incidence of consecutive strabismus was 11.2%. There were eight patients with exotropia and two patients with esotropia. Consecutive strabismus was associated with severe bilateral amblyopia (p = 0.036), previous treatment with BT injection (p = 0.025), and large recessions of the four horizontal muscles (p = 0.001). The hazard ratio for patients with severe bilateral amblyopia was 5.4 (95% CI 1.1-25.8), and for patients previously treated with BT was 6.1 (1.3-29.3). The survival rate was 95.4% at 6 months and 88.5% at 3 years.

CONCLUSION

Severe bilateral amblyopia, previous BT treatment, and type of surgery seem to be associated with consecutive strabismus after infantile nystagmus surgery. Most cases appear within the first months after surgery.

Clinical and surgical risk factors for consecutive exotropia

Introduction:

Consecutive exotropia is one of the complications of esotropia surgery. Its prevalence is estimated at 4%–27%. The aim of this study was to identify the risk factors for consecutive exotropia in the aftermath of surgical treatment of esotropia.

Methods:

Seventy-four patients examined in our strabismus consultation for a consecutive exotropia from January 2010 to June 2016 were retrospectively included. The age of onset of esotropia, the presence of amblyopia, the age of esotropia surgery and chosen procedure, the refractive errors, the anomalies of ocular motility, the age of onset of the consecutive exotropia and its angle of deviation were reported. Statistical analyses were performed with Student’s test and Fisher’s exact test.

Results:

Esotropia occurred in 65% of cases before the age of 1 year, was associated with amblyopia in 51%, hyperopia in 55% or anisometropia in 31%. Surgery was performed before the age of 6 years for 55% of the patients and involved for 52% the both medial recti. The angle of deviation of consecutive exotropia was ≤20 prism dioptres (PD) in 39%, 21-40 PD in 39% and ≥ 40 PD in 22%, related to amblyopia (p = 0.028), and to high hypermetropia (p = 0.05).

Discussion:

Amblyopia and hyperopia were the most important risk factors of consecutive exotropia in our series. Early onset esotropia, stereopsis abnormalities, anisometropia, oblique dysfunction, convergence insufficiency appeared but did not reach statistical significance.

Conclusion:

Amblyopia is a major risk factor that should be taken into consideration during surgery of an esotropia.

Time and Factors Affecting the Direction of Re-drift in Essential Infantile Esotropia

PURPOSE

To investigate the development pattern and related factors of postoperative re-drift in infantile esotropia.

METHODS

A total of 112 patients with infantile esotropia who underwent surgery before 3 years of age were included. Surgical outcomes were divided into (1) consecutive exotropia: more than 8 prism diopters (PD) of exodeviation; (2) recurrent esotropia: more than 8 PD of esodeviation; and (3) monofixation syndrome: maintenance of deviations within 8 PD. The occurrence rate, time of onset, and associated factors of the re-drift were evaluated.

RESULTS

At a mean follow-up of 9.5 years, consecutive exotropia developed in 37 patients (33.0%) and recurrent esotropia in 43 patients (38.4%). Whereas 76.7% of total recurrent esotropia cases were identified within postoperative 1 year, consecutive exotropia occurred constantly over 10 years postoperatively. The mean time to consecutive exotropia development from surgery was 78.6 months, greater than that of recurrent esotropia development (8.9 months) (P < 0.001). In multinomial logistic regression using monofixation syndrome as the reference category, fixation preference before surgery (odds ratio [OR]: 6.64, 95% confidence interval [CI]: 2.07 to 21.32) and the rate of myopic progression (OR: 15.07 per -1.00 D/year, 95% CI: 1.23 to 184.86) were associated with consecutive exotropia, whereas increase in the angle of esodeviation on postoperative day 1 (OR: 1.15, 95% CI: 1.04 to 1.26) was correlated with recurrent esotropia.

CONCLUSIONS

This study demonstrates a difference between the development pattern of exotropic and esotropic drift after infantile esotropia surgery. Detailed preoperative assessment and close postoperative observation of deviations and refractive status will help to determine surgical outcomes of infantile esotropia. [J Pediatr Ophthalmol Strabismus. 2018;55(2):128-134.].

Intraoperative Findings in Consecutive Exotropia with and without Adduction Deficit

PURPOSE

Consecutive exotropia may be associated with limited adduction, which has been reported to be caused by 1 or more anatomic abnormalities of rectus muscles or their insertions. We studied the relative frequency of grades of adduction deficit and the relative frequency of abnormal anatomic findings.

DESIGN

Retrospective cohort study.

PARTICIPANTS

Patients undergoing surgery for consecutive exotropia.

METHODS

Preoperative duction deficits were graded on a -5 (severe limitation) to 0 (normal) scale. Operative reports were reviewed to classify intraoperative factors: (1) medial rectus muscle attachment type (normal, abnormal [slipped or stretched scar], attached to pulley, behind pulley, or mixed [a tenuous normal attachment, but with muscle fibers also attached to the pulley or behind the pulley]), (2) medial rectus muscle distal fiber location (millimeters from original insertion), and (3) lateral rectus muscle tightness (normal, mild restriction, moderate restriction).

MAIN OUTCOME MEASURES

Relationship of grade of adduction deficit to each intraoperative factor.

RESULTS

Of 143 eyes, 124 (87%) had an adduction deficit. Eyes with abnormal (n = 23), pulley (n = 9), behind pulley (n = 8), or mixed (n = 7) attachments had worse adduction deficits than normal attachments (n = 96; P < 0.02). There was a significant correlation between distal medial rectus muscle fiber location (0-19.5 mm recessed) and grade of adduction deficit (P < 0.0001). Eyes with mild or moderate lateral rectus muscle tightness on forced duction testing (n = 48/143 eyes) had worse adduction deficits than eyes without tightness (P < 0.001). Nevertheless, despite overall correlation, there was considerable individual variability. For example, for -1 and -2 adduction deficits, medial rectus muscle attachment could be at the pulley, behind the pulley, or include the pulley (19/87 eyes [22%]), and the lateral rectus muscle was tight in 36 of 87 eyes (41%).

CONCLUSIONS

Adduction deficits are common in patients with consecutive exotropia. Overall, more severe preoperative adduction deficits are associated with medial rectus muscle insertion abnormalities and abnormal forced ductions, but frequently there are exceptions. Severe medial rectus muscle insertion abnormalities, including lost muscles, may be found despite mild preoperative adduction deficits.

Esotropia with an accommodative component after surgery for infantile esotropia compared to primary accommodative esotropia

PURPOSE

To compare the clinical outcomes of patients with an esotropia with an accommodative component after infantile esotropia surgery and patients with primary refractive accommodative esotropia.

METHODS

The medical records of patients with postoperative (secondary group) and primary refractive accommodative esotropia (primary group) were reviewed retrospectively. Changes in ocular alignment, refractive error, weaning rate, decompensation rate over time, and sensory outcomes were compared.

RESULTS

The overall change in ocular deviation with glasses correction was -0.5^Δ/year in the secondary group and -0.2^Δ/year in the primary group (P = 0.010). The overall change in spherical equivalent refractive error was -0.2 D/year in the secondary group and -0.3 D/year in the primary group (P < 0.001). The latest stereoacuity result was poorer in the secondary group than in the primary group (P = 0.027). No significant differences in the decompensation or weaning rates were detected between groups.

CONCLUSIONS

The changes in refractive error and the amount of esotropia over time were different between the secondary group and the primary group. Although refractive error was significantly lower and stereoacuity was poorer in the secondary group compared to the primary group, the majority of patients in the secondary group maintained good control of ocular alignment after hyperopic correction.

Risk factors analysis of consecutive exotropia: Oblique muscle overaction may play an important role

To evaluate clinical factors associated with the onset of consecutive exotropia (XT) following esotropia surgery.By a retrospective nested case-control design, we reviewed the medical records of 193 patients who had undergone initial esotropia surgery between 2008 and 2015, and had follow-up longer than 6 months. The probable risk factors were evaluated between groups 1 (consecutive XT) and 2 (non-consecutive exotropia). Pearson chi-square test and Mann-Whitney U test were used for univariate analysis, and conditional logistic regression model was applied for exploring the potential risk factors of consecutive XT.Consecutive exotropia occurred in 23 (11.9%) of 193 patients. Patients who had undergone large bilateral medial rectus recession (BMR) (P = 0.017) had a high risk of developing consecutive XT. Oblique dysfunction (P = 0.001), adduction limitation (P = 0.000) were associated with a high risk of consecutive XT, which was confirmed in the conditional logistic regression analysis. In addition, large amount of BMR (6 mm or more) was associated with higher incidence of adduction limitation (P = 0.045). The surgical methods and preoperative factors did not appear to influence the risk of developing consecutive XT (P > 0.05).The amount of surgery could be optimized to reduce the risk of consecutive XT. The presence of oblique overaction and postoperative adduction limitation may be associated with a high risk of consecutive XT, which may require close supervision, and/or even earlier operation intervention.

Clinical risk factors for the development of consecutive exotropia: a comparative clinical study

AIM

To compare a group of patients with consecutive exotropia with patients who had ≤10 prism diopters (PD) esotropia or no deviation postoperatively in terms of probable clinical risk factors for the development of consecutive exotropia.

METHODS

The study recruited fourteen patients who developed consecutive exodeviation during follow-up period after the correction of esotropia who were categorized as group 1 and thirty-one patients who had still ≤10 PD esotropia or no deviation at the final visit that were considered as group 2. Clinical risk factors leading the development of consecutive deviation were analyzed as the main outcome measures.

RESULTS

The mean age of patients was 4.57±3.11y in group 1 and 5.10±3.52y in group 2 (P=0.634). There was no significant difference of preoperative near and distant deviations among two groups (P=0.835, 0.928 respectively). The mean amount of medial rectus recession and lateral rectus resection was similar in both groups (P=0.412, 0.648 respectively). Convergence insufficiency and neurological diseases were more frequent in group 1 (P=0.007, 0.045). Accompanying neurological disease was found to be as a significant factor increasing the risk of the development of consecutive exotropia significantly [odds ratios (OR): 5.75 (1.04-31.93)].

CONCLUSION

Accompanying neurological disease appears to be a significant clinical risk factor for the development of consecutive exodeviation during postoperative follow-up after the correction of esotropia. However, larger studies are needed in order to interpret the results to the clinical practice and to ascertain other concurrent risk factors.

Long-term Cosmetic Alignment Following Surgery for Esotropia Versus Exotropia in Childhood: A Comparison Using Survival Curves

PURPOSE

Although long-term results following repair of esotropia and exotropia in childhood have been reported, the two entities have never been directly compared.

METHODS

Records of all children younger than 18 years who underwent horizontal strabismus surgery from 2000 through 2012 were reviewed. Children with structural eye pathology, severe vision loss, neurologic disorders, and incomitant or combined horizontal and vertical deviations were excluded. Failure was defined by a second horizontal surgery or a primary position deviation greater than 20 prism diopters (PD) at any time during follow-up (as long as 10 years). A threshold of 20 PD was chosen because families often consider deviations important enough to warrant a first or second surgery if it is larger but not if it is smaller.

RESULTS

Of 317 children, 235 with esotropia had surgery at a mean age of 42 months and 82 with exotropia had surgery at a mean age of 60 months. Overall, surgery was successful in 78% of those with esotropia and 65% of those with exotropia. A second surgery was performed in 29 (12%) of those with esotropia and 15 (18%) of those with exotropia. The mean deviation at last follow-up, using absolute values, was 9 PD for esotropia and 10 PD for exotropia. Survival curve success was better for esotropia (P = .008).

CONCLUSION

By survival curve analysis, success was more likely among children with esotropia. Many "failures" slipped beyond the 20 PD threshold only transiently and had deviations that were not noticeable to family or friends. Overall, children did reasonably well long-term following surgery for both esotropia and exotropia. Only 14% of the entire group required a second surgery during an average of 41 months of follow-up.

Consecutive exotropia: why does it happen, and can medial rectus advancement correct it?

PURPOSE

To investigate whether consecutive exotropia following medial rectus muscle recession is associated with muscle slippage and to assess the effectiveness of treating the condition with medial rectus advancement.

METHODS

The records of patients with consecutive exotropia after medial rectus recession were reviewed to determine medial rectus muscle insertion location at the time of advancement surgery. Measurements before and after medial rectus advancement were compared. Success was defined as alignment within 10(Δ) of orthotropia. The dose effect of medial rectus advancement was determined by nonlinear regression.

RESULTS

A total of 20 patients were included. The mean age (± standard deviation) at time of surgery was 19 ± 19 years (range, 1.1-65.4). The mean preoperative exotropia was 28(Δ) ± 16(Δ) (range, 12(Δ)-60(Δ)). Medial rectus slippage of 2.5 ± 1.7 mm (range, 1.0-5.0 mm) was found in 14 patients (36%) who had previously undergone medial rectus recession. Surgery corrected about 4(Δ) of exotropia per mm total medial rectus advancement. Although 95% of patients were aligned successfully immediately after surgery, averaging 2(Δ) ± 4(Δ) esotropia, there was significant late exodrift, averaging 17(Δ) at final follow-up. At final follow-up, 1.6 ± 1.8 (range, 0.10-6.2) years after surgery, 50% of patients maintained alignment within 10(Δ) of orthotropia (mean, 3(Δ) ± 4(Δ) exotropia); the rest experienced recurrent exotropia of 25(Δ) ± 8(Δ).

CONCLUSIONS

Medial rectus slippage is common in consecutive exotropia. Medial rectus advancement effectively treated consecutive exotropia, whether or not there was muscle slippage. It is however, associated with late exodrift; hence patients should be warned about potential for further XT recurrence.

Goal-determined metrics to assess outcomes of esotropia surgery

PURPOSE

To report outcomes of esotropia surgery with a goal-determined tool.

METHODS

A goal-determined outcomes analysis tool was devised to address a quality improvement initiative at Boston Children's Hospital. Surgeons preoperatively ranked four possible goals for intervention: enhancement of binocular potential, restoration of eye contact (reconstructive), management of diplopia, and resolution of torticollis. Criteria for success were goal specific; the primary outcome measure was surgical success at 2-4 months. Secondary outcomes included appraisal of risk factors and a comparison of outcomes with this methodology versus traditional criteria for success based on motor alignment. No patients were excluded based on diagnosis, systemic and ocular risk factors, or intervention performed.

RESULTS

A total of 824 patients underwent esotropia surgery from 2006 to 2012 and returned for evaluation at 2-4 months' follow-up. Of these, 777 had sufficient documentation for inclusion: 372 procedures were performed primarily to improve binocular potential; 238, to restore eye contact; 124, to resolve diplopia; and 43, to remediate torticollis. Excellent (71%) or good (13.7%) results were obtained in 84% of cases. Without associated risk factors, 75% had excellent and 14% had good outcomes. Risk factors were present in 444 (57%). Success diminished with prior strabismus surgery (P = 0.004), preoperative angle ≥50(Δ) (P = 0.002), and surgery before 12 months of age (P = 0.003). Patients having surgery to remediate diplopia had the best outcomes (excellent, 79%; good, 8%). Preoperative ranking of goals allowed demonstration of better results than would have been reported with requirement of "traditional" motor alignment criteria (P = 0.009).

CONCLUSIONS

Goal-determined methodology can be useful for monitoring outcomes of esotropia surgery in diverse populations.

Surgical dose-effect relationship in single muscle advancement in the treatment of consecutive strabismus

PURPOSE

To evaluate the dose-effect relationship for single muscle advancement in consecutive esotropia and consecutive exotropia.

METHODS

Medical records from 22 patients with consecutive esotropia (n = 11) or exotropia (n = 11) were retrospectively reviewed. All patients had undergone either single lateral rectus or medial rectus advancement surgery. The alterations in muscle position and the angle deviation were measured in millimeters and prism diopters (PD) and the change in deviation was determined by subtracting the postoperative angle of deviation at 1 week from the preoperative angle. To quantify the clinical effect of muscle advancement, the ratio of the change in muscle position to the change in visual angle deviation was calculated (ie, the surgical dose-effect relationship).

RESULTS

The mean deviation was 25.5 ± 10.4 PD preoperatively and 0 ± 6.9 PD at 1 week postoperatively. The success rate was 82% in the consecutive esotropia group and 91% in the consecutive exotropia group. The average correction ratio was 4.31 ± 0.96 PD/mm. In multiple regression analysis of total patients with consecutive strabismus and the consecutive esotropia group, the amount of muscle advancement and preoperative angle deviation were positively correlated with the correction ratio. In the consecutive exotropia group, there was no significant relationship between variables.

CONCLUSIONS

Single muscle advancement generally provides enough correction for most consecutive strabismus cases. Surgical dose-effect relationship increases with preoperative angle deviation and amount of muscle advancement. Surgeons should consider reducing the amount of muscle advancement in patients with larger angle deviations, especially patients with consecutive esotropia.

Treatment of consecutive exotropia: unilateral lateral rectus recession combined with medial rectus advancement or resection

PURPOSE

Consecutive exotropia presents a difficult clinical problem, especially when previously recessed medial recti are to be strengthened. Surgical options include advancement, typically with a small resection, and resection alone.

METHODS

The authors retrospectively reviewed records of all patients who underwent a second two-muscle surgery on a single eye for consecutive exotropia. Patients with paralytic strabismus and those with less than 1 month of postoperative follow-up were excluded. In 2003, one of the authors began medial rectus resections without advancements in most cases, whereas a second author continued to perform advancements. Two treatment groups were thus reviewed.

RESULTS

Forty-two patients qualified for inclusion, including 23 for the resection group and 19 for the advancement group. Preoperative deviations were similar (P = .35, 95% confidence interval: -2.64 to 9.82). Postoperative deviations averaged 11.4 prism diopters (PD) in the resection group and 11.5 PD in the advancement group (P = .98, 95% confidence interval: -12.2 to 12.3). Forty-eight percent of the resection group and 63% of the advancement group achieved alignment within 10 PD of orthophoria (P = .33, 95% confidence interval: -9.0% to 39%).

CONCLUSIONS

Surgical results were favorable following both techniques. Although both techniques appear to be adequate, resection of previously recessed medial recti may be preferable because they allow use of standard surgical tables and avoid advancement of inflamed tissue into the palpebral fissure.

Surgical results of consecutive exotropia

PURPOSE

To determine the success rates of different surgical procedures and the risk factors of surgical failure among patients with consecutive exotropia.

METHODS

Forty patients with exotropia were observed at least 6 weeks after their esotropia surgery. Surgical planning was based on the medial rectus muscle function. Lateral rectus weakening in patients with normal medial rectus function, medial rectus strengthening for patients with limited medial rectus function (-1 to -3), and combined procedure occurred when the correction of each type of surgery was less than the amount of deviation. Postoperatively, patients were divided into success (8 prism diopters [PD] or less) or failure (8 PD or greater) groups. The follow-up period was at least 3 months.

RESULTS

The mean preoperative exotropia was 29 ± 13 PD, which was reduced to 7 ± 7 PD postoperatively (P < .001). Successful results were achieved in 31 patients (77.5%), 17 (81%) in lateral rectus weakening, 10 (83%) in medial rectus strengthening, and 4 (57%) in the combined procedure group. More preoperative exodeviation was observed in the failure group compared to the success group (P = .015).The mean dose response was 2.27 ± 0.92 PD/mm in the lateral rectus weakening, 4.25 ± 2.27 PD/mm in the medial rectus strengthening, and 2.31 ± 0.66 PD/mm in the combined procedure groups.

CONCLUSION

If the choice of surgical planning is based on medial rectus function and the amount of exodeviation, satisfactory alignment would be achieved in the majority of patients with consecutive exotropia. The preoperative amount of exodeviation was the only risk factor of surgical failure in the study.

Analysis of risk factors for consecutive exotropia and review of the literature

PURPOSE

To evaluate the possible risk factors in patients with consecutive exotropia following esotropia surgery.

METHODS

Medical records of patients who had comitant esotropia surgery between June 1999 and April 2011 were reviewed. Those who developed consecutive exotropia composed the exotropia group; patients matched for age and duration of follow-up who did not develop consecutive exotropia composed the no exotropia group. The charts of the patients were reviewed and possible risk factors for development of consecutive exotropia were investigated.

RESULTS

The average ages of 47 patients in the exotropia group and 54 patients in the no exotropia group were 10.8 ± 8.7 years (range: 1 to 41 years) and 8.5 ± 6.3 years (range: 1 to 30 years), respectively (P = .292). Amblyopia was detected in 31 (66%) and 12 (22.2%) patients in the exotropia and no exotropia groups, respectively (P = .004). Anisometropia was observed in 20 patients (42.6%) in the exotropia group and 5 patients (9.3%) in the no exotropia group (P = .003). Preoperative average esodeviation values were 42.5 ± 8.3 prism diopters (PD) (range: 25 to 60 PD) in the exotropia group and 42 ± 9.4 PD (range: 20 to 65 PD) in the no exotropia group (P = .673). Postoperative deviations were 32.8 ± 23 PD exotropia (range: 10 to 90 PD exotropia) in the exotropia group and 4.4 ± 4.2 PD esotropia (range: 0 to 10 PD esotropia) in the no exotropia group (P = .000). Asymmetric surgery had been performed in 61.7% of the exotropia group (n = 29) and 9.3% of the no exotropia group (n = 5) (P = .000). Limitation of adduction was detected in 14 patients (29.8%) in the exotropia group; none was noted in the no exotropia group (P = .000). The mean interval between the initial surgery and the onset of consecutive exotropia was 11.1 ± 15.1 months (range: 0 to 126 months).

CONCLUSIONS

Anisometropia, amblyopia, asymmetric surgery, and postoperative adduction deficit were associated with the development of consecutive exotropia. Long-term follow-up should be considered because consecutive exotropia can develop after months or years.

Change in the location of the equator and recessed muscles in young rabbit eyes

PURPOSE

To study the changes in the location of the equator and the new insertion of extraocular muscle after recession surgery in a rabbit model.

METHOD

An experimental study was performed in ten eyes of five rabbits. Eyes were divided into two groups according to the amount of recession. In right eyes, 5 mm superior recti (SR) muscle recession, approximately 2 mm posterior to the equator, was performed (5 mm recession group), while in the left eyes, 3 mm recession was performed to the location of the equator (3 mm recession group). We measured the distance of the equator from the limbus, as well as the distance between the superior rectus insertion and the equator. The preoperative measurements were compared with the results 2 months after the surgery. The change in location of the superior rectus and the equator was compared between the two eyes.

RESULT

The recessed SR muscle did not show any significant change in location in both groups (p = 0.18 and 0.16 respectively). However, the location of the equator of rabbit eye showed movement of about 1 mm posterior to the initial location with the growth of the eyeballs (p = 0.04 and 0.03, respectively).

CONCLUSION

The location of the equator moved posteriorly at 2 months postoperatively in young rabbit model while the insertion of the recessed SR did not show any significant movement.

Dose-effect relationship of medial rectus muscle advancement for consecutive exotropia

PURPOSE

To evaluate the dose-effect relationship for medial rectus muscle advancement in patients with consecutive exotropia.

METHODS

Pre- and postoperative deviations 1 day and 6 months after surgery were measured by linear strabismometric method. The change in deviation (difference between preoperative and postoperative deviation at 6 months) was correlated to the surgical dose (dose-effect relationship) and the preoperative distance deviation by multiple regression analysis. Multivariate regression analysis was performed with three and two independent variables (preoperative distance deviation, millimeters of advancement, intraoperative muscle stretch test), with change in deviation as a dependent variable.

RESULTS

Twenty-four patients (mean age, 33 years; range, 18-60 years) were included. The mean preoperative deviation was 32(∆), the mean postoperative deviation was 0(∆) at day 1, and 9(∆) 6 months after surgery. The mean dose-effect relationship was 5(∆)/mm at day 1 and 4(∆)/mm 6 months after surgery. Mean exodrift 6 months after surgery was 9(∆). The univariate model was statistically significant for each variable (P < 0.05). The multivariate model was statistically significant for preoperative distance deviation and millimeters of advancement (P < 0.05) but not for intraoperative muscle stretch test (P = 0.1519).

CONCLUSIONS

The dose-effect relationship at 6 months after advancement of the medial rectus muscle for consecutive exotropia could be a useful guide for planning surgical correction, even considering the expected exodrift.

Effects of recession versus tenotomy surgery without recession in adult rabbit extraocular muscle

PURPOSE

Surgical recession of an extraocular muscle (EOM) posterior to its original insertion is a common form of strabismus surgery, weakening the rotational force exerted by the muscle on the globe and improving eye alignment. The purpose of this study was to assess myosin heavy chain (MyHC) isoform expression and satellite cell activity as defined by Pax7 expression in recessed EOMs of adult rabbits compared with that in muscles tenotomized but not recessed and with that in normal control muscles.

METHODS

The scleral insertion of the superior rectus muscle was detached and sutured either 7 mm posterior to its original insertion site (recession surgery) or at the same site (tenotomy). One day before euthanization, the rabbits received bromodeoxyuridine (BrdU) injections. After 7 and 14 days, selected EOMs from both orbits were examined for changes in fast, slow, neonatal, and developmental MyHC isoform expression, Pax7 expression, and BrdU incorporation.

RESULTS

Recession and tenotomy surgery resulted in similar changes in the surgical EOMs. These included a decreased proportion of fast MyHC myofibers, an increased proportion of slow MyHC myofibers, and increased BrdU-positive satellite cells. Similar changes were seen in the non-operated contralateral superior rectus muscles. The ipsilateral inferior rectus showed reciprocal changes to the surgical superior rectus muscles.

CONCLUSIONS

The EOMs are extremely adaptive to changes induced by recession and tenotomy surgery, responding with modulations in fiber remodeling and myosin expression. These adaptive responses could be manipulated to improve surgical success rates.