A cataract is a clouding of the natural lens inside your eye that causes blurry vision, glare, and faded colors. It’s the leading cause of blindness worldwide, affecting roughly 100 million people as of 2021. Cataracts develop slowly, often over years, and are overwhelmingly treatable with surgery when they start interfering with daily life.
How Cataracts Form
Your eye’s lens sits just behind the pupil and works like the lens of a camera, focusing light onto the retina at the back of your eye. The lens is made of specialized proteins called crystallins, which are arranged in precise patterns that keep the lens transparent. These proteins are extraordinarily soluble and don’t clump together under normal conditions.
Over time, those proteins accumulate damage from UV radiation, oxidation, and other chemical changes. This damage destabilizes the proteins, causing them to partially unfold and expose sticky surfaces that were previously hidden inside. Once exposed, these surfaces latch onto neighboring proteins, forming clumps large enough to scatter light. As more clumps form, the lens gradually becomes opaque, like fog spreading across a window. The result is a lens that no longer transmits a sharp image to your retina.
Types of Cataracts
Not all cataracts form in the same part of the lens, and the location affects which symptoms you notice first.
- Nuclear cataracts develop in the center of the lens. They tend to cause a gradual yellowing of vision and can temporarily improve close-up reading (sometimes called “second sight”) before worsening overall clarity.
- Cortical cataracts start as white, wedge-shaped streaks around the outer edge of the lens and work inward. They commonly cause problems with glare.
- Posterior subcapsular cataracts form as a small cloudy spot near the back of the lens, directly in the path of incoming light. These tend to progress faster than other types and are particularly disruptive to reading vision, bright-light vision, and night driving.
You can have more than one type at the same time, and each eye can progress at a different rate.
Common Symptoms
Cataracts rarely cause pain. Instead, you’ll notice gradual visual changes that may include blurred or dim vision, increased sensitivity to light and glare, halos around lights (especially at night), and colors that look faded or yellowed. Many people first realize something is wrong when nighttime driving becomes difficult or when they need brighter light for reading.
Because the clouding happens slowly, you may unconsciously adapt by holding things closer, turning on more lights, or avoiding night driving. A common early clue is needing frequent prescription changes for glasses that never quite seem right.
Who Gets Cataracts and Why
Age is the dominant risk factor. Most cataracts are age-related, and the majority of people will develop some degree of lens clouding by their 70s. But several other factors accelerate the process.
Diabetes is a well-established risk factor for cataracts, and the risk increases with longer duration of diabetes and poorer blood sugar control. Long-term use of corticosteroid medications, whether taken as pills or inhaled for asthma, also raises risk. UV exposure from sunlight contributes to the protein damage that drives lens clouding. Smoking, previous eye surgery, and eye injuries are additional contributors. Some cataracts are congenital, present at birth or developing in childhood, though these are far less common.
How Cataracts Are Diagnosed
A standard eye exam can detect cataracts, often before you notice symptoms yourself. Your eye doctor will typically perform several tests. A visual acuity test uses an eye chart to measure how well each eye reads at distance. A slit-lamp exam shines an intense, narrow line of light through the front of your eye, illuminating the lens in thin cross-sections so your doctor can pinpoint where clouding has formed and how dense it is. A retinal exam, done after dilating your pupils with drops, lets the doctor view the back of your eye and check for other conditions that might also be affecting your vision. An eye pressure test is usually included to screen for glaucoma.
These exams are painless and take about 30 minutes, though the dilating drops will blur your close-up vision for a few hours afterward.
When and How Cataracts Are Treated
Early cataracts don’t always need treatment. Updating your glasses prescription, using brighter lighting, and wearing anti-glare sunglasses can manage mild symptoms for months or even years. Surgery becomes the right option when vision loss interferes with activities that matter to you: driving, reading, working, or recognizing faces.
Cataract surgery is the most commonly performed surgery in the world, and over 95% of patients report significant improvement in vision. The procedure itself takes about 15 to 30 minutes per eye. Your surgeon makes a tiny incision (2 to 3 millimeters) in the cornea, uses an ultrasonic probe to break the clouded lens into small fragments, and suctions those fragments out. A clear artificial lens is then folded, inserted through the same small incision, and positioned where your natural lens used to sit. You’re awake during the procedure but numbing drops eliminate pain, and most people feel only mild pressure.
Choosing a Replacement Lens
The artificial lens implanted during surgery is permanent and doesn’t degrade over time. You’ll choose from a few options depending on your vision needs and the shape of your eye.
Monofocal lenses are the standard choice and are typically set for clear distance vision, meaning you’ll still need reading glasses afterward. Toric lenses are designed for people with significant astigmatism, a common condition where the cornea is slightly oval-shaped rather than round. In studies, toric lenses produced significantly better uncorrected vision at both near and far distances compared to standard monofocal lenses in patients with astigmatism. Multifocal and extended-depth-of-focus lenses aim to reduce dependence on glasses at all distances, though they can introduce halos or glare in some people, particularly at night. Your surgeon will recommend a lens type based on your eye measurements, lifestyle, and visual priorities.
What Recovery Looks Like
Most people notice clearer vision within a day or two, though it takes two to three weeks for vision to fully stabilize and up to a year for your eyes to feel completely normal. You can shower the day after surgery (just keep water from hitting your eye directly) and do light activities like walking right away.
For the first 48 hours, avoid bending over or putting your head below your waist, as this increases pressure inside the eye. Running, biking, golf, and similar exercise should wait 7 to 10 days. Swimming requires a two-week pause to minimize infection risk. You’ll use antibiotic and anti-inflammatory eye drops for several weeks, and your doctor may have you wear a protective shield over the eye at night while it heals. Avoid rubbing your eye during recovery.
Less than 10% of patients need a follow-up procedure within the first month due to complications. The most common issue months or years later is a condition where the thin membrane behind the implanted lens becomes cloudy, sometimes called a “secondary cataract.” This is easily treated with a quick, painless laser procedure in the office.
Can You Prevent Cataracts?
You can’t fully prevent age-related cataracts, but you can slow their progression. Wearing UV-blocking sunglasses outdoors reduces the cumulative light damage that destabilizes lens proteins. Not smoking removes one of the most significant modifiable risk factors. Managing blood sugar if you have diabetes directly lowers your cataract risk.
The role of nutrition is less clear-cut than supplement marketing suggests. A large clinical trial called AREDS2 tested daily supplements of lutein and zeaxanthin, two antioxidants concentrated in leafy greens and egg yolks, and found no overall effect on cataract progression or the need for surgery. The one exception: participants whose diets were already very low in these nutrients did show a 32% reduction in cataract surgery rates when they supplemented. This suggests that eating a diet rich in colorful fruits and vegetables matters more than taking pills, and that supplements may only help if your diet is notably poor in these nutrients to begin with. An earlier large trial testing vitamin C, vitamin E, and beta carotene also found no benefit for cataracts.