Visual evoked potentials after photostress in patients with primary open-angle glaucoma and ocular hypertension.

Visual evoked potentials (VEPs) were assessed in basal condition and after photostress in normal subjects, in subjects with ocular hypertension (OHT), and in subjects with primary open-angle glaucoma (POAG). The VEPs recorded in basal condition showed that in patients with OHT and POAG a latency of the P100 peak was higher than in controls. The amplitudes were reduced in POAG patients but not in OHT patients. In all eyes, the VEPs recorded 20 s after photostress showed an increase in latency and a decrease in amplitude. In the control eyes, the functional recovery was complete after 80 s. In the eyes with OHP and in the eyes with POAG, the parameters of VEP after photostress underwent greater changes than in the control eyes. VEPs were superimposable on the basal condition (recovery time) at 73.2 s in OHT patients and at 113.2 s in POAG patients. The longer VEP recovery time after photostress observed in OHT and POAG patients could be attributed to the reduced functionality of the outer layers or the inner retinal layers of the central retina, or both. This test may be useful in the clinical evaluation for early diagnosis of glaucoma.