Seven children and one adult with dominantly inherited retinitis pigmentosa have early receptor potentials (ERP) that are decreased in amplitude compared with normal. These abnormal ERP amplitudes localize a defect in the receptor outer segments. All five children with dominantly inherited retinitis pigmentosa with complete penetrance have faster-than-normal ERP recovery rates during dark adaptation. This acceleration of ERP recovery compared to normal must be caused by something more than loss of the rod ERP and appears to be due to abnormal cone function. In the two children with dominantly inherited retinitis pigmentosa with reduced penetrance, marked delays exist in the time course of the rod and cone b-waves of the electroretinogram, whereas the latency to peak of the cornea-negative phase (R2) of the ERP is normal or slightly shorter than normal.
Berson EL, Goldstein EB. Early Receptor Potential in Dominantly Inherited Retinitis Pigmentosa. Arch Ophthalmol. 1970;83(4):412-420. doi:10.1001/archopht.1970.00990030412005