A cataract forms when the lens of the eye becomes cloudy. This commonly occurs as part of the aging process, although certain factors can accelerate this condition. Cataracts interfere with vision by blocking light from entering the eye. If left untreated, they can lead to blindness.

The lens of the eye is located behind the pupil. During cataract extraction surgery, the pupil is dilated to make it as large as possible. The surgeon makes a few tiny incisions at the edge of the cornea—the clear tissue at the front of the eye—to access the pupil. Instruments are then inserted through the pupil and used to remove the cloudy lens.

The traditional technique of cataract removal is known as extracapsular cataract extraction (ECCE). The lens of the eye sits in an envelope of clear connective tissue called the capsule, which keeps the lens in place. During ECCE, an incision is made on the front of the capsule, and the cloudy lens is removed in one piece. In some cases, this process may be more challenging, requiring additional surgical equipment or techniques to safely remove the lens. This is known as complex ECCE. It is not always possible to determine in advance whether a particular ECCE procedure will be complex, and this is typically reported by the surgeon afterward.

A newer technique called phacoemulsification, or simply phaco, can also be used to remove cataracts. Phaco involves using ultrasound waves to break up the cloudy lens into very small pieces, which are then removed by suction. This method allows for much smaller incisions, leading to faster recovery times. Phaco has become the standard technique for cataract removal in the U.S., although ECCE is still used in certain cases.

To restore good vision after cataract surgery, it is necessary to replace the eye’s natural lens with an artificial one. Whether the cloudy lens has been removed through ECCE or phaco, the next step is to place an intraocular lens (IOL) into the remaining part of the capsule to hold it in place behind the pupil.

There are various types of IOLs available. The standard IOL is a monofocal IOL, which has a single focal point optimized for distance vision. People with monofocal IOLs generally need reading glasses for near vision. Additional premium IOL options include multifocal IOLs, which have different discrete focal distances within the same lens, and accommodating IOLs, which can change shape to adjust their focal distance, mimicking the natural lens’s functionality. Premium IOLs typically involve an additional cost to the patient.