Vision - night blindness
Definition
Night blindness is poor vision at night or in dim light.
Alternative Names
Nyctanopia; Nyctalopia; Night blindness
Considerations
Night blindness may cause problems with driving at night. People with night blindness often have trouble seeing stars on a clear night or walking through a dark room, such as a movie theater.
These problems are often worse just after a person is in a brightly lit environment. Milder cases may just have a harder time adapting to darkness.
Common Causes
The causes of night blindness fall into two categories: treatable and nontreatable.
Treatable causes:
- Cataracts
- Nearsightedness
- Use of certain drugs
- Vitamin A deficiency (rare)
Nontreatable causes:
- Birth defects
- Retinitis pigmentosa
Home Care
Take safety measures to prevent accidents in areas of low light. Avoid driving a car at night, unless you get your eye doctor's approval.
Vitamin A supplements may be helpful if you have a vitamin A deficiency. Ask your doctor.
Call your health care provider if
It is important to have a complete eye exam to determine the cause, which may be treatable. Call your eye doctor if symptoms of night blindness persist or significantly affect your life.
What to expect at your health care provider's office
Your health care provider will examine you and your eyes. The goal of the medical exam is to determine if the problem can be corrected (for example, with new glasses or cataract removal), or if the problem is due to something more serious.
The doctor may ask you questions, including:
- When did the night blindness begin?
- Did it occur suddenly or gradually?
- Does it happen all the time or just sometimes?
- How severe is the night blindness?
- Are you nearsighted?
- Do you have other vision changes?
- What other symptoms do you have?
- Do you have unusual stress, anxiety, or a fear of the dark?
- Does using corrective lenses improve night vision?
- What medications do you use?
- How is your diet?
- Have you recently injured your eyes or head?
- Do you have a family history of diabetes?
The eye exam will include:
- Color vision testing
- Pupil light reflex
- Refraction
- Retinal exam
- Slit lamp examination
- Visual acuity
Other tests may be done:
References
Tomsak RL. Vision loss. In: Bradley WG, Daroff RB, Fenichel GM, Jankovic J, eds. Neurology in Clinical Practice. 5th ed. Philadelphia, Pa: Butterworth-Heinemann;2008:chap 14.
Sieving PA, Caruso RC. Retinitis pigmentosa and related disorders. In: Yanoff M, Duker JS, eds. Ophthalmology. 3rd ed. St. Louis, MO;Mosby Elsevier;2008:chap 6.10.
Reviewed By: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington School of Medicine; Franklin W. Lusby, MD, Ophthalmologist, Lusby Vision Institute, La Jolla, California. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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