Abstract
Purpose: :
Evaluation of Retinitis Pigmentosa is one of the most common reasons for performing an ERG (Electroretinogram). This study aims to compare ERG results with psychophysical measures of visual function.
Methods: :
408 patients with non-syndromic Retinitis Pigmentosa and results from both ERG and psychophysical testing (visual acuity, contrast sensitivity and colour vision) were included in a retrospective study.
Results: :
ERG results were divided into four categories. There was a very wide distribution of results for all psychophysical measures and ERG results could not be predicted by psychophysical results. For visual acuity and colour vision, patients with non-recordable ERGs performed significantly worse than those with recordable ERGs. However, there was no difference in performance between patients in the three categories with abnormal, but recordable, ERGs. For contrast sensitivity, there was a gradual decline in performance with increasing ERG abnormality.
Conclusions: :
These findings are consistent with visual acuity and colour vision representing central cone functions, likely present until late stages of disease. Contrast sensitivity has been reported to accompany the decrease in visual fields in RP, consistent with a more gradual loss of function. Patients with RP should be referred for an initial, diagnostic ERG regardless of psychophysical results.
Keywords: electroretinography: clinical • retinal degenerations: hereditary • visual acuity