What happens to glaucoma patients during sleep?

PURPOSE OF REVIEW: To summarize the findings of the recent reports on nighttime events that may lead to the development or progression of glaucomatous optic neuropathy. RECENT
FINDINGS: Peak intraocular pressure (IOP) likely occurs at night because of the head and body positions assumed during sleep. Sleeping in a 30° head-up position leads to IOP lowering during this time period. Laser trabeculoplasty and glaucoma-filtering surgery are efficacious in controlling IOP over a 24-h period, although most medical therapies may be inadequate. The Sensimed Triggerfish (Sensimed AG, Lausanne, Switzerland) device is capable of recording IOP fluctuations over a 24-h period. A nocturnal increase in IOP and decrease in blood pressure leads to lower ocular perfusion pressure (OPP), which may significantly increase the risk of glaucomatous visual field progression. Prospective case-control studies report a positive association between obstructive sleep apnea (OSA) and glaucoma; larger, retrospective cohort studies report no association.
SUMMARY: Several nighttime events including increased IOP, decreased OPP, and possibly OSA contribute to the development and progression of glaucomatous optic neuropathy. These events may explain the occurrence and progression of glaucomatous disease in the setting of seemingly controlled office-measured IOP.