Night blindness doesn’t mean you are completely unable to see at night, but that your vision is poorer in the dark. The inability to see well at night or in poor light is called Night blindness, also known as nyctalopia. Night blindness is also called day sight or nocturnal amblyopia.
Night blindness is most dangerous when someone who has trouble seeing in the dark gets behind the wheel of a car. Headlights of oncoming vehicles can make it especially difficult to see clearly and drive safely. Night blindness is not a disease in itself, but a symptom of some other type of vision problem.
Symptoms of Night Blindness
The most observable symptom of night blindness is difficulty seeing in the dark. A person is more likely to experience night blindness when his/her eyes transition from a bright environment to a dimly lit area. Also, one is likely to experience poor vision when driving due to the intermittent brightness of headlights.
Other symptoms may also occur with night blindness. The nature of these symptoms will depend on the underlying cause which may include:
blurry, or cloudy vision
sensitivity to light
difficulty seeing into the distance
What Causes Night Blindness?
The problem comes from a disorder of certain cells in the eye’s retina that allow one to see in dim light. A number of eye conditions or diseases can cause the disorder of these cells that leads to night blindness, which include:
Myopia: Nearsightedness (seeing well up close but not far away).
Glaucoma: A disease of the optic nerve connecting the eye to the brain.
Glaucoma medications: Medications for glaucoma that work by constricting the pupil.
Cataracts: Cloudiness of the eye’s naturally clear lens. Older adults have a greater risk of developing cataracts.
Keratoconus: Having a cornea that is very steeply curved.
Vitamin A deficiency: Deficiency in vitamin A can also lead to night blindness. Vitamin A, also called retinol, plays a role in transforming nerve impulses into images in the retina. The retina is a light-sensitive area in the back of your eye.
Diabetes: People who have high blood glucose or sugar levels also have a higher risk of developing eye diseases, such as cataracts.
Sunlight exposure: Without proper eye protection, sunlight exposure can temporarily impair night vision for up to two days. Wearing sunglasses that protect against UVA and UVB rays will prevent temporary night blindness due to sunlight exposure.
Genetic Defect: Genetic conditions such as retinitis pigmentosa or Usher syndrome.
Aging eye: As we age several things happen to our eyes. Our iris, which regulates the amount of light going into the eye, gets weaker and less responsive. This can make adapting from light to dark more difficult and slower. Our pupils shrink slightly allowing less light into the eye. The lens of the eye becomes cloudier, as explained above in cataracts.
Diagnosing Night Blindness
To determine what is causing night blindness, an eye doctor will perform a thorough eye exam and may order any of a number of specialized tests.
Treatment for Night Blindness
Some types of night blindness are treatable, and other types aren’t. Treatment for night blindness will depend upon its cause which determines the type one has. Treatment may be as simple as getting a new eyeglass prescription or switching glaucoma medications.
When the cause is a lack of vitamin A, treatment involves adding more Vitamin A to the diet. Good sources of vitamin A include:
orange and yellow vegetables and fruits
cod liver oil
dark, leafy green vegetables
Eye surgery may be necessary in more severe cases. For example, LASIK is a type of surgery that changes the shape of the cornea to improve vision. Other types of surgery may aim to remove a cataract from the eye or to release pressure in the eye for treatment of glaucoma.
In some cases, night blindness may not be treatable. Both retinitis pigmentosa and Usher syndrome are progressive genetic eye diseases where the rods that regulate light, and cones that control colour perception and detail die. Progressive night blindness is one of the first visual symptoms of these two diseases. Currently there is no treatment for them as there is no way to treat or replace the dying rods. Also, there is no treatment for age-related night blindness. However, eating a diet rich in fruits and vegetables and low in saturated fat is the best way to slow the progression.
Take safety measures to prevent accidents in areas of low light. If you have night blindness, you should take precautions to keep yourself and others safe. Avoid driving at night until the cause of your night blindness is determined and possibly treated, unless you get your eye doctor's approval.
Arrange to do your driving during the day, or secure a ride from a friend, family member, or taxi service if you need to go somewhere at night.
Wearing sunglasses or a brimmed hat can also help reduce glare when you’re in a brightly lit environment, which can ease the transition into a darker environment.
Vitamin A supplements may be helpful if you have a vitamin A deficiency. Ask your health care provider.
What Is the Long-Term Outlook?
The outlook for night blindness depends on the cause. The cause may have a range of straightforward treatments in many cases. This can be as simple as new glasses or contact lenses or adapting to a different diet. More severe cases may require surgery.
Effective treatment can significantly improve vision at night, as well as other symptoms of the underlying condition causing it.
How to Prevent Night Blindness
Night blindness due to genetic conditions or aging cannot be prevented. However, if you properly monitor your blood sugar levels, protect your eyes from extreme sunlight and eat a balanced diet, you can reduce your chances for night blindness.
Eat foods rich in antioxidant vitamins and minerals, which may help prevent cataracts. Also, choose foods that contain high levels of vitamin A to reduce your risk of night blindness.
Whatever the case may be for the night blindness, difficulty seeing in dim environments can be frustrating and even dangerous, especially for the older population. If you struggle to navigate around your home in the dark or find yourself struggling to see clearly when driving at night, schedule an appointment with your ophthalmologist right away. Even if the cause is something harmless and curable, any sudden changes in vision are worth getting checked out.