(I) The impressionist painters Monet and Degas drastically changed their styles late in their lives, each becoming uncharacteristically abstract with visible brush strokes and darker colours. (II) This abrupt change was probably not a coincidence. (Ill) According to a recent study made by ophthalmologist M. Marmor, this change was not an artistic choice; instead, cataracts and retinal disease affected how these artists saw their own work. (IV) Bright colours and lines were not used by these artists. (V) Dr. Marmor created a computer stimulation to reproduce how the painters' diseases would have dulled colour and blurred lines, demonstrating how these transformations might explain their stylistic changes.