title: A case-control study of visual acuity in onychocryptosis.
abstract: BACKGROUND
  There are many theories surrounding the etiology of ingrown toenails (IGTN). Few factors have been formally assessed, but it is widely accepted that a poor nail cutting technique has a causative role.
  
  
  OBJECTIVE
  To investigate the hypothesis that decreased visual acuity may lead to inadequate nail cutting and the formation of IGTN.
  
  
  METHODS
  A prospective case-control study was performed. Near and distance visual acuity were tested on a population with IGTN (n = 19) and compared with that of an age- and sex-matched control cohort (n = 24) who underwent epidermal cyst excision in the same tertiary referral center. Comparisons of visual acuity were made between groups by Mann-Whitney U-test. Differences were taken to be significant if P < 0.05. Institutional Review Board approval was sought and granted.
  
  
  RESULTS
  No significant difference in visual acuity (near or distance) was demonstrated between patients with IGTN and the control group (P = 0.33).
  
  
  CONCLUSIONS
  Visual acuity does not appear to play a significant role in the development of IGTN.
authors.affiliation: St. Vincent's University Hospital, Adelaide & Meath Hospital, incorporating the National Children's Hospital, Dublin, Ireland.
authors.forename: Aisling M
authors.initials: AM
authors.lastname: Hogan
authors.forename: David
authors.initials: D
authors.lastname: Broe
authors.forename: Helen
authors.initials: H
authors.lastname: Stunnell
authors.forename: Andra
authors.initials: A
authors.lastname: Bobart
authors.forename: Paul F
authors.initials: PF
authors.lastname: Ridgway
mesh_terms: D000203:Activities of Daily Living; D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D005139:Eyeglasses; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009263:Nails, Ingrown / Q000209:etiology*; D011446:Prospective Studies; D012648:Self Care; D015354:Vision, Low / Q000150:complications*; D014792:Visual Acuity; D055815:Young Adult