2University of Health Sciences Turkey, Prof. Dr. Cemil Taşçıoğlu City Hospital, Clinic of Eye Diseases, İstanbul, Turkey
Abstract
Objective: Myotonic dystrophy type 1 (DM1) is characterized by myotonia and progressive muscle weakness caused by the cytosine-thymine-guanine trinucleotide repeat and is the most common muscular dystrophy in adults. Although various ocular abnormalities, particularly cataracts, are well known in patients with DM1, few studies and case reports are available on retinal involvement, such as retinal degeneration, the epiretinal membrane (ERM), and macular degeneration. In this study, we investigated the retinal involvement findings using optical coherence tomography (OCT) in patients who were followed up in the neuromuscular outpatient clinic with a diagnosis of DM1.
Methods: In this prospective cross-sectional study, 20 patients with genetically confirmed DM1 aged 18-65 years were included. The control group was formed from healthy individuals of a similar age and gender distribution to the patient group. Patients with diabetes mellitus, diabetic retinopathy, glaucoma, and previous cataract surgery were excluded from the study. Muscular impairment rating (MIR) scales were evaluated according to the distribution findings of myotonia and muscle weakness on a neurological examination. Patients were evaluated with OCT to examine macular and optic nerve morphology after ophthalmologic and fundus examinations were performed by a retinal specialist.
Results: The mean central macular thickness (CMT) values were 275.52±40.31 and 262.76±9.06 in the control and study groups, respectively (p=0.09). Subfoveal choroidal thicknesses (SFCT) were significantly higher in the study group (341.8±95.04 vs. 279.59±46.65; p=0.002). The mean retinal nerve fiber layer did not differ between the groups (103.6±14 vs. 101.3±12; p=0.12). No ERM was detected in any of the DM1 patients. No correlation was found between CMT, SFCT, and the MIR stages (p<0.05).
Conclusion: Visual disturbances associated with DM1 may be caused by cataracts as well as retinal disorders. An OCT examination is a beneficial part of the routine ophthalmologic evaluation in DM1 patients.