Abstract
Purpose: :
Previous studies have shown that glaucoma progression can be predicted using blue on yellow visual evoked potentials (byVEP) with stimulation by a Maxwellian view system. Purpose of this study was to test if byVEP results generated by an isoluminant CRT monitor stimulation are able to discriminate glaucoma patients from normals.
Methods: :
We examined 53 eyes with glaucoma (20 normal tension glaucoma, 5 PEX-glaucoma, 24 primary open angle glaucoma, 4 pigmentary glaucoma) and 24 healthy eyes. An isoluminant blue-yellow pattern on-off stimulus was presented on a CRT-monitor. A blue checkerboard pattern with a resolution of 2 cycles/degree appeared on an isoluminant yellow background for 200 ms. The stimulus covered the central 40° of the visual field. We evaluated the peak time of the first negative deflection N1.
Results: :
The age of glaucoma patients was 67,4 years (range 49 to 84) and 59,7 years (range 38- 80) of healthy subjects (p=0,0091). The mean peak time was 148,4 ± 14,0ms in glaucoma patients and 138,8 +/-13,8ms in normals. This difference was statistically significant (p=0,0064). There was also a statistically significant negative correlation between visual field loss and peaktime of the first negative deflection in glaucomatous eyes (r = -0,34; p=0,013).
Conclusions: :
Our results show that byVEP results due to isoluminant monitor stimulation may discriminate between healthy and manifest glaucomatous eyes. Further examinations will have to show whether the detection of early glaucoma or visual field loss progression is possible using this technique.
Keywords: electrophysiology: clinical • visual fields