Poor night vision is surprisingly common, and it usually comes down to how well your eyes collect and process the small amount of light available after dark. The causes range from simple things like dry eyes or a mild vitamin deficiency to age-related changes and, less often, conditions that need medical attention. Understanding what’s behind your difficulty can help you figure out whether it’s something easily fixable or worth bringing up with an eye doctor.
How Your Eyes See in the Dark
Your retina contains two types of light-detecting cells: cones, which handle color and detail in bright light, and rods, which take over in dim conditions. You have roughly 120 million rod cells compared to about 6 million cones, and those rods are what make night vision possible. They contain a light-sensitive pigment called rhodopsin, built from a protein and a form of vitamin A. When even a tiny amount of light hits rhodopsin, it triggers a chemical chain reaction that sends a signal to your brain.
After you step from a bright room into darkness, your rods need time to fully reactivate. This process, called dark adaptation, can take 20 to 30 minutes to complete. During that adjustment window, your vision feels noticeably worse. Anything that interferes with your rod cells, the rhodopsin pigment inside them, or the amount of light reaching your retina can make night vision significantly harder.
Age Is the Most Common Factor
If you’re over 40 and your night vision has gradually worsened, age is the most likely explanation. Two things happen as you get older. First, your pupils don’t open as wide in the dark as they used to, which limits how much light enters your eye. By age 60, the retina typically receives only about one-third the light that a 20-year-old’s retina gets. That’s a dramatic reduction, and it directly translates to dimmer, less detailed vision at night.
Second, the lens inside your eye slowly loses its clarity. Early cataracts are extremely common in people over 50, and they scatter incoming light rather than focusing it sharply. This scattering is why oncoming headlights seem to bloom into blinding glare, and why you might see halos or starbursts around streetlights. A specific type called a posterior subcapsular cataract is especially problematic at night because it forms right in the path light travels through the lens. Cataracts develop gradually, so you may not realize how much your night vision has declined until driving after dark starts feeling genuinely stressful.
Dry Eyes and Tear Film Problems
This one surprises most people. The thin layer of tears coating your cornea is actually the first surface that light passes through before it reaches the rest of your eye. When that tear film is stable and smooth, light enters cleanly. When it’s disrupted, light scatters.
Dry eye disease degrades the tear film through insufficient tear production, poor tear quality, or both. The result is increased stray light entering the eye, reduced contrast sensitivity, and those annoying halos or starbursts around lights at night. Dry eyes also contribute to irregular astigmatism and higher-order optical aberrations, which are essentially small distortions in how your eye focuses light. If your night vision problems are worse after long screen sessions, in air-conditioned rooms, or toward the end of the day, dry eyes could be a significant contributor. The good news is that this is one of the most treatable causes of poor night vision.
Vitamin A Deficiency
Rhodopsin, the pigment your rod cells depend on, cannot be made without vitamin A. Specifically, the active light-catching component of rhodopsin is a form of vitamin A called 11-cis-retinal. Without enough of it, your rod cells simply can’t regenerate their pigment fast enough to keep up with demand, and night vision suffers. Acute vitamin A deprivation directly impairs rod cell function and causes what doctors call nyctalopia, or night blindness.
True vitamin A deficiency is rare in developed countries if you eat a varied diet, but it can happen. People who’ve had bariatric surgery, those with conditions that impair fat absorption (like Crohn’s disease or celiac disease), and people on very restrictive diets are at higher risk. Orange and yellow vegetables, leafy greens, eggs, and liver are all rich sources. If a deficiency is the cause, improving your intake can restore night vision relatively quickly.
Nearsightedness and Uncorrected Prescriptions
Your pupils dilate in low light to let in more photons, but a wider pupil also means light enters through more of your lens and cornea, including the less optically precise edges. For people with even mild nearsightedness or astigmatism, this amplifies visual errors that are barely noticeable during the day. You might see fine with your current glasses in a well-lit office but struggle to read road signs after sunset.
An outdated prescription is one of the simplest explanations for worsening night vision. If it’s been more than a year or two since your last eye exam, an updated prescription alone could make a meaningful difference. Some people also benefit from glasses with an anti-reflective coating, which reduces the internal reflections that contribute to glare from headlights and streetlights.
Glaucoma and Optic Nerve Damage
Glaucoma damages the optic nerve, and one of its less well-known effects is reduced ability to see in dim conditions. People with even early to moderate glaucoma show measurably poorer contrast sensitivity compared to healthy eyes, and the difference becomes more pronounced at lower light levels. In one study, people with glaucoma had 7% lower accuracy at recognizing common objects under medium-contrast conditions simulating fog or dusk compared to controls.
Glaucoma also impairs dark adaptation, meaning it takes longer and works less completely. Because glaucoma typically damages peripheral vision first, you may notice that objects at the edges of your visual field seem to disappear more in dim lighting. The tricky part is that glaucoma progresses slowly and painlessly, so worsening night vision might be the first thing that catches your attention.
Retinitis Pigmentosa
Retinitis pigmentosa (RP) is a genetic condition that gradually destroys rod cells. Because rods are your primary night vision cells, difficulty seeing in the dark is often the earliest symptom, sometimes appearing in childhood or adolescence. Parents may notice that a child has unusual trouble navigating dimly lit rooms or adjusting when moving from bright to dark environments.
RP also causes progressive loss of peripheral vision, creating a “tunnel vision” effect that worsens over years or decades. It’s far less common than the other causes on this list, but if your night blindness started early in life and has steadily progressed alongside shrinking side vision, RP is worth ruling out. Diagnosis involves a dilated eye exam, a test called electroretinography that measures how your retina responds to light, and often genetic testing to identify the specific type.
What an Eye Doctor Looks For
When you describe night vision problems, an eye doctor will typically check several things. A standard dilated exam reveals cataracts, retinal changes, and signs of glaucoma. A visual field test maps your peripheral vision. If contrast sensitivity is a concern, they may use a specialized chart called the Pelli-Robson chart, which displays letters at progressively lower contrast levels against a white background. Your ability to read fading gray letters on a white page directly reflects how well you’d distinguish objects in low-light, low-contrast real-world conditions like nighttime driving.
For suspected RP or other retinal diseases, additional imaging of the retina and electrical testing of rod and cone cell function can pinpoint where the problem lies. In many cases, though, the cause turns out to be something straightforward: an outdated prescription, early cataracts, or dry eyes. All three are manageable, and addressing them can make nighttime driving and moving through dim spaces noticeably easier.