Night blindness is a condition which may have several causes that lead to different symptoms. Night blindness may exist from birth, or caused by an injury or malnutrition. Some types of night blindness are treatable while other types are not, depending on the nature of the cause. Once the cause of night blindness is identified, steps can be taken together with your healthcare provider to correct your vision. In this article, we will be discussing night blindness, the symptoms, the potential causes, treatment and prevention of night blindness.

What is night blindness?

Nyctalopia, or night blindness is the inability to see well at night or in places with poor lightings. Our eyes are constantly adjusting to light where the pupils will dilate and allow more light to enter while in low light. Night blindness is often associated with the inability of our eyes to adapt well from a well-illuminated to a poorly-illuminated environment. It can also be described as insufficient adaptation to darkness.

Why is knowing about night blindness important?

Night blindness is not a disease itself, but rather a symptom of an underlying eye problem. Although night blindness affects a person’s ability to see in a low light environment, it does not cause complete blindness. However, problems may arise while driving at night due to the inability to see the road signs and obstacles on the road, causing significant danger. It may also take a long time for our eyes to adapt when going from a light to dark setting.

What are the symptoms of night blindness?

Symptoms of night blindness can be detected when you are walking or driving in the dark, which includes:

• Having blurry or poor vision while driving in the dark
• Having to squint excessively especially at night or when the environment is dim-lighted
• Struggling to see and adapting to the dark while driving at night
• Having difficulties moving around in dark places
• Trouble adjusting from bright areas to darker areas

As night blindness is a symptom of underlying conditions, other symptoms may occur as well depending on the underlying cause such as:

• Eye pain
• Headache
• Cloudy vision or vision impairment
• Nausea and vomiting
• Sensitivity to light
• Difficulty in seeing far away objects

What are the common causes of night blindness?

The light sensitive tissue in the back of our eyes, which is called the retina, contains all the photoreceptor cells. Photoreceptors consist of cone cells and rod cells with different functions respectively. The cone cells provide colour vision which enables us to see during the day while the rod cells are responsible for black and white vision, enabling us to see in the dark. Night vision is mostly black and white therefore damages in the rod cells will cause night blindness. 

• Vitamin A deficiency

  One of the first signs of vitamin A deficiency is night blindness. Vitamin A is needed for our body to produce the pigment needed for night vision. Our photoreceptors in the eyes cannot work correctly without these pigments.

• Short-sightedness or myopia

  Myopia occurs when you have trouble seeing distant images and objects. Vision during daytime will appear unclear as well as during the night when seeing things in low light.

• Glaucoma

  Glaucoma occurs when the eye pressure increases and causes progressive damages to the optical nerve. This affects both daytime and nighttime vision.

• Age-related macular degeneration (AMD)

  Age-related macular degeneration (AMD) happens when aging causes damage to the macular region of the eyes, which affects our central vision. It can cause blind spots and image distortion.

• Diabetes

  Diabetic patients are at risk of damage to blood vessels that will lead to a condition called diabetic retinopathy. One of the symptoms of diabetic retinopathy include poor night vision.

• Cataracts

  Cataracts affect mainly older people as it is a natural aging process. Cataracts will affect vision clarity, causing blurry vision due to the proteins that make up the eye’s lens begin to crystallise and harden. The first sign of cataract is usually increased difficulty while driving at night due to decreased night vision.

• Retinitis pigmentosa

  This is a rare eye disease that affects the retina. It will make the cells in the retina break down slowly over time, causing permanent vision loss. Retinitis pigmentosa is a genetic disease and the most common early symptom presented is the loss of night vision and side vision.

How is night blindness diagnosed?

To identify the underlying causes of night blindness, your healthcare provider will ask about your family history and perform thorough eye exam to test for any eye diseases. Blood samples may be collected to measure your vitamin A and glucose levels. They may also consider asking a few questions related to your conditions, to check your eye health and see if you are showing any symptoms related to night blindness.

How to prevent night blindness?

Night blindness caused by genetic conditions cannot be prevented. Changes in lifestyle habits and diets can prevent and decrease the risk of some eye diseases and conditions that may affect night vision such as:

• Eating food rich in vitamin A

  Typically foods that are orange and yellow in colour are rich in vitamin A such as carrots, pumpkins, sweet potatoes and mangoes. Vitamin A can also be found in dark leafy greens and eggs.

• Having regular eye examinations

  Regular eye examinations can have an early detection of any eye diseases which increase your chances of a successful treatment outcome. This will reduce your risk of night blindness.

• Maintain a healthy glucose level

  Reduce your risk of diabetic retinopathy by taking your medication as prescribed, together with lifestyle changes and dietary intake.

• Get regular exercise

  Moderate exercise at least 5 times a week can help to maintain a healthy blood pressure and blood sugar. This in turn will reduce the risk of developing many eye conditions such as glaucoma. 

• Wearing sunglasses outdoors

  Sunglasses can protect our eyes from the harmful rays of UV which will cause retinal damages after prolonged exposure. This will increase the risk of us getting cataracts, AMD and glaucoma.

What treatment options are available?

Treatment for night blindness varies from patient to patient depending on the cause of the condition. Treatment may include:

• Surgery such as cataract surgery to replace the cloudy lens of the eyes
• Medicated eye drops such as that to treat glaucoma
• Wearing specific types of glasses or contact lenses to correct your vision
• Taking sufficient vitamin A through food or supplementation. Vision should return to normal once your vitamin A levels are well regulated
• If diabetic retinopathy is the cause of the night blindness, taking medication and undergo surgery can help to relieve night blindness problems

Although there are no current treatments for night blindness caused by genetic conditions, certain devices and therapies can help to improve the symptoms and quality of life.

Poor night vision may cause inconvenience and danger in daily activities therefore one should not be driving at night, or should avoid having to navigate in the dark alone.  Always schedule your eye exams regularly for early detection for any eye conditions for early treatment.

 

Reference

• MediLexicon International. (n.d.). Night blindness: Symptoms and treatments. Medical News Today. Retrieved December 6, 2022, from https://www.medicalnewstoday.com/articles/324004
  
• Russ. (2021, August 1). Night blindness: Treatments and prevention. Optometrists.org. Retrieved December 4, 2022, from https://www.optometrists.org/general-practice-optometry/guide-to-eye-conditions/guide-to-blurry-vision-and-headaches/having-difficulty-seeing-at-night/what-causes-night-blindness/night-blindness-treatments-and-prevention/
• Russ. (2021, July 22). What causes night blindness? Optometrists.org. Retrieved December 8, 2022, from https://www.optometrists.org/general-practice-optometry/guide-to-eye-conditions/guide-to-blurry-vision-and-headaches/having-difficulty-seeing-at-night/what-causes-night-blindness/