LEA SYMBOLS® Cards, 40M and 60M256100
These five LEA SYMBOLS® Cards can be used for presentation as single optotypes or arranged in a row as a line test. When the cards are next to each other, the space between the symbols is equal to the width of the symbols. To determine the visual acuity use the following formula:
VA=Viewing Distance Used(meters) / M-value
Measurements: 60M cards --. 8.6 in x 8.6 in (21.9 cm x 21.9 cm); 40M cards --. 6 in x 6 in (15.25 cm x 15.25 cm).