Yearly Rates of Rod and Cone Functional Loss in Retinitis Pigmentosa and Cone-Rod Degeneration

Abstract

Although night-blindness is typically the earliest symptom, little is known about the progression of rod loss in retinitis pigmentosa. Since detectable rod ERGs are unusual in adults with retinitis pigmentosa, despite detectable cone ERGs, it seems likely that the rate of progression is faster for rods than for cones. The ability to assess therapeutic intervention in young patients with measures that show rapid progression should enhance attempts to alter the natural history of this potentially blinding disease. We are presently conducting a prospective natural history study utilizing psychophysical and electrophysiological measures of rod function in a large sample of patients with either retinitis pigmentosa or cone-rod degeneration. The present report contains a preliminary analysis of relative rates of rod and cone ERG loss in these diseases and a summary of yearly changes in parameters of full-field rod ERGs and rod visual fields.