LEA NUMBERS® Cards, 40M and 60M
These five LEA NUMBERS® 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 numbers is equal to the width of the symbols. To determine the visual acuity use the following formula:
VA=Viewing Distance Used(meters)/M-value
60M cards are approx. 6" x 9" (15.25 cm x 22.9 cm). 40M cards are approx. 4" x 6" (10.2 cm x 15.25 cm).