Retinal early receptor potential in retinitis pigmentosa: correlations with visual field and fluorangiography...

The flash induced electroretinogram (ERG) and early receptor potential (ERP) were recorded in a population of patients with definite diagnosis of retinitis pigmentosa in the context of a study protocol including a complete diagnostic screening. ERPs were evoked by full-field 20-joule stimuli (5 stimuli at 10 min of interval in dark adaptation); recording was by skin electrodes positioned at the inferior orbital margin; amplifiers were set at 10-10,000 Hz. The flash ERG was absent or markedly abnormal in all cases, even at an early stage of development of the retinitis, while ERPs (with a normal morphology, latency of the R1 component increased and a reduced amplitude compared to normal controls) could be identified unambiguously in all cases. The amplitude reduction was highly correlated with the severity of the disease as determined by kinetic perimetry and fluorangiography.