Have you ever noticed your vision becoming blurry, only to have it clear up after you blink?
Maybe you notice it while reading, driving, working at a computer, or looking at your phone. A few blinks make things sharp again, but later the blurriness returns.
It can be easy to assume that your prescription is changing or that your eyesight is getting worse. But when blurry vision comes and goes and improves with blinking, the problem may actually be occurring on the surface of your eye, rather than inside the eye itself.
I’m Dr. Scott Spector, an eye surgeon, and this is one of the most common vision complaints I see. The good news is that when the tear film is responsible, there are several simple things you can do to help.
Think of Your Eye Like a Car
I often tell my patients that the eye is a little like a car. There can be problems with the engine, or there can be problems with the windshield.
A cataract, for example, is a problem inside the eye. The natural lens becomes cloudy, affecting the way light travels through the eye.
But when vision becomes blurry and then clears after you blink, the problem may be more like a dirty or uneven windshield.
The front of your eye is covered by a very thin layer of tears called the tear film. Every time you blink, that tear film is spread across the surface of your eye.
And that film is much more important to your vision than most people realize.
Your Tear Film Is Part of Your Focusing System
When light enters your eye, it changes direction as it moves from one material to another. The surface at the front of your eye plays an important role in focusing that light.
That surface needs to be smooth and evenly coated with tears.
When the tear film is stable, the surface of the eye remains smooth, helping light focus properly.
But when the tear film begins to break up between blinks, the surface becomes less uniform. Light can scatter rather than focusing cleanly, and your vision can become blurry or fluctuate.
This is one reason dry eye can cause intermittent blurry vision.
Dry eye isn’t simply about having “no tears.” It can involve a tear film that doesn’t remain stable on the surface of the eye for as long as it should.
Try This Simple Blink Test
You can actually observe this yourself.
Find something across the room with small print, such as a book spine or a label.
Look at it and try not to blink for several seconds. Pay attention to the sharpness of the letters.
Then close your eyes completely and blink several times.
If the image becomes noticeably sharper after blinking, you may be seeing the effects of an unstable tear film.
That doesn’t necessarily mean your glasses prescription is wrong. Your prescription may be perfectly adequate, while the surface of your eye is temporarily affecting the quality of your vision.
Why Does the Tear Film Break Up?
There are several factors that can contribute to tear-film instability, and many people have more than one.
1. You’re Not Blinking Enough
When you’re reading, working on a computer, driving, or concentrating on a screen, you may blink less frequently or incompletely.
Blinking is what redistributes the tear film across the surface of the eye.
When you’re concentrating for long periods, your eyes may remain open for longer between blinks, giving the tear film more time to break up.
Try consciously blinking fully several times when you’ve been concentrating for a long period.
2. Aging Can Affect the Tear Film
The eyelids contain small oil-producing glands that contribute to the tear film and help slow evaporation.
As we age, these glands can change, which can affect the stability of the tear film.
This is one reason dry-eye symptoms and fluctuating vision can become more noticeable over time.
3. Hormonal Changes Can Play a Role
Hormonal changes can also affect the ocular surface and tear film.
Dry-eye symptoms are particularly common around certain stages of hormonal change, including menopause and perimenopause.
If you notice that your eye symptoms seem to change along with hormonal fluctuations, it is worth mentioning that pattern to your eye doctor.
4. Moving Air Can Increase Evaporation
Your environment can make a difference, too.
Why Are My Eyes Watering If They’re Dry?
This can be confusing.
If your eyes are dry, why do they sometimes water?
When the surface of your eye becomes irritated, your eyes can respond by producing a sudden increase in watery tears. These reflex tears don’t necessarily provide the same long-lasting stability as the normal tear film.
As a result, you can have watery eyes and dry-eye symptoms at the same time.
In other words, excessive tearing doesn’t necessarily mean that your eyes are adequately lubricated.
What Can You Do About Fluctuating Vision?
If your blurry vision improves with blinking, there are some simple things you can try.
Blink Fully and More Often
When you’re concentrating, make a conscious effort to blink completely.
After finishing a page of reading, a phone call, or a period of screen work, take a moment to close your eyes fully and blink several times.
It sounds simple, but maintaining a healthy tear film starts with the blink.
Position Your Screen Slightly Below Eye Level
Looking upward at a screen can leave more of the surface of your eye exposed.
Positioning your computer monitor so that you’re looking slightly downward can reduce the amount of exposed ocular surface and may help reduce evaporation.
Use a Warm Compress
A warm compress over closed eyelids can be part of a routine for people with certain types of dry-eye or eyelid-gland problems.
The warmth can help soften the oils produced by the glands along the eyelid margins.
The exact technique and duration can depend on the individual, so ask your eye doctor what approach is appropriate for you.
Reduce Direct Airflow
Try not to have air blowing directly toward your eyes.
In the car, redirect vents away from your face. If a fan blows directly across your face while you sleep, consider changing its position.
In dry indoor environments, adding humidity may also help.
Air blowing directly toward your eyes—from a car vent, ceiling fan, air conditioner, airplane vent, or heating system—can increase evaporation from the surface of your eyes.
You may notice your symptoms getting worse after spending several hours in a dry or highly air-conditioned environment.
When Blurry Vision May Be Something Else
Not every case of blurry vision is caused by dry eye.
If blinking doesn’t improve your vision, or if your vision remains blurry throughout the day, there may be another cause that needs to be evaluated.
Other symptoms that deserve attention include:
- Persistent blurry vision
- Difficulty seeing clearly at night
- Halos around lights
- Increasing difficulty reading
- Vision that is consistently worse in one eye
- Changes that don’t improve with blinking
These symptoms can have a variety of causes, including problems involving the lens or other structures inside the eye.
That’s why it’s important not to assume that every change in vision is simply dry eye.
Why the Surface of Your Eye Matters Before Vision-Correction Surgery
The health of the ocular surface is particularly important if you’re considering a procedure such as LASIK or another form of vision correction.
Before performing vision-correction surgery, your eye surgeon needs accurate measurements of your eyes.
If the tear film is unstable, those measurements can be affected.
That’s why evaluating and optimizing the surface of the eye is an important part of preparing for certain vision-correction procedures.
In other words, before addressing the “engine,” it’s important to make sure the “windshield” is in good shape.
When Should You Call Your Eye Doctor?
Fluctuating vision that improves with blinking is often associated with tear-film instability, but sudden changes in vision should never automatically be attributed to dry eye.
If you experience sudden vision loss or a sudden change in vision in one eye, a sudden shower of new floaters, flashes of light, or a curtain or shadow moving across your vision, contact an eye-care professional promptly.
These symptoms can indicate a more serious eye problem and should be evaluated rather than watched at home.
The Bottom Line
If your vision becomes blurry and then sharpens after you blink, the problem may not be that your eyes are “getting worse.”
Your tear film may simply be breaking up between blinks and temporarily affecting the optical surface of your eye.
Start by paying attention to when the blurriness occurs. Notice whether it improves after a full blink, whether it gets worse during prolonged screen use, and whether your environment seems to make a difference.
Your eyes have a windshield—and keeping that windshield healthy can make a surprising difference in how clearly you see.
