A new standardized logMAR visual acuity chart: development and clinical application / 第二军医大学学报

ABSTRACT

Objective:To introduce a new standardized logMAR visual acuity chart and its clinical application.Methods: The new visual acuity chart and notations were designed based on Weber-Fechner theorem.The E optotype on the chart had 3 limbs of equal length.A regular geometric progression of optotype sizes and distribution was employed to arrange 14 lines with 4 optotypes on each line.The progression rate of optotype size between 2 lines was 10 and the testing distance was 3 m.The visual acuity score could be recorded as logarithm of the minimum angle of resolution(logMAR) notation or decimal notation.The reliability of naked distant measurements with this new chart was tested in one eye of 100 subjects taking the Chinese national standard logarithm visual acuity chart(CSVAC) standard.Results: This new chart overcame the shortcomings of different number of optotypes on each line and fewer optotypes at the top of CSVAC.Several visual acuity notations were adopted and conversion between different notations was very convenient in this new chart.The measurements of this new chart had significant correlation and good agreement with CSVAC.Conclusion: The new standardized logMAR visual acuity chart is reliable,easy to use and accurate.It can be applied in clinical teaching and research of ophthalmology and optometry.