Easily measure, record, and detect changes in the transfer of visual information when the change affects only visual acuity at low contrast levels. Charts include the following contrast levels: black, 25%, 10%, 5%, 2.5%, and 1.25%. Pages are offset for easy flipping. Each chart includes recording forms and instructions. 6 pages, 3.25" x 9" (8.25 cm x 22.9 cm).