A cataract is a clouding of the normally clear lens inside your eye. The lens sits behind your iris (the colored part) and focuses light onto the retina at the back of your eye. When that lens turns cloudy, it scatters light instead of focusing it, and your vision becomes blurry, dim, or washed out. Cataracts are the leading cause of blindness worldwide, though they’re highly treatable with surgery.
What Happens Inside the Lens
Your eye’s lens is made mostly of water and tightly organized proteins called crystallins. These proteins are arranged with remarkable precision, which is what keeps the lens transparent. For the lens to stay clear, every one of those proteins needs to hold its shape and stay dissolved in the surrounding fluid.
Over time, those proteins accumulate damage from UV radiation, oxidation, and other chemical changes. The damaged proteins begin to unfold and clump together into large, insoluble clusters. These clusters scatter incoming light instead of letting it pass through cleanly. The result is the foggy, frosted-glass effect that defines a cataract. The lens also has a built-in repair system (chaperone proteins that try to keep other proteins properly folded), but eventually the volume of damaged proteins overwhelms it.
How Cataracts Affect Your Vision
Cataracts develop gradually, so early changes can be easy to dismiss. You might notice you need a brighter lamp to read, or that night driving feels harder than it used to. Colors may look faded or take on a yellowish tint. Many people describe their vision as looking through a fogged-up window.
Common symptoms include:
- Blurred, cloudy, or dim vision
- Halos or starbursts around lights, especially at night
- Increased sensitivity to glare from sunlight or headlights
- Fading or yellowing of colors
- Frequent changes in your glasses prescription
- Double vision in one eye
One quirk of early nuclear cataracts is a temporary improvement in near vision, sometimes called “second sight.” The lens changes its refractive power as it hardens, briefly reducing the need for reading glasses. This improvement doesn’t last, and overall vision continues to decline.
Types of Cataracts
Not all cataracts form in the same part of the lens, and the type affects which symptoms show up first.
Nuclear cataracts develop in the center of the lens. The nucleus slowly yellows and hardens over years. Because the clouding is right in the middle of your line of sight, this type tends to affect distance vision first and can cause that temporary near-vision improvement mentioned above. Nuclear cataracts are the most common age-related type.
Cortical cataracts start in the outer shell of the lens, forming white, wedge-shaped streaks that work inward like spokes on a wheel. These are particularly likely to cause glare problems because the opaque streaks scatter light at the edges of the lens.
Posterior subcapsular cataracts form on the back surface of the lens, right in the path of light heading toward the retina. They tend to progress faster than the other types and are especially disruptive for reading and bright-light situations. This type is more common in people with diabetes or those who have used corticosteroid medications long-term.
What Raises Your Risk
Age is the primary driver. Most cataracts appear after 60, and by 80 more than half of people either have a cataract or have had one removed. But several other factors speed up the process considerably.
Diabetes is one of the strongest risk factors. Uncontrolled blood sugar accelerates chemical changes in the lens, and studies have found up to a fivefold increase in cataract prevalence among diabetic patients compared to non-diabetic individuals. Cortical and posterior subcapsular cataracts are especially common in this group.
Smoking exposes the lens to toxic compounds that directly damage lens proteins. One compound found in cigarette smoke disrupts the structure of a key crystallin protein. Smoking also depletes protective antioxidants like vitamin C and glutathione, leaving the lens more vulnerable to oxidative damage. Heavy metals in cigarettes, including lead and cadmium, further strip away the lens’s chemical defenses.
High blood pressure has been identified as an independent risk factor. Research has linked elevated systolic blood pressure to increased cataract development, possibly through chronic inflammation and oxidative stress in the lens. Some blood pressure medications that affect electrolyte balance across lens fibers may also contribute.
Other established risk factors include prolonged UV exposure without eye protection, heavy alcohol use, previous eye injuries or surgeries, and long-term use of corticosteroid medications.
How Cataracts Are Diagnosed
A routine dilated eye exam is the standard way cataracts are found. Your eye doctor will use a slit lamp, a microscope with a bright light, to examine the lens for clouding. They’ll also test your visual acuity (how clearly you can read letters at a distance) and may check how well you handle glare. Many cataracts are caught before you notice significant symptoms, which is one reason regular eye exams matter after age 40.
When Surgery Becomes the Right Call
There is no medication, eye drop, or supplement that reverses a cataract once it forms. Stronger lighting, updated glasses prescriptions, and anti-glare sunglasses can help you manage mild cataracts for a while. But when clouded vision starts interfering with daily life (driving, reading, working, recognizing faces), surgery is the only effective treatment.
The most common procedure uses a small probe inserted through a tiny incision in the eye. The probe emits ultrasound energy that breaks the clouded lens into fragments, which are then suctioned out. An artificial lens, called an intraocular lens (IOL), is placed in the same capsule that held your natural lens. The entire procedure typically takes under 30 minutes per eye and is done under local anesthesia.
Cataract surgery is one of the most frequently performed and safest surgeries in medicine. Data from the Moran Eye Center at the University of Utah showed that in 2024, nearly 99% of their cataract surgeries were complication-free across almost 5,000 procedures. Serious infections occurred in just 0.02% of cases.
Recovery After Surgery
Vision typically starts improving within a few days. Most people experience mild itching and discomfort for the first couple of days, which fades quickly. Full healing usually takes about eight weeks. You’ll have follow-up appointments the day after surgery and again about a month later to monitor healing.
Your eye doctor will wait until your eye has fully stabilized, usually one to three months after surgery, before writing a final eyeglass prescription. Depending on the type of artificial lens you received, you may still need glasses for certain tasks.
Choosing a Replacement Lens
The artificial lens implanted during surgery is permanent, so the choice matters. Several types are available, each with trade-offs.
- Monofocal lenses provide sharp vision at one distance. Most people choose to set them for distance and use reading glasses for close work. This is the most common and time-tested option.
- Multifocal lenses have built-in zones for near and far vision, similar to bifocal glasses. Some also correct intermediate distances. They reduce dependence on glasses but can cause halos around lights at night.
- Extended depth-of-focus (EDOF) lenses stretch a single corrective zone to cover distance and intermediate vision. They tend to produce fewer nighttime halos than multifocals.
- Toric lenses correct astigmatism in addition to replacing the clouded lens. They’re available in monofocal and some multifocal versions.
- Light-adjustable lenses are a newer option that can be fine-tuned after surgery using UV light treatments. This allows your doctor to correct any remaining prescription error once your eye has healed.
Another approach is monovision: setting one eye’s lens for distance and the other for near vision. This works well for some people but requires an adjustment period as your brain learns to favor the appropriate eye for each task. Your surgeon can help you trial this approach with contact lenses before committing.