Ocular Findings of Myotonic Dystrophy Type 1 in the Korean Population

Abstract

Purpose: To investigate ocular findings in a Korean population with myotonic dystrophy type 1 (DM1).

Methods: A total of 24 Korean patients with DM1, ranging in age from 4 to 71 years, were examined over a period from June 2004 to May 2014. Ophthalmologic examinations including visual acuity assessment, slit-lamp biomicroscopy, ocular motility, cycloplegic refraction, and fundus examination were performed in all patients, and brain magnetic resonance (MR) imaging was performed in 15 patients.

Results: The ocular findings, in order of decreasing prevalence, were as follows: cataract (17 patients, 71 %), myopia (22 eyes, 59 %), hyperopia (13 eyes, 35 %), ptosis (6 patients, 25 %), epiretinal membrane (5 patients, 21 %), exotropia (4 patients, 17 %), ocular motility limitations (4 patients, 17 %), blepharitis (2 patients, 8 %), pigmentary retinopathy (2 patients, 8 %), lid lag (1 patient, 4 %), esotropia (1 patient, 4 %), and myelinated nerve fiber layer (1 patient, 4 %). Five of eight patients (63 %) with CTG repeats ≥ 700 underwent cataract extraction, as did one of 13 patients (8 %) with CTG repeats < 700 (P = 0.014). All four patients who showed limited ocular motility had CTG repeats ≥ 1000. Brain MR imaging showed periventricular white matter lesions in three patients, diffuse brain atrophy in two patients, and extraocular muscle atrophy in two patients.

Conclusions: Korean patients with DM1 showed a high incidence of exotropia in comparison to Caucasian patients with DM1. Our study suggests a possible correlation between the severity of cataract and ocular motility limitation and the size of CTG repeats.

Keywords: CTG repeats; Cataract; Exotropia; Myopia; Myotonic dystrophy type 1.