Jha MK, Paudel BH, Badhu BP*, Limbu N, Thakur D. Department of Basic and Clinical Physiology and *Department of Ophthalmology, BPKIHS, Dharan, Nepal. Background: Visual evoked potentials (VEPs) assess the integrity of the visual pathways from the optic nerve to the occipital cortex. Primary open angle glaucoma is bilateral condition with optic atrophy and visual field defect. Optic disc cupping and visual field loss have been associated with prolongation of latency of VEP. Therefore, we studied the ocular glaucomatous damage and VEP abnormalities. Objectives: To study VEPs and ophthalmic variables in primary open angle glaucoma (POAG). Methods: Pattern reversal and flash VEP tests were done in consenting 20 primary open angle glaucoma eyes and 40 normal control eyes in Electrodiagnosis Lab II at BPKIHS. Statistical tests (paired t-test and Mann-Whitney test) were applied depending on distribution of observations. Results: In POAG cases the refractive error [3.51±1.88 vs. 1.88±1.11, D, p=0.001], cup disc ratio in percent [66.00±16.98 vs. 28.50±5.80, p=0.000], intraocular pressure [19.55±2.08 vs. 11.65±1.64, mmHg, p=0.000] and automated visual field pattern standard deviation [4.13±6.96 vs. 1.64±0.45, dB, p=0.000] were significantly more than in control. The visual acuity [0.41±0.29 vs. 1.00±0.00, p=0.000], foveal visual sensitivity [25.92±6.88 vs. 33.48±1.75, dB, p=0.000] and automated visual field mean deviation [-9.63±10.58 vs. 0.07±1.54, dB, p=0.000] were significantly less in cases than in control. Among VEP variables pattern reversal latency N145 [149.00±15.75 vs. 137.52±15.20, ms, p=0.011], flash amplitude N75 [2.18±.57 vs. 1.47±.38, μV, p=0.000] and flash amplitude N145 [1.99±.39 vs. 1.43±.38, μV, p=0.000] were increased in cases. The pattern reversal amplitude N75 [1.97±.35 vs. 2.47±.58, μV, p=0.001], amplitude P100 [3.09±.46 vs. 6.07±1.44, μV, p=0.000] and amplitude N145 [2.21±.58 vs. 4.45±1.99, μV, p=0.000] were decreased in cases. Conclusion: POAG caused deterioration in all the ophthalmic variables measured with increase in latency of N145. The amplitude is different between pattern reversal and flash methods.