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Vision - night blindness

Nyctanopia; Nyctalopia; Night blindness

 

Night blindness is poor vision at night or in dim light.

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.

 

Causes

 

The causes of night blindness fall into 2 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 health care provider.

 

When to Contact a Medical Professional

 

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 Office Visit

 

Your 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 that is not treatable.

The provider may ask you questions, including:

  • How severe is the night blindness?
  • When did your symptoms start?
  • Did it occur suddenly or gradually?
  • Does it happen all the time?
  • Does using corrective lenses improve night vision?
  • Have you ever had eye surgery?
  • What medicines do you use?
  • How is your diet?
  • Have you recently injured your eyes or head?
  • Do you have a family history of diabetes?
  • Do you have other vision changes?
  • What other symptoms do you have?
  • Do you have unusual stress, anxiety, or a fear of the dark?

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

Cukras CA, Zein WM, Caruso RC, Sieving PA. Progressive and ‘stationary’ inherited retinal degenerations. In: Yanoff M, Duker JS, eds. Ophthalmology. 4th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 6.13.

Thurtell MJ, Tomsak RL. Visual loss. In: Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SL, eds. Bradley's Neurology in Clinical Practice. 7th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 16.

Tsang SH, Gouras P. Molecular physiology and pathology of the retina. In: Tansman W, Jaeger EA, eds. Duane's Ophthalmology 2013 edition. Philadelphia, PA: Lippincott Williams & Wilkins; 2013:vol 3, chap 2.

 
  • External and internal eye anatomy

    External and internal eye anatomy - illustration

    The cornea allows light to enter the eye. As light passes through the eye the iris changes shape by expanding and letting more light through or constricting and letting less light through to change pupil size. The lens then changes shape to allow the accurate focusing of light on the retina. Light excites photoreceptors that eventually, through a chemical process, transmit nerve signals through the optic nerve to the brain. The brain processes these nerve impulses into sight.

    External and internal eye anatomy

    illustration

    • External and internal eye anatomy

      External and internal eye anatomy - illustration

      The cornea allows light to enter the eye. As light passes through the eye the iris changes shape by expanding and letting more light through or constricting and letting less light through to change pupil size. The lens then changes shape to allow the accurate focusing of light on the retina. Light excites photoreceptors that eventually, through a chemical process, transmit nerve signals through the optic nerve to the brain. The brain processes these nerve impulses into sight.

      External and internal eye anatomy

      illustration

    A Closer Look

     

      Talking to your MD

       

        Self Care

         

          Tests for Vision - night blindness

           

             

            Review Date: 8/20/2016

            Reviewed By: Franklin W. Lusby, MD, ophthalmologist, Lusby Vision Institute, La Jolla, CA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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