Why Is Your Night Vision Blurry?
March 02, 2023
You see well during the day, but the moment the sun goes down your vision seems to belong to a different set of eyes. So what causes the quality of your vision to change at night – and what can you do about it?
Poor night vision can be divided into three categories, each with their own causes. When the eye is out of focus and things appear fuzzy, it’s called night blurriness. When a bright light causes streaks or halos, the problem is glare. When someone has a tough time seeing anything at all in the dark, it’s called night blindness.
“It’s normal to see slightly worse at night because of a lack of contrast. But you should recognize any significant night vision issues that interfere with your ability to do things such as drive or find your way around in poorly illuminated areas,” says University Hospitals optometrist Thomas Stokkermans, OD, PhD.
“It’s important to discuss those problems with an eye care specialist who can examine your eyes, answer questions and provide the right care and treatment for your specific issue, offering you a life of healthier vision and less stress.”
Night Blurriness and Night Glare
The main symptom of poor night vision is difficulty seeing well in dark or dim lighting, especially when transitioning from a brighter to a lower light environment, like walking into a dimly lit room. Many people experience difficulty driving at night, particularly from the glare of streetlights or headlights from oncoming traffic.
Blurry or fuzzy night vision and glare have several possible causes.
Refractive errors. Nearsightedness, farsightedness or astigmatism can all cause night blurriness if someone is not wearing prescription glasses to correct their vision. Roughly half of people are affected by vision problems caused by refractive errors.
Night myopia. This occurs when the eye becomes more near-sighted in dark conditions, possibly due to the eye’s lack of ability to adjust or focus in dim light. Night myopia affects younger people, especially teenagers, more than others. While its exact cause is unknown, it may be due to nearsightedness that doesn’t seem significant in daylight and is therefore undiagnosed, or it may be an inability of the eyes to focus correctly in the dark.
Cataracts. As we age, the crystalline lens inside the eye slowly grows bigger, hardens and becomes cloudy. The prevalence of cataracts at age 65 is about 90 percent.
Dry eyes. A poor tear film can compromise vision. Often the first sign of dry eye is a blur that changes when you blink. Especially at night, you concentrate to see better and blink less. This causes even drier eyes and more blur.
Refractive surgery. When the pupil dilates in dim light, it becomes larger than the area of the cornea treated in refractive surgery. Vision beyond the cornea’s surgically corrected focus can cause night blurriness and glare.
Corneal scars due to injury or disease can cause glare or fuzzy areas in vision.
Difficulty seeing anything in the dark, even after an adjustment period of 10-20 minutes, happens when the retina cannot adapt. Night blindness is usually a sign of a toxicity or disease, or a result of aging.
Small pupils reduce the amount of light entering the eye and usually cause only mild night blindness. There are many causes for small pupil size. Pupils get smaller with age, so older people are at higher risk for night blindness. Pupil size can also be reduced by medications prescribed for glaucoma or presbyopia (the inability to focus close-up); narcotic drugs; toxicity from certain compounds in sedative, anxiety and blood pressure drugs; diseases such as diabetes; toxins in pesticides; inflammation in the eye; and cluster headaches.
Pan retinal photocoagulation (PRP), a treatment for advanced diabetic retinopathy and some vein obstructions of the eye, can cause moderate night blindness and tunnel vision.
Vitamin A deficiency, although extremely rare in the U.S., too little vitamin A can cause severe night blindness. In some cases, bariatric surgery can interfere with vitamin A absorption and result in dry skin, dry eyes and night blindness.
Retinitis pigmentosa and choroideremia are progressive diseases that cause severe night blindness and tunnel vision and can result in complete blindness.
“For the best possible quality night vision, wear glasses when they are prescribed for driving and don’t wait too long to have cataract surgery," says Dr. Stokkermans. "Also, don’t wait to see an eye care specialist for an exam if you can’t see anything in the dark after an adjustment period of 10-20 minutes, as this could indicate true night blindness.”
At University Hospitals, our team of board-certified ophthalmologists have the expertise to diagnose and treat a full spectrum of eye diseases and disorders in both adults and children. Learn more.