CLAUDE Monet (1840-1926), the first painter to be called an Impressionist, is of particular medical interest because of the way failing eyesight due to cataracts affected his late style. As his vision deteriorated, Monet had difficulty distinguishing colors, and he began delineating details less clearly. After lens opacities had made him officially blind, he underwent surgery in the right eye. Postoperatively he continued to paint, although he had severe difficulty with color balance and in adjusting to cataract glasses. The influence of ocular difficulties on Monet's health and work has often been misunderstood. I have studied a collection of Monet's letters to his eye surgeon that were recently acquired by the French Ophthalmologic Society, examined a pair of his glasses, and discussed his problems with the laboratory technician of Monet's last ophthalmologist as well as with art historians. The Onset of Visual Loss Since Monet's Impressionistic style was deliberately based