Ahmadi H, et al. - Researchers examined patients with normal tension glaucoma (NTG) for impairment of intrinsically photosensitive retinal ganglion cells (ipRGCs) and sleep quality. Fifteen patients with NTG and 17 healthy age-matched controls underwent sleep quality assessment and pupillometry [consisting of monocular stimulation with high illuminance (100 lux) red (633 nm, 300 cd/m² or 15.23 log quanta/cm²/s) and blue light (463 nm, 332 cd/m² or 15.27 log quanta/cm²/s) and binocular pupil measurements]. Compared to healthy subjects, NTG patients displayed lower ipRGC activity, however, there appeared no differences in sleep quality.