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Abstract #19005 Published in IGR 3-1
The photopic negative response of the flash electroretinogram in primary open angle glaucoma
Viswanathan S; Frishman LJ; Robson JG; Walters JWInvestigative Ophthalmology and Visual Science 2001; 42: 514-522
PURPOSE: To determine whether the photopic negative response (PhNR) of the electroretinogram (ERG) is reduced in patients with primary open-angle glaucoma (POAG). METHODS: ERGs were recorded with DTL electrodes from 62 normal subjects (16-82 years), 18 POAG patients (47-83 years), and seven POAG suspects (46-73 years) to brief flashes < 6 msec), and also in a few subjects to long (200 msec) red, full-field ganzfeld flashes delivered on a rod-saturating blue background. At the time of ERG measurements, the intraocular pressures of most of the patients were controlled medically. Visual field sensitivities were measured with the Humphrey C24-2 threshold test and optic nerve head cup-to-disc ratio (C/D) was determined by binocular indirect ophthalmoscopy. Results. ERGs. of normal subjects contained a slow negative potential following the a and b waves, the PhNR, that increased slightly in latency with age. The a and b wave amplitudes and implicit times of POAG patients were similar to age-matched controls. In contrast, their PhNRs were small or virtually absent. PhNR amplitudes were reduced even when visual sensitivity losses were small, and were correlated significantly (P < 0.05) with mean deviation (MD), corrected pattern SD (CPSD), and C/D across the population of POAG patients whose MD losses ranged from 1-13 dB, CPSDs from 0-11 dB and C/Ds from 0.6-0.9. PhNRs of most POAG suspects also were small. CONCLUSIONS. PhNR amplitudes in POAG patients are smaller than those of normal subjects. PhNR amplitudes are reduced when visual field sensitivity losses are mi ld and become even smaller as sensitivity losses increase. There is a potential role for the PhNR in early detection and possibly in monitoring the progression of glaucomatous damage.
Dr L.J. Frishman, College of Optometry, University of Houston, 4901 Calhoun Road, Houston, TX 77204-6052, USA
Classification:
6.7 Electro-ophthalmodiagnosis (Part of: 6 Clinical examination methods)
