Retinal changes in myotonic dystrophy include butterfly-shaped pigmentary changes in the macula, reticular pigmentary retinal changes in the midperiphery, and peripheral atrophic polygonal-shaped changes. To assess the prevalence and progressiveness of these changes in a large series, 49 patients with myotonic dystrophy were examined. Of the eyes studied, 26 (26.6%) had butterfly-shaped macular pigmentary changes, 24 (24.5%) had reticular pigmentary retinal changes, and 43 (43.9%) had peripheral atrophic polygonal-shaped changes. Ten patients (18 eyes) had two different types at once. Visual acuity was not severely affected. Electroretinographic examination showed diminished a and b wave amplitudes in eyes with and without retinal changes. Arden ratios on the electrooculogram were normal in 13 of 14 patients tested. During the follow-up period, which exceeded 5 years, 3 of 9 patients had newly developed or enlarged, patterned changes of the pigment epithelium. These results suggest that pigmentary retinal changes in patients with myotonic dystrophy are slowly progressive.