Abstract
Abstract: :
Purpose: To compare pattern ERG (PERG), multifocal ERG (mfERG) and rod and cone sensitivity in patients with retinitis pigmentosa that manifest a high density ring of fundus autofluorescence. Methods: 15 patients with a clinical diagnosis of RP were examined. All had rod–cone dystrophy (ISCEV–standard ERGs), normal visual acuity and an abnormal annulus of high density on autofluorescence imaging (AF) centred on the fovea. MfERG, PERG and photopic and scotopic fine matrix mapping (FMM) were performed. MfERG was expressed as the sum of responses associated with the central 1, 7, 19 or 61 stimulus elements and was compared with PERG P50 component amplitudes evoked using 3 different sizes of circular checkerboard. Results: Multifocal ERGs showed relative preservation over the central macula. The mean eccentricity at which the mfERG P1 was reduced to less than 33% of maximum showed high correlation with the radius of the ring of high density AF (r=0.72). Summed responses associated with different numbers of concentric stimulus elements correlated with PERGs evoked by similar stimulus areas (r=0.77). The radius of the high density ring correlated with the lateral extent of preserved photopic sensitivity (r=0.86). Scotopic sensitivity loss was more severe and occurred at less eccentric retinal locations. Conclusions: MfERG and PERG P50 correlate over the central macula in keeping with the measured cone sensitivity loss and the distribution of annular high density AF. The magnitude of rod sensitivity loss was greater and encroached upon more central areas.
Keywords: electroretinography: clinical • retinal degenerations: hereditary • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)