Foveal cone optical density in retinitis pigmentosa.

We have used a color matching technique to estimate the optical density of the foveal cone photopigments in a group of patients with retinitis pigmentosa. We find that foveal cone optical density is reduced in patients with retinitis pigmentosa. This reduction of density can occur early in the disease process and is found in patients with minimal visual field loss or 20/20 visual acuity. Foveal cone optical density is highly correlated with visual acuity and correlated with visual field area. Full-field ERG measurements are severely reduced early in the disease before significant foveal changes occur.