Cone and Rod Responses in a Family With Recessively Inherited Retinitis Pigmentosa

Psychophysical and electroretinographic (ERG) testing are used to evaluate retinal function in a Negro family with a recessively inherited retinitis pigmentosa. The abnormal ERGs with the autosomal recessive pattern of inheritance distinguish the retinal pigmentary degeneration in this family from other genetic types previously classified with electroretinography. All affected children have retinal disease visible with the ophthalmoscope. The youngest child has a reduction in amplitude and delay in timing of her cone ERG before any rod system abnormality can be detected. The older affected children have a reduction in amplitude and delay in implicit time of both cone and rod components. The reduced and delayed rod ERG to a relatively bright short wavelength light was simulated by presenting a relatively dim short wavelength light to normal subjects. The relative preservation of cone ERG amplitudes is discussed as a measure of severity of different types of retinitis pigmentosa in childhood.