The design and use of a new near-vision chart

Abstract

This paper describes the design of a new near-vision chart that uses unrelated words arranged in a logarithmic progression of size and that has standardized the test task by controlling typeface, spacings, and number of words per row, and making each group of words of approximately equal difficulty. These charts offer special advantages for systematic assessment of reading acuity and visual efficiency for reading. The logarithmic progression of print size on these charts can be used to facilitate prediction of the magnitude of changes in visual performance resulting from changes in optical parameters, and the magnitude of changes in optical parameters required to achieve desired levels of visual performance. Simple methods for converting from point size scaling to M units or Snellen equivalents are also described.