Primary open angle glaucoma is associated with an increased risk of mood and
sleep disorders. These adversities have been suggested to relate to a disrupted function of the intrinsically photosensitive retinal ganglion cells (ipRGCs). The ipRGCs are key components in the nonvisual photoreceptive system that mediates light effects on mood, sleep and circadian rhythm. We assessed the diurnal
hormone levels, pupillary responses and mood and sleep under seasons with different photoperiods in 24 patients with
glaucoma and 24 age- and sex-matched healthy controls to investigate responses to naturalistic seasonal changes in daylight. The patients had moderate-to-advanced
glaucoma with substantial visual field defects and reductions in the ipRGC-mediated pupillary responses (p < .001). In winter, compared with summer, patients with
glaucoma had higher daytime
melatonin concentration (p < .001) and lower nighttime
cortisol (p = .002). In winter, the daytime
melatonin level was inversely correlated with the ipRGC-mediated pupillary responses in the control group (p = .04). In the control group, there were no significant changes in
hormone levels between seasons or any correlations between
neurohormone levels and the ipRGC-mediated responses. The two groups showed a similar response to season with lower depression scores in summer compared with winter. In between-group comparison, the nocturnal
melatonin level (area under curve from 20:00 h to 08:00 h) in summer was lower in
glaucoma compared with controls (p = .03). In winter, nocturnal
cortisol (at 04:00 h) was lower (p = .004) and daytime
cortisol (12:00 h and 16:00 h) was higher (p = .007) in
glaucoma compared with controls. In conclusion, we found that patients with
glaucoma displayed a seasonal variation in diurnal
hormone levels that was not present in healthy controls. Such neurohormonal changes may contribute to the increased risk of mood and
sleep disorders seen in patients with
glaucoma.