Night Blindness. Symptoms, Causes, and Treatment

Night blindness, or nyctalopia, describes an inability to see well at night or in situations with poor lighting. Night blindness is not a disease in itself. Rather, it is a term that’s used to describe a symptom that may or may not be caused by a specific medical condition. Night blindness can be rather disruptive, and therefore it is natural to want to know what’s causing it and how to treat it.

Symptoms

Symptoms of night blindness can manifest in any dimly lit environment. People with night blindness will often describe driving at night as the most difficult of all tasks. When it is dark out, and road illumination is poor, seeing can be a challenge.

There is a lot at stake in this situation, and therefore night blindness can be anxiety provoking. Other environments that may be problematic include going to the movie theater or getting up in the middle of the night to go to the bathroom.

Causes

Nearsightedness. Also known as myopia, nearsightedness is a type of refractive error. Refractive error, like myopia, hyperopia, and astigmatism, occurs when the shape of your eye doesn’t bend light correctly. This creates a blurry image and is most commonly treated with glasses or contact lenses. Nearsighted people have trouble seeing distant objects, which can make night driving particularly challenging without correction.

Medication. Medications that constrict (shrink) the pupil can cause difficulties with night vision. When the pupil is smaller, it doesn’t let as much light into the eye, making it harder to see, especially in dimly lit environments. The most common medication that does this is pilocarpine. Pilocarpine used to be commonly used in glaucoma, but it is rarely used for this purpose anymore. Today, pilocarpine is sometimes prescribed to improve near vision in age-related presbyopia. Presbyopia causes the crystalline lenses inside the eyes to become inflexible, causing difficulties focusing up close.

Cataract. A cataract is a clouding of the lens inside the eye, called the crystalline lens. Early in life, the crystalline lens is clear and light passes through it flawlessly. With time, the lens becomes cloudy. This can cause vision to become blurry, hazy, and/or less colorful. Cataracts block light from getting into the eyes, which can cause difficulties with night vision.

Vitamin A deficiency. Vitamin A deficiency is rare in developed countries. Nevertheless, it may occur in people who have intestinal inflammation, liver and pancreas disease, or those with a history of bariatric (weight control) surgery. Night blindness is one of the first symptoms of vitamin A deficiency. If you suspect that your levels may be low, ask your doctor to test them for you.

Retinitis Pigmentosa. Retinitis pigmentosa (RP) is a rare disease of the retina, the light-sensitive tissue lining the inner part of the eyes. People are born with this genetic condition. Loss of night vision is the primary symptom of RP and generally manifests in childhood. RP can also cause sensitivity to light, difficulties with peripheral (side) vision, and loss of color vision.

Treatments

Treatment for night blindness will largely depend on the underlying cause.

Nearsightedness. Nearsightedness is most commonly treated with glasses or contact lenses. This will often improve night vision substantially.

Medication. If you’ve been prescribed pilocarpine and you notice difficulties with your night vision, ask your doctor if there’s an alternative treatment you can use. If you take pilocarpine to improve your near vision, you may consider only taking it earlier in the day, so its effects are worn off by nighttime.

Cataract. Cataracts can cause visual fluctuations that may temporarily be managed with a change in glasses. Getting an up-to-date prescription for eyeglasses may help to improve vision for some time. Once the cataracts reach a certain stage, however, they will need to be treated surgically. During cataract surgery, your ophthalmologist will remove the cloudy part of the crystalline lens and replace it with a synthetic intraocular lens.

Vitamin A deficiency. If you have low vitamin A levels, try eating foods that are rich in this important nutrient. These include:

  • Orange vegetables, such as carrots, sweet potato, pumpkin and butternut squash.
  • Cantaloupe.
  • Leafy green vegetables, such as spinach.
  • Milk.
  • Eggs.

Don’t take a supplement unless it’s been advised by your doctor, as vitamin A is fat-soluble and therefore could cause toxicity at high levels.

Retinitis Pigmentosa. There is no cure for retinitis pigmentosa, but various aids can help with the visual difficulties this condition causes. These may include glasses, magnifiers, telescopes, and more.

Key take-aways

Night blindness describes a symptom, not a disease.

There are many conditions that can cause difficulties with vision in low light situations. These include nearsightedness, medication, cataracts, vitamin A deficiency, retinitis pigmentosa, among others.

Seeing an optometrist or ophthalmologist for a comprehensive eye examination is the best way to find out exactly what’s causing your night blindness.

Once the root cause is identified, your eye doctor can help to put together an appropriate treatment plan to ease your nighttime vision difficulties.

References:

Boyd, K., 2016. Shedding Light on Night Blindness. American Academy of Ophthalmology.

Boyd, K., 2022. What is Vitamin A Deficiency? American Academy of Ophthalmology.

Night Blindness (Nyctalopia). Cleveland Clinic.

Retinitis Pigmentosa. National Eye Institute.

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