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

Abstract

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. 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. 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). 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.