1. Macular (9 x 9 deg) ERGs to homogenous sinusoidal flicker (8 Hz) and to sinusoidal gratings (1.7 c/deg) sinusoidally reversed in contrast at 8 Hz were recorded in 16 normal subjects, in 7 patients with ocular hypertension (OHT) and in 11 with early open angle glaucoma (OAG). 2. Steady-state analysis of responses was performed in order to isolate the 2nd harmonic components either to flicker (2F) or to pattern reversal (2P). Their peak-to-peak amplitude and phase angle were measured. 3. The mean 2F and 2P amplitudes were reduced, as compared to control, in both OHT and OAG patients. The mean 2F phase was delayed, as compared to control, in OHT but not in OAG patients. The mean 2P phase did not show any significant variation across group means. 4. In individual patients, the 2F component displayed a greater sensitivity than 2P in detecting a retinal dysfunction. The 2P component changes, but not those of 2F, were associated with the degree of optic nerve and visual field impairment (i.e. increase in cup/disk and decline in perimetric visual sensitivity). 5. These results suggest that the differences between macular flicker- and pattern-ERG 2nd harmonics in OHT and OAG may reflect different extents of involvement of neuronal subsets in the inner retina and that the analysis of both responses may be useful for evaluating early glaucomatous visual dysfunction.
|Original language||English (US)|
|Number of pages||7|
|Journal||Clinical Vision Sciences|
|State||Published - 1991|
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