Correction of exotropia and improved adduction by fixation of the anterior encircling fascia to the medial rectus insertion site following myectomy of the four horizontal rectus muscles for infantile nystagmus.

Myectomy of the four horizontal rectus muscles for infantile nystagmus syndrome without a null point may improve visual acuity and quality of life. Exotropia and adduction loss are complications of this procedure, although abduction is typically preserved. We investigated whether adduction loss may be rescued by reestablishing the attachment of the anterior intermuscular septum (AIMS) to the globe at the medial rectus insertion. We present 2 cases of exotropia and adduction loss following myectomy and transposition surgery, where the nasal AIMS and the medial rectus insertion site were joined with nonabsorbable polyester suture. Both patients experienced improvements in eye alignment and adduction. Based on radiologic observations of the posterior displacement of the pulley, or posterior intermuscular septum (PIMS), with medial rectus contraction, we hypothesize that adduction and alignment were improved by providing an anterior site of action for the posterior movement of the PIMS.

Myectomy of the four horizontal rectus muscles with pulley fixation for the treatment of horizontal nystagmus in 10 adults: a pilot study.

PURPOSE: Myectomy and release of the four horizontal rectus muscles can ameliorate nystagmus, but may result in adduction limitation, convergence insufficiency, or exotropia. We developed a modified four-muscle myectomy with pulley fixation, in which the myectomized muscles are attached to the pulley rather than released. The purpose of this study was to present a prospective review of the clinical, nystagmographic, and quality-of-life data in a cohort of adults. METHODS: Ten adults with horizontal infantile nystagmus syndrome were recruited between July 2018 and October 2018. Subjects were grouped according to presence or absence of foveal hypoplasia (FH). Following myectomy, all four horizontal rectus muscles were sutured within the pulley or encircling fascia. All participants completed a comprehensive sensorimotor examination, videonystagmography, and a nystagmus-specific quality-of-life questionnaire. RESULTS: Of the 10 subjects, 5 were in the FH group and 5 in the no-FH group. Postoperatively, all 10 subjects experienced an improved quality of life, with median increases of 73% (FH) and 104% (No-FH). Nystagmus amplitude and slow-phase velocity were reduced, and binocular best-corrected visual acuity improved in both groups. Foveation time increased, but inconsistently, within subjects and between groups. Horizontal ocular rotations were reduced by up to 58%. Five subjects required transposition surgery for symptomatic exotropia (4) or hypertropia (1). CONCLUSIONS: In this small study cohort, four-muscle myectomy with pulley fixation reduced the amplitude and velocity of nystagmus and improved quality of life and visual acuity, notwithstanding reduced ocular rotation and reoperation. Fixation of the muscle to the pulley did not reduce the risk of exotropia.

Myectomy of the Extraocular Muscles Without Reattachment as a Surgical Treatment for Horizontal Nystagmus.

PURPOSE: To report the comparative clinical findings for two nystagmus procedures in two consecutive case series: the Sinskey anterior extirpation procedure (SAEP) and a modification, myectomy without reattachment (MWR). METHODS: Twenty consecutive patients underwent the SAEP and 19 underwent MWR. The SAEP is a snare-assisted unmeasured deep myectomy, whereas MWR is a measured myectomy at posterior Tenon's fascia. All patients underwent comprehensive ophthalmologic and orthoptic examination with infrared videonystagmography. Binocular best corrected visual acuity, nystagmus amplitude, alignment, and versions outcomes were measured. RESULTS: The highest percentage of patients experiencing two or more lines of improvement in distance and near acuity was in the SAEP group, who were younger than 10 years and had no ocular comorbidity (100%). Distance and near acuity improved at least one line in 71% and 86% of patients in the SAEP group and 72% and 61% in the MWR group, respectively. In both groups, patients younger than 10 years had the best acuity gains. Average nystagmus amplitude was reduced 76.3% (SAEP) and 68% (MWR). Horizontal versions were more compromised in the SAEP group and one patient experienced intraoperative orbital bleeding. Patients requiring reoperation for strabismus numbered 5 of 20 (20%) in the SAEP and 3 of 19 (16%) in the MWR groups. CONCLUSIONS: Similar to SAEP, the MWR procedure reduces nystagmus amplitudes and improves visual acuity but with less limitation of versions, risk of intraoperative bleeding, and risk of postoperative strabismus. Data suggest that early surgery (for patients younger than 10 years) can have a greater beneficial effect on postoperative visual acuity. [J Pediatr Ophthalmol Strabismus. 2016;53(3):156-166.].

Reliability and application variability of a commercially available infrared videonystagmography unit.

PURPOSE: Nystagmus is a condition of involuntary eye movement. The causes for nystagmus may be congenital, idiopathic, or acquired. Considerable debate exists on the therapeutic potential of various surgical techniques. Currently, there are neither standardized protocols nor devices to record quantitative data on patients with clinical nystagmus undergoing various procedures at multiple centers to facilitate randomized prospective clinical trials. METHODS: The authors evaluated the reliability and variability of a commercially available infrared videonystagmography unit by recording eye movement waveforms elicited from normal volunteers (n = 117, 13 patients, 9 trials) by different examiners (A, B, and C). Five movement characteristics were examined, including saccadic latency, velocity and precision, and pursuit gain and velocity. RESULTS: The overall test/retest variability was low, where the median coefficient of variation of the three testers for all five eye movement categories was less than 15%, and less than 10% of the coefficients of variation calculated were more than 20%. However, there was a significant difference in interobserver variability for all outcomes, except saccade latency. CONCLUSIONS: The between-tester analysis was found to have greater variability than the test/retest reliability analysis. Future studies at multiple sites using videonystagmography measurements should aim to have each patient repeatedly tested by the same tester. In anticipation of multicenter, randomized, prospective clinical trials of surgical procedures for nystagmus, standardized protocols for nystagmographic data collection and analysis must be validated both within and among participating centers.