title: A Robust and Reliable Test to Measure Stereopsis in the Clinic.
abstract: OBJECTIVE
  The purpose of this study was to develop a convenient test of stereopsis in the clinic that is both robust and reliable and capable of providing a measure of variability necessary to make valid comparisons between measurements obtained at different occasions or under different conditions.
  
  
  METHODS
  Stereo acuity was measured based on principles derived from the laboratory measurement of stereopsis (i.e., staircase method). Potential premeasurement compensations are described if there is a significant degree of ocular misalignment, reduced visual acuity, or aniseikonia. Forty-six adults at McGill University, 44 adults at Auckland University, and 51 adults from the University of Bradford, with an age range of 20 to 65 years old and normal or corrected-to-normal vision participated in this study.
  
  
  RESULTS
  Stereo acuity within this normal population was widely distributed, with a significant percentage (28%) of the population with only coarse stereo (>300 arc seconds). Across subjects, the SD was approximately 25% of the mean. Measurements at two different times were strongly (r = 0.79) and significantly (P < 0.001) correlated, with little to no significant (P = 0.79) bias (0.01) between test and retest measures of stereopsis.
  
  
  CONCLUSIONS
  The application enables measurements over the wide disparity range and not just at the finest disparities. In addition, it allows changes in stereopsis of the order of 1.9 to be statistically distinguished.
authors.affiliation: McGill Vision Research Department of Ophthalmology, McGill University, Montreal, Quebec, Canada.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Hess
authors.affiliation: McGill Vision Research Department of Ophthalmology, McGill University, Montreal, Quebec, Canada.
authors.forename: Rifeng
authors.initials: R
authors.lastname: Ding
authors.affiliation: McGill Vision Research Department of Ophthalmology, McGill University, Montreal, Quebec, Canada.
authors.forename: Simon
authors.initials: S
authors.lastname: Clavagnier
authors.affiliation: McGill Vision Research Department of Ophthalmology, McGill University, Montreal, Quebec, Canada.
authors.forename: Catherine
authors.initials: C
authors.lastname: Liu
authors.affiliation: Department of Vision Science and Optometry, University of Auckland, Auckland, New Zealand.
authors.forename: Cindy
authors.initials: C
authors.lastname: Guo
authors.affiliation: School of Optometry and Vision Science, University of Bradford, Bradford, United Kingdom.
authors.forename: Catherine
authors.initials: C
authors.lastname: Viner
authors.affiliation: School of Optometry and Vision Science, University of Bradford, Bradford, United Kingdom.
authors.forename: Brendan T
authors.initials: BT
authors.lastname: Barrett
authors.affiliation: School of Optometry and Vision Science, University of Bradford, Bradford, United Kingdom.
authors.forename: Krupali
authors.initials: K
authors.lastname: Radia
authors.affiliation: McGill Vision Research Department of Ophthalmology, McGill University, Montreal, Quebec, Canada.
authors.forename: Jiawei
authors.initials: J
authors.lastname: Zhou
mesh_terms: D000328:Adult; D000368:Aged; D003867:Depth Perception / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results; D014787:Vision Tests / Q000379:methods*; D015348:Vision, Binocular / Q000502:physiology*; D014792:Visual Acuity; D055815:Young Adult