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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:

• Electroretinogram (ERG)
• Visual field

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.