Light Enters the Eye

Light Enters the Eye
medical animation:

As light enters the eye, it strikes the receptor cells of the retina, called the rods and cones.





Vision Impairment and Blindness

Also called: Low vision
Vision impairment, or low vision, means that even with eyeglasses, contact lenses, medicine or surgery, you don't see well. Vision impairment can range from mild to severe. The leading causes of vision impairment and blindness in the United States are age-related eye diseases: macular degeneration, cataract and glaucoma. Other eye disorders, eye injuries and birth defects can also cause vision loss.

A loss of vision means that you may have to reorganize your life and learn new ways of doing things. If you have some vision, visual aids such as special glasses and large print books can make life easier. There are also devices to help those with no vision, like text-reading software and braille books.

Sometimes, vision loss is preventable. Regular comprehensive eye exams and prompt treatment are critical.

Any changes in the appearance of your eyes or vision should be investigated further. Some examples include:

Unusual trouble adjusting to dark rooms;


Difficulty focusing on near or distant objects;


Squinting or blinking due to unusual sensitivity to light or glare;


Change in color of iris;


Red-rimmed, encrusted or swollen lids;


Recurrent pain in or around eyes;


Double vision;


Dark spot at the center of viewing;


Lines and edges appear distorted or wavy;


Excess tearing or "watery eyes";


Dry eyes with itching or burning; and


Seeing spots, ghost-like ../images.
The following may be indications of potentially serious problems that might require emergency medical attention:

Sudden loss of vision in one eye;


Sudden hazy or blurred vision;


Flashes of light or black spots;


Halos or rainbows around light;


Curtain-like blotting out of vision; and


Loss of peripheral (side) vision.
If you notice any signs of potential eye problems, see an eye doctor for a complete eye exam. Even if you have no signs, regular eye exams are recommended—especially for those with some chronic health conditions such as diabetes and high blood pressure. Early detection and treatment can be the key to preventing sight loss.