The card contains proportionally spaced reading segments in LogMAR on two sides. Side one increments ranging in size from 10m to 3m in Times Roman font. Side two features two charts From 4m to 0.6m, two sets are provided to avoid memorization. Each line contains the same number of letters and spaces. A diopter ruler is included.
Any patient who can read even one segment at any distance deserves a low vision evaluation.
Use of the diopter ruler allows a quick check of the reading distance against the reading add. It also allows verifying the reading acuity, using the modified Snellen formula: 1/V = M x D (M = letter size in M-units, D = viewing distand in diopters.) Examples: at 40 cm (2.5D) the 10m text represents 1/25 (20/500, 0.04), since 10m x 2.5D = 25. At 20cm (5D) 10m represents 1/50 (20/1000, 0.02), since 10m x 5D = 50. At 40cm (2.5D) the smalles print (0.06) represents 1/16 (20/32, 0.32), since 0.6m x 2.5D = 1.6.
Since all lines have the same length, reading performance can be times to determine the level of magnification that will give optimum performance.
AVAILABLE IN VARIOUS LANGUAGES:
CAT. NO. 4011 English
CAT. NO. 4012 Spanish
CAT. NO. 4013 Portuguese
CAT. NO. 4014 German
CAT. NO. 4015 Dutch
CAT. NO. 4016 Finnish
CAT. NO. 4017 Swedish
CAT. NO. 4018 Italian
CAT. NO. 4019 French