Luminance (cd/m2), contrast (%) and luminance uniformity of three EDTRS charts.

Measurements were made with room lights on. Values represent the mean of the nine values measured across the chart for black optotypes and for adjacent white areas. All charts met BS 4274 (≥ 120 cd/m2) and ICO requirements (≥ 80 cd/m2) for luminance and for contrast (BS 4274, Weber contrast ≥ 90%; ICO, Lblack/Lwhite ≤ 15%). Chart parameters which do not meet the BS 4274 luminance uniformity requirements (>80%) are in bold.