Pelli-Robson SLOAN Letter Contrast Chart from Precision Vision®

Designed by DG Pelli, JG Robson and A J Wilkins, because they see contrast sensitivity as a realistic assessment of how well the patient sees large faint objects.

The chart follows the luminance, font, and letter spacing recommendations of the Committee on Vision of the National Academy of Sciences and National Research Council (Adv. Ophthal 41, 103-148, 1980).

The letter sequences are organized into groups of three (triplets) with two triplets per line. Within each triplet, all letters have the same contrast. The contrast decreases from one triplet to the next, even within one line.

The testing of contrast sensitivity on a regular basis is key to detecting early signs of diseases such as Parkinson's, Glaucoma, and Cataracts. By testing with several different contrast levels configured together, the patient's contrast sensitivity level is better assessed and records will be more precise.