Visual evoked potential (VEP) is used to assess the functional integrity of the visual pathway. We studied VEP and other ophthalmic variables in clinically diagnosed primary open angle glaucoma (POAG) patients (n=20 eyes) and compared with health controls (n=40 eyes) with an objective of whether POAG causes any neuro-ophthalmic damage. Their age ranged from 38 to 74 years. Pattern reversal (checker board) VEP latency and amplitude; and refractive error, cup disc ratio, intraocular pressure, automated visual field pattern, visual acuity, and foveal visual sensitivity were recorded. The patients were on beta blocker (timolol) for intraocular pressure control. The patients with history of head injury or stroke, on drugs that might affect VEP, secondary glaucoma, diabetes mellitus, media opacity, amblyopia, aphakia, strabismus, high myopia or refractive error, macular degeneration, maculopathy, age-related macular degeneration, non-glaucomatous optic abnormality, & any retinal disorder other than due to glaucoma were excluded from the study. The study was approved by the institute ethical committee. Since some of the variables were not normally distributed Mann-Whitney U test was used to compare the cases and controls. The variables are expressed as mean and standard deviation. Both the groups were comparable in terms of BMI (23.27±1.82 vs. 22.1.47, kg/m sq., p=NS). In POAG cases, the refractive error (3.51±1.88 vs. 1.88±1.11, D, p<0.001), cup disc ratio in percentage (66.00±16.98, vs. 28.50±5.80, p<0.001), intraocular pressure (19.55±2.08 vs. 11.65±1.64, mmHg, p<0.001) and automated visual field pattern standard deviation (4.13±6.96 vs. 1.64±0.45, dB, p<001) were significantly more than in controls. However, the visual acuity (0.41±0.29 vs. 1.00±0.01, p<001), foveal visual sensitivity (25.92±6.88 vs. 33.48±1.75, dB, p<0.001), and automated visual field mean deviation (-9.63±10.59 vs. 0.07±1.54, dB, p<0.001) were significantly less in cases than in controls. Among VEP variables, pattern reversal latency of N145 ((149±15.75 vs. 137.52±15.20, ms, p<0.01) was more in cases than in controls. The amplitudes (microV) of pattern reversal VEP of N45 (1.97±0.35 vs. 2.47±0.58, p<0.001), P100 (3.09±0.46 vs. 6.07±1.44, p<0.001) and of N145 (2.21±0.58 vs. 4.45±1.99, p<0.001) were less in cases as compared to controls. It is concluded that primary open angle glaucoma caused marked deterioration in visual functions including prolongation of VEP latency and reduction in amplitude.