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

PURPOSE: To compare the surgical outcomes of unilateral lateral rectus recession to bilateral lateral rectus recession for small angle intermittent exotropia. METHODS: This was a retrospective cohort study of pediatric patients with an intermittent exotropia between 16 and 20 prism diopters (PD) who underwent unilateral lateral rectus recession or bilateral lateral rectus recession at a single tertiary care pediatric hospital. The primary outcome was success (exotropia < 10 PD of esotropia < 5 PD, no decrease in stereopsis > 0.6 log arcsec, and no reoperation) at 12 months postoperatively. Secondary outcomes included survival analysis of time to surgical failure, surgical dose-response, and improvement in central fusion or stereopsis. RESULTS: At 12 months, successful outcomes were achieved in 13 of 27 patients (46%) in the bilateral lateral rectus recession group and 19 of 28 patients (70%) in the unilateral lateral rectus recession group, which was not a statistically significant difference (P = .10). Survival analysis showed a trend toward a higher rate of failure in the bilateral lateral rectus recession group compared to the unilateral lateral rectus recession group (P = .04). The mean surgical dose-response was 1.7 PD/mm at 1 week and 1.0 PD/mm at 12 months for the bilateral lateral rectus recession group, and 2.0 PD/mm at 1 week postoperatively and 1.4 PD/mm at 12 months postoperatively for the unilateral lateral rectus recession group. There were no cases of long-term postoperative lateral incomitance in either group. CONCLUSIONS: Unilateral lateral rectus recession and bilateral lateral rectus recession have similar success rates for small angle intermittent exotropia after at least 12 months of follow-up. Randomized controlled trials in surgical management of intermittent exotropia should consider unilateral lateral rectus recession as a treatment arm. [J Pediatr Ophthalmol Strabismus. 2022;59(5):350-355.].

Ocular motility disturbances after glaucoma drainage device implantation for paediatric glaucoma: a cross-sectional study.

AIM: To grade extraocular motility in the field of action of each extraocular muscle following superotemporal glaucoma drainage device (GDD) implantation in a paediatric population and to investigate which drainage device (Ahmed vs Baerveldt) yields less extraocular motility disturbance. METHODS: Cross-sectional study of children with a GDD implanted consecutively by a single surgeon who underwent ocular motility examination by two masked orthoptists. Ductions in the cardinal positions were graded. Ocular alignment, visual acuity, binocularity, stereopsis and intraocular pressure were also measured, and patient charts were reviewed. RESULTS: Thirty children each had one eye included. Twenty-one eyes had an Ahmed GDD and 9 had a Baerveldt GDD. Mean time between GDD insertion and ocular motility exam was 68 months in the Ahmed group and 19 months in the Baerveldt group. Exotropia was present in 46% and vertical heterotropia in 46% of children post-GDD insertion. Thirty-three percent of eyes had a moderate or severe limitation of elevation in abduction, 30% of elevation in adduction, 10% of abduction and 10% of adduction. There was a trend towards more eyes in the Ahmed group (62%) having at least a moderate limitation in ocular motility (-2 or worse; scale -1 to -4) compared with the Baerveldt group (22%). CONCLUSION: Strabismus is common in children with GDDs. Our motility and alignment findings are consistent with either a mass effect of the device and bleb and/or scarring beneath the plate in the quadrant of the GDD causing dysmotility, most commonly limitation towards the GDD.

Population trends in adult strabismus surgery.

OBJECTIVE: To review the trends in adult strabismus procedures in Ontario from 2000-2013. DESIGN: Population-based, retrospective data analysis. PARTICIPANTS: All patients 18 years or older who underwent a strabismus related procedure in Ontario and all ophthalmologists who performed these procedures from 2000-2013. METHODS: Ontario Health Insurance Plan billing claims for strabismus procedures were collected and subdivided by number of muscles repaired, the use of adjustable sutures, repeat procedures, and pharmacological injection of the extraocular muscles adjusted by the total adult population. The number of ophthalmologists performing adult strabismus surgery was also analyzed, subdivided by high-volume and low-volume surgeons. RESULTS: From 2000-2013, per 100 000 adult population, the number of total strabismus surgeries in Ontario increased 26.0%; single-muscle surgery increased 24.2%, 2-muscle surgery increased 43.1%, and 3 or more muscle surgery increased 3.8%. During the study period, strabismus procedures using adjustable sutures increased 30.3%, and repeat procedures increased 19.1%. The number of surgeons performing adult strabismus surgery decreased 30.0% from 2000-2013. In 2013, 92.6% of surgeries were performed by 35.7% of surgeons who performed adult strabismus surgery. CONCLUSION: From 2000-2013, more strabismus surgery was performed in adults by fewer surgeons, including procedures using adjustable sutures and repeat procedures. These increases may be due to increases in health care funding and a heightened awareness of the functional and psychosocial benefits of strabismus surgery.

Idiopathic Enlargement of the Extraocular Muscles in Young Patients: A Case Series.

PURPOSE: To describe a case series of enlarged extraocular muscles in young patients. DESIGN: Retrospective interventional case series. METHODS: Study involves 6 young patients who presented with atypical restrictive strabismus and reduced eye movements. Examination, neuroimaging, biochemistry results, and biopsy results are presented. The surgeries are described, and the follow-up over 1-20 years is presented. RESULTS: All 6 patients had enlarged extraocular muscles that caused restrictive strabismus. The patients had no significant medical history. There was no identifiable underlying pathology on biochemistry tests or muscle biopsy. Three of the patients required multiple surgeries. CONCLUSION: Atypical presentations of strabismus should be investigated for systemic conditions. Neuroimaging of the orbit and brain and a biopsy of the affected muscles should be considered. The patients should be counseled that multiple surgeries may be necessary to improve the strabismus, and it is unlikely that orthotropia will be attained.

The accuracy of anterior segment optical coherence tomography (AS-OCT) in localizing extraocular rectus muscles insertions.

PURPOSE: To evaluate the accuracy of the anterior segment optical coherence tomography (AS-OCT) in measuring the distance from the limbus to the insertion of primary and previously operated rectus muscles in children. METHODS: In this prospective, double masked, observational study the distance of the extraocular muscle insertion from the limbus measured by AS-OCT preoperatively was compared to intraoperative measurement using the surgical calipers. Consecutive patients 4-18 years of age undergoing primary or repeat strabismus surgery on horizontal or vertical rectus muscles between September 2013 and May 2014 were included. Patients with any condition that interfered with imaging were excluded. Participants were asked to look in the direction opposite to the muscle to ensure that the middle third of the muscle was being imaged and measured. RESULTS: A total of 65 muscles were evaluated, including 9 muscles undergoing reoperation and 10 vertical rectus muscles. Of these, 62 muscles were successfully imaged. In all reoperated eyes, the AS-OCT measurements were within 1 mm of the intraoperative measurements. Overall, 89.7% (95% CI, 78.8%-96.1%) of the measurements were within the 1 mm difference considered "clinically acceptable." The intraclass correlation coefficient comparing the reliability of the AS-OCT measurements with intraoperative measurements was 0.73 (95% CI, 0.53-0.85), or "good" agreement. CONCLUSIONS: AS-OCT can accurately detect rectus muscle insertions in primary or previously operated cases in children as young as 4 years of age.

Cyclic strabismus in adults.

Cyclic strabismus is a rare condition that usually occurs in children and is characterized by alternating intervals of straight and strabismic eyes. In adults with the condition, strabismus surgery often eliminates the cycles. We report a case of adult-onset cyclic esotropia that was converted into a cyclic exotropia.

Achieving postoperative target range increases success of strabismus surgery in adults: a case for adjustable sutures?

BACKGROUND/AIMS: To evaluate the role of achieving immediate target angles on the success of strabismus surgery. METHODS: We performed a retrospective cohort study of all patients over 12 years old undergoing strabismus surgery with either adjustable or non-adjustable sutures. Target angle for patients with esotropia and vertical deviation was within 4 prism dioptres (PD) of orthotropia and for patients with exotropia between orthotropia and 8 PD of esotropia. Success was defined as alignment within 10 PD for horizontal rectus surgery and within 5 PD of orthotropia for vertical rectus surgery, without diplopia or reoperations. The main outcome measure was surgical success rate. RESULTS: Three hundred and fifty-three patients were included in the study with mean follow-up of 13.9 (4-132) months. Patients achieving the target angle immediately postoperatively had higher success rate than patients who did not (83.6% vs 63.7%, p<0.0001, OR 2.9, 95% CI 1.8 to 4.9). When target angle was achieved, adjustable and non-adjustable sutures had similar success (84.8% and 80.9%, respectively, p=0.46, OR 1.3, CI 0.58 to 2.9). However, patients undergoing adjustable surgery were more likely to obtain the target angle (75.5% vs 54%, p<0.0001, OR 2.7, CI 1.7 to 4.2). Success for exotropia surgery was significantly higher when the immediate target angle was achieved (86.4% vs 58.7%, p<0.0001, OR 4.47, CI 2.3 to 8.6). For esotropia and vertical deviations, a similar beneficial effect was not shown (p=0.31, OR 1.6, CI 0.65 to 4.0 and p=0.33, respectively). On multiple logistic regressions, sex, amblyopia, binocularity and reoperations were not significant factors in surgical success. CONCLUSIONS: Our results suggest that achieving the immediate target angle is the most significant factor in the success of strabismus surgery for exotropia. Adjustable suture surgery results in higher proportion of patients achieving this target angle.

Outcomes of three different vertical rectus muscle transposition procedures for complete abducens nerve palsy.

PURPOSE: To compare the efficacy of three different vertical rectus muscle transposition (VRT) techniques performed as a sole procedure to correct ocular alignment and improve abduction in cases of complete abducens nerve palsy. METHODS: The medical records of patients with complete abducens nerve palsy who underwent one of three different VRT procedures without simultaneous medial rectus weakening over a period of 20 years were retrospectively reviewed. The following procedures were used: full-tendon transposition (FTT), FTT with 4 mm resections before reinsertion (FTTR), and FTT with myopexy sutures (FTTM). We recorded the pre- and postoperative alignments, limitations of adduction and abduction, and complications. Follow-up was at least 6 months. RESULTS: A total of 26 patients (age range, 8-74 years) were included: 25 unilateral and 1 bilateral. Follow-up ranged from 6 to 21 months. Among 25 patients having unilateral surgery, the mean changes in esotropia were: 36.0(Δ) for FTT (n = 9), 46.4(Δ) for FTTR (n = 7), and 41.3(Δ) for FTTM (n = 9). Mean improvements in abduction grading were 0.94 for FTT (9 eyes), 1.64 for FTTR (7 eyes), and 1.41 for FTTM (11 eyes). For both measures the means were not significantly different. Three patients (2 FTT and 1 FTTM) had new postoperative vertical tropias >3(Δ). Only 1 patient (with FTTR) had an overcorrection. CONCLUSIONS: FTTR corrected the most esotropia and improved abduction to the greatest degree, with the advantages of a low risk of creating a new vertical deviation and avoiding the risks of extra scleral sutures.

Localising rectus muscle insertions using high frequency wide-field ultrasound biomicroscopy.

AIM: The ultrasound biomicroscope (UBM) can accurately locate an extraocular muscle (EOM) insertion. The authors compared the accuracy of the Sonomed UBM (SUBM), a new 'wide-field ultrasound biomicroscope', with the older model Humphrey UBM (HUBM) in localising EOM insertions and compared their ranges of detection of muscle insertions. METHODS: Prospective, double-masked, observational study of 27 patients undergoing primary (n=40 muscles) or repeat (n=10 muscles) horizontal or vertical rectus muscle surgery. EOM insertional distances were measured with SUBM, and then intraoperatively with callipers. A Bland-Altman analysis and intraclass correlation coefficient were used to compare the SUBM and surgical data. RESULTS: For all muscles, the differences between SUBM and surgery measurements were less than 1.0 mm. The mean of the SUBM insertion distances was 6.67 mm (SD 1.65 mm) versus 6.7 mm (SD 1.6 mm) at surgery. The intraclass correlation coefficient showed 'excellent' correlation between the two sets of data and was higher than that reported with HUBM. The image quality with the SUBM was superior to the HUBM, and its range of field was much larger (14×18 mm vs 5×6 mm). CONCLUSION: The SUBM with its smaller, more manoeuvrable probe handpiece and a wider scanning field was more accurate in detecting muscle insertions compared with HUBM.

Utility of adjustable sutures in primary strabismus surgery and reoperations.

PURPOSE: To evaluate the success of adjustable suture (AS) and nonadjustable suture (NAS) strabismus surgery in primary procedures and reoperations. DESIGN: Retrospective case series. PARTICIPANTS: Four hundred four patients older than 12 years who underwent strabismus surgery over a 13-year period. METHODS: All eyes underwent the same hang-back suturing technique by a single surgeon (S.P.K.) in both the AS and NAS groups. Success was defined as alignment within 10 prism diopters (PD) for horizontal recti and within 5 PD of orthophoria for vertical recti without diplopia or further surgery. MAIN OUTCOME MEASURES: Surgical success rate of AS and NAS primary surgery or reoperations was the primary outcome measure. Effects of amblyopia, binocularity, and strabismus type on success were secondary outcome measures and were analyzed using multiple logistic regression. RESULTS: Patients in the AS group required adjustment in 28.8% of cases. Higher overall success was seen with AS (77.7%) compared with NAS (69.1%) surgery, although this did not reach significance (P = 0.059). Overall success for AS in exotropia surgery (80.8%) was significantly higher than that in the NAS group (65.9%; P = 0.011). This was because of higher success in patients undergoing primary surgery (82.5% vs. 50%; P = 0.003), but not in patients undergoing reoperation (80.2% vs. 77.6%; P = 0.71). On multiple regression analysis, male gender and not having a mechanical or neurogenic cause for strabismus were significant factors for a successful outcome. Overall, other factors including amblyopia, binocularity, strabismus type, and primary or reoperation were not significant. CONCLUSIONS: These results suggest that primary surgery in adults with exotropia has a more successful outcome with AS surgery. This advantage was not present with esotropia and vertical deviations in this series.

Long-term efficacy of botulinum a toxin for blepharospasm and hemifacial spasm.

OBJECTIVE: To determine whether the duration of relief from symptoms in patients with essential blepharospasm (EB) or hemifacial spasm (HFS) who receive serial treatments with botulinum toxin type A (BtA) changes over the long-term. METHODS: Retrospective longitudinal comparative analysis. The main outcome measure is the mean duration of relief from symptoms after an injection with BtA. Participants included 34 patients who received 30 or more serial BtA treatments for facial dyskinesia (EB or HFS). Repeated measures and linear regression analyses were used to determine trends and the mean duration of relief from symptoms was compared between early (first ten effective treatments) and late (last ten treatments) sessions in each group. RESULTS: In the EB group (18 patients), the mean duration of relief was 13.5 weeks for the early and 11.4 weeks for the late sessions (P = 0.04). In the HFS group (16 patients) the mean duration of relief was 12.4 weeks in both treatment periods (P = 0.91). The duration of relief had a small negative correlation with mean late session BtA dose in the EB group (P = 0.03) but no correlation in the HFS group (P = 0.12). CONCLUSIONS: There was a trend towards a decreased duration of relief from symptoms in patients with EB over the long-term, but no changes for HFS. The treatment remains effective in relieving symptoms and signs for both conditions.

Lateral rectus resection strabismus surgery in unilateral duane syndrome with esotropia and limited abduction.

BACKGROUND: Resection of the lateral rectus in Duane retraction syndrome (DRS) with esotropia (ET) and limited abduction can be a useful component of surgical planning in specific circumstances, when combined with medial rectus (MR) recession. This article reports the results of a prospective series of patients for whom this approach was used successfully. METHODS: Seven patients were treated, aged 3 to 52 years, with uniltaeral DRS with the following features: 1) ET at least 25 PD; 2) "mild" retraction on adduction; 3) clinically normal adduction; 4) significantly limited abduction; 5) no or mild upshoots/downshoots; and 6) positive forced duction to abduction at surgery. surgery involved MR recession up to 5.0 mm and LR resection of maximum 3.5 mm. Postoperative followup was at least 6 months in all cases. RESULTS: ET angles ranged from 25 to 32 PD; abduction limitations ranged from -3.5 to -4. All patients had face turn postures preoperatively. Postoperatively, the binoclar alignment in primary position was orthotropia and head postures wre eliminated in all patients. Abduction postoperatively ranged from -1 to -2.5; adduction ranged from -0.5 to -1. Two patients had minimal worsening of upshoots and downshoots after surgery. CONCLUSION: In treating DRS with ET and limited abduction, a small LR resection can be a safe and effective component of surgery. It has a low risk of worsening retraction or "crippling" adduction when done in appropriate cases.

Dissociated vertical deviation in patients with intermittent exotropia.

PURPOSE: To determine whether the age of strabismus onset and the degree of stereopsis are related to the development of dissociated vertical deviation (DVD) in patients with intermittent exotropia and to describe the characteristics of DVD in patients with intermittent exotropia and DVD. METHODS: Retrospective record review of patients with (1) intermittent exotropia with DVD; (2) infantile esotropia with DVD; and (3) intermittent exotropia without DVD. Age of strabismus onset, stereopsis, strabismus measurements, and the response of DVD to the Bielschowsky head-tilt test were compared among the three groups. RESULTS: Fifty-two children with intermittent exotropia and DVD were identified. In patients with intermittent exotropia with DVD and intermittent exotropia without DVD group, the mean age of strabismus onset was 12.7 months and 28.9 months, respectively (p = 0.03), and mean stereopsis was 147 arcsec and 65 arcsec (p = 0.02). In patients with intermittent exotropia with DVD and infantile esotropia with DVD, the mean amount of DVD was 9.7(Delta) and 17.2(Delta), respectively (p < 0.01). Bielschowsky head-tilt test showed an increase of DVD on ipsilateral head tilt in 91% and 63.3%, respectively. CONCLUSIONS: Intermittent exotropia with DVD is characterized by earlier onset of strabismus and worse stereopsis, suggesting that these factors may be related to the development of DVD in patients with intermittent exotropia. Unlike DVD in infantile esotropia, DVD in intermittent exotropia was smaller in amount and demonstrated a more uniform response to the Bielschowsky head-tilt test.

Evaluation of vertical rectus muscles using ultrasound biomicroscopy.

PURPOSE: To evaluate the accuracy of ultrasound biomicroscopy (UBM) in measuring the distance (in mm) from limbus to the insertion of vertical rectus muscles (superior rectus and inferior rectus compared with the "gold standard" surgical caliper at the time of surgery. METHODS: Prospective, masked, observational study of 31 vertical rectus muscle insertions in which we compared the measurements from the limbus as measured by 50 MHz UBM, either preoperatively or at the time of anesthesia, with that measured by surgical caliper intraoperatively. Measurements (UBM and surgical) were evaluated by two different observers and analyzed using the Bland-Altman method. All UBM measurements were done by the same author. The intraclass correlation coefficient (ICC) and Pearson coefficient with 95% confidence intervals were used to quantify the degree of agreement between the two methods. RESULTS: Thirty-one vertical muscles were evaluated (13 superior rectus and 18 inferior rectus, of which 7 muscles were reoperations). The average for UBM measurements was 6.63 mm and for surgical caliper was 7.09 mm. The measurements for the two methods were all within +/-2 standard deviations of the mean. Only three measurements showed differences more than 1 mm. The ICC was 0.78 and Pearson coefficient was 0.85, indicating a "very good" correlation between the two methods. The longest distance from the limbus that could be accurately measured with the UBM was 12 mm. In one case a pseudotendon was differentiated from the true insertion of a previously recessed superior rectus muscle. CONCLUSIONS: The UBM and surgical measurements showed "very good" correlation when allowing for a margin of error of +/-1.0 mm between the two modalities, indicating that the UBM is a good predictor of the position of the vertical rectus muscles.