What Is Night Blindness? (Should You Be Concerned?)
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If you find you have trouble seeing at night, transitioning from bright into dim light, or bright lights hurt your eyes, you may have night blindness.
While many people notice night blindness first, this problem is most often a symptom of other underlying conditions. Many of these underlying problems are treatable, although some may progress faster than others.
Table of Contents
These are the main causes of night blindness:
- Nearsightedness
- Diabetes
- Cataracts
- Certain medications, such as those for glaucoma
- Retinitis pigmentosa
- Vitamin A deficiency
Symptoms of night blindness, or nyctalopia, can include other physical symptoms, which may indicate a more severe underlying cause of night vision issues.
What Is Night Blindness?
While there are many root causes of night blindness, the common symptom is the inability to see well or clearly at night.
Despite its name, night blindness doesn’t mean you can’t see at night. It simply means you have difficulty seeing at night or in dark conditions.
Different causes of this condition will require different approaches to treatment. Getting regular eye exams to diagnose some issues before night blindness occurs can help to reduce your risk.
What Are the Symptoms of Night Blindness?
The primary symptom of night blindness, or nyctalopia, is trouble seeing in the dark. However, this can take many forms.
- Difficulty seeing well after transitioning from an area with lots of light to an area with dim light
- Trouble seeing while driving at night due to darkness on the road with intermittent bright headlights
- Problems seeing furniture or objects in a dark room at night when there is a little light, such as from a nightlight
- Difficulty recognizing faces in dim or low light
- Needing more light to perform routine tasks
Night blindness may be the most obvious symptom of many different conditions, some of which can get worse over time until, without treatment, you lose your sight.
Some underlying conditions that cause night blindness have other symptoms associated with them, so if you experience any of the following symptoms along with trouble seeing at night, get in touch with your physician and your optometrist:
- Headaches
- Eye pain
- Nausea, vomiting, or other stomach issues
- Blurry or cloudy vision
- Sensitivity to light, even if it is not bright
- Trouble seeing objects in the distance
Underlying Conditions That May Lead to Night Blindness
The causes of night blindness can affect almost any part of the eye, from the pupil or the shape of the eye to the optic nerve or the brain itself. The most common causes of night blindness are:
Cataracts
Cataracts are a clouding of the lens of the eye due to damaged proteins. The lens itself may have spots of cloudiness, streaks, general blurriness, or look dark or dirty.
Aging is the most common cause of cataracts, although an injury to the eye can also lead to this issue. In addition to difficulty seeing at night or in dim light, cataracts can lead to a loss of color vision due to light filtering differently through the lens; distortions or double vision; extra sensitivity to bright lights; and general blurry vision.
Typically, an optometrist or ophthalmologist will monitor the progress of this condition and adjust prescriptions for reading glasses or contact lenses to ease some of the blurriness. When the cataracts become serious enough that the person cannot get around safely, surgery can remove the damaged lens and replace it with an artificial lens.
Choroideremia
This is a genetic condition primarily affecting males, which is characterized by progressive vision loss.
The first symptom is night blindness, which can begin in early childhood and may not be noticeable for years. Progressive tunnel vision, or narrowing of the visual field from peripheral inward, is the next phase, along with a loss of visual acuity.
Due to genetic differences, light-receiving cells in the retina begin to atrophy at an early age, and the choroid, a nearby network of blood vessels, begins to disappear. The progression can vary between different people, but everyone with choroideremia eventually loses all of their sight, typically in late adulthood.
Glaucoma
This disease involves damage to the optic nerve that causes progressive vision loss. Fluid pressure builds up in the eye because it cannot drain. With enough pressure, blood does not get to the retina very well, and this can lead to damage to tissues and eventual cell death.
Glaucoma is the leading cause of blindness in people who are 60 or older. Sensitivity to light and trouble seeing in dim light are two early warning signs of glaucoma, along with pain in the eyes from eye strain, headaches, increasingly blurry vision, double vision, difficulty focusing even with corrective lenses, loss of peripheral vision, and halos or flares around lights.
There are several types of glaucoma, one of which involves damage to the optic nerve without high fluid pressure; however, most types do involve high fluid pressure in the eye. An optometrist can diagnose this problem before damage to the optic nerve and vision loss even begin.
Treatment for glaucoma means relieving high pressure in the eyes, either with eye drops or surgery. The eye drops that lower fluid pressure can sometimes change the size of the pupils, increasing sensitivity to light and making night blindness worse. Let your ophthalmologist know if this side effect from glaucoma treatment hurts your quality of life.
Keratoconus
This is a condition in which the cornea, the layer of clear cells over the iris and pupil, bulges outward into a cone shape. This distorts how light enters the eye, and a symptom of the condition can be night blindness. Other symptoms may be distorted and blurry vision, trouble with bright lights and glares, and eye redness or swelling. The problem typically affects both eyes, and it makes it hard for the person to wear contact lenses.
Medical professionals are unsure what causes keratoconus. It may be genetic, or it may be associated with eye allergies or even excessive eye rubbing. People who have mild keratoconus, which progresses slowly over years, will benefit from annual eye exams and wearing glasses. You may also get prescription eye drops to slow cell growth. In rare cases, you may need a corneal transplant.
Nearsightedness
Having high myopia can lead to problems with processing light, including at night.
Retinitis pigmentosa
This condition is actually a group of conditions that affect the retina and how it processes light to the optic nerve. Vision loss occurs slowly, and for most people, it does not lead to total blindness. Night blindness is one of the symptoms, and it may be the only progressive symptom depending on the type of retinitis pigmentosa that occurs. It is a genetic condition, so treatment focuses on alleviating symptoms. It may include recommendations to eat more foods with vitamin A or to take vitamin A supplements.
Vitamin A deficiency
There are many health problems that can lead to issues getting enough vitamin A, but without this nutrient, vision loss begins. About 250,000 to 500,000 children worldwide go blind every year because they do not have enough vitamin A in their diets.
One symptom of vitamin A deficiency in both children and adults is night blindness because the rod cells in the retina will begin to atrophy. This vitamin can be found in leafy green vegetables and orange fruits and vegetables. Kale, spinach, carrots, sweet potatoes, mangoes, cantaloupe, and collard greens are all great sources of vitamin A. If you eat a balanced diet and still struggle with night vision, you may have another digestive issue, so work with your physician along with your optometrist.
Night Blindness Treatments
Night blindness caused by nearsightedness, vitamin A deficiency, refractive surgery, and cataracts are all treatable, so you can return to normal levels of vision in dim or low light. Other causes, including progressive conditions and genetic disorders, may be manageable, but the condition will ultimately not go away.
If you begin to struggle with seeing at night, work with your optometrist and ophthalmologist to diagnose the cause.
References
- Night Vision. (December 19, 2018). American Academy of Ophthalmology (AAO).
- What Are Cataracts? (November 9, 2018). American Academy of Ophthalmology (AAO).
- Choroideremia. (July 2013). Genetics Home Reference, U.S. National Library of Medicine (NLM).
- What Is Glaucoma? (November 28, 2018). American Academy of Ophthalmology (AAO).
- What Is Keratoconus? (March 21, 2019). American Academy of Ophthalmology (AAO).
- What Is Retinitis Pigmentosa? (March 6, 2019). American Academy of Ophthalmology (AAO).
- What Is Vitamin A Deficiency? (November 8, 2012). American Academy of Ophthalmology (AAO).
- Reversible Night Blindness – A Reminder of the Increasing Importance of Vitamin A Deficiency in the Developed World. (July 2013). Journal of Optometry.