title: Effects of central corneal thickness on the efficacy of topical ocular hypotensive medications.
abstract: OBJECTIVE
  To determine the effect of central corneal thickness (CCT) on the efficacy of intraocular pressure (IOP)-reducing drugs in patients with ocular hypertension (OHT).
  
  
  METHODS
  This retrospective study analyzed research records of 115 OHT patients and 97 ocular normotensive (ONT) volunteers. CCT was measured by slit-lamp pachymetry and IOP by pneumatonometry. The OHT patients were divided into Thick (>540 microm, n=52) and Thin (<or=540 microm, n=63) Cornea groups. Measurements in the OHT group were made after washout of all IOP-lowering drugs and at 1 week of treatment with latanoprost 0.005%, dorzolamide 2%, brimonidine 0.2%, apraclonidine 0.5%, pilocarpine 2%, or unoprostone 0.15% to 1 eye and vehicle contralaterally. ONT volunteers also were divided into Thick (n=34) and Thin (n=63) Cornea groups. Results were compared between groups using unpaired t tests or nonparametric Wilcoxon tests and within groups using linear regression analyses.
  
  
  RESULTS
  Baseline IOPs were not different between CCT groups of OHT patients or of ONT volunteers. After 1 week of drug treatment, IOP was significantly (P=0.02) lower in the OHT Thin Cornea group (16.0+/-3.0 mm Hg, mean+/-SD) than the OHT Thick Cornea group (17.4+/-2.8 mm Hg). There was a positive correlation between IOP and CCT (R=0.06, P=0.007) in OHT drug-treated eyes, but not OHT vehicle-treated or ONT untreated eyes. The final IOP was significantly lower in the Thin than the Thick Cornea group treated with brimonidine (P=0.02) but not with latanoprost (P=0.91).
  
  
  CONCLUSIONS
  When dosed with IOP lowering drugs, eyes with thinner corneas had lower IOPs than eyes with thicker corneas. This suggests a reduced efficacy of some glaucoma medications in ocular hypertensive patients with thick corneas.
authors.affiliation: Department of Ophthalmology, University of Nebraska Medical Center, Omaha, Nebraska, USA.
authors.forename: Thomas V
authors.initials: TV
authors.lastname: Johnson
authors.forename: Carol B
authors.initials: CB
authors.lastname: Toris
authors.forename: Shan
authors.initials: S
authors.lastname: Fan
authors.forename: Carl B
authors.initials: CB
authors.lastname: Camras
mesh_terms: D000287:Administration, Topical; D000328:Adult; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D003315:Cornea / Q000473:pathology*; D006801:Humans; D007429:Intraocular Pressure / Q000187:drug effects*; D008875:Middle Aged; D009798:Ocular Hypertension / Q000188:drug therapy*; D009883:Ophthalmic Solutions / Q000627:therapeutic use; D012189:Retrospective Studies; D014065:Tonometry, Ocular; D016896:Treatment Outcome
chemical_list: D000959:Antihypertensive Agents; D009883:Ophthalmic Solutions