title: Association between corneal thickness, mean intraocular pressure, disease stability and severity, and cost of treatment in glaucoma: a Canadian analysis.
abstract: OBJECTIVE
  We determined the association between the mean corneal thickness (CT) and visual field mean defect (VF) severity as well as with mean intraocular pressure (IOP), disease stability, and cost of glaucoma therapy in a Canadian setting.
  
  
  METHODS
  Data were collected from charts of patients diagnosed with primary open-angle glaucoma (POAG). CT measures, VF scores, IOP measurements, physicians' impressions, and resources used (physician visits, diagnostic tests, procedures, and medications) were recorded over a minimum of 2.5 years. CT was compared across the three VF severity levels [mild (0 to < 5 dB), moderate (5 to < 12 dB), and severe (>/= 12 dB)] using a Kruskall-Wallis test. Initial VF was regressed on Age, CT, IOP, and Optic Disc Ratio. Stability and Cost were regressed on IOP.
  
  
  RESULTS
  Of the 411 charts, 132 included CT measures. Patients included 50 with mild, 43 with moderate, and 39 with severe disease. The mean CTs of the overall, mild, moderate, and severe groups were 545.9 mum, 554.7 mum, 549.8 mum, and 523.3 mum, respectively. There were statistically significant differences (p < 0.05) between the CT pp of the mild and severe groups as well as between the moderate and severe groups. Regression analyses suggested that CT may be a predictor of disease severity, but not of cost. It was also found that IOP may be a predictor of disease progression.
  
  
  CONCLUSIONS
  Patients with severe VFs tend to be those who have thinner corneas. Further research is warranted, as a result of the limited sample size, to clarify the definitive association among corneal thickness, disease progression, and the cost of therapy.
authors.affiliation: PharmIdeas Research and Consulting Inc., Oakville, ON, Canada.
authors.forename: John H
authors.initials: JH
authors.lastname: Walker
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Buys
authors.forename: Graham
authors.initials: G
authors.lastname: Trope
authors.forename: Colin
authors.initials: C
authors.lastname: Vicente
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Einarson
authors.forename: David
authors.initials: D
authors.lastname: Covert
authors.forename: Michael
authors.initials: M
authors.lastname: Iskedjian
mesh_terms: D000368:Aged; D015415:Biomarkers; D003315:Cornea / Q000473:pathology*; D018450:Disease Progression; D005260:Female; D005901:Glaucoma / Q000145:classification / Q000191:economics* / Q000473:pathology*; D017048:Health Care Costs / Q000706:statistics & numerical data*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D012720:Severity of Illness Index
chemical_list: D015415:Biomarkers