To study visual evoked potential in patients with optic nerve diseases

To study Visual Evoked Potential in patients with Optic Nerve diseases. Study design and settings: Cross – Sectional study. 72 patients were included in our study, aged 12 years and above, diagnosed as optic nerve diseases like optic neuritis, Nonarteritc ischemic optic neuropathy (NAION), hereditary, nutritional and compressive optic neuropathy etc. Flash and Pattern VEPs were used. VEP amplitude and latency were noted. Out of total 144 eyes, 107 eyes were affected. Ethambutol induced Toxic optic neuropathy was the most common etiology, followed by secondary optic neuropathy, idiopathic, traumatic optic neuropathy, optic neuritis, NAION, compressive and post CRAO (Central Retinal Artery Occlusion) optic neuropathy. Mean latency of all affected eyes was 132±22.5 msec. mean amplitude of the all affected eyes was 6.36±2.1 microvolt. Latency was moderately delayed (110-140 msec) in 45.8%, while severely delayed (>140 msec) in 40.3% of total eyes. Amplitude was reduced in 36.5% of total eyes. Prolonged latency with normal amplitude was found in most of the eyes with optic neuritis while latency was also prolonged in fellow eyes of optic neuritis. In case of NAION prolonged latency and reduced amplitude was found in all eyes. Flash or pattern VEP can be used as an important tool for diagnosis of optic neuropathies or revealing of recurrence of disease and for follow up. VEP can also be used to detect subclinical damage in the fellow eyes of optic neuritis and also useful in differentiating the optic neuritis from ischemic optic neuropathy.