Night Vision Problems

Night vision problems are causes why someone cannot see clearly in low-light conditions. The most common reasons are age-related eye conditions, glaucoma, cataracts, presbyopia, diabetic retinopathy and complications for eye surgery, among others.

Eye doctors can sometimes help someone see better at night by performing glaucoma surgery or cataract surgery and sometimes by refractive eye surgery.

Intro

Night vision describe the ability of someone to see clearly in low-light situations — even in near-darkness.

There are two ways for someone to have night vision:

• Thermal imaging (passive night vision)
• Image intensification (active night vision)

Passive night vision refers to seeing objects because they heat up a thermal imagining system, which detects heat and tends not to clarify non-heated objects

Active night vision refers to a situation when images and objects can been see because they are intentionally lit up by an outside source.

Millions of Americans have problems issues with their night vision, which is the ability to see in low-light conditions. In addition to finding it more difficult to see in dim light and at night, it also takes you longer than normal to adjust your vision when you move between a well-lit place and a low-light situation.

The condition is often called night blindness, or nyctalopia, but it doesn’t mean you cannot see at night. Night blindness is often a symptom of an underlying condition. Some types of night vision problems are treatable while other types are not. With early detection, there are several treatment options to restore your vision.

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Differences Between Day and Night Vision

Day vision and night vision are separate types of visual perception. They have several key differences, including:

• For day vision, visual perception is primarily performed by cone photoreceptor cells while for night vision, it is by rod photoreceptor cells.
• Day vision is chromatic, meaning color perception is present while night vision is achromatic meaning color perception is mainly in black and white.
• The pupils become larger in low light situations to let in more light.

How Do We See at Night?

Your eyes constantly adjust to light. In low-light situations, the iris opens wider, making the pupil larger allowing more light into the eye. The retina, which is the light sensitive tissue at the back of the eye, is covered in two types of photoreceptor cells, cones and rods.

The cone photoreceptor cells are responsible for giving us color perception in adequate light. Rod photoreceptor cells are more sensitive in low light and help us see in the dark, but only in black and white. 

In low-light situations, most of the rods in the retina are turned off, while only a few cones are turned on. That causes black and white vision.

Cones begin to work and contribute some color perception when the amount of light increases. The amount of light during a starry night, for example, is enough to give some color perception. If rods stop working because of injury, disease or another condition, a person’s ability to see in the dark becomes limited.

Symptoms of Night Vision Problems

The only symptom of night vision problems is difficulty in seeing in low-light situations. You are more likely to notice this when you move between a bright and low light environment. You will find it more difficult to see, or it will take you longer than normal to adjust your vision and distinguish between objects.

The American Academy of Ophthalmology suggests that people consider the following questions to help with identifying night blindness.

• Do you have a problem moving around the house in dim light?
• Is it increasingly difficult to drive at night?
• Is recognizing faces in dim light a challenge?
• Does it take you longer than normal to adjust to a bright room after being in the dark?
• Does it take you an abnormally long time to see in a dark room after being in the light?
• Do you have trouble moving around your house at night even with small night lights?
• Do you have trouble recognizing people’s faces in low-light settings?

Other symptoms of night vision problems include:

• Headache
• Nausea
• Eye pain
• Blurry or cloudy vision
• Vomiting
• Difficulty seeing into the distance
• Sensitivity to light

Causes of Night Vision Problems

A range of diseases and conditions can affect your night vision. Among the common causes:

• Age
• Presbyopia
• Glaucoma
• Cataracts
• Diabetic retinopathy
• Retinitis pigmentosa
• Nutritional deficiency
• Sun exposure
• Complications following LASIK surgery

Age

With age, our pupils lose their ability to dilate in the dark as much as they should, which reduces the amount of light that filters into the eye. The cornea also becomes less clear, increasing the amount of glare and reducing contrast sensitivity which can make distinguishing objects at night a challenge.

Presbyopia

This is a condition that develops with age and which makes adjusting to changes in lighting more difficult.

Glaucoma

It’s in a group of eye conditions characterized by a build-up of pressure in the eye,  which can affect peripheral vision. Additionally, glaucoma medications that constrict the pupil can also cause night vision problems.

Cataracts

A clouding of the eye lens due to a build-up of debris which makes it difficult to see objects clearly. Most people with cataracts have difficulty with glare and halos in low light situations.

Diabetic Retinopathy

Over time, high blood sugar damages blood vessels and nerves in your eyes resulting in diabetic retinopathy. This condition can cause a significant loss of vision.

Retinitis Pigmentosa

A rare genetic disorder in which dark pigment collects in the retina resulting in tunnel vision. Its earliest symptom is worsening night vision.

Nutritional Deficiency

A deficiency of vitamin A and zinc can increase your risk of night vision problems. Vitamin A, found in vegetables and carrots, helps keep the retina healthy. Zinc helps the body absorb vitamin A, so, with zinc deficiency, Vitamin A is not as effective.

Sun Exposure

Prolonged, unprotected exposure to sunlight can impair night vision for up to two days. Sun exposure is a leading cause for the development of cataracts, which in turn is a major cause of night-vision problems.

Eye doctors recommend always wearing UVA-rated sunglasses that protect against UVA and UVB to ensure your eyes do not get damaged from your time outdoors.

Complications Following LASIK

Although rare, patients who have had LASIK eye surgery may experience night-vision issues following surgery. Common complaints include glare and halos around objects, a condition that distorts vision and becomes more noticeable in dim light.

Problems People Have with Night Vision

Although poor night vision can come from a variety of sources, the following are the most common:

• Weak vision in low light. This means you cannot properly perceive objects in low light. Objects might also appear blurry.
• Difficulty adapting to changing light levels. Although the process of adjusting to changing light levels is slow even for a healthy eye, poor night vision makes the process even more difficult. Many people with night vision problems often go temporarily blind when moving from a bright space to a dim one.
• Difficulty driving at night. Driving past sunset for people with night vision problems is particularly hard and often dangerous. Streetlights and headlights with intermittent spaces of darkness make it difficult to drive.
• Halos. People with night vision problems complain of seeing halos or glares from light sources in dim areas. This is often an indication that the eye is unable to focus and process light correctly.

Diagnosis

Eye doctors diagnose night-vision issues a comprehensive eye exam. Your doctor will ask you questions about your medical history and conduct a series of tests with the objective of identifying a cause.

The doctor will use drops to dilate your eyes, then look at them through a slit-lamp, an upright microscope with a bright light. 

Many doctors also use the Pelli-Robson contrast sensitivity chart to detect night vision problems. The chart has several rows of letters of different shades of gray on a white background.

Some doctors may also request for a blood test to determine your glucose and Vitamin A levels.

Treatment Options

Treatment options for trouble seeing at night depend on the underlying cause of the condition. Many are treatable.

Cataract Surgery

Cataracts can be removed through surgery where the clouded lens is replaced with a clear, artificial lens known as an intraocular lens. Most report immediate improvement in their night vision although some still need glasses.

Zinc and Vitamin A Deficiency

Your doctor will recommend zinc and vitamin A supplements and  also advise you to adopt a balanced diet high in vitamins and vital minerals. Good sources of vitamin A include:

• Carrots
• Pumpkins
• Mangoes
• Cantaloupes
• Sweet potatoes
• Butternut squash
• Spinach
• Milk
• Eggs
• Collard greens

Good sources of Zinc include:

• Whole grains
• Milk products
• Oysters
• Red meat
• Poultry
• Baked beans
• Chickpeas
• Nuts such as almonds and cashews

Glaucoma Surgery

Treating glaucoma through laser treatments, eye drops or surgery may help improve your night vision. However, certain glaucoma medications, known as miotics, constrict the pupils resulting in reduced night vision.

Retinitis Pigmentosa

Unfortunately, retinitis pigmentosa is a genetic disorder that does not respond to retinal surgery or corrective lenses. Scientists are yet to find an effective treatment for retinitis pigmentosa.

Your doctor can advise you on ways to cope with decreased night vision and improve your quality of life.

Diabetic Retinopathy

Addressing diabetic retinopathy with laser treatments, surgery and anti-VEGF medication in addition to controlling your diabetes can help relieve your night vision problems.

Refractive Eye Surgery

If procedures such as LASIK or PRK are the cause of your night vision difficulties, your doctor can add an anti-refractive coating to your glasses to reduce halos and glares.

How to Improve Night Vision

Night-vision problems caused by genetics cannot be prevented. But you can improve your night vision and prevent vision loss by doing the following:

• Adopt a balanced diet rich in vitamin A and zinc.
• Schedule regular eye exams to detect signs of the disease and track progress.
• Maintain healthy glucose levels.
• Wear sunglasses outdoors, which should:
  • Filter out 75 to 90 percent of visible blue light
  • Block out 99 to 100 percent of UVA and UVB rays
  • Be large enough to protect your eyes from all sides
• Get regular exercise. Moderate exercise, at least three times a week, can significantly reduce your risk of disease including ocular conditions by lowering eye pressure and blood glucose levels.
• Update your optical prescription, either for eyeglasses or for contact lenses.

FAQs

Why is my vision so bad at night?

A few eye conditions can cause you to have poor night vision. If you are having trouble making out objects in dim light or adjusting to changes in lighting, contact your doctor as soon as possible. They will evaluate your symptoms and identify the cause of your night vision problems.

How can I improve my night vision?

The first step is to ensure that any night vision problems you might have are under control by visiting your doctor. You can also adopt a healthy diet, get regular exercise, corrective eye prescription and avoid prolonged exposure to sunlight.

What can affect night vision?

Some of the conditions and diseases that can affect night vision are:

• Cataracts
• Glaucoma
• Retinal disease including retinitis pigmentosa
• Refractive surgery such as LASIK and PRK
• Zinc and Vitamin A deficiency
• Diabetes
• Nearsightedness (myopia)

References

1. Night Vision. (December 2018). American Academy of Ophthalmology.

2. Night Blindness (Nyctalopia). (December 2020). Cleveland Clinic.

3. Shedding Light on Night Blindness. (September 2016). American Academy of Ophthalmology.

4. Night vision disturbances after successful LASIK surgery. (April 2007). British Journal of Ophthalmology.

5. Normal values for the Pelli-Robson contrast sensitivity test. (February 2001). Journal of Cataract & Refractive Surgery.

6. Retinitis Pigmentosa. (July 2019). National Eye Institute.

7. How can I improve my night vision? Are there glasses for night vision? (December 2010). American Academy of Ophthalmology.