title: Repeatability of visual acuity testing using a psychometric function.
abstract: OBJECTIVE
  To evaluate the repeatability of a new method of measurement of visual acuity by use of a psychometric function.
  
  
  METHODS
  The visual acuity of 15 healthy adults was measured by use of a psychometric function (PFVA) and by use of a conventional method using a decimal visual acuity chart (DeVA). We performed two tests. To evaluate intra-rater reliability, a tester measured the visual acuity three times for each subject, and the intraclass correlation coefficients, ICC (1,1), were calculated for PFVA and DeVA. Next, to evaluate inter-rater reliability, three testers measured the visual acuity for one subject, and the ICC (2,1) were calculated for PFVA and DeVA. The PFVA and DeVA of five subjects with ocular diseases were also measured.
  
  
  RESULTS
  In the evaluation of intra-rater reliability, the ICC (1,1) of the DeVA was 0.83 and the ICC (1,1) of the PFVA was 0.95. In the evaluation of inter-rater reliability, the ICC (2,1) of the DeVA was 0.88 and the ICC (2,1) of the PFVA was 0.93. In both tests the standard deviations of the PFVA were significantly lower than those of the DeVA. For four of the five subjects with ocular diseases, the PFVA was significantly improved by treatment.
  
  
  CONCLUSIONS
  The repeatability of our method is better than that of the conventional method using a decimal visual acuity chart.
authors.affiliation: Department of Ophthalmology 2, Kawasaki Medical School, Okayama, Japan.
authors.forename: Tomoki
authors.initials: T
authors.lastname: Tokutake
authors.forename: Tomofusa
authors.initials: T
authors.lastname: Yamauchi
authors.forename: Norihiro
authors.initials: N
authors.lastname: Mita
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Kawamoto
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Tabuchi
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Kani
authors.forename: Heihachiro
authors.initials: H
authors.lastname: Hara
authors.forename: Akio
authors.initials: A
authors.lastname: Tabuchi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sasaki
mesh_terms: D000368:Aged; D002386:Cataract / Q000503:physiopathology; D005128:Eye Diseases / Q000503:physiopathology; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008269:Macular Edema / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011594:Psychometrics; D015203:Reproducibility of Results; D014787:Vision Tests / Q000295:instrumentation / Q000379:methods*; D014792:Visual Acuity / Q000502:physiology*; D014822:Vitreous Body / Q000473:pathology; D055815:Young Adult