title: Visual acuity measurement and ocular co-morbidity in diabetic retinopathy screening.
abstract: OBJECTIVE
  To evaluate the relationship between best corrected visual acuity (BCVA), age, type of diabetes, sight-threatening diabetic retinopathy (STDR) and ocular co-morbidity.
  
  
  METHODS
  1549 randomly selected people with diabetes mellitus (DM) from a countywide digital photographic screening programme had standardised logarithm of minimum angle of resolution (logMAR) BCVA measurement, followed by slit-lamp biomicroscopy examination by an experienced ophthalmologist.
  
  
  RESULTS
  Subnormal vision (logMAR > or =0.3, Snellen < or =6/12) and blindness (logMAR >1.3, Snellen <3/60) in the better-seeing eye were found in 9.0% and 0.45%. The sensitivity, specificity and positive and negative predictive values of using subnormal vision to screen for STDR in an individual eye were 33.4%, 85.9%, 18.6% and 93.0%, respectively. Important contributory causes of moderate visual loss (logMAR 0.50 to 0.98, Snellen 6/18 or worse but better than 6/60) and of Acuity Blindness (logMAR > or =1.0, Snellen 6/60 or worse) in an individual eye were lenticular opacity (including capsular opacification) 49%, macular degeneration (including myopic degeneration) 29%, diabetic maculopathy 15%, other media causes (including corneal opacity) 13% and amblyopia 10%.
  
  
  CONCLUSIONS
  The majority of visual loss in a population with diabetes is due to causes other than diabetic retinopathy. BCVA alone is not a reliable criterion in predicting STDR.
authors: Gloucestershire Eye Unit, Cheltenham General Hospital, Sandford Road, Cheltenham GL53 7AN, UK. peter.scanlon@glos.nhs.uk
authors: P H
authors: PH
authors: Scanlon
authors: C
authors: C
authors: Foy
authors: F K
authors: FK
authors: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000550:Amblyopia / Q000150:complications / Q000503:physiopathology; D001766:Blindness / Q000209:etiology*; D002386:Cataract / Q000150:complications / Q000503:physiopathology; D003920:Diabetes Mellitus / Q000503:physiopathology*; D003930:Diabetic Retinopathy / Q000150:complications / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008268:Macular Degeneration / Q000150:complications / Q000503:physiopathology; D008297:Male; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D012680:Sensitivity and Specificity; D015354:Vision, Low / Q000209:etiology*; D014792:Visual Acuity