title: A 25-year prospective study of visual acuity in the Japan Air Self Defense Force personnel.
abstract: BACKGROUND
  In the Japan Air Self Defense Force (JASDF), new vision standards for student pilots allow lower uncorrected monocular acuity (from 1.0 to 0.8). In flight environments, where the use of corrective lenses may present problems, the risk of decreasing visual acuity in pilots who should wear corrective lenses must be defined.
  
  
  METHODS
  We conducted a 25-yr prospective study of visual acuity with regard to distance vision in 752 JASDF nonaviation personnel followed from ages 20 to 45. The test subjects were divided into four groups according to their right monocular visual acuity at entry: > or =1.0, between 0.9 and 0.7, between 0.6 and 0.2, and <0.2.
  
  
  RESULTS
  At entry, 94.1% of all subjects had visual acuity > or =0.7. The proportion of subjects who required corrective lenses for distance increased with age from 15.8% to 37.1%. After 25-yr, 30.2% of subjects with visual acuity > or =1.0 at entry and 62.7% of subjects with visual acuity between 0.9 and 0.7 at entry required corrective lenses.
  
  
  CONCLUSIONS
  Over 25 yr, the population with the best eyesight at age 20 had a lower increase in the need for corrective lenses than the population with visual acuity between 0.9 and 0.7 at age 20. These results suggest an increased risk of visual acuity loss in pilots over time as a result of the lower vision standards for student pilots in the JASDF.
authors.affiliation: Crew Health Care Section, Aeromedical Laboratory, Japan Air Self Defense Force, Tokyo.
authors.forename: A
authors.initials: A
authors.lastname: Kikukawa
authors.forename: S
authors.initials: S
authors.lastname: Yagura
authors.forename: T
authors.initials: T
authors.lastname: Akamatsu
mesh_terms: D000328:Adult; D000337:Aerospace Medicine; D017677:Age Distribution; D004185:Disability Evaluation; D004215:Distance Perception; D005139:Eyeglasses; D006801:Humans; D007564:Japan; D008875:Middle Aged; D008889:Military Personnel / Q000706:statistics & numerical data*; D009216:Myopia / Q000175:diagnosis* / Q000209:etiology / Q000534:rehabilitation; D011446:Prospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D015351:Vision Screening / Q000379:methods; D015349:Vision, Monocular; D014792:Visual Acuity