title: A control experiment for studies that show improved visual sensitivity with intraocular pressure lowering in glaucoma.
abstract: OBJECTIVE
  Contrast sensitivity sometimes increases in patients with open-angle glaucoma when intraocular pressure (IOP) is decreased. Although often interpreted as demonstrating reversible glaucoma-induced dysfunction, this result, if true, could simply reflect a general relationship between sensitivity and IOP in visual mechanisms unaffected by glaucoma. To investigate this relationship, we test the hypothesis that reducing IOP in eyes without glaucoma (ocular hypertension) does not increase perimetric contrast sensitivity.
  
  
  METHODS
  Comparative case series.
  
  
  METHODS
  A total of 692 participants drawn from the Ocular Hypertension Treatment Study (OHTS) (22 clinical centers).
  
  
  METHODS
  Commercially available topical ocular hypotensive medications.
  
  
  METHODS
  Post hoc analysis of IOP and perimetric contrast sensitivity (mean deviation [MD] and pattern standard deviation [PSD]) both at baseline (0 months, immediately before ocular antihypertensive therapy) and at 6-month review. An additional 618 control eyes from OHTS that did not receive treatment were examined over the same period. Data from the second phase of OHTS also were examined, and control eyes then received treatment.
  
  
  RESULTS
  Treated eyes had a decrease in IOP at 6 months (5.1 mmHg, P<0.001) but no significant change in MD (0.04 decibels [dB], P = 0.59) or PSD (0.03 dB, P = 0.19), relative to controls. A similar decrease in IOP was found for eyes that began treatment in the second phase of OHTS, but no significant change in MD or PSD.
  
  
  CONCLUSIONS
  Despite using a large sample size, we found no relationship between perimetric contrast sensitivity and IOP reduction in ocular hypertension, which suggests that previous sensitivity changes seen in patients with glaucoma, if true, are indicative of reversible glaucoma-induced dysfunction rather than a general relationship between sensitivity and IOP in visual mechanisms unaffected by glaucoma.
authors.affiliation: Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Australia. Electronic address: aaj@unimelb.edu.au.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Anderson
authors.affiliation: Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Australia.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Stainer
mesh_terms: D000704:Analysis of Variance; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D015350:Contrast Sensitivity / Q000502:physiology*; D005901:Glaucoma / Q000188:drug therapy / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*
chemical_list: D000959:Antihypertensive Agents