Bilateral optic nerve atrophy in myotonic dystrophy.

PURPOSE: To document a case of bilateral optic atrophy in a patient with myotonic dystrophy. Myotonic dystrophy is an autosomal dominant disorder, genetically resulting from an expansion of an unstable CTG repeat in the 3'-untranslated region of a protein kinase gene (DMPK) on chromosome 19q13.3.

METHODS

Case report, clinical examination, fundus photographs, visual fields, visual evoked potentials, electroretinograms, and genetic studies of a 56-year-old woman clinically diagnosed with myotonic dystrophy.

RESULTS

The patient experienced decreased vision consisting of light perception with the right eye and 20/25 with the left. Fundus examination showed bilateral pallor of the optic disks. Intraocular pressure was normal. Visual field testing, visual evoked potentials, and electroretinogram were abnormal. A pathologic CTG expansion in the myotonic dystrophy gene was found.

CONCLUSIONS

In a patient with myotonic dystrophy, confirmed with genetic molecular diagnosis, bilateral optic atrophy was present. Optic atrophy should be considered a possible complication of myotonic dystrophy.