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 ± 45.8 ms, respectively, with corresponding amplitudes of 7.7 ± 2.8 and 7.3 ± 3.4 μV, respectively. In glaucoma patients, the implicit time of the on and off responses was 135.0 ± 28.9 and 368.2 ± 17.3 ms, respectively. The corresponding amplitudes of the on and off responses in these patients were 0.47 ± 0.18 and 0.66 ± 0.32 μV, 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.