ON THE REPRODUCIBILITY OF THE PATTERN ELE CTRORETINOGRAM

The pattern ERG (PERG) is used as an indicator of retinal ganglion cel l function. Up to now, reports on the reproducibility of the PERG have been contradictory. We investigated the reproducibility under the con ditions of the forthcoming ISCEV guidelines for the PERG. We simultane ously recorded the PERG and VEP in 42 eyes of 21 subjects to phase-rev ersing checkerboard stimuli with DTL electrodes. Both transient (2 rps ) and steady-state (16 rps) stimulation was employed. The check sizes were 0.4 degrees, 0.8 degrees and 16 degrees, the mean luminance 45 cd /m(2), the contrast 98%, and the field size 32 degrees x27 degrees. Me asurements were repeated at the same time of day after 1 week. In addi tion, we compared two different electrode positions in 16 eyes: (1) ac ross the cornea along the lower lid; and deep in the conjunctival sac. With position (1) the amplitudes were found to be higher by 20% than (2). We calculated the coefficient of variation (CV) of amplitude as a measure of reproducibility. CV was 7+/-1% for the steady-state PERG, 9+/-1% for the transient PERG, 12+/-2% for the steady-state VEP and 14 +/-3% for the transient VEP. For the latency of the PERG, the interses sion CV was found to be 1.5%. Amplitude reproducibility was somewhat h igher under steady-state as compared to transient stimulation; we attr ibute this to the high noise rejection of the Fourier analysis. Altoge ther, the amplitude reproducibility of the PERG is somewhat higher tha n that of the VEP.