title: Twenty-four-hour time course of intraocular pressure in healthy and glaucomatous Africans: relation to sleep patterns.
abstract: OBJECTIVE
  The study was performed in early middle-aged African natives with primary open-angle glaucoma to compare the 24-hour intraocular pressure (IOP) variations in healthy versus young glaucoma patients, because IOP follows a circadian (24-hour) oscillation in healthy Caucasians.
  
  
  METHODS
  Case-control study.
  
  
  METHODS
  Sixteen healthy African volunteers (age 24.5 +/- 1 years, mean +/- standard error of the mean) and 11 open-angle glaucoma African patients (age 36.2 +/- 3.3 years).
  
  
  METHODS
  IOP was measured hourly during 24 hours with a Modular One pneumatonometer (Modular One, Digilab, Cambridge, MA), which allows measures in supine subjects. To allow the IOP measurement at night, subjects were awakened under polysomnography (electroencephalogram, electromyogram, electro-oculogram) recorded at night and during a 90-minute afternoon nap.
  
  
  METHODS
  Hourly IOP values were analyzed for circadian rhythmicity with the Cosinor technique and in relation to the state of wakefulness, light sleep (stages 1 and 2), slow-wave sleep (stages 3 and 4), and rapid eye movement (REM) sleep upon awakening.
  
  
  RESULTS
  Sleep patterns did not differ between patients and healthy volunteers. As expected, in the healthy subjects, IOP followed a 24-hour rhythm with a nocturnal peak value (acrophase), and the variations in IOP during sleep were related to sleep structure, being lowest during REM sleep and highest during slow-wave sleep. In the glaucoma patients, however, the 24-hour rhythm 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.
authors.affiliation: Service d'ophtalmologie, C.H.U. de Grenoble, Grenoble, France.
authors.forename: C
authors.initials: C
authors.lastname: Noël
authors.forename: A M
authors.initials: AM
authors.lastname: Kabo
authors.forename: J P
authors.initials: JP
authors.lastname: Romanet
authors.forename: A
authors.initials: A
authors.lastname: Montmayeur
authors.forename: A
authors.initials: A
authors.lastname: Buguet
mesh_terms: D000328:Adult; D044383:Black People; D016022:Case-Control Studies; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D005902:Glaucoma, Open-Angle / Q000208:ethnology* / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009548:Niger; D017286:Polysomnography; D012894:Sleep Stages / Q000502:physiology*; D014065:Tonometry, Ocular; D014851:Wakefulness / Q000502:physiology