The eyes are not just a window to the soul. For older adults, they're also the canary in the coal mine for other health problems.

The American Geriatrics Society recommends seniors get their eyes examined annually, to monitor both normal age-related deterioration and what they might reveal about another condition -- diabetic retinopathy, to name but one.

Like every other body part, eyes fail long before we do. Presbyopia, the condition that requires bifocals or reading glasses, typically appears in the 40s for most people, and is entirely normal. Cataracts, the growths over the eyes that cause cloudy vision in many older people, can be easily treated with surgery.

Other symptoms may indicate more serious problems, such as macular degeneration, diabetes or even stroke. As a general rule, any change in vision that comes on suddenly should be treated urgently; stroke symptoms include abrupt changes in vision.

Others can be monitored through regular appointments with an eye-care professional -- optometrist or ophthalmologist. The National Institute on Aging offers a good primer on elder eye care here.

Macular degeneration, a syndrome that can lead to early blindness, is discussed in detail here. Seniors should also know about cataracts and glaucoma.