Spider dystrophy as an ocular manifestation of myotonic dystrophy.

BACKGROUND: Myotonic dystrophy is the most common adult-onset muscular dystrophy. It is an autosomal dominant inherited neuromuscular disease that is characterized by myotonia, muscle weakness, and atrophy. It affects multiple systems including skeletal muscular, gastrointestinal, cardiac, respiratory, central nervous, endocrine, and ocular. Ocular manifestations of myotonic dystrophy include cataract, ocular muscle changes, hypotony, and retinal pigmentary changes in the periphery or in the macula (known as pigment pattern dystrophy). This report presents and discusses the case of a pigmented pattern dystrophy known as spider dystrophy as an ocular manifestation of myotonic dystrophy.

CASE REPORT: A 44-year-old man with myotonic dystrophy presented to the eye clinic for routine examination. Ocular history included previous bilateral cataract surgery and mild bilateral ptosis for the last "few years." Dilated fundus examination was remarkable for bilateral macular pigmentary changes in an irregular "spider"-shaped pattern. The patient was asymptomatic without decrease in vision or Amsler grid defects. Optical coherence tomography was normal. A retinal consult concurred with the diagnosis of spider dystrophy. Photo documentation was obtained, and the patient is being monitored annually.

CONCLUSION: Pigmented pattern dystrophies, including spider dystrophy, have been associated with myotonic dystrophy. They are set apart from other retinal dystrophies because they rarely affect visual acuity, and the majority of patients are asymptomatic. Progression may lead to reduced vision and in rare cases choroidal neovascularization. Annual dilated examinations, photo documentation, optical coherence tomography, and home Amsler grid monitoring are recommended for follow-up care.