How cataracts develop and what you notice first
Cataracts form when the lens in your eye becomes cloudy. This happens gradually in most people, which means the early signs are subtle—you might notice them only in certain light or only in one eye at first. The cloudiness starts small and spreads over months or years, so the symptoms you experience depend on how far the cataract has progressed and where in the lens it sits.
The earliest sign is often a slight blurriness or haziness in your vision, as though you are looking through a dirty window. You might also notice that colors appear less bright or slightly yellowed, or that you need more light to read comfortably. Some people describe it as a film over their vision that does not go away when they blink or clean their glasses.
Key Takeaways
- Early cataracts often cause blurred or hazy vision, difficulty with night driving, and colors that appear duller or more yellow.
- Glare and halos around lights—especially headlights or streetlights—are common signs that a cataract is affecting how light enters your eye.
- You may need stronger glasses or more frequent prescription changes as the cataract grows, even though new glasses cannot fully correct the cloudiness.
- An eye doctor can see a cataract during a routine eye exam before you notice symptoms, so regular checkups catch them early.
- Cataracts develop at different speeds in different people; some grow slowly over years while others progress faster.
Vision changes that point to a cataract
Blurred or fuzzy vision is the most common symptom, but it does not feel like the blur you get from needing new glasses. With a cataract, the blur stays even after you blink, and new glasses may help only a little. You might find that one eye is blurrier than the other, since cataracts often develop in one eye first.
Difficulty seeing at night or while driving is another early warning sign. Headlights from oncoming cars, streetlights, or even dashboard lights may create halos or starbursts around them. This happens because the cloudy lens scatters light instead of focusing it clearly. You might also feel that you need the headlights brighter than before, or that you are less confident driving after dark.
Colors may look faded, yellowed, or less vibrant than they used to. This occurs because the clouding lens filters light and shifts how colors reach the back of your eye. Over time, this color shift becomes more noticeable—whites may look yellowish, and blues and purples may be harder to tell apart.
Changes in how you need your glasses
A sudden or frequent need for a new glasses prescription can signal a developing cataract. As the lens becomes cloudier, its shape and density change, which shifts how light bends through your eye. You might find that your current prescription no longer works well, even though you just got new glasses months ago.
This is different from the gradual prescription changes that happen with aging. If your eye doctor measures your vision and finds that your prescription has shifted significantly in a short time, they will look more carefully at the lens to see if a cataract is forming. Sometimes a new glasses prescription helps temporarily, but as the cataract grows, stronger glasses will not restore clear vision.
When to schedule an eye exam
You should see an eye doctor if you notice any of the symptoms above—blurred vision, difficulty with night driving, glare around lights, or a sudden change in your glasses prescription. An eye doctor can confirm whether you have a cataract and how advanced it is, even if your symptoms are mild.
If you do not notice symptoms but are over 60, have diabetes, take certain medications like steroids, or have had an eye injury, ask your eye doctor how often you should have your eyes checked. Many cataracts are found during routine exams before the person realizes they have one. Regular eye exams are the most reliable way to catch cataracts early.
If you have a cataract that is not yet affecting your daily life, you do not need treatment right away. Your eye doctor will monitor it over time and discuss with you when surgery might become necessary. The decision to have surgery depends on how much the cataract interferes with your work, hobbies, or safety—not on the cataract's size alone.
What an eye doctor sees during an exam
During a standard eye exam, your eye doctor uses a slit lamp—a microscope with a bright light—to look directly at your lens. A cataract appears as a cloudy or opaque area within the lens. The doctor can see it even if you have not noticed symptoms yet, which is why cataracts are often found during routine checkups.
Your eye doctor will also measure how much the cataract is affecting your vision using a standard eye chart and other tests. They may dilate your pupils with drops to get a better view of the lens and the back of your eye. This entire process takes only a few minutes and is painless.
Cataracts in one eye versus both eyes
Cataracts can develop in one eye or both, and they do not always progress at the same rate. If you have a cataract in only one eye, you might not notice it at first because your other eye compensates. You may only realize something is wrong when you cover your good eye and notice how much hazier the other one is.
If both eyes have cataracts, the symptoms are usually more obvious because you cannot rely on one clear eye. Some people develop cataracts in both eyes but at different speeds—one may need surgery years before the other. Your eye doctor will monitor each eye separately and discuss treatment timing with you.
Symptoms that are not cataracts
Some vision problems feel similar to cataracts but have different causes. Presbyopia—difficulty focusing on close objects as you age—is common and is not a cataract. Dry eyes can cause blurred vision and glare sensitivity but usually improve with eye drops. Floaters (small specks that drift across your vision) are usually harmless and are not cataracts.
If you experience sudden vision loss, eye pain, flashing lights, or a shower of floaters, contact an eye doctor right away. These can signal other eye conditions that need prompt attention. A cataract develops slowly and does not cause pain, so sudden symptoms warrant immediate evaluation.
Frequently Asked Questions
Can you have a cataract and not know it?
Yes. Many cataracts are found during routine eye exams before a person notices any symptoms. Early cataracts may not affect vision enough to be noticeable, especially if they are small or at the edge of the lens. Your eye doctor can see them with a slit lamp even when you cannot feel a difference in how you see.
Does a cataract always get worse?
Cataracts progress at different rates in different people. Some grow slowly over many years and may never significantly affect vision. Others progress faster. Once a cataract forms, it does not go away on its own, but it may stay stable for a long time. Your eye doctor can track how it changes during regular exams.
What if I see halos around lights but my eye doctor says I do not have a cataract?
Halos can be caused by other conditions, including astigmatism, dry eyes, or certain eye surgeries. Your eye doctor can determine the cause during an exam. If halos are bothersome, there are treatments depending on what is causing them.
Can you drive safely with a cataract?
That depends on how much the cataract affects your vision and your ability to see the road clearly. If a cataract makes night driving difficult or unsafe, you may need to limit driving or have surgery. Talk with your eye doctor about whether it is safe for you to drive, and be honest about any situations where your vision makes you uncomfortable.
Does wearing sunglasses prevent cataracts?
Sunglasses that block ultraviolet (UV) light may slow cataract development, especially if you spend a lot of time outdoors. However, cataracts develop for many reasons—age, genetics, and certain health conditions all play a role. Sunglasses are one protective measure, but they cannot prevent cataracts entirely.