ipRGCs: possible causation accounts for the higher prevalence of sleep disorders in glaucoma patients

Abstract

Sleep accounts for a third of one's lifetime, partial or complete deprivation of sleep could elicit sever disorders of body function. Previous studies have reported the higher prevalence of sleep disorders in glaucoma patients, but the definite mechanism for this phenomenon is unknown. On the other hand, it is well known by us that the intrinsically photosensitive retinal ganglion cells (ipRGCs) serve additional ocular functions, called non-image-forming (NIF) functions, in the regulation of circadian rhythm, melatonin secretion, sleep, mood and others. Specifically, ipRGCs can directly or indirectly innervate the central areas such as suprachiasmatic nucleus (SCN), downstream pineal gland (the origin of melatonin), sleep and wake-inducing centers and mood regulation areas, making NIF functions of ipRGCs relate to sleep. The more interesting thing is that previous research showed glaucoma not only affected visual functions such as the degeneration of classical retinal ganglion cells (RGCs), but also affected ipRGCs. Therefore, we hypothesize that higher prevalence of sleep disorders in glaucoma patients maybe result from the underlying glaucomatous injuries of ipRGCs leading to the abnormalities of diverse NIF functions corresponding to sleep.

Influence of Circadian Rhythm in the Eye: Significance of Melatonin in Glaucoma

“…Exactly how the mechanism of glaucoma may induce sleep problems is not clear, but one possibility is that the ipRGC loss that occurs in glaucoma results in decreased light inputs to the SCN via retino-hypothalamic tract. This may result in a decreased synchronization of the SCN with the 24 h circadian rhythm, altering neurotransmitters in the cerebrum by means of irregular secretions of cortisol, norepinephrine, acetylcholine, or melatonin throughout the day, thereby resulting in sleep disorders [218].…”

Can Extra Daytime Light Exposure Improve Well-Being and Sleep? A Pilot Study of Patients With Glaucoma

“…A large cross-sectional study with more than 6,700 patients reported an association between glaucoma and very long sleep duration ( 20 ). Lanzani et al reported increased wakefulness with lower sleep efficiency at night ( 21 ) and similarly Gubin et al found later bed times and shorter sleep duration in primary open angle glaucoma patients ( 22 ) suggesting a higher prevalence for sleep disturbances in patients with glaucoma ( 13 , 23 , 24 ). There is some evidence that obstructive sleep apnea might be a systemic risk factor for glaucoma ( 25 – 28 ), even though not all study reports confirmed this ( 20 , 29 ).…”