Development of Strabismus in Children Initially Diagnosed with Pseudostrabismus

Purpose: To evaluate the incidence of strabismus in children initially diagnosed with pseudostrabismus and to identify risk factors for the development of strabismus.

Methods: The medical records of patients who were diagnosed with pseudostrabismus at initial examinations in outpatient clinic were reviewed retrospectively. Follow-up examinations were made at the strabismus department. Age at first examination, gender, family and developmental history, ophthalmic and orthoptic findings including orbit, and eyelid pathologies were investigated.

Results: Sixty-five patients with the diagnosis of pseudostrabismus were identified; 2 patients (3.1%) had pseudoexotropia, and 63 patients (96.9%) had pseudoesotropia. The mean age at the initial exam was 29.26±26.68 months (range; 4–120 months). Epicanthal skin folds (n=35), flat broad nasal bridge (n=17), blepharophimosis syndrome (n=1), hypertelorism (n=1), telecanthus (n=1), and multiple pathologies (n=10) were the reasons for pseudostrabismus. Six patients (9.2%) had clinically significant hypermetropia. Anisometropia and amblyopia were detected in 1 (1.5%) and 3 patients (4.6%), respectively, at the initial examination. The mean follow-up period was 25.2±23.28 months (range; 1–154 months). During the follow-up period, true strabismus was detected in 8 cases (12%); of these, 5 cases had non-refractive esotropia, 2 cases had refractive accommodative esotropia, and 1 case had exotropia. Binocular single vision was not developed following amblyopia therapy and refractive correction in esotropic cases. Binocular single vision and best corrected visual acuity were statistically significant risk factors for the development of strabismus (P=0.001).

Conclusion: The pseudostrabismic children with subnormal binocular single vision or low visual acuity require follow-up for the risk of development of true strabismus.     

Multifocal Surgically Induced Necrotizing Scleritis Following Strabismus Surgery: A Case Report

Purpose: To present clinical findings of a 28-year-old woman with multifocal surgically induced necrotizing scleritis following uncomplicated strabismus surgery.

Method: A 28-year-old woman underwent uncomplicated strabismus surgery of her right eye for sensory exotropia under general anesthesia (6 mm right medial rectus muscle resection and 8 mm right lateral rectus muscle recession).

Design: Retrospective, observational case report and literature review.

Results: One month after strabismus surgery, the patient presented with surgically induced necrotizing scleritis in the nasal aspect of sclera. Bacterial culture of the bed of the scleral melt showed no growth and all laboratory evaluation was normal. The scleritis completely resolved after initiation of systemic corticosteroids and oral azathioprine. Three weeks later (after tapering dose of systemic medication), the patient returned with large area of necrotizing scleritis in the same eye, but this time in the temporal aspect of sclera.

Conclusion: To our knowledge, this is the first documented case of multifocal surgically induced necrotizing scleritis occurring after strabismus surgery. This study also highlights the fact that scleritis may recur even in an area distant from the site of surgery, despite initial control. It seems that maybe with a longer course of treatment it is less likely to recur, and tapering medications should be carefully managed.     

The Effect of Prism Adaptation on the Angle of Deviation in Convergence Excess Esotropia and Possible Consequences for Surgical Planning

Convergence excess esotropia describes a heterophoria with binocular single vision (BSV) on distance viewing that becomes esotropic on accommodation upon near fixation. Prism adaptation test (PAT) is a procedure routinely used to reveal the maximum angle of deviation preoperatively for many types of strabismus and has been shown to improve surgical outcomes; however, it is not conventionally used for convergence excess esotropia.

Aim: This study compares the angle of deviation at 1/3 m and 6 m before and after prism adaptation in subjects with convergence excess esotropia to determine if a masked distance angle of deviation can be demonstrated similar to the masked near angle of deviation in some intermittent exotropes. Surgical results are reported.

Results: Fifty-eight children with convergence excess esotropia were prescribed prism adaptation prior to strabismus surgery and 49 met the inclusion criteria. A median increase in the angle of deviation of 20 prism dioptres (PD) was seen at both 1/3 m and 6 m following PAT. These changes were statistically significant (p < 0.001) at both distances. Following one surgical procedure, 83.6% were fully binocular postoperatively.

Conclusion: Prism adaptation frequently reveals an otherwise masked large distance angle of deviation in convergence excess esotropia. Convergence excess esotropia can be subdivided into two categories: true and simulated. Those with true convergence excess exhibit a manifest convergent strabismus when viewing a close object and a small, well-controlled latent strabismus upon fixation of a distant object. Those with simulated convergence excess have a comparable near deviation to those with true convergence excess but can be shown to have a distance deviation that approaches the size of the near strabismus once the normal fusional mechanisms are disrupted by a period of prism adaptation.     

Long-term Surgical Outcomes in the Sagging Eye Syndrome

Background/aims: Strabismus due to sagging eye syndrome (SES) caused by age-related connective tissue involution is now an established cause of diplopia in older people. High suspicion of the condition results in early recognition, often obviating extensive neurological investigations and enabling surgical correction of the strabismus.

Methods:This retrospective study reviewed surgical results in 93 patients (40 males) of average age 68 ± 12 years, who had small-angle strabismus due to SES, during the 20-year period 1994–2014.

Results: In central gaze, mean distance pre-operative esotropia was 4.2 ± 7.5Δ (mean, SD), while mean hypertropia was 4.7 ± 5.9Δ. Surgeries comprised medial rectus (MR) recession; lateral rectus (LR) resection; plication, imbrication, and superior transposition of the LR to the superior rectus (SR) for esotropia; and graded vertical rectus tenotomy (GVRT) or vertical muscle recession for hypertropia. Mean post-operative immediate and long-term deviation after 316 ± 265 months average follow-up was 0.2 ± 1.2Δ and 1.1 ± 2.7Δ esotropia (both distance), respectively, and 0.00Δ and 1.1 ± 2.7Δ, respectively, for hypertropia. Strabismus recurred in 19 cases.

Conclusions: Progressive connective tissue involution in SES may occasionally result in symptomatic recurrences of the small-angle strabismus in about 20% of patients, irrespective of surgical procedures performed, possibly because of progressive involutional changes. This risk should be disclosed pre-operatively.     

Cortical Visual Connections via the Corpus Callosum are Asymmetrical in Human Infantile Esotropia

Purpose: Besides chiasmal hemidecussation, interhemispheric connections are likely important in human binocularity. The corpus callosum (CC) is the major fiber bundle in the mammalian brain which mostly connects homologous cortical areas in the two hemispheres. Visual interhemispheric connections were found abnormal in strabismic cats. No studies have investigated these pathways in humans with infantile strabismus.

Methods: Diffusion tensor imaging was used in four subjects with infantile esotropia (IE) and nine control subjects with normal binocularity, in order to study interhemispheric fibers in the CC connecting the right and left primary visual cortical areas.

Results: The number of callosal fibers linking both visual cortical areas between the hemispheres was found to be higher in subjects with IE. Also in IE, the amount of visual callosal fibers found after analysis from the primary visual cortical areas on one side appeared significantly different from the amount starting from the contralateral primary visual areas. The distribution area on one side is wider.

Conclusion: We show callosal visual fibers to be abnormal in human IE. Subjects with IE showed abnormal numbers of transcallosal fibers connecting the visual cortical areas on both sides which likely results from an abnormal elimination process during development. Pruning of these fibers in IE favors the side of the visual cortex ipsilateral to the dominant eye. This study underlines the likely role of the CC in the development of human binocularity.     

Effect of Limited Tenon Capsule and Intermuscular Membranes Dissection on the Outcome of Surgery in Patients with Horizontal Strabismus

Purpose: The aim of the study was to evaluate the effect of limited dissection of Tenon capsule on the outcome of strabismus surgery.

Methods: Patients between the ages of 2 and 50 years with pure horizontal strabismus were enrolled in a prospective study. Patients were divided into two groups: case and control as a non-randomized study. The method of operation was similar in both groups except for the amount of sheath Tenon dissection. In the control group the intermuscular connections and Tenon capsule were cut as much as possible. In the study group, Tenon capsule, 3-4 mm posterior to the location of the sutures over the muscle (recessed or resected), were cut and intermuscular connections remained intact.

Results: The study enrolled 54 patients with 27 patients in each group. In both groups, after operation, regardless of the type of surgery, the angle of strabismus was reduced (P< 0.05). For patients who had undergone bimedial recession, the angle of strabismus was corrected to 2.6 ± 0.4 prism diopters per mm (PD/mm) of muscle recession in the case group, and 2.2 ± 0.9 in the control group (P=0.2). For patients who had undergone monocular recession and resection (R&R) for esotropia, the angle of strabismus was corrected 3.4 ± 0.3 PD/mm of muscle recession or resection in the case group, and 3.2 ± 0.2 in the control group (P=0.05). For patients who had undergone bilateral recession, the angle of strabismus was corrected 2.3 ± 0.2 PD/mm of muscle recession in the case group, and 2.2±0.2 in the control group (P=0.03). For patients who had undergone R&R for exotropia, the angle of strabismus was corrected 3.1 ± 0.5 PD/mm of muscle recession or resection in the case group, and 2.7 ± 0.3 in the control group (P=0.02).

Conclusion: Connective tissue ensheathments, whether disturbed or removed, do not ultimately affect the success of the strabismus surgery.     

Prevalence and Risk Factors of Strabismus in a UK Multi-ethnic Birth Cohort

Purpose: To determine the prevalence, types and early-life risk factors associated with strabismus in a multi-ethnic birth cohort of children aged 4-5 years in the first year of school.

Methods: Data were collected prospectively over a 3-year period (2012-2015) from children participating in the vision screening program provided by orthoptists and carried out in schools located in the city of Bradford, UK. Prevalence of strabismus was determined for 17,018 children aged 4 to 5 years. Data linkage was undertaken for 4563 children participating in the Born in Bradford birth cohort study and the vision screening program. 4067 children had complete data and were included in the multivariable regression analyses to determine associated factors.

Results: 401/17018 (2.4%) children were found to have either a constant or an intermittent strabismus; 179/401 (45%) had an esotropic deviation, 214 (53%) an exotropic deviation, and 8 (2%) had a vertical deviation. No significant difference in the overall prevalence of strabismus was found between the white British, Pakistani, or children of other ethnic origin (P=0.41). Multivariable analysis showed that children of white British ethnicity have twice the odds of having esotropia (OR 2.4, 95% CI: 1.1, 5.3). The odds of having esotropia were highest in children with a hyperopic mean spherical equivalent (OR 2.0, 95% CI: 1.7, 2.6). There was some evidence of an interaction between ethnicity and mean spherical equivalent in children with esotropia (P=0.058).

Conclusions: Prevalence of strabismus is consistent with other population-based studies in this cohort of children aged 4-5 years. Prevalence of esotropia (constant or intermittent) is greater in the white British population, odds of esotropia increased with increasing hyperopic refractive error in both white British and Pakistani children. Exotropia (constant or intermittent) was not found to be associated with refractive error, ethnicity, or other early life factors.     

Pedigree Analysis of Familial Primary Concomitant Horizontal Strabismus in Northern India

Purpose: Familial clustering of common forms of primary strabismus like esotropia (ET) and exotropia (XT) is observed in a proportion of the strabismus cohort. The genetic components of this remain unidentified. Linkage studies have demonstrated susceptibility locus for primary strabismus at the STBMS1 locus on 7p22.1 as well as other loci on 4q28.3 and 7q31.2. Recently next generation sequencing (NGS) technology has emerged as a powerful tool in discovery genomics and a large number of novel disease-causing variants are being reported. In this study, we recruited informative families for subsequent genetic analysis for disease-causing variant identification.

Methods: All consecutive families with two or more affected members with primary concomitant horizontal strabismus were prospectively recruited at the ophthalmic outpatients department (OPD) of Lady Hardinge Medical College, New Delhi, from August 2014 to February 2017. Detailed phenotypic evaluation and pedigree documentation was performed.

Results: Of the 39 recruited families of north Indian origin, 18 families each had affected family members demonstrating either ET or XT. 100% concordance of the phenotype in the affected family members was observed in these families. While vertical transmission was observed in 17/18 families with XT, 7 with ET had affected members across one generation, 2 demonstrated consanguineous pedigree, and 2 comprised identical twin families. In 3 families, a combination of ET and XT was noted. This comprised one family with the ET and XT patients being from 2 separate arms of the family related by marriage, one family where one sibling had XT and the other had ET, and another family where the maternal aunt of the affected proband with ET had XT.

Conclusions: Subjects with familial primary concomitant strabismus recruited in this study may provide a valuable resource to unravel the genetic determinants of this condition, which is a common disorder of early childhood with high ophthalmic morbidity.     

Strabismus,Visual Acuity,and Uncorrected Refractive Error in Portuguese Children Aged 6 to 11 Years

Introduction: Visual anomalies that affect school-age children represent an important public health problem. Data on the prevalence are lacking in Portugal but is needed for planning vision services. This study was conducted to determine the prevalence of strabismus, decreased visual acuity, and uncorrected refractive error in Portuguese children aged 6 to 11 years.

Methods and materials: A cross-sectional study was carried out on a sample of 672 school-age children (7.69?±?1.19 years). Children received an orthoptic assessment (visual acuity, ocular alignment, and ocular movements) and non-cycloplegic autorefraction.

Results: After orthoptic assessment, 13.8% of children were considered abnormal (n?=?93). Manifest strabismus was found in 4% of the children. Rates of esotropia (2.1%) were slightly higher than exotropia (1.8%). Strabismus rates were not statistically significant different per sex (p?=?0.681) and grade (p?=?0.228). Decreased visual acuity at distance was present in 11.3% of children. Visual acuity ≤20/66 (0.5 logMAR) was found in 1.3% of the children. We also found that 10.3% of children had an uncorrected refractive error.

Conclusions: Strabismus affects a small proportion of the Portuguese school-age children. Decreased visual acuity and uncorrected refractive error affected a significant proportion of school-age children. New policies need to be developed to address this public health problem.     

Strabismus Following Scleral Buckling Surgery

Purpose: To assess the incidence of strabismus, relationship of strabismus with type and width of scleral buckle after scleral buckling surgery for retinal detachment.

Methods: Retrospective analysis was done of 360 eyes of 344 patients treated for rhegmatogenous retinal detachment with scleral buckling surgery between January 2008 and January 2013.

Results: The mean age of patients was 38.45 ± 18.12 years (range: 7 to 89 years). Strabismus was detected in 48 out of 344 (13.95%) patients at 6 weeks after scleral buckling surgery. Horizontal deviation was the commonest type. Incidence of strabismus was higher after repeat scleral buckling surgery (4/9, 44.4%) compared to patients who had single scleral buckling surgery (44/335, 13.1%) (P=0.02). Strabismus was observed in 18.5% of patients with implants, compared to 11.3% of patients who received explants (P=0.02). Strabismus surgery was performed on 2 (4.1%) cases.

Conclusion: Horizontal strabismus is common after scleral buckling surgery for repair of retinal detachment. Repeat scleral buckling and use of implants resulted in a higher incidence of strabismus in the postoperative period. Majority of these cases resolve with conservative management.     

Age-related distance esotropia – fusional amplitudes and clinical course

Background: Age-related distance esotropia (ARDET) is a form of acquired strabismus that affects elderly patients and manifests as an esotropia greater with distance fixation. Limited information exists regarding fusional amplitudes and deficient divergence in this disorder.

Methods: In this retrospective study, patient characteristics, ocular alignment and motility, and clinical course of patients with ARDET were recorded. Fusional amplitudes were analyzed to assess whether deficient divergence was present in patients with ARDET.

Results: Twenty patients with ARDET were identified. Median age was 77.5 years (range, 59 to 89 years) and median best-corrected visual acuity was 20/25. Median esotropia angle with distance fixation was 5.5Δ (range, 2 to 18Δ); median angle with near fixation was esotropia 2.5Δ (range, exotropia 3Δ to esotropia 13Δ). Fusional divergence amplitudes were decreased in all but two patients. The median amplitude with distance fixation was 4.5Δ for break (range, 1 to 11Δ) and 2Δ for recovery (range, 0 to 9Δ). In 5 patients, the fusional divergence amplitude was as large or larger than the esotropia angle. Most patients remained stable throughout a mean follow-up of 18 months (range, 3 to 37 months). Nineteen patients were managed with prisms. Strabismus surgery was performed in one patient.

Conclusions: Fusional divergence amplitude was deficient in most but not all patients with ARDET. In this study, most patients with ARDET remained stable and free of diplopia with prism treatment.     

The Italian Version of the Amblyopia and Strabismus Questionnaire: Translation,Validation, and Reliability

Objective: To develop a culturally adapted Italian version of the Amblyopia and Strabismus Questionnaire (A&SQ) Health Survey and to test its acceptability, reliability, and validity in patients with strabismus.

Study Design and Setting: The English A&SQ was translated into Italian after established cross-cultural adaptation procedures. The questionnaire was administered to 99 consecutive outpatients with strabismus and 39 normal adults and readministered after 2 weeks to 15 randomly selected patients and 26 adults with normal vision.

Results: None of the participants had any problem in understanding the Italian A&SQ and 99% of the questionnaires were fully completed. The translated questionnaire has good discriminatory power between patients and healthy controls. Principal component analysis identified 7 factors, instead of the 6 in the original version. Cronbach’s alpha coefficient ranged from 0.64 to 0.77, and the test-retest reliability ranged from 0.92 to 1 and was adequate for all scales. Correlations with other disease activity parameters were generally as expected.

Conclusion: The Italian A&SQ, with modified scales as principal component analysis suggest, appears to be an acceptable, reliable, and valid instrument for measuring health-related quality of life in Italian patients with strabismus.     

Oculocardiac Reflex during Strabismus Surgery: Experience from a Tertiary Hospital

Purpose: To evaluate the incidence of the oculocardiac reflex (OCR) and its associated risk factors during strabismus surgery at a tertiary referral center.

Methods: Over a 2-year period, all strabismus surgery candidates were enrolled in the study. OCR was defined as heart rate reduction ≥15% after traction on extraocular muscle(s). The rate of OCR was determined and possible associations were explored. Variables included age, gender, type of strabismus, nature of surgery (weakening versus strengthening), specified extraocular muscle, times of surgery, and the sequence of operated muscles (eg, first, second, or third operated muscle). We avoided the use of atropine pre- and postoperatively.

Results: Seventy-six patients with mean age of 15±12 years were enrolled; 51.3% of subjects were male. OCR occurred in 65 out of 76 (85.5%) patients and with 84 out of 173 (48.6%) operated muscles. OCR was more common in subjects less than 20 years of age; however, it showed a decreasing trend afterwards. OCR was more frequent during operation on cyclovertical muscles than horizontal recti (P=0.02). Moreover, during procedures on horizontal rectus muscles, OCR was more common if baseline heart rate was more than 61 (P=0.008). OCR was not correlated with gender, type of strabismus, nature of surgery, times of the surgery, or the sequence of operated extraocular muscles.

Conclusions: The great majority of patients undergoing strabismus surgery, especially younger subjects, those undergoing operation on cyclovertical muscles, and subjects with higher baseline heart rate, experience OCR during strabismus surgery. During surgery on cyclovertical muscles, the amount of pull is usually more due to more difficult exposure.     

Long-Term Results of Bilateral Medial Rectus Muscle Recession in Children with Developmental Delay

Purpose: To assess the long-term results of a reduced amount of medial rectus recession in children with esotropia and developmental delay.

Methods: A retrospective chart analysis of 42 children with developmental delay who had undergone surgery for esotropia during a 20-year period in a large referral center was performed. The pre- and postoperative angle of deviation was calculated for each subject as the mean of distant and near angles measured by a cover test or the Krimsky measurement. Surgical success was categorized as esotropia or exotropia of ≤10 prism diopters (PD). The main outcome measure was a stable surgical result after several years of follow-up.

Results: The chart review identified 42 children who met inclusion criteria, with a mean age of 2.9 years (range, 0.8-10 years). The mean angle of esotropia prior to surgery was 44.29 ± 13.9 PD (range 20-80 PD). All patients had bilateral medial rectus muscle recessions, with a mean surgical dosage of 5.04 ± 0.62 mm per muscle, on average 0.66 mm less than the standard amount. The average postoperative follow-up was 4.6 years (median 3.67 years, range 8 months-15 years). Twenty-four children (57%) achieved surgical success, 13 (31%) were undercorrected, and 5 (12%) were overcorrected. Ten of the 18 with an unsuccessful surgical outcome underwent a second procedure. The overall surgical success rate for all patients after all procedures was 71%.

Conclusions: The main reason for surgical failure after bilateral medial rectus muscle recession (BMR) in developmentally delayed children remains residual esotropia. However, with time, more patients demonstrated consecutive exotropia. Although it is difficult to achieve a stable long-term ocular alignment in children with developmental delay, satisfactory results may be achieved with additional surgical procedures. The optimal amount of primary recession and whether to perform the surgical schedules according to the Parks tables or to reduce the amount of the recession when operating on children with developmental delay is still debatable.     

Preliminary Study: Impact of Strabismus and Surgery on Eye Movements When Children are Reading

Aim: To evaluate differences in eye movements during reading in strabismic children and in non-strabismic age-matched children, and to evaluate the potential effect of strabismus surgery on eye movement performance.

Methods: The eye movements of nine strabismic children from 11 to 15 years old were recorded with an eye tracker as they were reading a text under three visual conditions before and six months after eye surgery. The results were compared with those obtained from control groups of non-strabismic age-matched children. Eye movements were recorded during reading a text with both eyes open and under monocular vision with the dominant and non-dominant eye alternately covered.

Results: The duration of fixation was longer in strabismic children than in age-matched non-strabismic children. Children read faster under dominant eye open condition than under both eyes open condition. Surgery allowed an increase of reading speed and decrease of fixation duration. The number of backward saccades significantly decreased after surgery.

Conclusion: In strabismic children, eye movements during reading are impaired. The reduction of the squint allowed a better word comprehension.     

Adjustable Strabismus Surgery under Topical Anesthesia: Alignment in Supine vs Seated Position

Purpose: To compare ocular deviation in the operating room depending on whether the patient is in supine decubitus or seated after single-stage adjustable strabismus surgery under topical anesthesia.

Material and method: We performed a prospective observational study of 30 patients with horizontal and/or vertical strabismus who underwent single stage adjustable strabismus surgery under topical anesthesia. Both distance and near deviation were evaluated before surgery, during surgery in both positions (seated and supine), and at 1 day, 1 month, and 3 months after surgery. A final horizontal deviation <10 pd and a vertical deviation <5 pd without diplopia was considered to be a good outcome (3 months after surgery).

Results: The mean age of the sample was 55 years and 76.7% were women. Most had esotropia (70%). The most frequently used surgical combination was the medial rectus and lateral rectus (36.7%). Surgical adjustment was necessary in 40% of cases. Mean preoperative deviation was 21.9 ± 12.63 pd (distance) and 20.66 ± 4.76 (near). Deviation with the patient supine was 8 ± 8.25 pd (distance) and 7.26 ± 5.81 (near). Deviation with the patient seated was 8.13 pd±8.38 (distance) and 8.5 ± 7.41 (near). There was no significant difference between the positions. Outcome was favorable in 70% of patients; this percentage increased to 83.33% at 1 day, 1 month, and 3 months after surgery.

Conclusions: No statistically significant differences were found between ocular deviations in the seated or supine position in the operating room. Outcome was favorable in most cases 3 months after surgery. Intraoperative ocular deviation was not a predictor of outcome.     

Long-term follow-up after vertical extraocular muscle surgery to correct abnormal vertical head posture

Purpose: To report outcomes of vertical extraocular muscle surgery to correct abnormal vertical head posture in children with horizontal infantile nystagmus.

Methods: Retrospective case series of seven patients evaluated at one institution with abnormal vertical head position (chin-up or chin-down) in the setting of horizontal infantile nystagmus. All patients underwent bilateral vertical extraocular muscle surgery with the same surgeon. Pre- and postoperative vertical head position under binocular viewing conditions was the primary outcome measure. Secondary outcomes included visual acuity, stereopsis, degree of cyclotorsion, and residual ocular alignment.

Results: Seven children with infantile nystagmus syndrome, ranging in age from 4 months to 5 years at presentation, underwent extraocular muscle surgery to correct chin-down or chin-up head position associated with a null position in the setting of horizontal nystagmus. Five children had other ocular pathology (albinism, n = 4; cone-rod dystrophy, n = 1). Five of the seven patients had combined vertical recti and oblique muscle surgery. Three of the patients had additional extraocular muscle surgery to correct horizontal misalignment (exotropia, n = 2; esotropia, n = 1). One patient underwent a separate Kestenbaum procedure (bilateral horizontal resection/recession) to correct concomitant horizontal face turn. Median postoperative follow-up was 8.0 years (range 1–9.5 years). Postoperatively, three patients had complete resolution of their abnormal head position, and three had an improvement in their head posture, with a mean reduction in original vertical head position of 25 degrees. One of these patient had a reversal of their head position from a chin-up to a small chin-down position. Only one patient had no clinically significant improvement in their head position. No patients had signs or symptoms of cyclotorsion postoperatively.

Conclusion: Combined vertical recti and oblique muscle surgery can successfully improve and even resolve vertical head posture, and prevents cyclorotary disorders postoperatively.     

Sustained improvement of reading symptoms following botulinum toxin A injection for convergence insufficiency

Introduction: We evaluated the use of botulinum toxin A in adults with convergence insufficiency in whom prior treatment had failed.

Methods: We studied 8 patients (median age 36 years, range 17 to 77 years) with reading symptoms due to convergence insufficiency defined as an exodeviation greater at near, not exceeding 10 PD in the distance measured by prism and alternate cover test, and either convergence near point >6?cm or reduced fusional amplitudes. All patients were still symptomatic after prior treatment by convergence exercises (n?=?8), base-in prism glasses (n?=?5) or strabismus surgery (n?=?2). Five patients received injection of 5?IU botulinum toxin in 0.1?ml saline to one lateral rectus muscle, two received 2.5?IU, and one received 2.5?IU to both lateral rectus muscles.

Results: At 1 month post injection, all patients had an initial reduction of exodeviation from baseline (median 9 PD, p?=?0.008) at near, although 2 patients had a temporary intermittent esotropia in the distance with diplopia associated with difficulty driving. At 6 months, when the pharmacological effect of botulinum toxin had completely worn off, patients still maintained a small reduction of exodeviation (median 4 PD, p?=?0.3) at near. Reading symptoms improved in 7 of 8 patients at 1-month post injection, and in all patients at 6 months. Two patients had health-related quality of life assessed with the Adult Strabismus 20 Questionnaire, showing improved Reading Function scores at 6 months. Interestingly, 3 patients reported improved reading despite returning to the baseline angle at 6 months, and 2 of 4 with 12-month follow-up still reported improvement.

Conclusions: In adult convergence insufficiency, botulinum toxin injection to a lateral rectus muscle improves reading symptoms beyond the duration of the pure pharmacological effect. Botulinum toxin injection may be useful in management of adult convergence insufficiency, although repeat injections may be needed.     

Bupivacaine injection combined with recession of antagonist rectus muscle to treat sensory strabismus

Purpose: This study aims to evaluate the effect of bupivacaine injection at 1.5% combined with recession of the antagonist rectus muscle to treat sensory strabismus in adult patients.

Methods: Nine patients with a horizontal deviation, visual acuity of <20/60 in the worst-seeing eye, and no previous strabismus surgery were selected. Patients with vertical strabismus were excluded. Lateral rectus (LR) recession was performed in patients with exotropia and medial rectus (MR) recession in patients with esotropia according to Park’s Table, as modified by Wright. Bupivacaine 1.5 mL at 1.5% was injected in the antagonist of the recessed muscle. The patients were evaluated after 1, 7, 30, 60, 90, and 180 days of the procedure. Successful motor alignment was defined as within 10 prism diopters (PD) of orthophoria. Dose-response was considered as the total amount of correction, divided by recession performed in millimeters, associated with bupivacaine injection in the antagonist muscle.

Results: Of the patients, 44% (4/9) had a successful motor alignment. The mean correction for exotropia (n = 5) with a preoperative horizontal deviation of 50 ± 6.12 PD was 23 ± 14.4 PD with a dose-response of 2.6 PD/mm. For esotropia (n = 4), the mean correction of 21.25 ± 4.8 PD was achieved with a preoperative deviation of 28.7 ± 14.9 PD with a final dose-response of 5 PD/mm. All unsuccessful patients had a preoperative deviation of ≥45 PD.

Conclusion: Bupivacaine injection in the antagonist of a recessed extraocular muscle (EOM) appears to add an effect to the standard dose-response of a muscle recession. For patients with esotropia (<25 PD), a single MR recession combined with bupivacaine in the LR can produce a successful motor alignment. For patients with large horizontal strabismus (>45 PD), larger bupivacaine doses (volume and concentration) combined to larger recessions may be needed.     

Retinal Dysfunction in Patients with Congenital Fibrosis of the Extraocular Muscles Type 2

Introduction: Congenital fibrosis of the extraocular muscles type 2 (CFEOM2) is a distinct non-syndromic form of congenital incomitant strabismus secondary to orbital dysinnervation from recessive mutations in the gene PHOX2A. The phenotype includes bilateral ptosis, very large angle exotropia, ophthalmoplegia, and poorly-reactive pupils. Other than amblyopia, afferent visual dysfunction has not been considered part of CFEOM2; however, we have repeatedly observed non-amblyopic subnormal vision in affected patients. The purpose of this study was to document this recurrent feature of the phenotype.

Methods: A retrospective case series (2002–2012).

Results: Eighteen patients (four families) were identified; all affected individuals had confirmed homozygous recessive PHOX2A mutations except one individual for whom genetic testing was not done because of multiple genetically confirmed family members. Age at assessment ranged from 5–62 years old (median 10 years old). All patients had decreased best-corrected visual acuity not completely explainable by amblyopia in both the preferred and non-preferred eye. In those patients who had further ancillary testing, visual fields (five patients) and electroretinography (10 patients) confirmed abnormalities not ascribable to amblyopia.

Conclusions: In addition to a distinct form of congenital incomitant strabismus, the phenotype of CFEOM2 includes subnormal vision consistent with retinal dysfunction. This could be the direct result of PHOX2A mutations or a secondary effect of orbital dysinnervation.