title: Effect of medical therapy on glaucoma filtration surgery rates in Ontario.
abstract: OBJECTIVE
  To analyze trends of glaucoma filtration surgery in Ontario.
  
  
  METHODS
  From April 1, 1992, through March 31, 2004, correlations were examined between the annual rates of trabeculectomies in Ontario, the use of glaucoma medications, and the numbers of practicing ophthalmologists and optometrists.
  
  
  RESULTS
  The number of trabeculectomies per 1000 persons at risk for primary open-angle glaucoma increased from 33.5 in 1992 to 46.2 in 1996 (37.7% increase; 6.6% increase per year) and then steadily decreased to 38.2 in 2004 (17.0% decrease; 2.7% decrease per year). The number of glaucoma medications dispensed in Ontario increased from 766 000 in 1992 to 1 466 543 in 2004 (91.5% increase; 10.5% annual increase). The increase in dispensed prostaglandin analogues strongly correlated (P<.001; 95% confidence interval, -0.87 to -0.41) with the decreasing number of trabeculectomies. The decreasing number of ophthalmologists positively correlated (r = 0.87) with the filtration surgery rate after 1997.
  
  
  CONCLUSIONS
  The number of trabeculectomies has decreased substantially in Ontario coinciding with the introduction of medications for the treatment of glaucoma in December 1996. This decrease in trabeculectomies highly correlated with the introduction of prostaglandin analogues (P<.001) and the decreasing number of ophthalmologists from 1997 through 2004.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Toronto Western Hospital, and Department of Public Health Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario. rachmiel_r@hotmail.com
authors.forename: Rony
authors.initials: R
authors.lastname: Rachmiel
authors.forename: Graham E
authors.initials: GE
authors.lastname: Trope
authors.forename: Mary L
authors.initials: ML
authors.lastname: Chipman
authors.forename: Pieter
authors.initials: P
authors.lastname: Gouws
authors.forename: Yvonne M
authors.initials: YM
authors.lastname: Buys
mesh_terms: D000959:Antihypertensive Agents / Q000627:therapeutic use*; D011307:Drug Prescriptions / Q000706:statistics & numerical data; D004363:Drug Utilization / Q000639:trends; D005902:Glaucoma, Open-Angle / Q000188:drug therapy* / Q000453:epidemiology / Q000601:surgery*; D006801:Humans; D009864:Ontario / Q000453:epidemiology; D009885:Ophthalmology; D009907:Optometry; D015995:Prevalence; D014130:Trabeculectomy / Q000706:statistics & numerical data / Q000639:trends*; D000078329:Workforce
chemical_list: D000959:Antihypertensive Agents