Binocular Summation and Control of Intermittent Exotropia

BACKGROUND

Binocular summation (BiS), or improvement in binocular vision exceeding the better eye alone, is affected by strabismus. Being easily measured, BiS may be a useful indicator for subjective outcomes like stereopsis in strabismus. This study aims to investigate the relationship between BiS and measures of control of intermittent exotropia (IXT).

METHODS

Patients with IXT were recruited before undergoing strabismus surgery and underwent tests of binocular and monocular high- and low-contrast visual acuity, stereopsis at distance and near, and Newcastle Control Score (NCS), a score developed by incorporating home control and clinic control criteria into a control rating scale. BiS was calculated using high-contrast Early Treatment of Diabetic Retinopathy Study (ETDRS) and Sloan low-contrast acuity charts (LCA) at 2.5% and 1.25% contrast as the difference between the binocular score and that of the better eye. The relationship between BiS and measures of IXT control (NCS and distance near stereoacuity disparity) was evaluated using a correlation analysis by Spearman correlation coefficients and the Kruskal-Wallis test.

RESULTS

Thirty-four patients were included (mean [± standard deviation (SD)] age 19±16 years) having a mean (±SD) of 26±16Δ IXT at distance and 20±16Δ at near. Mean (±SD) BiS for ETDRS and Sloan LCA at 2.5% and 1.25% was 0.8±3.6, 1.9±6.0, and -2.3±7.2, respectively. The Spearman correlation coefficient of BiS and NCS was -0.53 (95% CI -0.85 to -0.25) for 2.5% LCA and -0.43 (95% CI -0.77 to -0.13) for 1.25% LCA. BiS at 2.5% LCA (P=0.006) and at 1.25% LCA (P=0.029) significantly differed between the groups based on NCS score groupings (1-3, 4-6, and 7-9), with patients who had better control scores having higher levels of BiS. BiS did not differ significantly between patients grouped according to the difference between stereoacuity measured at near versus distance.

CONCLUSION

Significantly lower low-contrast BiS in patients with higher NCS may suggest that decreased BiS is associated with less control in IXT. This finding suggests that BiS may reflect control in IXT across a population of patients with IXT.

Decreased Binocular Summation in Strabismic Amblyopes and Effect of Strabismus Surgery

PURPOSE

Binocular summation (BiS) occurs when binocular visual function surpasses that of the better eye alone. We sought to evaluate whether strabismic amblyopia reduces BiS more than strabismus alone, and determine whether BiS improves in strabismic amblyopes after strabismus surgery.

METHODS

We prospectively recruited 15 patients with strabismic amblyopia who then underwent strabismus surgery. Thirty age-matched normal subjects and 30 non-amblyopic strabismic patients served as controls. Subjects underwent binocular and monocular visual acuity testing on high-contrast Early Treatment Diabetic Retinopathy Study (ETDRS) as well as 2.5% and 1.25% Sloan low contrast acuity (LCA) charts. BiS was calculated as the difference between better eye and binocular scores.

RESULTS

Strabismic amblyopes and strabismic controls did not significantly differ in preoperative BiS, but both had subnormal BiS preoperatively on LCA charts. Among 11 strabismic amblyopes with preoperative and postoperative BiS measurements, average postoperative BiS was not significantly different from preoperative. Improved LCA BiS postoperatively occurred in some patients and was associated with measurable preoperative stereoacuity (P=0.02), older age at strabismus onset (P=0.02), and larger preoperative angle of strabismus (P=0.0043).

CONCLUSIONS

In this preliminary study, strabismic amblyopes experienced subnormal BiS, but amblyopia generally did not further impair BiS beyond that due to strabismus alone. Some strabismic amblyopes experienced improved low-contrast BiS after strabismus surgery. This suggests that further investigation in larger groups of patients should be undertaken to analyze a previously unrecognized functional benefit of strabismus surgery in strabismic amblyopes.

Inferior Rectus Transposition: A Novel Procedure for Abducens Palsy

PURPOSE

Superior rectus transposition has been popularized for the treatment of abduction deficiencies. Potential complications include induced vertical deviation and torsion. A new procedure, the inferior rectus transposition (IRT), may be similarly beneficial for patients at risk for postoperative vertical deviation or incyclotropia. The purpose of this study is to describe the outcomes of patients undergoing IRT.

DESIGN

Prospective, interventional case series.

METHODS

Five patients in an academic pediatric ophthalmology and strabismus practice with a complete lateral rectus palsy who underwent IRT were studied. Changes in anomalous head posture, ocular rotations, ocular alignment, and torsion preoperatively to postoperatively were compared.

RESULTS

The patients ranged in age from 19-89 years. There was a significant correction in the angle of esotropia (ET) from 39±17Δ (14-55Δ) to 12 ± 9.8Δ (0-22Δ) postoperatively (P = .02). Two of 5 patients had preoperative hypertropia of the affected eye (1.4 ± 2.2Δ; range, 2-5Δ). One of those had no vertical deviation postoperatively and 1 patient resulted in 2Δ hypotropia. One patient without vertical misalignment preoperatively developed a small postoperative vertical deviation. Torticollis significantly improved from 31.4 ± 11.6° to 5 ± 5.8° (P = .004). All patients improved abduction, with a mean of -4.4 ± 0.5 preoperatively to -3.4 ± 0.9 postoperatively (P = .07).

CONCLUSION

Initial postoperative follow-up in patients with abducens palsy undergoing IRT shows a significant improvement in ocular alignment and torticollis. In patients with preoperative hypertropia, IRT resulted in a downward shifting effect on the operated eye. IRT may be a beneficial procedure for patients with preoperative hypertropia or intorsion requiring transposition procedures. Future studies with larger populations and longer durations of follow-up will be required before this procedure can be recommended.

Relationship Between Binocular Summation and Stereoacuity After Strabismus Surgery

PURPOSE

To describe the relationship between binocular summation and stereoacuity after strabismus surgery.

DESIGN

Prospective case series.

METHODS

setting: Stein Eye Institute, University of California Los Angeles.

PATIENT POPULATION

Pediatric strabismic patients who underwent strabismus surgery between 2010 and 2015.

OBSERVATION PROCEDURES

Early Treatment Diabetic Retinopathy Study visual acuity, Sloan low-contrast acuity (LCA, 2.5% and 1.25%), and Randot stereoacuity 2 months following surgical correction of strabismus.

MAIN OUTCOME MEASURES

The relationship between binocular summation (BiS), calculated as the difference between the binocular visual acuity score and that of the better eye, and stereoacuity.

RESULTS

A total of 130 postoperative strabismic patients were studied. The relationship between binocular summation and stereoacuity was studied by Spearman correlation. There were significant correlations between BiS for 2.5% LCA with near and distance stereoacuity (P = .006 and P = .009). BiS for 1.25% LCA was also significantly correlated with near stereoacuity (P = .04). Near stereoacuity and BiS for 2.5% and 1.25% LCA were significantly dependent (Pearson χ(2), P = .006 and P = .026). Patients with stereoacuity demonstrated significantly more BiS in 2.5% LCA of 2.7 (P = .022) and 3.1 (P = .014) letters than did those without near or distance stereoacuity, respectively.

CONCLUSIONS

These findings demonstrate that stereopsis and binocular summation are significantly correlated in patients who have undergone surgical correction of strabismus.

Adjustable small-incision selective tenotomy and plication for correction of incomitant vertical strabismus and torsion

PURPOSE

To evaluate the effectiveness of adjustable small-incision selective tenotomy and plication of vertical rectus muscles in correcting vertical strabismus incomitant in horizontal gaze positions and cyclotorsion.

METHODS

The medical records of all patients who underwent adjustable small-incision selective tenotomy or plication of a vertical rectus muscle for correction of horizontally incomitant vertical strabismus or cyclotorsion by a single surgeon at a single eye institute from July 2013 to September 2014 were retrospectively reviewed. Selective tenotomy and plication were performed on either the nasal or temporal side of vertical rectus muscles, based on the direction of cyclotorsion and incomitance of vertical strabismus.

RESULTS

Of 9 patients identified, 8 (89%) had successful correction of horizontally incomitant vertical strabismus, with postoperative vertical alignment within 4(Δ) of orthotropia in primary position, lateral gazes, and downgaze. Of the 8 patients with preoperative cyclotorsion, 4 (50%) were successfully corrected, with <5° of cyclotorsion postoperatively. Of the 4 patients in whom cyclotorsion did not improve, 3 had undergone prior strabismus surgery, and 2 had restrictive strabismus. Eight of the 9 patients (89%) reported postoperative resolution of diplopia.

CONCLUSIONS

Adjustable small-incision selective tenotomy and plication effectively treat horizontally incomitant vertical strabismus. These surgeries may be less effective for correcting cyclotorsion in patients with restriction or prior strabismus surgery. Advantages are that they may be performed in an adjustable manner and, in some cases, under topical anesthesia.

Bilateral Congenital Posterior Capsular Defects and Ectopic Cataracts

Preexisting posterior capsular defects are rare and can be associated with infantile cataracts. The authors review possible etiologies of this condition and emphasize the importance of cautious preoperative planning and surgery.

Improvement in binocular summation after strabismus surgery

IMPORTANCE

Binocular summation (BiS), or improvement in visual acuity using binocular vision compared with the better eye alone, is diminished in patients with strabismus. However, it is still not known how strabismus surgery affects BiS.

OBJECTIVE

To determine whether BiS improves after strabismus surgery.

DESIGN, SETTING, AND PARTICIPANTS

Prospective study of 97 patients undergoing strabismus surgery between September 1, 2011, and January 31, 2014, comparing preoperative and postoperative measures of BiS. Patients were recruited within 1 month before undergoing strabismus surgery. The study took place at an academic pediatric ophthalmology and strabismus practice.

INTERVENTION

Strabismus surgery.

MAIN OUTCOMES AND MEASURES

All patients underwent high- and low-contrast visual acuity testing binocularly and monocularly at preoperative and 2-month postoperative visits. Binocular summation was calculated for high-contrast Early Treatment of Diabetic Retinopathy Study charts and Sloan low-contrast acuity charts at 2.5% and 1.25% contrast as the difference between the binocular score and that of the better eye. Preoperative and postoperative values were compared.

RESULTS

There was an improvement in BiS at the 2 low-contrast levels for all patients and for all contrast levels in the 75 patients in whom surgery successfully restored binocular alignment. For low-contrast acuity, the proportion of patients with a BiS score of at least 5 letters postoperatively was almost twice that of preoperatively (21% to 30% and 13% to 26% for 2.5% contrast and 1.25% contrast, respectively). Similarly, the proportion of patients with binocular inhibition (BiS score worse by at least 5 letters than the better eye score) was decreased postoperatively at all contrast levels (from 22% to 14% for 1.25% contrast). Thirty-one percent of patients experienced improvement in BiS scores postoperatively at the lowest contrast level.

CONCLUSIONS AND RELEVANCE

Binocular summation scores improved postoperatively in most patients undergoing strabismus surgery. This occurred most frequently at the lowest contrast level. These findings suggest that improved BiS could represent a newly recognized functional benefit from the surgical correction of strabismus. Further studies evaluating the correlation of BiS with stereopsis, visual field expansion, and quality of life will be necessary to fully evaluate the role that improved BiS has in improving binocularity postoperatively.

Quality of life in adults with strabismus

PURPOSE

To assess relative quality of life in patients with strabismus.

DESIGN

Retrospective cohort study.

METHODS

The 25-item National Eye Institute Visual Functioning Questionnaire (NEI VFQ-25) was performed in 42 strabismic adults over the age of 50 years at a single institution. Subscale scores were compared with those of patients with other ocular diseases, including diabetic retinopathy, age-related macular degeneration (AMD), glaucoma, cataract, cytomegalovirus (CMV) retinitis, and low vision.

RESULTS

Median visual acuity was 20/20 (range 20/12.5-20/50), and 34 patients (81%) reported diplopia. Strabismic patients performed the same or worse on nearly all vision-related subscales than did patients with diabetic retinopathy, age-related macular degeneration, glaucoma, cataract, and CMV retinitis. Additionally, strabismic patients reported significantly worse ocular pain than all comparison groups before any surgery was performed.

CONCLUSIONS

Strabismus impacts quality of life through both functional and psychosocial factors. Physicians treating strabismic patients should recognize these quality-of-life issues and address them accordingly.

Surgical management of strabismus in Duane retraction syndrome

While Duane retraction syndrome (DRS) is relatively common, surgical management of the associated strabismus can be challenging because of the lack of abduction/adduction, the variable severity of muscle contracture, and the variety of clinical presentations. In this workshop a panel of experienced surgeons provide their perspective and practical tips on the management of strabismus in patients with DRS.

Ophthalmic manifestations of cherubism

Cherubism is a rare craniofacial disorder characterized by progressive replacement of mandibular and maxillary bone with multicystic fibro-osseous tissue, potentially resulting in significant deformity and morbidity. The severity of the disorder is variable; more advanced disease may affect the orbit and impact vision. We detail the ophthalmological findings in 2 patients, 7 and 8 years of age, with cherubism.

The effect of rectus muscle recession, resection and plication on anterior segment circulation in humans

BACKGROUND

Plication is an alternative tightening procedure to resection. In monkeys, plication has been shown to preserve anterior segment circulation compared with full-tendon tenotomy, but this is unconfirmed in humans.

PURPOSE

To evaluate anterior segment circulation by iris angiography before and after strabismus surgery in humans.

METHODS

Prospective, blinded study of 14 patients (mean age (SD), 58.6 (14.3)) undergoing plication and/or full tendon tenotomy (resection or recession) from August 2013 to March 2014. Eight patients (mean age (SD), 59.0 (13.3)) underwent plication of one muscle with or without recession of a second muscle on the same eye and six patients (mean age (SD), 58.2 (16.8)) underwent tenotomy of one to two muscles on the same eye. Preoperative and postoperative iris angiograms were compared for changes in perfusion by a masked examiner. In patients undergoing binocular surgery, one eye was chosen preoperatively to be the study eye.

RESULTS

Postoperative iris filling defects were present in four patients (67%) after tenotomy and one patient (12.5%) after plication (p=0.09). Of the seven total vertical rectus muscles operated (three tenotomies and four plications), filling defects were present after three tenotomies and one plication (100% vs 25%; p=0.14). Of the 13 total horizontal rectus muscles operated (eight tenotomies and five plications), filling defects were present after one tenotomy and none of the plications (13% vs 0%; p=0.99).

CONCLUSIONS

Rectus muscle plication spares the ciliary vessels and may be considered a safer alternative to resection for patients at risk for anterior segment ischaemia, especially when surgery involves a vertical rectus muscle.

Normative reference ranges for binocular summation as a function of age for low contrast letter charts

PURPOSE

Binocular summation (BiS), defined as the superiority of binocular over monocular viewing on visual threshold tasks, is most often studied in laboratory settings. Few studies have evaluated BiS with readily available clinical tools. Low contrast acuity (LCA) charts are increasingly popular in clinical research, yet their utility in detecting BiS has not been evaluated.

METHODS

129 normal subjects aged 3 to 85 years were prospectively enrolled and underwent monocular and binocular testing using 2.5% and 1.25% Sloan LCA charts and Pelli-Robson (PR) contrast sensitivity (CS) charts at an academic institution. Subjects also underwent similar testing with Early Treatment Diabetic Retinopathy Study (ETDRS) VA charts. BiS was calculated as the difference between the better eye and binocular scores.

RESULTS

Monocular and binocular scores decreased with increasing age for all metrics. The mean (±SD) BiS scores for 2.5% and 1.25% Sloan LCA were 6±4.5 and 3±5 letters, respectively. BiS score was 4.5±7 letters for PR charts and 2±3 letters for ETDRS VA. There was a significant effect of age on BiS for the low contrast metrics (P≤0.001 for all), but not for high-contrast ETDRS VA. Linear regression revealed significant associations between increased interocular difference (IOD) in acuity and decreased BiS for all tests, and associations between increasing age and decreased BiS for the LCA tests.

CONCLUSION

Of the clinical tests evaluated, 2.5% and 1.25% Sloan LCA charts most readily demonstrated BiS in young normal subjects. BiS declined with increasing age and increased IOD. Median values presented in this study may be useful for future clinical studies utilizing LCA.

Binocular inhibition in strabismic patients is associated with diminished quality of life

PURPOSE

To characterize the relationship between binocular summation (BiS) and binocular inhibition (BI) on the quality of life of adults and children with strabismus.

METHODS

Strabismus patients at a single center from 2010 to 2012 were prospectively enrolled. A BiS score was measured using ETDRS and Sloan low-contrast visual acuity (LCA) protocols at 2.5% and 1.25% contrast. Patients were categorized as having BiS (binocular better than better-eye visual acuity by ≥5 letters), BI (binocular worse than better-eye visual acuity by ≥5 letters), or otherwise indeterminate visual acuity (a difference between binocular visual acuity and monocular visual acuity of the better eye of <5 letters). Quality of life was evaluated by the National Eye Institute Visual Functioning Questionnaire 25 (VFQ-25), 20-item Adult Strabismus Questionnaire (AS-20), and the Amblyopia and Strabismus Questionnaire.

RESULTS

A total of 108 patients were included. There was no significant BiS or BI for high-contrast ETDRS or 2.5% LCA tests; however, a mean BiS score of -2.14 ± 7.0 letters for 1.25% LCA demonstrated significant binocular inhibition (P = 0.004) for this contrast level. The mean composite VFQ-25 score was significantly lower in subjects with BI on ETDRS (80 ± 19 vs 57 ± 7 for subjects with BiS and BI, resp. [P = 0.03]), 2.5% LCA (81 ± 14 vs 66 ± 16 for subjects with BiS and BI, resp. [P = 0.01]), and 1.25% LCA tests (91 ± 9 vs 72 ± 14 for subjects with BiS and BI, resp. [P = 0.005]). After accounting for potential covariates, significant association persisted for BI, demonstrated by 1.25% LCA (P = 0.01). With BI demonstrable at 2.5%, AS-20 scores were also significantly lower (P = 0.04).

CONCLUSIONS

Strabismic patients with BI had significantly lower quality-of -life scores than those who did not, even after accounting for potential covariates and the absence of diplopia.

Assessment of torsion after superior rectus transposition with or without medial rectus recession for Duane syndrome and abducens nerve palsy

BACKGROUND

Superior rectus transposition with or without medial rectus recession has been advocated for the treatment of abducens nerve palsy and esotropic Duane syndrome. Early reports have focused mainly on postoperative ocular alignment, but there is concern that superior rectus transposition may induce torsional misalignment. The purpose of this study was to evaluate torsional outcomes after superior rectus transposition surgery using prospective preoperative and postoperative torsional assessments.

METHODS

Prospective measurements were performed on all patients undergoing superior rectus transposition. Preverbal infants were assessed using fundus torsion evaluating the position of the fovea relative to the optic nerve; older children/adults underwent double Maddox rod (DMR) assessment of torsion.

RESULTS

A total of 11 subjects met the study inclusion criteria. The etiology of strabismus was an abducens nerve palsy (n = 7) or Duane syndrome (n = 4). For the subjects evaluated by fundus torsion (n = 4), there was no significant change in torsion for 3 (75%). For those subjects undergoing DMR (n = 7), there was a significant change in subjective torsion (4.7 ± 3.8°excyclotorsion vs 0.0° ± 5.0° excyclotorsion; P = 0.004). Esotropic deviation improved significantly for all subjects (39(Δ) ± 23(Δ) vs 6.5(Δ) ± 13(Δ); P = 0.001) and no significant mean vertical deviation postoperatively, although 1 patient had a clinically significant postoperative hypertropia measuring 14(Δ). Abduction also improved significantly (-4.2 ± 0.9 vs -2.8 ± 1, P = 0.0001).

CONCLUSIONS

In this patient series, superior rectus transposition with medial rectus recession did not have clinically significant induction of torsional diplopia as a result of the procedure.

Outcomes in patients with esotropic duane retraction syndrome and a partially accommodative component

Background:

The management of Duane retraction syndrome (DRS) is challenging and may become more difficult if an associated accommodative component due to high hyperopia is present. The purpose of this study is to review clinical features and outcomes in patients with partially accommodative esotropia and DRS.

Setting and Design:

Retrospective, non-comparative case series.

Materials and Methods:

Six cases of DRS with high hyperopia were reviewed.

Results:

Of the patients studied, the mean age of presentation was 1.3 years (range: 0.5-2.5 years). The mean amount of hyperopia was + 5D (range: 3.50-8.50) in both eyes. The mean follow up period was 7 years (range: 4 months-12 years). Five cases were unilateral while one was bilateral. Four cases underwent vertical rectus muscle transposition (VRT) and one had medial rectus recession prior to presentation; all were given optical correction. Two (50%) of the four patients who underwent vertical rectus transposition cases developed consecutive exotropia, one of whom did not have spectacles prescribed pre-operatively. All other cases (four) had minimal residual esotropia and face turn at the last follow-up with spectacle correction.

Conclusion:

Patients with Duane syndrome can have an accommodative component to their esotropia, which is crucial to detect and correct prior to surgery to decrease the risk of long-term over-correction. Occasionally, torticollis in Duane syndrome can be satisfactorily corrected with spectacles alone.

Adjustable augmented rectus muscle transposition surgery with or without ciliary vessel sparing for abduction deficiencies

BACKGROUND

Vertical rectus transposition (VRT) is useful in abduction deficiencies. Posterior fixation sutures enhance the effect of VRT, but usually preclude the use of adjustable sutures. Augmentation of VRT by resection of the transposed muscles allows for an adjustable technique that can reduce induced vertical deviations and overcorrections.

METHODS

We retrospectively reviewed the records of all patients undergoing adjustable partial or full tendon VRT augmented by resection of the transposed muscles. Ciliary vessels were preserved in most of the patients by either splitting the transposed muscle or by dragging the transposed muscle without disrupting the muscle insertion.

RESULTS

Seven patients with abducens palsy and one with esotropic Duane syndrome were included. Both vertical rectus muscles were symmetrically resected by 3-5 mm. Preoperative central gaze esotropia of 30.6 ± 12.9Δ (range, 17-50Δ) decreased to 10.6 ± 8.8Δ (range, 0-25Δ) at the final visit (p = 0.003). Three patients required postoperative adjustment by recession of one of the transposed muscles due to an induced vertical deviation (mean 9.3Δ reduced to 0Δ), coupled with overcorrection (mean exotropia 11.3Δ reduced to 0 in two patients and exophoria 2Δ in one patient). At the final follow-up visit 3.8 ± 2.6 months postoperatively, one patient had a vertical deviation <4Δ, and none had overcorrection or anterior segment ischemia. Three patients required further surgery for recurrent esotropia.

CONCLUSIONS

Augmentation of VRT by resection of the transposed muscles can be performed with adjustable sutures and vessel-sparing technique. This allows for postoperative control of overcorrections and induced vertical deviations as well as less risk of anterior segment ischemia.

Functional burden of strabismus: decreased binocular summation and binocular inhibition

IMPORTANCE

Binocular summation (BiS) is defined as the superiority of visual function for binocular over monocular viewing. Binocular summation decreases with age and large interocular differences in visual acuity. To our knowledge, BiS has not heretofore been well studied as a functional measure of binocularity in strabismus.

OBJECTIVE

To evaluate the effect of strabismus on BiS using a battery of psychophysical tasks that are clinically relevant and easy to use and to determine whether strabismus is associated with binocular inhibition in extreme cases.

DESIGN

Case-control study.

SETTING

University-based eye institute.

PARTICIPANTS

Strabismic patients recruited during 2010 to 2012 from a preoperative clinic and control participants with no history of eye disease other than refractive error.

INTERVENTION

A battery of psychophysical and electrophysiological tests including Early Treatment Diabetic Retinopathy Study visual acuity, Sloan low-contrast acuity (LCA) (2.5% and 1.25%), Pelli-Robson contrast sensitivity, and sweep visual evoked potential contrast sensitivity.

MAIN OUTCOME AND MEASURE

Binocular summation was calculated as the ratio between binocular and better-eye individual scores.

RESULTS

Sixty strabismic and 80 control participants were prospectively examined (age range, 8-60 years). Mean BiS was significantly lower in the strabismic patients than controls for LCA (2.5% and 1.25%, P = .005 and <.001, respectively). For 1.25% LCA, strabismic patients had a mean BiS score less than 1, indicating binocular inhibition (ie, the binocular score was less than that of the better eye's monocular score). There was no significant difference in BiS for contrast thresholds on Early Treatment Diabetic Retinopathy Study visual acuity, Pelli-Robson contrast sensitivity, or sweep visual evoked potential contrast sensitivity. Regression analysis revealed a significant worsening of BiS with strabismus for 2.5% (P = .009) and 1.25% (P = .002) LCA, after accounting for age.

CONCLUSIONS AND RELEVANCE

Strabismic patients demonstrate subnormal BiS and even binocular inhibition for LCA, suggesting that strabismus impairs visual function more than previously appreciated. This may explain why strabismic patients who are not diplopic close 1 eye in visually demanding situations. This finding clarifies the visual deficits impacting quality of life in strabismic patients and may represent a novel measure by which to evaluate and monitor function in strabismus.

Postoperative drift in patients with thyroid ophthalmopathy undergoing unilateral inferior rectus muscle recession

BACKGROUND

Extraocular muscles of patients with thyroid ophthalmopathy (TO) may respond differently to strabismus surgery than those of other strabismic patients. This study reports postoperative alignment changes in patients with TO compared with patients with non-restrictive strabismus following unilateral inferior rectus muscle recession (IRR).

METHODS

We reviewed records of patients with and without TO who underwent unilateral IRR. Group A had adjustable muscle sutures, while Group B had permanent or semi-adjustable sutures. Controls were patients undergoing adjustable unilateral IRR for other indications.

RESULTS

Mean preoperative hypotropias were 17 ± 9, 21 ± 7, and 11 ± 4 PD for groups A (n=13), B (n=14), and controls (n=19), respectively. Postoperative day one (POD1) measurements after adjustment were 1.2 ± 2.5, 3.7 ± 4.9, and 0.3 ± 2.4 PD, respectively, representing overall undercorrections in all cases (the preoperative deviation was given a positive (+) value and overcorrections were deemed negative (-) deviations). Dose response from linear regression analysis of thyroid patients compared with control patients for IRR was 3.26 PD/mm (SE 0.18) vs 2.38 PD/mm (SE 0.18) (p=0.001). Mean final measurements were -0.7 ± 5.6 (overcorrection), 2.7 ± 5.7, and 1.7 ± 5.7 PD of hypotropia, respectively. Final overcorrections occurred in 23%, 14%, and 16% of patients, for adjustables, permanent sutures, and control subjects, respectively. Drifts from POD1 measurements after adjustment to final measurements were -1.9 ± 4.3, -1.0 ± 4.6, and 1.4 ± 5.9 PD respectively (p=0.05 for comparison between Group A and controls).

CONCLUSIONS

TO patients with adjustable sutures drift toward postoperative overcorrection.

Risk factors influencing the outcome of strabismus surgery following retinal detachment surgery with scleral buckle

PURPOSE

To determine factors associated with surgical success in patients undergoing strabismus surgery after retinal detachment repair with scleral buckle.

METHODS

The medical records of consecutive patients who underwent strabismus surgery after repair of retinal detachment with scleral buckle were retrospectively reviewed. A successful "motor" outcome was defined as horizontal deviation <10(Δ) and vertical deviation <4(Δ) in the primary position; successful "sensory" outcome was no diplopia in the primary position. Various factors such as removing the scleral buckle at the time of strabismus surgery, the macula structural status, size of the preoperative deviation, presence of restriction to passive movement, and whether the eye with the scleral buckle was the operated eye were compared among groups based on motor success.

RESULTS

A total of 25 patients were included. The overall motor success rate was 72% after 1.8 ± 0.9 operations, with 62% of patients diplopia free in the primary position. Horizontal deviation <10(Δ) (P = 0.005) and minimal restriction on forced duction test were associated with motor success after the first surgery (P = 0.05). Partial or entire scleral buckle removal (n = 15) and fellow-eye surgery were not significantly correlated with motor success in our cohort. There were no retinal redetachments after scleral buckle removal.

CONCLUSIONS

A small preoperative horizontal deviation, and minimally restricted ocular rotations were associated with better results. Removing the scleral buckle did not improve results.

Rectus muscle plication using an adjustable suture technique

PURPOSE

Rectus muscle plication is an alternative muscle-strengthening procedure to rectus muscle resection. Possible advantages of rectus muscle plication include a lower risk of "lost" muscles and anterior segment ischemia.

METHODS

This was a retrospective case series describing a surgical procedure for rectus muscle plication using an adjustable suture technique that can be used on any of the four rectus muscles.

RESULTS

A total of 5 adult patients underwent adjustable suture plication procedures. Of these, 2 patients required suture adjustment postoperatively. At the final follow-up visit, all the patients maintained satisfactory ocular alignment within 6(Δ) of orthotropia for horizontal deviations and 2(Δ) of orthotropia for vertical deviations. Diplopia was eliminated in all cases with preoperative diplopia. There were no postoperative complications or unexpected shifts in ocular alignment.

CONCLUSIONS

Rectus muscle plication using this adjustable suture technique may serve as an alternative to rectus muscle resection and may be particularly useful in patients who are at risk for anterior segment ischemia or those in whom a shorter anesthesia time is recommended.

Asymmetric inferior oblique anterior transposition for incomitant asymmetric dissociated vertical deviation

BACKGROUND

Inferior oblique anterior transposition (IOAT) is indicated in patients with incomitant dissociated vertical deviation (DVD) larger in adduction. In general, bilateral surgery is recommended in patients with DVD unless there is deep monocular amblyopia. The purpose of this study is to evaluate the results of asymmetric IOAT in patients with asymmetric incomitant DVD larger in adduction.

METHODS

Retrospective chart review of the records of all patients with incomitant asymmetric DVD associated with inferior oblique (IO) overaction who underwent asymmetric IO weakening procedure. In all patients, the eye with more DVD in adduction underwent IOAT to the temporal corner of the insertion of the inferior rectus (IR) muscle, and the eye with less DVD underwent IOAT to a position 3-4 mm posterior to the insertion of the IR. No other muscles were operated simultaneously. No patient had previous surgery on any cyclovertical extracular muscle.

RESULTS

Fourteen patients were included. Mean age at surgery was 10.3 ± 8.8 years (range 4-33). Primary position DVD preoperatively was 18 ± 2 PD in the eye with the larger DVD compared to 1.1 ± 1.0 PD postoperatively (p < 0.0001). DVD asymmetry between the lateral gaze with the largest DVD and the lateral gaze with the smallest DVD was 9.8 ± 3.1 PD (range 5-14 PD) preoperatively vs 1.1 ± 1.0 PD (range 0-2 PD), (p < 0.0001). Ten patients had preoperative V-pattern >10 PD (24.7 ± 8.7 PD, range 12-50 PD) preoperatively vs no patients postoperatively (mean V-pattern 4.4 ± 2.0 PD), (p < 0.0001). Postoperative follow up was 1.6 ± 0.7 years (range 1-3 years).

CONCLUSION

In patients with asymmetric incomitant DVD, asymmetric IOAT improves lateral incomitance without increasing the risk of antielevation, limitation in upgaze rotation, or hypertropia, or worsening the DVD in the eye with less deviation preoperatively.

Isolated y-splitting and recession of the lateral rectus muscle in patients with exo-duane syndrome

PURPOSE

Weakening of both horizontal rectus muscles is performed for patients with Duane syndrome and significant misinnervation of the lateral rectus (LR) muscle resulting in strabismus, limitation to ocular rotations, and globe retraction. In patients with severe up-/downshoots, a Y-splitting of the LR is often recommended. The purpose of this study was to evaluate the efficacy of isolated unilateral LR recession-Y splitting in exo-Duane patients with limitation to adduction and up-/downshoots.

METHODS

etrospective review of the records of consecutive patients with exo-Duane syndrome and up/down-shoots who underwent isolated Y-splitting-recession of the affected LR.

RESULTS

The records of 10 patients were reviewed (mean age at surgery 23 ± 21 years). The Y-split was performed 10 mm posterior to the insertion and was combined with a mean LR recession of 8.7 ± 2.9 mm. Torticollis decreased from 12.7 ± 4.4° to 4.8 ± 5.3° (P = 0.003). Exotropia improved from 18.4 ± 7.3 to 6.2 ± 5.9 PD postoperatively (P < 0.001). Exotropia in contralateral gaze improved from 33.7 ± 11.8 to 18.7 ± 18.1 PD postoperatively (P = 0.09). No significant postoperative changes in esotropia in ipsilateral gaze, vertical deviations, or ocular rotations in adduction or abduction were observed. Downshoots were significantly decreased (P = 0.01), and there was a trend toward improvement of upshoots (P = 0.07). There were no overcorrections, although 3 patients required additional LR weakening and transposition.

CONCLUSIONS

LR Y-splitting-recession improves ocular alignment, torticollis, and up-/downshoots. LR recession improves ocular alignment and torticollis, while the addition of a Y-split procedure improves up-/downshoots.

Rectus muscle resection in Graves' ophthalmopathy

BACKGROUND

In the treatment of Graves' ophthalmopathy, rectus muscle resections generally are avoided because of the concern of reaggravating inflammation and creating excessive extraocular muscle restriction. In patients with large-angle strabismus and in patients with residual strabismus after maximal recession surgery, however, rectus muscle resection may be considered. We report a series of 8 patients with Graves' ophthalmopathy who underwent rectus muscle resections.

METHODS

The records of 270 patients with Graves' ophthalmopathy who had undergone strabismus surgery were retrospectively reviewed. Data from subjects who had undergone rectus muscle resections were collected, including age at surgery, duration of disease, duration of diplopia, previous eye or strabismus surgeries, history of radioactive iodine or corticosteroid treatment, current thyroid medications, current use of corticosteroids, tobacco use, and signs and symptoms used to diagnose Graves' ophthalmopathy.

RESULTS

Eight patients (5 females) were identified (mean age, 51.1 ± 17.6 years). Preoperatively, 4 patients had a horizontal deviation and 4 patients had both horizontal and vertical deviations in primary gaze. Mean preoperative horizontal deviation was 27.9(Δ) ± 15.2(Δ) and mean vertical deviation was 6.3(Δ) ± 5.4(Δ). At final follow-up examination, 7 patients were orthotropic in primary gaze; 1 patient had a larger deviation from slippage as the result of a broken suture within the first postoperative week. None of the patients were overcorrected or developed atypical inflammation.

CONCLUSIONS

In this series, patients with Graves' ophthalmology were successfully treated with the use of rectus muscle resections as part of the surgical plan. Careful ocular motility assessment and patient selection is critical if this option is contemplated.

Surgical results of patients with unilateral superior oblique palsy presenting with large hypertropias

PURPOSE

Surgical management of superior oblique palsy (SOP) is challenging because of combined vertical, horizontal, and torsional misalignment. The authors report the surgical results of patients with large primary position hypertropias (> 20 prism diopters [PD]) due to unilateral SOP.

METHODS

Criteria for success included correction of the anomalous head posture, primary position alignment between orthotropia and 6 PD of undercorrection, and no reoperation required for residual deviations in any direction of gaze.

RESULTS

Forty-five patients met inclusion criteria. Mean preoperative alignment in primary gaze was 26.5 ± 6.5 PD compared to 3.0 ± 4.4 PD postoperatively (P < .001). Twenty-three (51%) cases met the criteria for success with one operation. Of the patients who had single muscle surgery, 14% had a successful outcome, with a mean 67% (17.3 PD) reduction in hypertropia. Of patients who underwent simultaneous multiple muscle surgery, 58% met the criteria for a successful result, with a mean 92% (24.6 PD) reduction in primary gaze hypertropia. Success was the highest in patients who underwent ipsilateral inferior oblique combined with contralateral inferior rectus recessions with (60% success) or without (65% success) a Harada-Ito procedure.

CONCLUSION

Undercorrections are frequent following surgery for unilateral SOP with preoperative deviations greater than 20 PD in primary position, especially after single-muscle surgery. Simultaneous multiple muscle surgery rarely results in overcorrection and is recommended in patients with SOP and more than 20 PD of hypertropia in primary position.

Does inferior oblique recession cause overcorrections in laterally incomitant small hypertropias due to superior oblique palsy?

AIM

To evaluate the effects of inferior oblique muscle recession (IOR) in cases of laterally incomitant hypertropia <10 prism dioptres (PD) in central gaze thact 2t are clinically consistent with superior oblique palsy (SOP).

METHODS

We retrospectively reviewed patients with SOP and hypertropias <10 PD in central gaze who underwent graded IOR. Primary outcomes were reduction of lateral incomitance and number of overcorrections in central gaze.

RESULTS

Twenty-five patients were included. Mean follow-up was 13.8 months (range 1.4-66). Mean central gaze hypertropia decreased from 5.6±2.1 to 0.2±1.6 PD (p<0.001). Contralateral gaze hypertropia decreased from 15.9±7.6 to 2.3±3.3 PD (p<0.001). Lateral incomitance (central vs contralateral gaze) was 10.3±6.9 PD preoperatively and 2.0±3.0 PD postoperatively (p<0.001). There were two patients overcorrected in central gaze, and one patient overcorrected in downgaze. One patient necessitated further surgery for overcorrection.

CONCLUSIONS

Although small hypertropias can be treated with prisms or small, adjustable inferior rectus recessions, IOR collapses incomitance without causing much overcorrection. IOR is a reasonable treatment for small, laterally incomitant hypertropia due to SOP.

Function of transected or avulsed rectus muscles following recovery using an anterior orbitotomy approach

PURPOSE

To assess the function of muscles retrieved from a retrobulbar location using an anterior orbitotomy approach and to identify the prognostic factors favoring a good outcome.

METHODS

The records of all patients undergoing anterior orbitotomy for the retrieval of a transected or avulsed muscle in a retrobulbar location were reviewed. Ocular motility, before and after retrieval (with ductions scaled from -4 to +4), was evaluated.

RESULTS

Record review identified 11 patients who had suffered trauma to 12 muscles (5 inferior, 6 medial, and 1 lateral rectus muscle). Ductions improved from -4 ± 0.4 preoperatively to -2.7 ± 0.9 postoperatively (P = 0.002); mean primary position deviation improved from 34(Δ) ± 14(Δ)-15(Δ) ± 9(Δ) (P < 0.001), and mean deviation in the field of action improved from 47(Δ) ± 20(Δ)-20(Δ) ± 22(Δ) (P = 0.02). Ductions improved by at least two units in three patients, all of whom had medial rectus trauma. Single binocular vision in primary gaze was achieved in 6 patients. Patients with medial rectus muscle injury and patients injured by sinus surgery had the lowest likelihood of recovering single binocular vision.

CONCLUSIONS

Our results are similar to historical series in which muscles were not retrieved and transpositions performed; however, muscle retrieval avoids risks associated with transposition surgeries such as anterior segment ischemia. Muscle recovery via the anterior orbitotomy approach may be reasonable to consider in those cases with a reasonable possibility of having active force generation postoperatively.

Postoperative outcomes of patients initially overcorrected for intermittent exotropia

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Risk factors for consecutive exotropia after vertical rectus transposition for esotropic Duane retraction syndrome

PURPOSE

To define risk factors for postoperative exotropia after vertical rectus transposition (VRT) for Duane syndrome.

METHODS

The records of patients with Duane syndrome who underwent augmented VRT were retrospectively reviewed; those with postoperative exotropia (study group) were compared with those with postoperative esotropia/orthotropia (controls).

RESULTS

A total of 51 patients were included, of whom 14 were exotropic postoperatively. Of the 14, 6 became exotropic after augmented VRT, and 8 who were initially esotropic became exotropic after subsequent medial rectus muscle (MR) recession. Study subjects were significantly younger (2 ± 2 years vs 6 ± 10 years, P = 0.04) and demonstrated less restriction on intraoperative forced duction testing than control subjects. Subjects who became exotropic after MR muscle recession had significantly less esotropia at near (5.2(Δ) ± 6.5(Δ) vs 18.4 (Δ) ± 7.9(Δ) esotropia, respectively; P = 0.005) and in adduction (1(Δ) ± 2(Δ) exotropia vs 3(Δ) ± 4(Δ) esotropia, respectively; P = 0.02) than control patients who also underwent VRT and MR muscle recession. Forced duction testing was also significantly different among these groups (P = 0.03).

CONCLUSIONS

Risk factors for exotropia after augmented VRT include younger age and less restriction on forced duction testing. Additional risk factors for exotropia after VRT and subsequent MR muscle recession include preoperative exotropia in adduction and smaller deviation at near. These factors may be useful in distinguishing patients at risk, allowing for consideration of less powerful procedures.

Abducens Nerve Ocular Neuromyotonia Following Non-sellar or Parasellar Tumors

Ocular neuromyotonia is an uncommon disorder resulting from episodic involuntary discharge of ocular motor nerves producing sustained contraction of their respective ocular muscles. Ocular neuromyotonia manifests in brief spells of diplopia occurring spontaneously or after eccentric gaze holding. In most cases, ocular neuromyotonia follows months or years after radiotherapy to the sellar and parasellar region and involves the oculomotor nerve. We report two unusual cases of abducens nerve ocular neuromyotonia that followed radiation therapy of tumors in areas other than the sellar or parasellar region.

Toward an implantable functional electrical stimulation device to correct strabismus

PURPOSE

To investigate the feasibility of electrically stimulating the lateral rectus muscle to recover its physiologic abduction ability in cases of complete sixth cranial (abducens) nerve palsy.

METHODS

In the feline lateral rectus muscle model, the effects of a charge-balanced, biphasic, current-controlled stimulus on the movement of the eye were investigated while stimulation frequency, amplitude, and pulse duration was varied. Eye deflection was measured with a force transducer. Denervated conditions were simulated by injection of botulinum toxin A.

RESULTS

Three chemically denervated and 4 control lateral rectus muscles were analyzed. In control lateral rectus muscles, the minimum fusion frequency was approximately 170 Hz, and the maximum evoked abduction was 27 degrees. The minimum fusion frequency was unchanged after 4 weeks of chemical denervation. Stimulation of chemically denervated lateral rectus muscle resulted in 17 degrees of abduction. For both innervated and chemically denervated lateral rectus muscle, frequencies greater than 175 Hz yielded very little increase in abduction. Modulating amplitude produced noticeable movement throughout the tested range (0.2 to 9 mA).

CONCLUSIONS

Results from the feline lateral rectus muscle showed that electrical stimulation is a feasible approach to evoke a contraction from a denervated lateral rectus muscle. The degree of denervation of the feline lateral rectus muscle was indeterminate. Varying the stimulation amplitude allowed greater eye movement. It is very likely that both frequency and amplitude must be modulated for finer control of static eye position.

Management of vertical deviations after vertical rectus transposition surgery

PURPOSE

To describe options for the management of vertical deviations after vertical rectus muscle transposition surgery (VRT).

METHODS

Retrospective case series including 7 children who underwent VRT for esotropic Duane syndrome and developed the complication of a vertical deviation.

RESULTS

Eighty-two consecutive children underwent VRT for Duane syndrome. Seven eyes of 7 patients (4 boys, 3 girls) were found to have induced vertical deviations postoperatively. Average length of follow-up was 12.7 months (range, 3-28 months). Median induced vertical deviation was 10.1(Delta) (range, 8-12). All patients required only one additional surgery to ameliorate the vertical deviation. At final follow-up, the mean vertical tropic deviation was 0. Six patients were operated on within 4 days of VRT. Surgical strategies included recession of one vertical rectus muscle and repositioning of a posterior fixation suture.

CONCLUSIONS

In children undergoing VRT for esotropic Duane syndrome, the complication of a vertical deviation occurred in 8.5% of cases. The vertical deviation was completely ameliorated in each case by one surgical procedure involving recession of one of the transposed muscles.

Surgical management of dissociated vertical deviation associated with A-pattern strabismus

INTRODUCTION

Dissociated vertical deviation (DVD), pattern strabismus, and oblique muscle dysfunction frequently coexist, and the recognition of bilaterality, symmetry, and lateral incomitance is important in selecting appropriate surgical management. In this study, we compare 3 different surgical approaches in patients with DVD associated with A-pattern strabismus.

METHODS

This was a retrospective review of 40 consecutive patients with DVD and A-pattern strabismus who underwent strabismus surgery. Bilateral superior rectus muscle recession was performed in 9 patients, bilateral superior rectus recession and superior oblique posterior tenectomy were performed in 14 patients, and bilateral superior oblique temporal tenotomy and inferior oblique recession were performed in 17 patients.

RESULTS

Bilateral superior rectus muscle recession corrected 7(Delta) +/- 2(Delta) of A pattern, 10(Delta) +/- 3(Delta) of vertical deviation and 4(Delta) +/- 2(Delta) of DVD asymmetry. Bilateral superior rectus muscle recession combined with superior oblique posterior tenectomy corrected 17(Delta) +/- 3(Delta) of A pattern, 10(Delta) +/- 2(Delta) of vertical deviation, and 4(Delta) +/- 2(Delta) of asymmetry. Bilateral superior oblique muscle temporal tenotomy combined with inferior oblique recession corrected 30(Delta) +/- 4(Delta) of A pattern, 9(Delta) +/- 3(Delta) of vertical deviation, and 2(Delta) +/- 2(Delta) of asymmetry.

CONCLUSIONS

In patients with DVD and A patterns, the size of the A pattern and the symmetry of the DVD are of major importance for surgeons determining appropriate procedures. Bilateral superior rectus muscle recession corrects small amounts of A pattern. Larger amounts of A pattern require additional superior oblique weakening or weakening of all four oblique muscles. superior rectus muscle recession is warranted if the asymmetry is larger than 5(Delta).

Lemierre's syndrome with fourth nerve palsy

Lemierre's syndrome is characterized by acute oropharyngeal infection with secondary internal jugular vein thrombophlebitis and subsequent metastatic infections. The anaerobe Fusobacterium necrophorum is the usual etiologic agent, although other microorganisms, including Streptococcus, Staphylococcus, Enterococcus, Bacteroides, and Lactobacilli, may be present alone or in combination with F. necrophorum. Common sites of metastatic infection include the lungs and joints. Thromboembolic complications, such as septic pulmonary embolism, persistent jugular vein occlusion, hepatic abscesses, and nephropathy, may occur. We report a case of Lemierre's syndrome in a 3-year-old Caucasian boy who subsequently presented with manifestations of a fourth (trochlear) nerve palsy.

High-resolution magnetic resonance imaging demonstrates reduced inferior oblique muscle size in isolated inferior oblique palsy

PURPOSE

The diagnosis of isolated inferior oblique muscle palsy is controversial for 2 reasons: first, clinical findings seem inconsistent with our current understanding of oculomotor neuroanatomy and, second, similar findings can occur with other causes. Because denervated extraocular muscles atrophy, we used high-resolution magnetic resonance imaging (MRI) to assess inferior oblique muscle size in patients with clinically suspected inferior oblique muscle palsy.

METHODS

A diagnosis of inferior oblique muscle palsy in 6 patients (4 unilateral, 2 bilateral) was made clinically. High-resolution coronal and sagittal orbital MRI were obtained in subjects with clinical inferior oblique muscle palsy and in 30 age-matched control subjects. Cross sections of the inferior oblique, inferior rectus (IR), and medial rectus muscles were determined together because each is innervated by the common inferior division of the oculomotor nerve. No subject had pupillary abnormalities or other extraocular muscle weakness or restriction.

RESULTS

Mean cross-sectional area of the affected inferior oblique muscle (n = 8) at the midpoint of the inferior rectus muscle was 10.2 +/- 1.05 mm(2), which was significantly smaller than the value of 18.8 +/- 3.6 mm(2) for control subjects (n = 58, p < 0.00001). Unilaterally affected inferior oblique muscles were significantly smaller than unaffected inferior oblique muscles (p < 0.05). Mean medial rectus muscle cross section (n = 8) ipsilateral to the affected inferior oblique muscle was 36.8 +/- 2.4 mm(2), which was not significantly different from the 35.1 +/- 3.7 mm(2) value for the medial rectus muscles of control subjects (n = 61, p > 0.1). Mean inferior rectus muscle cross section (n = 8) ipsilateral to the affected inferior oblique muscle was 32.5 +/- 2.3 mm(2), which was significantly greater than the 29.9 +/- 3.3 mm(2) measurement for the control subjects (n = 61, p < 0.01).

CONCLUSIONS

We used MRI to demonstrate reduced inferior oblique muscle size in patients with clinically diagnosed inferior oblique muscle palsy, supporting the concept of isolated inferior oblique muscle weakness.

Surgical treatment of strabismus secondary to glaucoma drainage device

OBJECTIVE

To describe surgical strategies in a series of patients with diplopia following implantation of a glaucoma drainage device.

METHODS

Retrospective review of 9 consecutive patients who underwent strabismus surgery because of strabismus and diplopia after implantation of a glaucoma drainage device.

RESULTS

Seven patients with marked limitation to ocular rotations and incomitant strabismus underwent surgery on the eye with the implant. Two patients with mild limitation to ocular rotations of the involved eye underwent surgery on the contralateral eye. All patients had a large fibrous capsule surrounding the implant plate, adjacent muscles, and sclera. Intraocular pressure was not elevated postoperatively. Postoperative diplopia in the primary position was eliminated in 5 patients and markedly improved in 3 patients.

CONCLUSIONS

Strabismus following implantation of a glaucoma drainage device is an uncommon but serious complication. Restoration of ocular alignment is a complex undertaking requiring strabismus and glaucoma surgical expertise. Multiple surgical complications may occur. Surgical intervention may require complete removal of the fibrous capsule surrounding the implant and involved adjacent structures. Size reduction of the implant plate is helpful and did not interfere with postoperative intraocular pressure control in this study. Surgery on the contralateral eye is an option in patients with mild restriction.

Superior oblique anterior tenectomy

PURPOSE

To describe a surgical approach to selectively weaken the anterior cyclotorsional fibers of the superior oblique muscle in subjects with incyclotorsion.

METHODS

Retrospective review of five consecutive subjects with diplopia and incyclotorsion who underwent unilateral tenectomy of the anterior fibers of the superior oblique alone or in combination with surgery on another horizontal or vertical rectus muscle.

RESULTS

The mean preoperative incyclotorsion was 7.2 degrees . The mean postoperative follow-up was 4 months. Superior oblique anterior tenectomy corrected 5.2 degrees of incyclotorsion. No patient developed pattern strabismus induced vertical deviation or diplopia due to excyclotorsion postoperatively. The mean incyclotorsion present at the last follow-up was 2 degrees . Torsional diplopia persisted in two (40%) subjects.

CONCLUSIONS

Anterior tenectomy of the superior oblique tendon at the insertion may be helpful in subjects with incyclotorsion who have no vertical deviation in the primary position or in whom there is risk of pattern anisotropia or anterior segment ischemia by operating upon vertical rectus muscles.

Incomitant Esotropia Following Pterygium Excision Surgery

OBJECTIVE

To report the clinical characteristics and treatment of subjects with incomitant esotropia following unilateral pterygium excision.

METHODS

A retrospective review of 6 consecutive patients who developed incomitant esotropia, limited abduction, and diplopia following unilateral pterygium excision surgery.

RESULTS

The mean preoperative deviation was 6 prism diopters (PD) (range, 0-25 PD) in the primary position and 13.8 PD (range, 6-25 PD) in the abducting field of the involved eye. Four patients underwent simultaneous surgery on the conjunctiva-perimuscular connective tissue complex and the medial rectus muscle. One subject had conjunctival-perimuscular connective tissue complex surgery alone. Postoperatively, all patients had orthotropia in the primary position and the deviation in the abducting field was improved to 5.2 PD (range, 0-14 PD).

CONCLUSIONS

Incomitant esotropia is an uncommon but serious complication following pterygium excision surgery. Medial rectus muscle recession combined with scar tissue removal is required to eliminate diplopia in the primary position. Conjunctiva-perimuscular scar tissue removal may suffice to improve diplopia in the abduction gaze position.

Superior oblique muscle paresis and restriction secondary to orbital mucocele

Mucoceles are chronic cystic lesions of the paranasal sinuses lined by respiratory epithelium. Their extension into the adjacent orbit may result in proptosis, ocular motility disorders, and diplopia. Brown syndrome secondary to extension of a mucocele into the orbit has been reported previously. Superior oblique (SO) muscle weakness, either isolated or in combination with an ipsilateral limitation to elevation in adduction, has not been previously reported in patients with orbital mucocele.

Inferior oblique muscle fixation to the orbital wall: a profound weakening procedure

INTRODUCTION

Recurrent or persistent inferior oblique overaction may occur after inferior oblique (IO) recession or anterior transposition. IO nasal and temporal myectomy and anterior-nasal transposition may result in undesirable IO palsy, exotropia, incyclotorsion, or limitation of elevation. Previous studies have shown that a rectus extraocular muscle may be profoundly weakened if the muscle insertion is reattached to adjacent orbital periosteum. We describe a reversible profound weakening surgical procedure of the IO muscle.

METHODS

A total of 10 consecutive subjects with V-pattern strabismus and/or IO overaction underwent IO orbital fixation procedure by attaching its insertion to the periosteum of the lateral orbital wall. One subject was not included because short follow-up. Five subjects with persistent IO overaction after IO anterior transposition underwent bilateral IO orbital wall fixation. Four subjects with no previous IO surgery underwent unilateral IO orbital wall fixation; 3 of these 4 subjects had superior oblique palsy with a large vertical deviation in primary position and 1 had a V pattern with asymmetric IO overaction.

RESULTS

V pattern significantly improved from 22(Delta) preoperatively to 7(Delta) postoperatively (p = 0.002). IO overaction improved from 2.5 (range, + 1.5 to + 4) to 0.1 (range, -2 to +3) postoperatively (p < 0.001). Six of 9 subjects had no residual overelevation in adduction postoperatively. Unilateral IO orbital fixation corrected 7(Delta) of vertical deviation in the primary position and 23(Delta) in adduction. Mean postoperative follow-up was 5 months.

CONCLUSIONS

IO orbital fixation has a profound weakening effect on the IO muscle. Advantages of this procedure include reversibility and that it can be converted into another form of weakening procedure, if required.

Maximum motor fusion combined with one-hour preoperative prism adaptation test in patients with acquired esotropia

PURPOSE

Preoperative prism adaptation and the maximum motor fusion test reduce the risk of postoperative undercorrection, overcorrection, and bifocal requirements in acquired esotropia. The purpose of our study is to determine the efficacy of the maximum motor fusion test followed by a short prism adaptation test in patients with acquired esotropia undergoing bilateral medial rectus muscle recession.

METHODS

We undertook a retrospective review of 29 subjects with acquired esotropia without history of amblyopia, previous strabismus surgery, use of bifocals, pattern anisotropia, dissociated vertical deviation, or oblique muscle dysfunction. All subjects underwent bilateral medial rectus muscle recessions based on the distance angle of deviation measured with the maximum motor fusion test followed by prism adaptation test. Alternate prism and cover testing was performed after 1 hour of prism adaptation to determine the angle of deviation for surgical correction.

RESULTS

The age at surgery was 4.5 +/- 1 years. The preoperative angle of deviation at distance was 20.4 +/- 4.2(delta). It increased to 36.2 +/- 4.2(delta) after the maximum motor fusion test followed by 1 hour of prism adaptation testing. The final preoperative angle of deviation post motor fusion test-prism adaptation test was significantly larger than the initial angle of deviation (p < 0.0001). The final postoperative deviation at distance was 1.3 +/- 3.3(delta), and 5.2 +/- 1.5(delta) at near. Postoperative follow up was 18 +/- 2.6 months (range, 13-24 months).

CONCLUSIONS

The combination of maximum motor fusion and preoperative prism adaptation allowed increased amounts of medial rectus muscle muscle recession, decreasing the risk of postoperative undercorrection without increasing the risk of overcorrection.

Superior oblique posterior tenectomy in patients with Brown syndrome with small deviations in the primary position

INTRODUCTION

Procedures used to weaken the superior oblique muscle (SO) tendon in the treatment of patients with Brown syndrome, may result in severe complications, including complete SO palsy, overcorrections, foreign body extrusion, and scarring with limitation to ocular rotations. SO posterior tenectomy moderately weakens abduction and depression while preserving most of the torsional action of the SO muscle.

PURPOSE

We sought to evaluate motor and sensorial results after SO posterior tenectomy in patients with Brown syndrome who had a small vertical deviation (less than 7 prism diopters [PD]) in primary position but severe limitation to elevation in adduction.

METHODOLOGY

We retrospectively analyzed 12 consecutive patients with unilateral Brown syndrome who underwent a 15 mm tenectomy of the posterior four-fifths fibers of the ipsilateral SO tendon. Intraoperative forced duction showed restriction to elevation in adduction in all subjects. No patient had concomitant surgery on any other extraocular muscle.

RESULTS

The mean patient age at diagnosis was 6.9 +/- 1.7 years. Preoperative vertical deviation measured 4 +/- 1 PD in the primary position and 12 +/- 2 PD in elevation in adduction. Postoperative follow-up was 24.7 +/- 9.2 months. Postoperatively, all patients had less than 2 PD of orthotropia in the primary position, and the deviation in elevation in adduction was significantly improved at 3 +/- 2 PD (P < 0.05). Elevation in adduction improved from -4.0 preoperatively to -1.9 +/- 1 postoperatively (P = 0.0000003) and no patient experienced underaction of the SO. Postoperatively, all patients had stereopsis in primary position.

CONCLUSION

The use of SO posterior tenectomy improves alignment and ocular rotations in patients with Brown syndrome, resulting in fusion, small vertical deviation in primary position, and minimal-to-no anomalous head posture, in whom the most important finding is a disfiguring downshoot on attempted adduction. Other advantages include minimal-to-no postoperative SO muscle underaction and no risk of foreign body extrusion, fibrosis, and scarring.

Importance of sagittal orbital imaging in evaluating extraocular muscle trauma following endoscopic sinus surgery

BACKGROUND/AIMS

Orbital trauma may result in severe restrictive, paralytic, or combined strabismus. Clinical diagnosis may be extremely challenging. Orbital imaging is helpful in determining the exact site of injury, functionality, and integrity of the extraocular muscles. A typical study now includes coronal and axial views of the muscles. This study aimed to emphasise the importance of sagittal imaging of the orbit when evaluating extraocular muscle injury or entrapment.

METHODS

A retrospective review of two subjects who underwent endoscopic sinus surgery procedures that resulted in trauma to the medial rectus muscle. High resolution orbital imaging studies were performed.

RESULTS

High resolution magnetic resonance imaging (MRI) scans with coronal and axial views suggested a large section of the muscle was not present and was probably destroyed. In both cases there was a displacement of the mid-portion of the medial rectus muscle into an area of bony defect not seen on the axial and coronal views. Sagittal images demonstrated continuity between the anterior and posterior segments of the medial rectus muscle in each case.

CONCLUSION

Surgical strategies are dependent on accurate interpretation of MRI scans. Muscle displacement may result in axial and coronal orbital imaging misinterpretation. Sagittal views were essential to determine muscle integrity.

Vertical rectus muscle transposition for bilateral Duane syndrome

BACKGROUND

Augmented transposition of the superior and inferior rectus muscles to the lateral rectus muscle is effective surgical treatment for esotropia in unilateral Duane syndrome. Medial rectus muscle recession in bilateral Duane syndrome may increase the risk of consecutive exotropia and cause limitation to adduction postoperatively. Vertical rectus muscle transposition may be useful in bilateral Duane syndrome with esotropia.

METHODS

We undertook a retrospective review of 11 patients with bilateral Duane syndrome and esotropia in primary position. All patients had vertical rectus muscle transpositions. Six patients had unilateral vertical rectus transpositions (2 eyes with and 4 without suture augmentation). Twelve eyes from 7 children (2 unilateral and 5 bilateral) had transpositions augmented with posterior fixation sutures. Posterior fixation suture were added to large deviations in patients without prior medial rectus recessions.

RESULTS

The preoperative esotropia at distance was 22.8 +/- 6.3 prism diopters (PD). It reduced to 2.0 +/- 6.7 PD postoperatively. (P < 0.001) Esotropia at near changed from 21.0 +/- 5.8 PD preoperatively to 1.2 +/- 8.1 PD postoperatively. (P < 0.001) One patient with a 10-degree face turn had complete resolution postoperatively. One patient had a small undercorrection and developed a vertical deviation requiring additional surgery. All patients had improvement in abduction. Nine of 11 patients did not develop any limitation to adduction. One patient developed a -1 adduction deficit 5 years later. Three patients achieved fusion with a mean stereovision of 67 seconds of arc (range, 80-40 seconds.). Follow-up averaged 22.2 months (range, 1-100 months).

CONCLUSION

Vertical rectus muscle transposition in patients with bilateral Duane syndrome and esotropia is an effective procedure to improve ocular alignment and motility while preserving adduction.