May 2004
Volume 45, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2004
The Development of a High Resolution Computer Assisted Visual Acuity Test for Use in Routine Clinical Practice.
Author Affiliations & Notes
  • L. Crawley
    Ophthalmology, Gloucestershire Eye Department, Cheltenham General Hospital, Sandford Road, Cheltenham. GL53 7AN, United Kingdom
  • B.A. Johnson
    Ophthalmology, Gloucestershire Eye Department, Cheltenham General Hospital, Sandford Road, Cheltenham. GL53 7AN, United Kingdom
  • S. Asteriades
    Ophthalmology, Gloucestershire Eye Department, Cheltenham General Hospital, Sandford Road, Cheltenham. GL53 7AN, United Kingdom
  • S.C. Walton
    Cranfield University, School of Industrial and Manufacturing Science, Building 62, Cranfield University, College Rd., Cranfield, Beds. MK43 0AL, Cranfield, United Kingdom
  • N. Davies
    Visual Research Group, Biophysics, Imperial College, South Kensington,, London SW7 2BZ, United Kingdom
  • R.S. McMaster
    Cranfield University, School of Industrial and Manufacturing Science, Building 62, Cranfield University, College Rd., Cranfield, Beds. MK43 0AL, Cranfield, United Kingdom
  • R.L. Johnston
    Ophthalmology, Gloucestershire Eye Department, Cheltenham General Hospital, Sandford Road, Cheltenham. GL53 7AN, United Kingdom
  • Footnotes
    Commercial Relationships  L. Crawley, None; B.A. Johnson, None; S. Asteriades, None; S.C. Walton, Haag Streit F; N. Davies, Haag Streit P; R.S. McMaster, Haag Streit F; R.L. Johnston, Haag Streit P.
  • Footnotes
    Support  none
Investigative Ophthalmology & Visual Science May 2004, Vol.45, 5453. doi:
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      L. Crawley, B.A. Johnson, S. Asteriades, S.C. Walton, N. Davies, R.S. McMaster, R.L. Johnston; The Development of a High Resolution Computer Assisted Visual Acuity Test for Use in Routine Clinical Practice. . Invest. Ophthalmol. Vis. Sci. 2004;45(13):5453.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Abstract: : Purpose:To determine whether a new high resolution computer–based visual acuity test (VAT)performs as well as the current gold standard logMAR acuity test. Method:We tested the visual acuity of 24 patients with the ETDRS logMAR chart and computer–based VAT. The inclusion criteria were (a) logMAR VA <1.0 (b) a diagnosis of cataract, pseudophakia or refractive error. All subjects wore their habitual spectacle prescription. All measurements were conducted under consistent lighting conditions using a forced choice paradigm. LogMAR VA was measured at 4m using individual letter scoring. The computer VAT measured the VA using a randomly interleaved double staircase technique terminating after repeated testing around the subjects' threshold. The program allows high resolution of 0.02 log units. A single test letter was presented for 3 seconds with crowding letters either side. The Bland Altman method was used to assess correlation between the two tests Results:The mean difference was 0.02 logMAR indicating good agreement between the methods. The 95% limits of agreement were –0.011 to 0.07 logMAR(95% of the differences in measured VA lie within this range.) Conclusions:VA is a vital marker of disease progression. This study confirms that the computer VAT correlates closely with the ETDRS logMAR method. It has several advantages including providing an estimate of the error in the measurement, eliminating the memory and comparison effects of the current logMAR chart and is psychophysically robust. The high resolution allows precise VA measurement which is theoretically preferable to the single letter interpolation method on the ETDRS chart

Keywords: clinical (human) or epidemiologic studies: systems/equipment/techniques • visual acuity 
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