title: Rise of intraocular pressure in a caffeine test versus the water drinking test in patients with glaucoma.
abstract: BACKGROUND
  There is increasing emphasis on the importance of intraocular pressure peaks and fluctuations as risk factors for glaucoma progression. It is well recognized that the water drinking test raises intraocular pressure and there is reasonable evidence that caffeine can also raise intraocular pressure. The aim of this study is to directly compare the effect of a caffeine test to that of the water drinking test on intraocular pressure, in patients with glaucoma.
  
  
  METHODS
  Prospective, observer-masked, cross-over study.
  
  
  METHODS
  Fourteen eyes of 14 patients with primary open-angle glaucoma.
  
  
  METHODS
  Patients were initially randomized to either caffeine test or water drinking test. Intraocular pressure was measured in both eyes with a Goldmann applanation tonometer at baseline and every 15 min for 1 h, by a masked examiner. This was repeated the following week at the same time of day for the other test (the cross-over). Peak intraocular pressure and maximum fluctuation from baseline were compared between groups using paired t-tests.
  
  
  METHODS
  Peak and fluctuation of intraocular pressure, time of maximum frequency of peak intraocular pressure.
  
  
  RESULTS
  The maximum intraocular pressure from the water drinking test (19.7 ± 4.1) was greater than the caffeine test (16.7 ± 4.1) and showed greater fluctuation in intraocular pressure (4.3 ± 2.7 mmHg [27.7%]; P < 0.0001) compared with the caffeine test (1.8 ± 1.9 mmHg [11.7%]); P = 0.004).
  
  
  CONCLUSIONS
  The rise in intraocular pressure was greater with water drinking test than the caffeine test. Caffeine does not appear to provide an alternative for patients unable to tolerate the water drinking test.
authors.affiliation: Centre for Eye Research Australia, Glaucoma Unit, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia.
authors.forename: Tuan
authors.initials: T
authors.lastname: Tran
authors.forename: Nuwan
authors.initials: N
authors.lastname: Niyadurupola
authors.forename: Jeremy
authors.initials: J
authors.lastname: O'Connor
authors.forename: Ghee Soon
authors.initials: GS
authors.lastname: Ang
authors.forename: Jonathan
authors.initials: J
authors.lastname: Crowston
authors.forename: Dan
authors.initials: D
authors.lastname: Nguyen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001082:Aqueous Humor / Q000378:metabolism; D002110:Caffeine; D000697:Central Nervous System Stimulants; D018592:Cross-Over Studies; D003941:Diagnostic Techniques, Ophthalmological; D004311:Double-Blind Method; D004326:Drinking / Q000502:physiology*; D005260:Female; D005902:Glaucoma, Open-Angle / Q000175:diagnosis* / Q000503:physiopathology; D006068:Gonioscopy; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014065:Tonometry, Ocular; D014690:Venous Pressure
chemical_list: D000697:Central Nervous System Stimulants; D002110:Caffeine
keywords: caffeine; glaucoma; intraocular pressure; water drinking