Abstract
1. Pattern-reversal (8 Hz) electroretinograms (PERGs) to sinusoidal gratings of variable spatial frequency (0.6-4.8 c/deg) have been recorded in 28 normal subjects and in 20 patients with ocular hypertension (OHT; n = 11) or early open-angle glaucoma (EOAG, n = 9) who were under timolol maleate treatment during a 24-month clinical follow-up.
2. Visual fields and optic disk appearances did not vary significantly in all patients over the follow-up period. Under treatment intraocular pressure (IOP) ranged 15-25 mmHg in both OHT and EOAG patients.
3. Two PERG recording were obtained for each patient: the first after 12 months and the second after 24 months of treatment and clinical follow-up. At the first recording, the mean PERG amplitude was significantly reduced, as compared to age-matched controls, on both OHT (1 and 1.4 c/deg) and EOAG (0.6-1.4 c/deg) patients. PERG amplitudes tended to be mom reduced in EOAG than OHT patients and did not correlate with the corresponding IOP values before or under treatment.
4. At the second PERG recording the average PERG amplitude was not significantly different from the first control at any of the tested spatial frequencies. However, some patients showed amplitude decreases (2 OHT and 2 EOAG) or increases (3 OHT and 3 EOAG) which exceeded the range of normal test-retest variability.
5. In individual OHT and EOAG patients, amplitude differences between the 1st and 2nd PERG recording (2nd - 1st test) were negatively correlated (P < 0.05) with the corresponding IOP values recorded during the follow-up period. This relationship was statistically significant only at intermediate spatial frequencies (1-1.4 c/deg). The amount of PERG reductions with increasing IOP tended to be larger in EOAG than in OHT patients.
6. These results indicate that there are selective PERG changes associated with IOP control in treated OHT and EOAG patients.
