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Artificial lenses used to correct vision

Procedure is relatively safe, effective.

Dharmendra (Dave) Patel, M.D.

Medical Edge from Mayo Clinic

September 16, 2010

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DEAR MAYO CLINIC: What are intraocular lenses? Are the lenses themselves and the procedure to place them considered safe?

ANSWER: Intraocular lenses are artificial lenses placed within the eye to correct a person's vision. The lenses are approved by the Food and Drug Administration (FDA), and the risk of complications associated with the procedure to place the lenses is low.

Intraocular lenses have long been successfully used to replace natural lenses that are removed due to a cataract—clouding of an eye's normally clear lens. During cataract surgery, the damaged lens is taken out, and an intraocular lens is implanted in its place. Intraocular lenses are made of plastic, acrylic or silicone. Once placed, intraocular lenses can't be seen or felt. They become a permanent part of the eye and don't require any care.

A variety of intraocular lenses with different features are available. Some lenses are rigid plastic and implanted through an incision that requires several stitches to close. However, many intraocular lenses are flexible, allowing a smaller incision that requires no stitches. The surgeon folds this type of lens and inserts it into the empty capsule where the natural lens used to be. Once inside the eye, the lens unfolds, filling the space left by the natural lens.

Some types of intraocular lenses block ultraviolet light and other types work like bifocals to provide both near and distant vision. If you're considering cataract surgery, before the procedure you should discuss the different types of intraocular lenses with your eye surgeon to determine what's best for you.

Cataract surgery is one of the safest and most effective surgical procedures performed in the United States. Possible risks of cataract surgery include inflammation, infection, bleeding, swelling and retinal detachment. But these complications are rare and most can be effectively treated.

More recently, intraocular lenses have been used not only for cataract surgery, but also to correct for nearsightedness (myopia). These lenses are called phakic intraocular lenses. The term "phakic" refers to an eye that still has its natural lens. Instead of replacing the eye's lens, a phakic intraocular lens is implanted in front of the lens to retain the eye's natural focusing ability.

Some people have opted for phakic intraocular lenses rather than other types of refractive surgery to correct their vision, such as LASIK surgery or photorefractive keratectomy (PRK). One of the main benefits of phakic intraocular lenses over other surgical options is that the procedure is reversible. Should a person's prescription change, or if the results are unsatisfactory, the lens can be adjusted or removed completely. Another advantage is its capability to correct high degrees of nearsightedness that are not easily corrected by other surgical procedures.

Although phakic intraocular lenses have been in use for several years, initial data shows that they are both safe and effective. One side effect that has been noted with phakic intraocular lenses is that, because the implanted lenses have a relatively small diameter, they can cause a halo effect or glare while driving at night, especially in people who have large pupils.

If you're interested in intraocular lenses, talk to your eye-care professional about the risks and benefits. He or she can help you determine if these lenses are a good fit for your long-term visual health. —Dharmendra (Dave) Patel, M.D., Ophthalmology, Mayo Clinic, Scottsdale, Arizona

(Medical Edge from Mayo Clinic is an educational resource and doesn't replace regular medical care. To submit a question, write to: medicaledge@mayo.edu, or Medical Edge from Mayo Clinic, c/o TMS, 2225 Kenmore Ave., Suite 114, Buffalo, N.Y., 14207. For health information, visit www.mayoclinic.com.)