Chart uses true Snellen optotypes for acuity vision testing. C, D, E, F, L, O, P, T optotypes feature defined serifs on each letter, making them unique to Snellen. These optotypes also fit in a 5x5 grid, also designed by Herman Snellen. This Snellen eye chart also features Snellen equivalents on the sides for accurate vision recording. This traditional Snellen chart is great for school vision screenings, as it also incorporates a red and green bar for color vision testing.