Nyctalopia Physiology Nighttime Vision: Investigating the Causes and Treatments for Night Blindness

Explore the physiology of nyctalopia, also known as night blindness, and delve into the causes and potential treatments for this condition.

Understand the intricate mechanisms of night blindness.

Night Blindness Test

What is night blindness?

Night blindness (nyctalopia) is your inability to see well at night or in poor light such as in a restaurant or movie theater.

It is often associated with an inability to quickly adapt from a well-illuminated to a poorly illuminated environment.

It is not a disease in itself, but rather a symptom of an underlying eye problem, usually a retina problem.

It is common for people who are myopic to have some difficulties with night vision, but this is not due to retinal disease, but rather optical issues.

What happens to the eye in low or no light?

Your eyes are constantly adjusting to light. When you’re in low or no light, your pupils (that black circle in the center of your eyes).

Will get bigger (dilate) so that more light will enter your eye. That light is then received by the retina — tissue in the back of your eye that houses all of the rod and cone cells.

Cone cells help you see color. Rod cells help you see in the dark. When those rods are not working well because of a disease, injury, or condition, you can’t see as well or at all in the dark.

What are the most common causes of night blindness?

Night blindness has many possible causes, including:

Myopia (nearsightedness).

Glaucoma medications that work by constricting the pupil.

Cataracts

Retinitis pigmentosa

Vitamin A deficiency, especially in individuals who have undergone intestinal bypass surgery.

Diabetes

To determine what is causing your night blindness, an eye specialist will perform a thorough eye exam and may order any of a number of specialized images, tests or exams.

How is night blindness treated?

Treatment for your night blindness depends on the cause. Treatment may be as simple as getting yourself a new eyeglass prescription or switching glaucoma medications, or it may require surgery if the night blindness is caused by cataracts.

If you have a retinal disease, the treatment will depend on the type of the disease and will require additional investigation by a retina specialist.

What can I do to treat night blindness at home?

Night blindness cannot be treated at home. Medical advice is necessary so that the appropriate treatment, if any, is given.

How can night blindness be prevented?

You can’t prevent genetic predispositions, but you can alter your lifestyle habits. Try the following to possibly prevent night blindness:

Eat foods that have Vitamin A, Some suggestions include:

1. Carrots.
2. Cantaloupes.
3. Butternut squash.
4. Spinach.
5. Milk.
6. Eggs.

Get regular eye exams. See an eye specialist consistently so that they can figure out early if you have problems with your eyes.

Wear sunglasses. Sunglasses protect your eyes from the sun. UV rays increase your risk of cataracts, macular degeneration and glaucoma.

Make sure that your sunglasses do the following:

Block out at least 99% of UVA and UVB rays.

Protect your eyes from every angle.

Filter 75% to 90% of visible blue light.

Exercise. Exercise may reduce your risk of eye conditions. It may lower eye pressure and blood glucose levels.

When should night blindness be treated by a healthcare provider?

If you struggle to see while you’re driving at night — or can’t see at all, or if you’re sitting in a barely lit restaurant and you can hardly see, you might have night blindness.

See your healthcare provider right away because night blindness can be a symptom of a serious disease.

Genetic conditions

Genetic conditions that cause night blindness, such as retinitis pigmentosa, aren’t treatable. The gene that causes pigment to build up in the retina doesn’t respond to corrective lenses or surgery.

People who have this form of night blindness should avoid driving at night.

How can I prevent night blindness?

You can’t prevent night blindness that’s the result of birth defects or genetic conditions, such as Usher syndrome.

You can, however, properly monitor your blood sugar levels and eat a balanced diet to make night blindness less likely.

Eat foods rich in antioxidants, 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.

Certain orange-colored foods are excellent sources of vitamin A, including:

1. cantaloupes
2. sweet potatoes
3. carrots
4. pumpkins
5. butternut squash
6. mangoes
7. spinach
8. collard greens
9. milk
10. eggs

What’s the long-term outlook?

If you have night blindness, you should take precautions to keep yourself and others safe.

Refrain from driving at night as much as possible until the cause of your night blindness is determined and, if possible, treated.

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.

Blurry vision

Blurry eyes can be a first sign of diabetes. Several causes can stem from diabetes, as it may be a sign your glucose level is not in the right range — either too high or too low.

The reason your sight blurs may be fluid leaking into the lens of your eye. This makes the lens swell and change shape.

Those changes make it hard for your eyes to focus, so things start to look fuzzy.

You may also get blurred vision when you start insulin treatment. This is due to shifting fluids, but it generally resolves after a few weeks.

For many people, as blood sugar levels stabilize, so does their vision.

Diabetic retinopathy
Causes of blurry vision in the longer term can include diabetic retinopathy, a term that describes retinal disorders caused by diabetes.

The stages of diabetic retinopathy include:

Stage 1: mild nonproliferative diabetic retinopathy
Stage 2: moderate nonproliferative diabetic retinopathy
Stage 3: severe nonproliferative diabetic retinopathy
Stage 4: proliferative diabetic retinopathy

Most people don’t show symptoms of diabetic retinopathy until it has progressed to stage 4 Symptoms at this stage include:

1. blurry vision
2. eye floaters
3. loss of vision
4. distorted vision

Cataracts
You might also have blurry vision if you’re developing cataracts.

People with diabetes tend to develop cataracts at a younger age than other adults.

Cataracts cause the lens of your eyes to become cloudy.

Other symptoms include:

1. faded colors
2. clouded or blurry vision
3. double vision, usually in just one eye
4. sensitivity to light
5. glare or halos around lights
6. vision that doesn’t improve with new glasses or a prescription that must be changed often
7. Hyperglycemia
8. Hyperglycemia results from glucose building up in the blood when the body lacks enough insulin to process it.

Besides blurred vision, other symptoms of hyperglycemia include:

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1. increased thirst and urination.

2. Managing your glucose levels to avoid hyperglycemia is important because, over time, poor blood sugar control can lead to more problems with sight and potentially increase the risk of irreversible blindness.

Glaucoma

Blurry vision can also be a symptom of glaucoma, a disease in which pressure in your eye damages the optic nerve.

According to the National Eye Institute Trusted Source, if you have diabetes, your risk of glaucoma is double that of other adults.

Other symptoms of glaucoma may include:

1. loss of peripheral vision or tunnel vision
2. around lights
3. reddening of the eyes
4. ocular (eye) pain
5. nausea or vomiting
6. Macular edema

The macula is the center of the retina, and it’s the part of the eye that gives you sharp central vision.

Macular edema is when the macula swells due to leaking fluid. Other symptoms of macular edema include wavy vision and color changes.

Diabetic macular edema (DME) stems from diabetic retinopathy. It usually affects both eyes.

The National Eye Institute estimates that around 7.7 million Americans Trusted Source have diabetic retinopathy, and of those, nearly 1 in 10 has DME.