Fonda G
Ann Ophthalmol. 1987 May;19(5):178-80.
Two wall test charts with Snellen letters on both sides have been designed for the purpose of testing vision accurately, especially for the patient with low vision. Visual designations of 20/160 (6/48) and 20/125 (6/37.5) are included on the chart. This makes each line 26% larger. Sloan letters are used and arranged so that each line is of equal difficulty.
为了精确测试视力，特别是针对视力低下的患者，已设计了两面都带有斯内伦字母的双壁视力检查表。检查表上包含20/160（6/48）和20/125（6/37.5）的视力标识。这使得每行字母尺寸增大26%。使用并排列了斯隆字母，以便每行难度相等。
