The Single Symbol Book is designed for testing children and adults who have difficulties perceiving symbols in lines. The visual acuity values measured with single symbols are often several lines better than the line acuity values in persons with impaired vision and thus overestimate the quality of visual functioning. This book features single optotype line sizes from 20/200 to 20/8 (6/60 to 6/2.4) equivalent, 0.10 to 2.50. Includes isolating mask, response key, instructions, and 13 offset pages for easy flipping.

Dimensions: 5" x 5" (12.7 cm x 12.7 cm).

Testing distance: 10 feet/3 meters.