title: Effect of experimentally induced astigmatism on functional, conventional, and low-contrast visual acuity.
abstract: OBJECTIVE
  To report the changes in functional visual acuity (FVA) in eyes with experimentally induced astigmatism.
  
  
  METHODS
  This study included 26 right eyes from 26 healthy participants (mean age: 27.0±4.4 years). After confirming best correction under cycloplegia, the cylinder power ×90° and ×180° (against-the-rule [ATR] and with-the-rule [WTR] astigmatism, respectively) were added with 0.50-diopter (D) steps, from 0.50 to 2.50 D. Conventional visual acuity (VA), FVA as measured by the FVA Measurement System (NIDEK Co Ltd), and 10% low-contrast visual acuity (LCVA) were measured with 3-mm artificial pupil under each condition.
  
  
  RESULTS
  The mean corrected logMAR VA, FVA, LCVA were -0.18±0.00 (20/13), -0.10±0.08 (20/16), and 0.06±0.06 (20/23), respectively. The VA, FVA, and LCVA had a significant linear negative correlation with the addition of cylinder irrespective of the axes. A significant decrease in FVA was noted on addition of ⩾0.50 D WTR astigmatism and ⩾1.00 D ATR astigmatism. With the addition of 1.00 D of cylindrical lens, 96% of eyes with WTR and ATR astigmatism could maintain 20/20 in VA testing, whereas only 50% and 62% of eyes with WTR and ATR astigmatism, respectively, could maintain 20/20 in FVA testing.
  
  
  CONCLUSIONS
  Astigmatism may be associated with deterioration of visual function even when conventional VA of 20/20 is attained. Functional VA testing seems to be useful in evaluating the masked astigmatic visual impairment that cannot be detected by conventional VA testing.
authors: Department of Opthalmology, Keio University School of Medicine, Tokyo, Japan.
authors: Kazuhiro
authors: K
authors: Watanabe
authors: Kazuno
authors: K
authors: Negishi
authors: Miho
authors: M
authors: Kawai
authors: Hidemasa
authors: H
authors: Torii
authors: Minako
authors: M
authors: Kaido
authors: Kazuo
authors: K
authors: Tsubota
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000503:physiopathology*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D014792:Visual Acuity / Q000502:physiology*; D055815:Young Adult