Contributions of the Melanopsin-Expressing Ganglion Cells, Cones, and Rods to the Pupillary Light Response in Obstructive Sleep Apnea.

Purpose: To investigate the impact of obstructive sleep apnea (OSA) on the contribution of inner and outer retinal photoreceptors to the pupillary light response (PLR). Methods: Ninety-three eyes from 27 patients with OSA and 25 healthy controls were tested. OSA severity was graded according to the apnea-hypopnea index. PLR was measured monocularly with an eye tracker in a Ganzfeld in response to 1-second blue (470 nm) and red (640 nm) flashes at -3, -2, -1, 0, 1, 2, and 2.4 log cd/m2. Peak pupil constriction amplitude, peak latency, and the postillumination pupil response were measured. The Cambridge Colour Test, standard automatic perimetry, spectral domain optical coherence tomography, polysomnography, and the Pittsburgh Sleep Quality Index were used. Results: OSA patients have a significantly decreased peak pupil constriction amplitude for blue stimuli at -3, -2, -1, 1 log cd/m2 and at all red flash luminances (P < 0.050), revealing reduction of outer retina contributions to PLR. OSA patients showed reduced peak latency for blue (-2, 0, 2, 2.4 log cd/m2) and red stimuli (-2, 0 log cd/m2; P < 0.040). No significant difference was found in the melanopsin-mediated PLR. Conclusions: This study is the first to evaluate the inner and outer retinal contributions to PLR in OSA patients. The results showed that the outer retinal photoreceptor contributions to PLR were affected in moderate and severe OSA patients. In contrast, the inner retina contributions to PLR are preserved.

A positive association between intrinsically photosensitive retinal ganglion cells and retinal nerve fiber layer thinning in glaucoma.

PURPOSE: To assess the integrity of intrinsically photosensitive retinal ganglion cells (ipRGCs) using the pupillary light reflex in glaucoma patients. METHODS: A cross-sectional study was conducted, including 76 eyes from 38 patients with primary open-angle glaucoma and 36 eyes from 18 control subjects. The patients were tested in the dark with light stimuli using the Ganzfeld system, and the pupil diameter was measured with the assistance of an eye tracker consisting of two infrared cameras fit to an eyeglass frame. To preferentially stimulate ipRGCs, we used a 1-second 470-nm flash with a luminance of 250 cd/m(2). To stimulate different retinal photoreceptors (cones and rods), we used a 1-second 630-nm flash with a luminance of 250 cd/m(2). Standard automated perimetry (SAP), matrix frequency-doubling technology (FDT), and high-definition optical coherence tomography (Cirrus HD-OCT) were also performed. The correlation between the ipRGC-mediated sustained response following the pupillary light reflex and the structural and functional changes in glaucoma patients was analyzed using generalized estimating equation. RESULTS: An association was observed between the average retinal nerve fiber layer (RNFL) thickness, as measured by Cirrus HD-OCT, and the sustained pupillary response to the blue flash (P = 0.024). The severity of glaucoma, based on the mean deviation of SAP (Hodapp-Anderson-Parrish system), was also associated with the sustained response to the blue flash (P = 0.006). CONCLUSIONS: This study showed a correlation between the mean RNFL thickness and the pupillary light response. A decrease in the number of ipRGCs is potentially related to the reduced RNFL thickness.