title: Validation of a Tablet as a Tangent Perimeter.
abstract: OBJECTIVE
  To describe a tangent perimeter developed on an Apple iPad (Melbourne Rapid Field, MRF).
  
  
  METHODS
  The MRF assays 66 locations over 28° × 18° by having the patient vary fixation. Spot size and background luminance are paired to yield constant thresholds across the field. Spot locations were selected after analysis of 360 patient records. The capacity of the MRF to detect defects was verified in five participants (age 22-28 years) by simulating four common losses: central, arcuate, quadrant, and hemianopia. We also consider the effect of: myosis, blur (+3 DS), viewing distance (25-75 cm), ambient light (4-600 lux), and retest repeatability (1-week apart) on thresholds. Group means [SEM] are compared by Student'st-test and repeatability returned from Bland-Altman analysis.
  
  
  RESULTS
  We found a 5 cd.m-2background replicates the Weber fraction produced by a Humphrey spot shown at 35 dB. Our variable size gives constant thresholds (29.6 [0.2] dB) across all locations. Altering viewing distance (25 cm = 29.8 [0.9] dB; 75 cm = 28.9 [0.6] dB) and ambient lighting (4 lux, 29.8 [0.8] dB; 600 lux, 29.5 [1.0] dB) did not affect threshold although screen reflections must be avoided. Myosis (-1.2 dB) and blur (-1.5 dB) will reduce sensitivity (P< 0.05). Simulated defects with a mean defect (MD) of -3.3 dB are detected by the MRF. The Coefficient of repeatability was 9.6% (SD ∼2.9 dB) in normal regions and 48.1% (SD ∼8.0 dB) in areas of simulated scotoma.
  
  
  CONCLUSIONS
  Tablet technology can return efficient and reliable thresholds to 30° as a tangent perimeter.
  
  
  CONCLUSIONS
  The MRF will allow testing at a bedside, at home, in rural or remote areas, or where equipment cannot be financed.
authors.affiliation: Department of Optometry & Vision Sciences Melbourne School of Health Sciences, University of Melbourne, 3010, Victoria, Australia.
authors.forename: Algis J
authors.initials: AJ
authors.lastname: Vingrys
authors.affiliation: Department of Optometry & Vision Sciences Melbourne School of Health Sciences, University of Melbourne, 3010, Victoria, Australia.
authors.forename: Jessica K
authors.initials: JK
authors.lastname: Healey
authors.affiliation: Department of Optometry & Vision Sciences Melbourne School of Health Sciences, University of Melbourne, 3010, Victoria, Australia.
authors.forename: Sheryl
authors.initials: S
authors.lastname: Liew
authors.affiliation: Department of Optometry & Vision Sciences Melbourne School of Health Sciences, University of Melbourne, 3010, Victoria, Australia.
authors.forename: Veera
authors.initials: V
authors.lastname: Saharinen
authors.affiliation: Department of Optometry & Vision Sciences Melbourne School of Health Sciences, University of Melbourne, 3010, Victoria, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Tran
authors.affiliation: Department of Optometry & Vision Sciences Melbourne School of Health Sciences, University of Melbourne, 3010, Victoria, Australia.
authors.forename: William
authors.initials: W
authors.lastname: Wu
authors.affiliation: Centre of Eye Research Australia, 32 Gisborne St East Melbourne, Victoria, Australia.
authors.forename: George Y X
authors.initials: GY
authors.lastname: Kong
keywords: automated perimetry; iPad; simulated scotoma; visual field