Ocular Findings of Myotonic Dystrophy Type 1 in the Korean Population

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

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.

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.

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.