Contrast Sensitivity

Prior sample-size assumptions were based on evidence that carotenoid supplementation increased contrast sensitivity at 6 cycles per degree by 0.08 units after 12 months. The primary outcome is the change in contrast sensitivity at 6 cycles per degree from baseline to 12 months. Contrast sensitivity is measured across five spatial frequencies using the M&S clinical contrast sensitivity measurement tool. The trial focuses on contrast sensitivity because it is a sensitive indicator of visual performance and relevant to daily visual tasks. The trial emphasises 6 cycles per degree because it reflects everyday visual demands and is sensitive to AMD-related impairment.