Nyctalopia or Night Blindness
What causes Nyctalopia or Night Blindness?
This is a condition where vision can be partially or severely impaired in low light conditions or at night.
Night blindness may exist from birth, or can be caused by injury or malnutrition (for example, a lack of vitamin A).
Night blindness caused by nearsightedness, cataracts, glaucoma medications or vitamin A deficiency is treatable. Corrective lenses, such as eyeglasses or contacts, can improve nearsighted vision both during the day and at night.
Vitamin A deficiency is a rare cause of night blindness. It occurs mostly in people with problems absorbing nutrients from the gastrointestinal tract. This might occur as a result of different diseases and conditions such as Crohn’s disease, celiac disease, cystic fibrosis, or pancreatic insufficiency.
The most common cause for night blindness is Retinal Genetic Disease such as Retintis Pigmentosa where the retinal photoreceptors for light (the Rods) are affected in a progressive fashion. Night blindness is usually severe by midteenage years.
In a certain condition children can be born with sever loss of night vision without progression, which is usually caused by X-Linked stationary night blindness. This condition affects young boys where daytime vision can be normal.
The incidence of primary photoreceptor degeneration is in the range 1:3000_1:5000.
What are the symptoms of Nyctalopia or Night Blindness?
The sole symptom of night blindness is difficulty seeing in the dark. You are more likely to suffer from night blindness when transitioning from a bright environment to an area of low light. You are likely to experience poor vision when driving, due to the intermittent brightness of headlights and streetlights on the road.
People suffering from Retinitis Pigmentosa may experience prolongs in the time required to adjust to change in light, as when dark theatres or dim restaurant lights are entered or even when moving from sunlight into room light. They may also suffer from visual field constriction in dimmer light.
Children with this condition may also present with other symptoms such as Nystagmus (involuntary movements of the eye balls), strabismus or high myopia.
Specialised Electro Diagnostic testing ERG can help to identify any weakness in the retinal function and help with diagnosis.
Geneticcounselling is usually required as most of these conditions are genetic or hereditary.
What are the treatments for Nyctalopia or Night Blindness?
Treatment for night blindness will depend upon its cause. Treatment may be as simple as getting a new eyeglass prescription or switching medications, or it may require surgery if the night blindness is caused by cataracts.
If a retinal disease is discovered, the treatment will depend on the type of the disease and will require additional investigation by a retina specialist.
Current treatments for Retinitis Pigmentosa are not highly effective, although new research outcome especially with Vitamin A supplements is showing some positive outcome in slowing down the disease progression.
Other studies of with genetic therapy or stem cells treatment are currently in progress and some results are promising.