Cataract surgery removes the cloudy natural lens from your eye and replaces it with a clear artificial one. The entire procedure takes about an hour, is nearly painless, and you go home the same day. It’s one of the most commonly performed surgeries in the world, with complication-free outcomes in nearly 99% of cases.
Before Surgery: Measuring Your Eye
In the days or weeks before your procedure, your eye doctor takes precise measurements of your eye to determine the right replacement lens. This process, called biometry, involves two key measurements: the curvature of your cornea (the clear front surface of your eye) and the length of the eye from front to back. Corneal curvature is measured with a device called a keratometer or a more detailed corneal topographer. Eye length is measured using either ultrasound or a laser-based method that calculates the distance from the cornea to the retina.
These numbers feed into a formula that calculates the exact optical power your new lens needs to give you the clearest possible vision after surgery. The accuracy of the length measurement is especially important, since even small errors change the outcome. If you have astigmatism, your doctor will also map the shape of your cornea in detail to decide whether a specialized lens can correct it.
How Your Eye Is Numbed
Cataract surgery doesn’t require general anesthesia. The two most common approaches are topical anesthesia and a technique called sub-Tenon’s block. With topical anesthesia, numbing drops (sometimes supplemented with a gel) are applied directly to the surface of your eye. In many cases, an additional numbing agent is injected inside the eye through a tiny incision during surgery for deeper pain control. A sub-Tenon’s block involves depositing anesthetic beneath a thin membrane covering the eye, which numbs it more completely. Either way, you’re awake but comfortable, and you won’t feel sharp pain during the procedure.
The Step-by-Step Procedure
The standard technique used today is called phacoemulsification. Your surgeon works through incisions so small they typically don’t need stitches.
First, the surgeon creates a tiny main incision in the cornea, usually between 2.8 and 3.2 millimeters wide, along with one or two even smaller side openings. Through these, a special dye is used to make the front surface of the lens capsule (the thin membrane surrounding the lens) easier to see. The surgeon then carefully tears a circular opening in that capsule, creating a window to access the cloudy lens inside.
Next comes hydrodissection: a gentle stream of fluid is injected between the lens and its capsule to loosen and separate them. This allows the lens to rotate freely inside its bag. The surgeon then uses an ultrasonic probe, inserted through the main incision, to break the hard central core of the lens into fragments. The probe vibrates at extremely high frequency, emulsifying the cloudy lens material into tiny pieces that are simultaneously suctioned out. After the core is gone, the softer outer layer of the lens is irrigated and aspirated from the capsular bag.
Finally, the artificial replacement lens is folded and loaded into an injector, which slides it through the same small incision. Once inside the eye, the lens unfolds and is positioned within the now-empty capsular bag, where it stays permanently. The tiny corneal incisions seal on their own.
Laser-Assisted Surgery
Some surgeons use a femtosecond laser to perform several of the early steps before switching to the standard ultrasonic probe. The laser creates the corneal incisions, the circular capsule opening, and pre-fragments the lens with greater precision and reproducibility than manual techniques.
The practical advantages are measurable. The laser-created capsule opening is more perfectly circular and consistently sized, which helps the replacement lens sit centered and stable over time. Corneal incisions made by the laser show more precise positioning and less tissue disruption, with studies finding less corneal swelling and reduced damage to the delicate cell layer on the inner surface of the cornea. One randomized study found 8% cell loss in the laser group versus nearly 14% in the conventional group at three months.
Perhaps the biggest difference is in ultrasound energy. Because the laser pre-softens and fragments the lens, the amount of ultrasound needed drops dramatically. One study of 150 patients found an 83% reduction in ultrasound energy in the laser group, with 30% of those patients needing zero ultrasound at all. For softer cataracts, some surgeons report eliminating ultrasound entirely in 100% of cases. Less ultrasound means less stress on the inner structures of the eye.
Laser-assisted surgery typically costs more and isn’t always covered by insurance. For most patients, both approaches produce excellent results.
Choosing a Replacement Lens
The artificial lens implanted in your eye is permanent, so the choice matters. There are three main types:
- Monofocal lenses are the standard option. They correct vision at one distance, usually far. Most people with monofocal lenses still need reading glasses for close-up tasks like books or phones.
- Multifocal or accommodating lenses are designed to reduce dependence on glasses at multiple distances, including near, intermediate, and far. They work well for many people but can sometimes cause glare or halos around lights, especially at night.
- Toric lenses correct astigmatism, the uneven curvature of the cornea that causes blurred or distorted vision. If you have significant astigmatism, a toric lens can reduce or eliminate the need for astigmatism-correcting glasses after surgery.
Multifocal and toric lenses are considered premium options and often come with extra out-of-pocket costs. The decision depends on your pre-existing astigmatism, how much you want to avoid glasses afterward, and your budget. Your surgeon will walk through the tradeoffs based on your eye measurements.
Recovery and What to Expect After
After the lens is placed, you rest briefly in a recovery area while the medical team checks your eye for any immediate problems. You’ll need someone to drive you home. Most people notice improved vision within a day or two, though it continues to sharpen as the eye heals over the following weeks.
You’ll use prescription eye drops for several weeks to prevent infection and control inflammation. For the first couple of weeks, avoid heavy lifting and vigorous exercise, which can raise pressure inside the eye. Swimming and hot tubs are typically off-limits for a few weeks as well, to reduce infection risk. Most daily activities, including reading, watching TV, and light walking, can resume almost immediately.
Risks and Complication Rates
Cataract surgery has one of the highest success rates of any surgical procedure. Data from the University of Utah’s Moran Eye Center in 2024 showed that out of 4,919 surgeries, intraoperative complications occurred in only 1.14% of cases. The most feared complication, a serious eye infection called endophthalmitis, occurred in just 1 out of those nearly 5,000 surgeries (0.02%). Across multiple large studies in the U.S., Europe, and Asia, the rate of this infection averages about 1 in 1,500.
The most common long-term issue is posterior capsule opacification, sometimes called a “secondary cataract.” This happens when the thin membrane left behind to support the new lens gradually becomes cloudy. It affects roughly 21% of patients within two years and about 29% within five years. The fix is quick and straightforward: a painless laser treatment creates a small opening in the cloudy membrane, restoring clear vision. It takes a few minutes in the office and only needs to be done once.