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Visual acuity measurement and ocular co-morbidity in diabetic retinopathy screening
  1. P H Scanlon1,
  2. C Foy2,
  3. F K Chen1
  1. 1
    Gloucestershire Eye Unit, Cheltenham General Hospital, Cheltenham, UK
  2. 2
    Gloucestershire R & D Support Unit, Cheltenham, UK
  1. Dr P Scanlon, Gloucestershire Eye Unit, Cheltenham General Hospital, Sandford Road, Cheltenham GL53 7AN, UK; peter.scanlon{at}


Aims: 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 ⩾0.3, Snellen ⩽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 ⩾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%.

Conclusion: 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.

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  • Funding: Project Grant South West R&D Directorate.

  • Funding: None.

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