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What is Night Blindness (Nyctalopia): Causes, Symptoms and Treatment
Night blindness, scientifically known as nyctalopia, is an eye condition that causes the eyes to struggle to see in dim light and experience poor night vision. According to an article published in the National Library of Medicine, nyctalopia is defined as the inability of a person’s eyes to adapt quickly from lightness to darkness. Night blindness can affect a person’s daily life as it can make driving at night difficult. The main causes of night blindness include cataracts, glaucoma, myopia and diabetes. The main symptom of nyctalopia is not being able to see well at night or in low-light conditions. Treatments for night blindness (nyctalopia) depend on the underlying cause of this vision issue. For example, if it is caused by vitamin A deficiency, it may be treated by consuming more of this vitamin. Keep reading to learn more about night blindness and its causes and symptoms.
What are the Causes of Night Blindness?
Night blindness is caused due to either an issue with the rod cells, which are photoreceptor cells in the eye, or the pupils. If there are issues with these two functions, then it may cause a person to have trouble seeing in dim light or at night. The main causes of night blindness include cataracts, glaucoma, myopia and diabetes. These causes and their definitions are listed below.
- Cataracts: Cataracts are an age-related eye condition that affects a person’s lens. Due to a disruption to the lens, it limits the amount of light that can enter the eye, causing night blindness.
- Glaucoma: Glaucoma is a term for a group of eye conditions that causes damage to the optic nerve, resulting in vision loss. According to Glaucoma Australia, people with glaucoma can experience impaired dark adaptation which can affect a person’s ability to drive safely.
- Myopia: Myopia is a refractive error that causes a person’s distance vision to be blurry. This eye condition may cause a person’s night vision to be blurry as if their vision is affected in daylight, it is likely to worsen in low light.
- Diabetes: Diabetes is characterised by uncontrolled blood sugar levels and can lead to the eye condition diabetic retinopathy which may cause symptoms such as poor night vision.
Other causes of night blindness may include retinitis pigmentosa, which is a group of rare eye diseases that affect the retina, and ocular albinism which is a genetic condition that reduces the pigment of a person’s iris.
How Do Cataracts Cause Night Blindness?
Cataracts are an age-related eye condition that limits the amount of light that can enter the eye, causing night blindness. A cataract is a clumping of protein in the eye’s lens which causes the lens to become cloudy instead of clear, which is called opacification. According to Medical News Today, cataracts interfere with a person’s vision via the lens which can lead to night blindness. Cataracts are most commonly treated through cataract surgery which in turn can treat night blindness as it corrects the issues with the lens. Cataract surgery involves removing and replacing the lens with an artificial one called an intraocular lens.
How Does Glaucoma Cause Night Blindness?
Glaucoma is a term for a group of eye conditions that causes damage to the optic nerve, resulting in vision loss. According to Glaucoma Australia, people with glaucoma can experience impaired dark adaptation which can affect a person’s ability to drive safely. Glaucoma has also been recognised by the National Transport Commission and Austroads as an eye condition that affects a person’s capacity to drive safely. A common glaucoma symptom is a loss of peripheral vision which can make it difficult to rapidly adapt to changes in lighting, causing issues with driving at night as it impedes a person’s ability to manage glare and also judge the distance of other cars on the road.
How Does Myopia Cause Night Blindness?
Myopia is a refractive error that causes a person’s distance vision to be blurry. This eye condition may cause a person’s night vision to be blurry as if their vision is affected in daylight, it will worsen in low light. According to the Cleveland Clinic, people who have myopia commonly experience poor night vision due to optical issues. Myopia can be treated through prescription glasses which can also be helpful for night blindness caused by this refractive error. People with night myopia may also benefit from a stronger prescription to help them see better in low-light conditions.
How Does Diabetes Cause Night Blindness?
Diabetes is characterised by uncontrolled blood sugar levels and can lead to the eye condition diabetic retinopathy which in its early stages can cause symptoms such as poor night vision. According to Optometrists.org, diabetes may lead to diabetic retinopathy as the condition changes the shape of the lens, leading to damaged blood vessels in the eye. Other symptoms besides poor night vision in diabetic retinopathy include seeing floaters in your vision, blurry vision and empty and dark spots in your vision.
How Do Eyes With Night Blindness Differ in Function?
A person who has eyes with night blindness will function differently than those without this vision issue. According to the National Library of Medicine, night blindness, scientifically known as nyctalopia, either affects the functionality of the rod cells or the pupils. The rod cells in eye anatomy are photoreceptors that are sensitive to low levels of light which help people see at nighttime. If the rod cells are damaged, it can result in night blindness, light sensitivity and diminished peripheral vision. The pupils are responsible for letting light into the eye and they adjust depending on the amount of light present. This is called the pupillary light reflex and if it is impaired, it can result in night blindness.
What is the Research Available About Night Blindness?
There is noteworthy research available regarding night blindness, scientifically known as nyctalopia. Some of the research and learnings about night blindness are found in the American Academy of Ophthalmology and the National Library of Medicine which are listed below.
- According to an article published by the American Academy of Ophthalmology titled Shedding Light on Night Blindness published by Kierstan Boyd in 2016, night blindness is not the inability to see at night, rather it means your vision is worse when it is dark.
- An article that was updated in 2022 in the National Library of Medicine titled, Physiology, Night Vision, by Divy Mehra and Patrick H. Le, discusses night blindness on a cellular level and also explains the development, mechanism and clinical significance, among other areas of night blindness.
What are the Symptoms of Night Blindness?
Night blindness symptoms mainly stem from a person’s difficulty seeing when it is
dark.
The symptoms of night blindness include poor night vision, blurry vision at night and sensitivity
to light. These symptoms and their definitions are listed below.
| Symptoms of night blindness | Definition | Commonality |
|---|---|---|
| Poor night vision | Night blindness is characterised by having poor vision at night and can make certain activities difficult such as driving in the dark. | Poor night vision is the main symptom of night blindness. |
| Blurry vision at night | A person who has myopia will have blurry distance vision in the daytime which will most likely worsen at night. | Blurry vision at night is common for people who have myopia. |
| Sensitivity to light | A person may develop a sensitivity to light if there is damage to the rod cells in their eyes. | Sensitivity to light is a less common symptom of night blindness. |
According to an article titled Physiology, Night Vision published in the National Library of Medicine, the main symptom of night blindness is difficulty seeing in dim light or at nighttime.
What are the Treatments for Night Blindness?
There are various treatments available for night blindness that are prescribed depending on the underlying cause of this eye problem. For example, if night blindness is caused by a cataract in the eye, cataract surgery may be required to treat this eye condition. If myopia is contributing to poor night vision, your optometrist will prescribe prescription glasses and if you already wear glasses, then a stronger prescription may be advised. According to the Cleveland Clinic, treatment for night blindness that is caused by a retinal disease will need additional investigation, performed by a retina specialist.
How to Protect Eyes from Night Blindness with Dietary Changes?
To protect the eyes from night blindness, a person can implement certain dietary changes by consuming Vitamin A and zinc. Vitamin A and zinc have been shown to play a role in the normal function of a person’s eyesight, therefore, it is beneficial to ensure you do not have a Vitamin A or zinc deficiency. The vitamins and minerals that can help protect the eyes from night blindness are listed below.
- Vitamin A: Vitamin A is a fat-soluble vitamin that is important for normal eyesight function. According to the World Health Organisation, night blindness is one of the first signs of vitamin A deficiency. Foods containing vitamin A include carrots, pumpkin, sweet potato, eggs and fortified milk.
- Zinc: Zinc is a mineral that supports many functions of the body including the immune system and thyroid function. According to an article published in the National Library of Medicine, a person with a zinc deficiency may develop night blindness. There are many foods that contain zinc including fish, poultry, meat and dairy.
How to Diagnose Night Blindness?
Night blindness can be diagnosed in the same way as many other eye conditions or issues which is through a comprehensive eye test. The steps in a comprehensive eye test may include pre-testing, a slit lamp test, a visual acuity test and a visual field test. These tests and their definitions are listed below.
- Pre-testing: Pre-testing occurs before the main testing with an optometrist and is typically performed by an optical dispenser or a trained staff member. This test will involve an eye pressure test, also known as a tonometry test, which will assess intraocular eye pressure. A digital photograph may also be taken of your eye to assess any changes in the eye.
- Slit lamp test: A slit lamp test will assess your eye health and examine the anterior and posterior of the eye which includes your cornea and iris.
- Visual acuity test: A visual acuity test measures the clarity and sharpness of a person's vision using a letter chart. The results for this test will be denoted using a fraction such as 20/20 which is the measurement of normal vision.
- Visual field test: A visual field test assesses your peripheral vision and it is particularly useful for detecting glaucoma, which is a condition that can cause vision loss.
An eye test is very important for assessing the health of a person’s eyes and their vision. Regular eye tests can help detect and treat any eye conditions you may have. If you are in need of an eye test, find an Oscar Wylee Optometrist Australia near you.
How Do Optometrists Perform Night Blindness Tests?
An optometrist performs multiple tests throughout an eye test, many of which may be helpful in diagnosing night blindness. According to Optometrist.org, an optometrist may perform a test using the Pelli-Robson contrast sensitivity chart which can help detect signs of night blindness. It is similar to a visual acuity test in that it uses a letter chart but in this case, the letters are in different shades of grey.
Does Oscar Wylee Help for Night Blindness?
Yes, Oscar Wylee can help with night blindness by adding our Premium Anti-Reflective coating to any pair of prescription and non-prescription glasses which is an additional $45 on top of the price of a standard pair of glasses. Anti-reflective glasses have many benefits such as enhancing the clarity of your lenses, reducing glare from computer screens, eliminating reflections in your glasses and improving your night vision. Visit an Oscar Wylee store to browse our wide range of frames to suit your needs where you can add an anti-reflective coating among other add-ons and lens types.
How to Drive During Night Blindness?
If you have night blindness, driving in the dark can be difficult but according to Welia Health, there are certain ways you can improve your night blindness when driving. These instructions include slowing down to allow a bigger reaction time, cleaning your windshield to improve visibility, wearing prescription glasses, driving during the day where possible and finally, wearing glasses with an anti-reflective coating. At Oscar Wylee, we offer a Premium Anti-Reflective lens coating for an additional $45 on top of a pair of standard glasses which can be worn as night driving glasses. This coating reduces reflections, providing the wearer with clear vision and it is also scratch and smudge resistant as well as anti-static. According to Glaucoma Australia, people who have glaucoma that affects their vision may be issued a conditional licence which may prohibit them from driving at night.
How Does Night Blindness Differ From Normal Vision?
Night blindness differs from normal vision as it is characterised by not being able to see well at night. While a person’s nighttime vision is affected, their daytime vision will be unimpaired. When it is dark, a person’s pupils with normal vision will expand to see better at night or in dim lighting. A person who has night blindness will have a different experience when in the dark as conditions such as glaucoma or cataracts affect how the eyes work. In the case of glaucoma, some of its medications can constrict a person’s pupil, making it difficult to see at night. If you struggle to see at night or in dim lighting, book an appointment with an eye care professional as it may be a symptom or a more serious condition.
Is Night Blindness a Caused By Common Eye Problems?
Yes, night blindness (nyctalopia) may be caused by common eye problems such as cataracts, glaucoma and myopia. Cataracts cause night blindness as it limits the amount of light that can enter the eye. Night blindness can be caused by glaucoma as it damages the optic nerve resulting in vision loss. Finally, myopia may cause night blindness as if a person’s distance vision is blurry in daylight, it is likely to be worse in low light.
What is the Difference Between Night Blindness and Colour Blindness?
The difference between night blindness and colour blindness is how they affect a person’s vision. Night blindness is an eye condition that causes the eyes to struggle to see in dim light and experience poor night vision. Colour blindness, more accurately called colour vision deficiency, is an eye condition in which the eyes have difficulty seeing colours in a normal way.