The Stiles-Crawford effect in retinitis pigmentosa.

Stiles-Crawford functions were obtained from the maculas of 22 patients with different genetic types of retinitis pigmentosa and visual acuity of 20/40 or better. Reduced cone directional sensitivity was seen in the fovea with both focal cone electroretinographic testing and psychophysical testing. Functions from the parafovea determined with psychophysical testing showed either significant flattening or displaced peak locations. Results are discussed in terms of factors know to affect photoreceptor orientation and histologic findings in retinitis pigmentosa.