Night blindness


Night blindness

Description, Causes and Risk Factors:

ICD-10: H53.69

Alternative Name: Nyctalopia, nocturnal amblyopia.

Night blindness is a medical condition that affects a person's vision, particularly at night or in an area with little to no light. In addition to having difficulty seeing at night, a person with night blindness may have difficulty seeing when moving from a brightly lit area to one that is dimly lit. As a result, individuals with night blindness generally experience difficulty driving at night or in the evening.

The underlying cause of night blindness is usually a problem with the retina. The retina is well supplied with an important chemical substance called rhodopsin. Light falling on the retina brings about certain chemical changes in the rhodopsin and other substances present in the rods and cones. These changes occur very rapidly, but large quantities of vitamin A are needed to bring about. If there is any marked deficiency of vitamin A, night blindness may occur.

Other common cause of night blindness is cataracts, which are opaque or cloudy areas in the eye's lens. This is more common in individuals over 50 years of age. In a younger person, night blindness can often be the first sign of retinitis pigmentosa. This eye disease, which has a genetic link, causes the retina to become damaged and progressively worsens over time.

A person with myopia, or nearsightedness, may also experience night blindness. With myopia, the person has difficulty focusing his or her eyes. As a result, far away objects appear blurry, and the person may also have difficulty adapting to darkness.

Certain drugs can also cause night blindness, particularly those that block the body's ability to absorb vitamin A. Some types of birth defects can also cause deformities in the retina and lead to night blindness.

Risk factors may include:

    Retinitis pigmentosa.

  • Macular degeneration.

  • Rod-cone dystrophy.

  • Cataracts.

  • Malabsorption - if it affects vitamin A absorption

  • Celiac disease.

  • Cystic fibrosis.

  • Bile duct obstruction.

  • Cirrhosis of the liver.

  • Diabetes.

  • Severe short-sightedness.

  • Congenital night vision disorder.

If you experience night blindness, it is important to take safety precautions, like not driving in the evening or at night. Also, eating a diet with adequate amounts of vitamin A may help prevent night blindness.

Symptoms:

    A major symptom is poor or blurred vision, in low lit areas or during and after evening time. One more sign is prolonged vision loss after exposure to bright light.

  • The night blindness phases may be transient or may be getting gradually prolonged.

  • Persistent dry eyes are another indication of this disease.

Diagnosis:

A doctor will give you a medical examination to determine the cause of your night blindness. Some of the things a doctor might do are: Ask detailed questions about your experience of night blindness, test the levels of vitamin A in your blood. He also asksabout your medical history, including diet, medications, use of corrective lenses, and family history of diabetes.

He may also perform following tests:

    Color vision testing.

  • Pupil light reflex.

  • Refraction.

  • Retinal exam.

  • Slit lamp examination.

  • Visual acuity.

  • Electroretinogram (ERG)

  • Visual field.

Treatment:

Depending on the reason for your night blindness, treatment will address the specific cause. Treatments generally include:

    Vitamin A deficiency induced night blindness treatment: The treatment for this type of night blindness is a regular intake of vitamin A. Progressive intake of vitamin A rich foods and supplements can also cure this condition.

  • Myopic night blindness might be cured by the use of corrective glasses or lenses. In some cases, refractive surgery might be required.

  • Glaucoma medication induced night blindness can be treated by switching off glaucoma medicines.

  • Cataract induced night blindness may be treated by cataract surgeries, which can completely cure the problem.

  • Retinitis pigmentosa induced night blindness treatment: This condition is not completely curable yet but the rate of progression of this disease can be reduced by intake of vitamin A supplements and surgeries. Complete cure has not yet been found. Though future developments like retinal transplants may help in curing this problem completely.

  • Diabetes induced night blindness treatment: Early detection of diabetic condition and treatment methods like insulin injections, can reduce the severity of diabetes. This will reduce the possibility of further deterioration of vision. The treatment involves use of eyeglasses and in severe cases, some surgery might be required.

NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.

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