Abstract

Photopic negative response(PhNR) ,is component of electroretinography(ERG),which indicates retinal ganglion cell activity.Detection of glaucoma prior to visual field loss is important.A 33 year old,male patient has come for regular eye checkup.He had strong family history of glaucoma.BCVA 6/6,N6.IOP 12mm Hg RE,10 mm of Hg LE.Gonioscopy shows open angles in both eyes.Fundus shows optic disc ratio of 0.8 with superior notching and inferior NRR thinning in both eyes.Visual fields BE WNL.RNFL OCT AND GCC IPL COMPLEX BE WNL.PhNR ERG shows reduced PhNR amplitude wave and reduced P72/b wave ratio in RE.PhNR is relatively slow negative wave produced by ganglion cells. In early stages of glaucoma the retinal ganglion cells axons are damaged locally which can be detected by PhNR ERG.It provide additional information in diagnosing early glaucoma.PhNR is useful imaging modality in pre-perimetric glaucomatous eyes when both RNFL OCT and visual fields fail to show any changes.