Pattern reversal visual evoked response in retinitis pigmentosa

Purpose: To determine if the pattern reversal visual evoked response (PVER) can objectively evaluate visual function in retinitis pigmentosa (RP). Met hods: We retrospectively reviewed the medical records of 29 patients (29 ey es) with RP a visual acuity (WA) better than 20/100, and for whom an electr oretinogram (ERG) and a PVER had been recorded. A steady-state PVER was mea sured using five check sizes: 160, 80, 40, 20 and 10 min of are. The best-c orrected VA was measured using the ETDRS chart. Visual fields (VFs) were me asured using standard Goldmann perimetry. To quantify the VFs, we measured the field size (isopter IV-2) in four meridians and averaged them. Twenty-f ive eyes of 25 normal subjects served as controls. Results: The mean and me dian VAs were 20/40 (logMAR = 0.30 +/- 0.20). The average VF (isopter IV-2) was 20 degrees (median, 9 degrees; range, 2 degrees to 62 degrees). All pa tients had a recordable PVER. Only 12 (41%) patients had a recordable ERGs, all subnormal. The PVER amplitudes showed a relatively good correlation wi th VA in the intermediate check sizes (40 min of are, r = 0.611, P = 0.0004 ; 20 min of are, r = 0.596, P = 0.0007). The PVER amplitude-check size func tion had a flattened inverted V shape in the RP patients and an inverted U shape in the normal subjects, with the mean amplitudes for the RP patients significantly smaller than the normals at all check sizes. Conclusion: The PVER is a useful method for objectively evaluating the visual function in R P patients whose central vision is still preserved.