Twenty-four-hour time course of intraocular pressure in healthy and glaucomatous Africans: Relation to sleep patterns

Objective: The study was performed in early middle-aged African natives wit h primary open-angle glaucoma to compare the 24-hour intraocular pressure ( IOP) variations in healthy versus young glaucoma patients, because IOP foll ows a circadian (24-hour) oscillation in healthy Caucasians, Design: Case-control study, Participants: Sixteen healthy African volunteers (age 24.5 +/- 1 years, mea n +/- standard error of the mean) and 11 open-angle glaucoma African patien ts (age 36.2 +/- 3.3 years). Methods: IOP was measured hourly during 24 hours with a Modular One pneumat onometer (Modular One, Digilab, Cambridge, MA), which allows measures in su pine subjects. To allow the IOP measurement at night, subjects were awakene d under polysomnography (electroencephalogram, electromyogram, electro-ocul ogram) recorded at night and during a 90-minute afternoon nap. Main Outcome Measures: Hourly IOP values were analyzed for circadian rhythm icity with the Cosinor technique and in relation to the state of wakefulnes s, light sleep (stages 1 and 2), slow-wave sleep (stages 3 and 4), and rapi d eye movement (REM) sleep upon awakening. Results: Sleep patterns did not differ between patients and healthy volunte ers. As expected, in the healthy subjects, IOP followed a 24-hour rhythm wi th a nocturnal peak value (acrophase), and the variations in IOP during sle ep were related to sleep structure, being lowest during REM sleep and highe st during slow-wave sleep. In the glaucoma patients, however, the 24-hour r hythm of IOP was reversed, with an afternoon acrophase and an early morning trough. Conclusions: These data suggest a circadian phase shift in IOP in glaucoma patients, with maintained relation to sleep structure. Ophthalmology 2001;1 08:139-144 (C) 2001 by the American Academy of Ophthalmology.