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May 1983

Cone Dystrophy, Nyctalopia, and Supernormal Rod Responses: A New Retinal Degeneration

Author Affiliations

From the Department of Ophthalmology, Columbia University College of Physicians and Surgeons, New York.

Arch Ophthalmol. 1983;101(5):718-724. doi:10.1001/archopht.1983.01040010718003

• An unusual retinal degeneration considered to be inherited as an autosomal recessive trait occurred in two of four children in a Hispanic family. The abnormality causes a progressive and generalized loss of cone vision, including decreased acuity, decreased color vision, central scotomas to small test objects, photo-phobia, and a profound diminution of the cone-mediated electroretinographic (ERG) pattern. A loss of the foveal reflex and an increased granularity of the macula is seen funduscopically. In addition, there is a most unusual alteration of the rod system detectable in the rodmediated ERG pattern. This rod response is supernormal in amplitude (>1,000 μV, extrapolated), delayed in time course, and insensitive to dim stimuli, ie, the function relating response to light intensity has been drastically altered. The insensitivity to dim stimuli is accompanied by a mild nyctalopia. Some of these abnormalities could be caused by a defect in the retinal enzyme, cyclic nucleotide phosphodiesterase.

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