From the article:
Exercise can slow or prevent the development of macular degeneration and may benefit other common causes of vision loss, such as glaucoma and diabetic retinopathy, new research suggests.
The new study from the University of Virginia School of Medicine found that exercise reduced the harmful overgrowth of blood vessels [choroidal neovascularization] in the eyes of lab mice by up to 45%. This tangle of blood vessels is a key contributor to macular degeneration and several other eye diseases.