How is the intraocular lens (IOL) implanted?

The IOL is implanted in an outpatient surgical procedure that takes approximately 15 to 20 minutes.

In addition to a preoperative eye exam, measurements of the eye are taken to give the surgeon the necessary information to perform the procedure. These measurements include:

• Refractive error measurement;
• Pupil evaluation and size measurement;
• Measurement of the curvature (keratometry) and overall shape of the cornea (topography);
• Measurement of the length of the eye from the cornea to the retina (called an A-scan);
• Calculations to determine the correct power of lens (IOL) to use.

After the eye is numbed with topical or local anesthesia, one to three small incisions are made close to the edge of the cornea. A tiny, high-frequency ultrasound instrument is inserted into the eye to break up the center of the eye’s natural lens. The natural lens is then gently vacuumed out through one of the incisions. The IOL is folded and inserted through the same incision that was used to extract the natural lens and placed into the “capsular bag” that originally surrounded the natural lens. After the procedure, these incisions are usually “self-sealing,” requiring no stitches. Once the multifocal or accommodative IOL is implanted, your eye can focus on near, intermediate and far distances.

It should be noted that the focusing ability of the lens may not be fully realized for six to eight weeks after the procedure. In addition, your eye must relearn how to focus on objects at various distances in order to see clearly. Patients who are pilots, night drivers or those who spend a lot of time in front of the computer may not be good candidates for the multifocal or accommodative IOLs. Patients who are intolerant of a small amount of glare, halos, or both around lights, especially at night, may not be good candidates for these types of lenses.

• Some of the risks and possible side effects of IOL implantation include:
• Overcorrection or undercorrection (with a possible need for a retreatment);
• Infection;
• Increased floaters or retinal detachment;
• Dislocation of implant;
• Halos and glare;
• Decreased contrast sensitivity;
• Clouding or hazing of a portion of the IOL (called posterior capsular opacification);
• Dry eye;
• Possible need for additional surgery to fine-tune the IOL prescription;
• Loss of vision.

Cataract surgery is the removal of a cloudy human ("crystalline") lens followed by the insertion of and artificial (IOL) lens. During the removal of the crystalline lens the outer skin (capsular bag)of the cataract is left in place. This capsular bag is the used to hold the IOL as it will eventually collapse and heal around the IOL sealing it in place. Most modern implants are foldable and can be gently injected in its folded state into the capsular bag. The surgeon watches the IOL unfold slowly and can gently place it in the desired position. In most cataract surgeries the IOL is placed in the same position as the human lens, behind the iris. Occasionally this is not possible and a specially designed IOL can be placed in front of the iris. Sometimes the surgeon has to make the ultimate decision of which implant to use during the surgery.

The vast majority of patients who have undergone cataract surgery have an artificial intraocular lens (IOL) implanted to replace the clouded lens that is removed during surgery. Most often, surgeons place the new lens behind the iris, within the portion of the lens capsule that remains after surgery. Occasionally, the lens implant is inserted in front of the iris (colored part of the eye), especially if the capsule is faulty. In either case, plastic loops (called haptics) hold the implant in place.

Unlike some other eye surgeries, cataract surgery does not use lasers, except in some follow-up procedures. To remove the original lens during cataract surgery, the surgeon makes a tiny incision in the eye, a delicate procedure done with the aid of special surgical microscopes.