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.