From The New York Times:
For Claude Monet, 1912-22 was a watershed decade. He was perhaps the most successful artist of his time, and his genius had already assured him a place in history. But as he aged, his painting noticeably lost subtlety. Brush strokes became bolder, and colors strikingly blue, orange or brown. His images lost detail and flowed into one another. His days as an avant-garde rebel had long passed, but some critics would later wonder whether the Impressionist was suddenly trying to become an abstract expressionist.
What has long been known about Monet’s later years is that he suffered from cataracts and that his eyesight worsened so much that he painted from memory. He acknowledged to an interviewer that he was “trusting solely to the labels on the tubes of paint and to the force of habit.”
More here.