title: Effects of interpupillary distance on stereoacuity: the Frisby Davis distance stereotest versus a 3-dimensional distance stereotest.
abstract: OBJECTIVE
  To evaluate the effect of interpupillary distance (IPD) on stereoacuity using 2 kinds of stereoacuity tests in a normal population.
  
  
  METHODS
  The distance stereoacuities of 33 healthy volunteers with no evidence of ocular diseases were measured with the Frisby Davis distance (FD2) stereotest and a 3-dimensional monitor-based distance stereotest (distance 3-D stereotest). These 2 kinds of stereotests were repeated using horizontal periscopes to increase the IPD 2- and 3-fold in order to investigate the effect of IPD increase on stereoacuity.
  
  
  RESULTS
  The mean age of the participants was 28.5 years (range 20-41 years). The mean logarithms of the individual minimum angle of stereodiscrimination (logMAS) were 1.04 ± 0.23 (range 0.70-1.48 logMAS) with the FD2 stereotest and 1.52 ± 0.19 (range 1.00-1.85 logMAS) with the distance 3-D stereotest. As the IPD increased 2- and 3-fold, the logMAS measured with the FD2 stereotest improved from 1.04 to 0.98 and 0.91 (P = 0.061 and P = 0.003), respectively, and those measured with the distance 3-D stereotest worsened from 1.52 to 1.73 and 1.85 (P < 0.001 and P < 0.001), respectively.
  
  
  CONCLUSIONS
  Changes in IPD measured with the FD2 stereotest exhibited opposite effects to those measured with the distance 3-D stereotest. This reflects what is known to happen in the real world, i.e., that stereoacuity improves as IPD increases.
authors.affiliation: Department of Ophthalmology, Guro Hospital, Korea University College of Medicine, 80 Guro-dong, Guro-gu, Seoul, 152-703, South Korea.
authors.forename: Youngsub
authors.initials: Y
authors.lastname: Eom
authors.forename: Jong-Suk
authors.initials: JS
authors.lastname: Song
authors.forename: Soh-Eun
authors.initials: SE
authors.lastname: Ahn
authors.forename: Su-Yeon
authors.initials: SY
authors.lastname: Kang
authors.forename: Young-Woo
authors.initials: YW
authors.lastname: Suh
authors.forename: Jaeryung
authors.initials: J
authors.lastname: Oh
authors.forename: Seung-Hyun
authors.initials: SH
authors.lastname: Kim
authors.forename: Hyo Myung
authors.initials: HM
authors.lastname: Kim
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D003867:Depth Perception / Q000502:physiology*; D064368:Healthy Volunteers; D006801:Humans; D021621:Imaging, Three-Dimensional; D007498:Iris / Q000033:anatomy & histology*; D011680:Pupil / Q000502:physiology*; D014787:Vision Tests / Q000295:instrumentation*; D015348:Vision, Binocular / Q000502:physiology*; D014792:Visual Acuity / Q000502:physiology*; D055815:Young Adult