Abstract

Increment thresh old studies have reported selective S-cone damage within the macula in RP. To evaluate widespread S-cone damage, we obtained S-cone ERGs with a 50° field from 11 patients with RP who had detectable full field 30-Hz flicker ERGs. To evaluate peak macular S-cone density, we also measured S-cone acuity. S-cone amplitudes ranged from 0.6 to 1.4 log units below normal, while amplitudes for L- and M-cones ranged from 0.0 to 0.9 log unit below nor mal. Full intensity-response functions could only be measured in five patients; four had normal semisaturation constants, and all five functions were consistent with the primary loss being decreased number of photoreceptors rather than decreased photoreceptor sensitivity. S-cone acuity was normal for eight patients, including four with extinguished S-cone ERGs. These data suggest that peak macular S-cone density may be normal despite widespread loss of S-cones across the posterior pole. In patients with RP, S-cone loss seems to follow the pattern previously seen for L- and M-cones, with foveal sparing despite widespread degeneration.

© 1992 Optical Society of America