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Pattern reversal visual evoked response in retinitis pigmentosa
F R Paranhos1, O Katsum, M Arai
1Shepens Eye Research Institute, Department of Ophthalmology, Harvard Medical School, and Schepens Retina Associates, Boston, Massachusetts, USA. frlp@zaz.com.br
Purpose:
To determine if the pattern reversal visual evoked response (PVER) can objectively evaluate visual function in retinitis pigmentosa (RP).
Methods:
We retrospectively reviewed the medical records of 29 patients (29 eyes) with RP, a visual acuity (VA) better than 20/100, and for whom an electroretinogram (ERG) and a PVER had been recorded. A steady-state PVER was measured using five check sizes: 160, 80, 40, 20 and 10 min of arc. The best-corrected VA was measured using the ETDRS chart. Visual fields (VFs) were measured using standard Goldmann perimetry. To quantify the VFs, we measured the field size (isopter IV-2) in four meridians and averaged them. Twenty-five eyes of 25 normal subjects served as controls.
Results:
The mean and median 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 patients had a recordable PVER. Only 12 (41 %) patients had a recordable ERGs, all subnormal. The PVER amplitudes showed a relatively good correlation with VA in the intermediate check sizes (40 min of arc, r = 0.611. P = 0.0004: 20 min of arc, r = 0.596. P = 0.0007). The PVER amplitude-check size function 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 RP patients whose central vision is still preserved.