What is Night Blindness Most Commonly Caused By?

While night blindness is not a disease, it is frequently a symptom of an underlying condition. Night blindness is most commonly caused by nearsightedness, cataracts, retinitis pigmentosa or vitamin A deficiency. It can also be a side effect of glaucoma medications.

Definition

• Night blindness, also called nyctanopia or nyctalopia, is the inability to see in low light or at night. People with night blindness might have trouble driving in the evening or at night. While for some people, night blindness may just be the eye's inability to adapt effectively, there are often other reasons behind it.

Myopia (Nearsightedness)

• Night blindness is most commonly connected to myopia, commonly called nearsightedness. Nearsightedness results when the entire eye's physical length (from cornea to retina) is longer than the length required for the eye to focus on an image. The image, as a result, is focused in front of the retina rather than on it. Myopia can be corrected with glasses, contact lenses or LASIK treatment.

Cataracts

• A cataract is a clouding of the lens. Cataracts are most common in people over the age of 60. Cataracts can be caused by environmental factors, injuries, some medications, diabetes, and radiation or ultraviolet light (sunlight) exposure. Cataracts can be treated with surgery if they restrict normal activity, but for some patients, different or stronger glasses, a magnifying glass or bifocals are sufficient.

Retinitis Pigmentosa

• Retinitis pigmentosa is another possible cause of night blindness. Retinitis pigmentosa is a progressive disease in which the retina is damaged. The damage usually affects the retina's rods, the cells governing night vision. As the disease progresses, patients gradually lose peripheral and then central vision, although total blindness is rare. No effective treatments are available currently, but clinical trials are underway to find new treatments. Wearing sunglasses may protect the retina from ultraviolet light damage.

Vitamin A Deficiency

• Vitamin A, also called carotenoids or retinol, helps maintain the health of soft and skeletal tissues, mucous membranes, skin, teeth and the pigments found in the retina of the eye. Vitamin A is needed for good vision, particularly in low light or night conditions. Vitamin A deficiency can result in vision problems or an increased susceptibility to infectious diseases. The best way to avoid deficiency is to eat a balanced diet rich in deep-colored fruits and vegetables.

Glaucoma Medications

• Certain glaucoma medications can cause symptoms of night blindness, particularly those drugs that constrict the pupil. Glaucoma is an eye disorder in which pressure builds within the eye. This additional pressure can, over time, damage the optic nerve, slowly leading to blindness. Medications prescribed today for glaucoma have fewer side effects than previous generations of medications. Discuss ways to handle these side effects, including night blindness, with your doctor.