A cataract is a clouding of the natural lens inside your eye that gradually blurs your vision. The lens sits just behind your pupil and is normally crystal clear, focusing light onto the back of your eye the way a camera lens focuses light onto film. When proteins in the lens clump together, they form opaque patches that scatter light instead of transmitting it, and your vision becomes hazy, dim, or washed out. Cataracts are the leading cause of blindness worldwide, though surgery to remove them is one of the most common and successful procedures in medicine.
How a Cataract Forms
Your eye’s lens is made almost entirely of water and tightly organized proteins. Those proteins are arranged in a precise structure that keeps the lens transparent to visible light. Over a lifetime, the proteins accumulate damage from ultraviolet radiation, oxidation, and normal metabolic wear. This damage destabilizes the proteins, causing them to partially unfold and expose sticky surfaces that were previously tucked away inside their structure.
Once exposed, these damaged proteins clump together into larger and larger aggregates. These clumps change the way light passes through the lens, scattering it instead of letting it travel in a straight line to your retina. The result is the cloudy, frosted-glass effect that defines a cataract. Because the damage accumulates slowly, cataracts typically take years to develop enough to affect your daily life.
Three Main Types
Not all cataracts form in the same part of the lens, and the location determines which symptoms you notice first.
- Nuclear sclerotic cataracts develop in the center of the lens. The core gradually yellows and hardens over years, shifting colors toward brown tones and making distant objects look blurry. In an odd early twist, this type can temporarily improve your close-up reading vision, sometimes called “second sight,” before overall vision worsens.
- Cortical cataracts form in the outer shell of the lens as spoke-like opacities that work inward. The hallmark symptom is glare, especially from oncoming headlights while driving at night.
- Posterior subcapsular cataracts develop on the back surface of the lens. They tend to progress faster than the other types and interfere with reading vision and bright-light situations early on.
Many people eventually develop more than one type, and each eye can progress at a different rate.
Symptoms to Recognize
Early cataracts often produce no noticeable symptoms at all. The changes are so gradual that your brain adapts, and you may not realize your vision has shifted until a routine eye exam picks it up. As the cataract grows, common signs include blurry or dim vision, increased sensitivity to light and glare, halos around lights, fading or yellowing of colors, trouble seeing at night, and double vision in a single eye. You might find yourself needing brighter light to read or frequently updating your glasses prescription without lasting improvement.
Because these changes creep in slowly, many people assume their vision is “just getting older” rather than recognizing a treatable condition. If colors look duller than they used to or nighttime driving has become noticeably harder, a cataract is a likely explanation.
What Raises Your Risk
Age is the dominant risk factor. Most cataracts are age-related, and the protein damage that drives them begins decades before symptoms appear. Beyond aging, several factors speed up the process.
Ultraviolet light exposure is one of the best-documented accelerators. Years of sun exposure without UV-blocking sunglasses increases the cumulative damage to lens proteins. Smoking roughly doubles the risk, likely because it floods the lens with oxidative chemicals. Diabetes raises risk significantly because high blood sugar alters the chemical environment inside the lens. Long-term use of corticosteroid medications, previous eye injuries, and prior eye surgery also increase the chances. Heavy alcohol use and a history of significant radiation exposure are additional contributors.
How Cataracts Are Diagnosed
An eye care professional can detect cataracts during a comprehensive dilated eye exam. The key tool is a slit lamp, a microscope with a thin beam of bright light that lets the examiner see the structures inside your eye at high magnification. By adjusting the angle and width of the light beam, the examiner can pinpoint where in the lens the clouding is located and grade its severity using a standardized classification system. The exam is painless and takes only a few minutes. Dilation drops widen your pupil to give a better view, but they temporarily blur your near vision for a few hours afterward.
When Surgery Becomes Necessary
There is no medication, eye drop, or exercise that reverses a cataract once it forms. The only treatment is surgical removal. That said, not every cataract needs immediate surgery. Many people live with mild cataracts for years by using stronger lighting, anti-glare sunglasses, or updated prescriptions. Surgery becomes worth considering when the cataract interferes with activities you care about: driving safely, reading, working on a computer, or recognizing faces.
The standard procedure, called phacoemulsification, uses ultrasound energy delivered through a tiny probe to break the clouded lens into fragments, which are then suctioned out through an incision roughly 2.5 millimeters wide. An artificial lens, called an intraocular lens (IOL), is folded, inserted through the same small incision, and unfolded into position inside the natural lens capsule. The whole procedure typically takes 15 to 30 minutes per eye under local anesthesia, and you go home the same day.
Choosing an Artificial Lens
The IOL implanted during surgery replaces your natural lens permanently, and the type you choose determines what kind of glasses (if any) you’ll need afterward.
- Monofocal lenses are the most common. They correct vision at one distance, usually set for seeing far away. Most people with monofocal lenses still wear reading glasses for close-up tasks. Some people opt for “monovision,” where one eye is set for distance and the other for near.
- Multifocal and extended depth of focus lenses are designed to reduce dependence on glasses at multiple distances. They work well for many people but can produce more glare and halos than monofocal lenses, especially at night.
- Toric lenses correct astigmatism in addition to the focusing power. They’re available in monofocal or multifocal versions and reduce the glare artifacts that people with astigmatism commonly experience.
- Light-adjustable lenses are a newer option. After implantation, your doctor fine-tunes the lens power using targeted UV light treatments in the office, allowing more precise correction once healing is underway.
Recovery After Surgery
Most people in well-resourced settings regain functional vision within a few weeks. The American Academy of Ophthalmology puts full recovery at 4 to 8 weeks. During the first week, you’ll use prescribed eye drops to prevent infection and control inflammation, and you’ll need to avoid rubbing your eye, heavy lifting, and swimming. Vision often improves noticeably within the first few days, though mild blurriness, light sensitivity, and a gritty sensation are normal during early healing.
The surgery has a high success rate. Complications like infection, significant swelling, or retinal detachment are rare. The most common long-term issue is posterior capsule opacification, where the membrane holding the IOL becomes hazy months or years later. This is easily treated with a quick, painless laser procedure in the office.
Can You Slow Cataract Development?
You can’t guarantee prevention, but several habits appear to slow progression. Wearing sunglasses that block both UVA and UVB light reduces the cumulative UV damage to lens proteins. Quitting smoking removes one of the strongest modifiable risk factors. Managing blood sugar levels matters for anyone with diabetes or prediabetes.
Diet plays a role as well, though the evidence is more nuanced. A large clinical trial (AREDS2) found that people with the lowest dietary intake of lutein and zeaxanthin, two pigments found in leafy greens and eggs, had a 32% lower risk of needing cataract surgery when they took supplements of those nutrients. However, the same research found that a broader antioxidant formula containing vitamin C, vitamin E, and beta carotene had no statistically significant effect on cataract progression. The practical takeaway: a diet rich in dark leafy greens, colorful vegetables, and whole foods likely offers more lens protection than high-dose vitamin supplements alone.