Visual Evoked Potentials in Primary Open Angle Glaucoma

Abstract

Background and Aims. Visual evoked potentials (VEPs) assess the integrity of the visual pathways from the optic nerve to the occipital cortex. Optic disc cupping and visual field loss have been associated with prolongation of latency of VEP 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. Results. In POAG cases, the refractive error [3.51±1.88 versus 1.88±1.11, D, p=0.001], cup-disc ratio in percent [66.00±16.98 versus 28.50±5.80, p=0.001], intraocular pressure [19.55±2.08 versus 11.65±1.64, mmHg, p=0.001], and automated visual field pattern standard deviation [4.13±6.96 versus 1.64±0.45, dB, p=0.001] were significantly more than in control. The visual acuity [0.41±0.29 versus 1.00±0.00, p=0.001], foveal visual sensitivity [25.92±6.88 versus 33.48±1.75, dB, p=0.001], and automated visual field mean deviation [−9.63±10.58 versus 0.07±1.54, dB, p=0.001] were significantly less in cases than in control. Among VEP variables, pattern reversal latency N145 [149.00±15.75 versus 137.52±15.20, ms, p=0.011], flash amplitude N75 [2.18±.57 versus 1.47±.38, μV, p=0.001], and flash amplitude N145 [1.99±.39 versus 1.43±.38, μV, p=0.001] were increased in cases. The pattern reversal amplitude N75 [1.97±.35 versus 2.47±.58, μV, p=0.001], amplitude P100 [3.09±.46 versus 6.07±1.44, μV, p=0.001], and amplitude N145 [2.21±.58 versus 4.45±1.99, μV, p=0.001] were decreased in cases. Conclusions. POAG caused glaucomatous damage to optic pathway.