|Normal Anatomy of the Eye|
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- Cones—These cells are found mostly in the center of the retina. Cones are needed for central vision and to see colors.
- Rods—Located mostly away from the center, rods respond to dim light. They provide night and peripheral vision.
- Night blindness (the most common symptom)
- Eyes take longer to adjust to dim lighting or are slow to make adjustment from bright sun to indoor lighting
- Trouble seeing in foggy or rainy weather
- Decreased peripheral vision/visual field narrows, often called "tunnel vision"
- Difficulty seeing colors, especially blue
- Visual loss, partial or complete, usually gradually progressive
- Clumsiness from lack of sight, especially in narrow spaces such as doorways
- Visual field testing—To check peripheral vision, which is how well you see off to your side, rather than directly ahead, without moving your eyes.
- Visual acuity—Checks how well you can see progressively smaller objects, usually a row of letters or numbers.
- Dark adaptometry—Tests how your vision adapts to darkness.
- Color testing—Tetermines how well you can differentiate colors.
- Electroretinogram (ERG)—A test to measure electrical activity in the eye. This test identifies the loss of cell function in the retina and is used to track progression of the disease.
- Magnifying glasses
- Electronic magnifiers, which project an enlarged image onto a screen
- Night vision scopes, which enlarge distant objects under conditions of low light
- Lenses for distant vision (eyeglasses or contacts)
Prevent Blindness America http://www.preventblindness.org
RP International http://www.rpinternational.org
Canadian Association of Optometrists http://www.opto.ca
The Canadian National Institute for the Blind http://www.cnib.ca
Cecil Textbook of Medicine. 21st ed. WB Saunders Co; 2000.
The Foundation of the American Academy of Ophthalmology. Retina and Vitreous, Basic and Clinical Science Course. 2001-2002.
Harrison's Principles of Internal Medicine. 14th ed. The McGraw-Hill Companies; 2000.
Ophthalmology. Mosby International Ltd; 1999.
- Reviewer: Michael Woods, MD
- Review Date: 10/2014 -
- Update Date: 03/15/2013 -