Night blindness, or keratomalacia, means that a person has poor vision in dim light or at night. The National Institutes of Health lists night blindness as a rare disease, meaning that it commonly affects less than 200,000 people in the United States. One of the major causes of night blindness is a deficiency in vitamin A, also known as retinol.
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People with night blindness often have difficulty driving at night or seeing long distances in low light. The most common cause of night blindness is a vitamin A deficiency, but other disorders can cause the condition. Cataracts, birth defects, certain medications and a disease called retinitis pigmentosa, which causes retinal damage, can all cause night blindness, according to the National Institutes of Health. Symptoms of night blindness include loss of side or peripheral vision, loss of central vision, and decreased vision at night.
Vitamin A Deficiency
Vitamin A is essential for healthy growth and development. A vitamin A deficiency occurs most often in people who do not consume enough foods or supplements rich in vitamin A. Night blindness is often one of the first signs of a vitamin A deficiency, according to MayoClinic.com. Prolonged vitamin A deficiencies can lead to chronic dry eye and a buildup of keratin debris in the corners of the eye. Over time, people will experience retinal and corneal damage, leading to blindness.
Unfortunately, once night blindness sets in, there are very few treatment options. The National Institutes of Health explains that while some studies have suggested high levels of vitamin A can slow disease progression. However, these high dosages can also potentially damage the liver. Physicians and patients must weigh the risk of disease progression against the possibility of permanent liver damage.
Sources of Vitamin A
People can help to prevent a vitamin A deficiency and night blindness by consuming foods rich in vitamin A. Good sources of vitamin A include meat, milk, cheese, cream, liver, cod, kidney, and halibut. As these choices can often be high in fat, a good alternative is sources of beta carotene, a carotenoid that the body easily converts to vitamin A.
Good sources of beta carotene include dark green leafy vegetables, pink grapefruit, cantaloupe, squash, carrots, pumpkin, sweet potatoes, apricots, spinach and broccoli. The University of Maryland Medical Center explains that the more intense the color of the vegetable or fruit, the higher its amount of beta carotene.
A Vitamin A deficiency is rare and, just as consuming too little vitamin A can cause health problems, so can consuming too much. Large doses of vitamin A can cause liver damage and birth defects. Infants and small children are more sensitive to vitamin A and should never be given vitamin A supplements without consulting a physician first. Ingesting large amounts of beta-carotene can affect skin pigmentation, causing the skin to turn orange or yellow. Skin color will return to normal once beta-carotene levels decrease.