title: Visible difference.
authors.forename: D L
authors.initials: DL
authors.lastname: Martin
mesh_terms: D006801:Humans; D007256:Information Systems; D008499:Medical Records; D009786:Occupational Health Services / Q000331:legislation & jurisprudence; D014481:United States; D015351:Vision Screening / Q000295:instrumentation / Q000331:legislation & jurisprudence / Q000379:methods*