Night blindness is a vision disorder which keeps people from seeing in dim light. People with nyctalopia--the medical name for night blindness--also have difficulty adjusting their vision in darkness.
Symptoms
Inability to see while driving at night is the most common indication of night blindness. Someone with normal vision will be able to see the surroundings even when headlights pass. A person with night blindness can usually see only the headlights. Blindness when entering a dark room from a light one can also be a sign. Other possible symptoms include dry eyes or blurred vision.
Causes
Night blindness is the result of a birth defect, vitamin A deficiency or other vision problems. A lack of vitamin A can cause disorders in the retina, which contains the cells that enable sight in dim light. Old age is associated with night blindness due to other vision problems that are brought on with aging, such as certain types of retinal degeneration and cataracts, a disorder which clouds vision.
In the Eye
In normal vision, light centers on the retina, which is composed of rods and cones. These rods enable people to see in dim light. In night blindness, the rods don't function properly. Also, a chemical agent called rhodopsin helps the eyes function in dim light, which can only work with enough vitamin A.
Precautions
Eating your carrots actually does help your sight. Vitamin A in the diet is necessary to aid with night vision. Other foods rich in vitamin A include milk, egg yolks, spinach and liver. Intestinal or disorders may affect absorption of vitamin A.
People with night blindness should never drive at night.
Treatment
People blindness or who wish to prevent it need to monitor vitamin A intake to keep the eyes healthy. If night blindness is caused by another condition, correcting that problem can treat night vision, such as new glasses or cataract removal. Consult an eye doctor if you are experiencing night blindness.
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