Pelli-Robson Chart

The Pelli-Robson chart is a clinical tool used to measure contrast sensitivity — the ability to detect objects at low-to-moderate contrast levels. The chart consists of a series of letter-charts composed of different contrasts, mapping a contrast-sensitivity function for the patient. Unlike visual acuity tests that measure the smallest detail a person can resolve at high contrast, the Pelli-Robson chart reveals how well a person can see when contrast is reduced, which is more representative of real-world visual conditions. Contrast sensitivity is particularly important for computer use, as it affects the ability to read text and perceive interface elements.