Electrophysiological responses from intrinsically photosensitive retinal ganglion cells are diminished in glaucoma patients

PURPOSE To record electroretinograms (ERGs) from intrinsically photosensitive retinal ganglion cells (ipRGCs) of glaucoma patients. METHODS ERGs were recorded in 10 normal subjects and 15 patients with glaucoma. The ERG illumination system was built to achieve receptor-silent substitution, and comprised an optical diffuser and four-in-one light-emitting diodes. RESULTS The ERG recordings of ipRGC from normal subjects showed an "on" response and an "off" response. The mean (±SD) implicit time for the on and off responses in normal subjects was 103.0±24.9 and 337.9±45.8ms, respectively, with corresponding amplitudes of 7.7±2.8 and 7.3±3.4μV, respectively. In glaucoma patients, the implicit time of the on and off responses was 135.0±28.9 and 368.2±17.3ms, respectively. The corresponding amplitudes of the on and off responses in these patients were 0.47±0.18 and 0.66±0.32μV, respectively. CONCLUSIONS The results demonstrate successful ERG recording of ipRGCs from advanced glaucoma patients, with marked reductions in amplitude, although not implicit time, compared with normal subjects.