Abstract

Cone-rod degeneration is characterized by atrophic macular degeneration with progressive decline in visual acuity and peripheral pigmentary disturbances with associated field loss¹. The mode of inheritance is typically autosomal recessive². Besides fundus appearance, patients with cone-rod degeneration can be distinguished from patients with retinitis pigmentosa on the basis of full-field electroretinography (ERG). Patients with cone-rod degeneration show markedly reduced cone ERG amplitudes with relative preservation of rod ERG amplitude. Rod b-wave implicit times are typically shorter than in patients with retinitis pigmentosa^1,3-5. Rod sensitivity, as indexed by the semi-saturation constant (log k) of the Naka-Rushton function, is often only slightly elevated above normal^4-5. These differences in rod ERG function suggest that the pattern of rod loss across the retina may differ between patients with cone-rod degeneration and patients with retinitis pigmentosa.

© 1990 Optical Society of America