Screening for vestibular impairment in congenital neurosensory hearing loss identifies a population at high risk of ocular anomalies, including Usher syndrome

Abstract

Purpose : Although many studies have reported the visual characteristics of patients with general deaf-blind disorders, and showed a variable degree of visual problems, no effective screening guidelines have been implemented. This retrospective observational clinical study aimed at characterizing the ophthalmological findings of a patients with congenital neurosensory hearing loss (SNHL) and bilateral vestibular dysfunction, treated with cochlear implantation.

Methods : All patients were referred from the cochlear implant program at the Hospital for Sick Children. Demographic information, refractive error, ophthalmic exam findings, Goldmann visual field (GVF) and electroretinogram (ERG) data were collected . Patients with ERG findings consistent with generalized photoreceptor degeneration were classified as having Usher syndrome; and tested for mutations in Usher syndrome related genes.

Results : 35 patients met our inclusion criteria (22 males; 13 females). Mean age at initial visit was 10.34 years (range 2 - 21 years). An underlying ocular abnormality was diagnosed in 82.86%. The mean best corrected visual acuity at initial assessment was 0.153 logMAR (SD ± 0.2, range 0.0-1.0). Twenty-six (76.47%) patients had refractive errors; 18 of them showed improvement of visual function with refractive correction. Twelve cases (35.29%) had isolated refractive errors with no other ocular abnormality, all of whom improved with correction. Sixteen cases (45.71%) had generalized rod-cone dysfunction on ERG testing. Seven of 22 (31.81%) patients with GVF data, had visual fields less than 80 degrees in the better eye. Of these patients with Usher syndrome, mutational analysis was positive in 14 /16 cases. Genetic results remain pending in 2 cases.

Conclusions : Majority of patients with combined SNHL and vestibular dysfunction had an ocular abnormality. More than half those identified with refractive errors had improved vision with refractive correction. Nearly half the patients had USH1, which is an important syndrome to be screened in this cohort. Our results emphasize that when the cause of SNHL is unknown, patients with bilateral vestibular dysfunction should undergo an eye exam including electrophysiology testing, to ensure early identification of refractive errors and retinal degeneration inorder to optimize support for education and rehabilitation.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.