title: Baseline visual field characteristics in the ocular hypertension treatment study.
abstract: OBJECTIVE
  The Ocular Hypertension Treatment Study (OHTS) seeks to evaluate the safety and efficacy of topical ocular hypotensive medication in preventing or delaying the onset of visual field loss and/or optic nerve damage in ocular hypertensive subjects at risk for developing primary open-angle glaucoma. This study evaluates the baseline visual field test characteristics (visual field status, reliability properties, etc.) of patients who underwent eligibility visual field testing for entry to the OHTS.
  
  
  METHODS
  Cross-sectional study of baseline data as part of a longitudinal randomized clinical trial.
  
  
  METHODS
  Two thousand eight hundred nineteen ocular hypertensive individuals, aged 40 to 80 (mean age, 55).
  
  
  METHODS
  Subjects underwent at least two Humphrey Field Analyzer Program 30-2 Full Threshold visual field examinations in both eyes for study eligibility. A third examination was performed if a prior test was abnormal, questionable, or unreliable. For final eligibility, two sets of visual field examinations had to meet OHTS criteria for reliability and had to be classified as "normal." All OHTS visual field tests of potential subjects were submitted for eligibility assessment to the OHTS Visual Field Reading Center.
  
  
  METHODS
  The percentage of visual fields that were normal and reliable according to OHTS criteria.
  
  
  RESULTS
  Of the subset of 2304 subjects who completed the eligibility assessments, 1828 (79%) were OHTS-eligible based on visual field test requirements. A third eligibility test was required for 11% of all eyes because of unreliable, questionable, or abnormal test results. With the 33% fixation loss cutoff in the OHTS, 97% of all eligibility visual field examinations were reliable and 3% were unreliable. The most frequent cause (69.5%) of unreliability was excessive fixation losses.
  
  
  CONCLUSIONS
  Permitting one repeat test after an abnormal or unreliable test allowed an extra 560 patients to be "eligible" for the study based on visual field tests. A clinical screening review of otherwise normal and reliable tests was not restrictive. The adoption of a 33% fixation loss cutoff significantly reduced the number of required retests and prevented study rejection of 89 patients.
authors.affiliation: Discoveries in Sight, Devers Eye Institute, Portland, Oregon.
authors.forename: Chris A
authors.initials: CA
authors.lastname: Johnson
authors.forename: John L
authors.initials: JL
authors.lastname: Keltner
authors.forename: Kimberly E
authors.initials: KE
authors.lastname: Cello
authors.forename: Mary
authors.initials: M
authors.lastname: Edwards
authors.forename: Michael A
authors.initials: MA
authors.lastname: Kass
authors.forename: Mae O
authors.initials: MO
authors.lastname: Gordon
authors.forename: Donald L
authors.initials: DL
authors.lastname: Budenz
authors.forename: Douglas E
authors.initials: DE
authors.lastname: Gaasterland
authors.forename: Elliot
authors.initials: E
authors.lastname: Werner
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000959:Antihypertensive Agents / Q000008:administration & dosage; D003430:Cross-Sectional Studies; D004608:Eligibility Determination; D005260:Female; D005902:Glaucoma, Open-Angle / Q000517:prevention & control; D006801:Humans; D007429:Intraocular Pressure; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000188:drug therapy* / Q000503:physiopathology*; D009883:Ophthalmic Solutions / Q000008:administration & dosage; D009901:Optic Nerve Diseases / Q000517:prevention & control; D011446:Prospective Studies; D015203:Reproducibility of Results; D014786:Vision Disorders / Q000517:prevention & control; D014792:Visual Acuity; D058609:Visual Field Tests / Q000379:methods; D014794:Visual Fields / Q000502:physiology*
chemical_list: D000959:Antihypertensive Agents; D009883:Ophthalmic Solutions