Implantable Lenses (Phakic IOLs)

Surgically implanted lenses, also called phakic IOLs (intraocular lenses), are a new option for people seeking more permanent correction of common vision errors such as myopia (nearsightedness). These implants, which resemble contact lenses, are placed between the clear front covering of the eye (cornea) and the iris (colored portion of the eye) or just behind the iris.

Implantable lenses are a surgical alternative to LASIK. Both procedures alter the way light rays enter the eye to achieve sharper focus. LASIK does this by removing tissue from the eye's cornea to change its shape; implantable lenses function like glasses or contact lenses, except they do it from within your eye. Implantable lenses do not require tissue to be removed from the eye as with LASIK; these lenses are effectively added to the eye.

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Implantable lenses are similar to the intraocular lenses (IOLs) used in cataract surgery. However, implantable lenses are placed in eyes that retain their natural lens, unlike in cataract surgery where IOLs replace a natural lens that has turned cloudy.

Eye surgeons may consider implantable lenses for their patients when other vision correction procedures aren't a good option, such as in cases of thin corneas or myopia between -3.00 diopters and -20.00. With some patients receiving phakic IOLs, LASIK may be used as a follow-up to refine vision correction.

Insertion of the Verisyse phakic IOL.

Two Food and Drug Administration-approved implantable lenses now are available in the United States, including:

• Verisyse (Advanced Medical Optics, Santa Ana, Calif. Marketed as the Artisan outside the United States by Ophtec, Groningen, The Netherlands) In September 2004, one phakic IOL known as the Verisyse received FDA approval for correcting nearsightedness in moderate to severe ranges of -5 to -20 diopters; patients must be 21 years or older. Made of a type of plastic known as PMMA, this lens has been marketed for a number of years in Europe under the trade name Artisan.
   
• Visian ICL (Staar Surgical, Monrovia, Calif.) A second lens, the Visian ICL or Implantable Collamer Lens, received final FDA approval for marketing in the United States in late December 2005. The Visian ICL is made partly from a biocompatible material known as collagen. The ICL is foldable, which means smaller surgical entry incisions and potentially reduced recovery times. FDA approval is for patients older than 21 with nearsightedness in moderate to severe ranges of -3 to -20 diopters. Many years before FDA approval, the Visian ICL was approved and marketed in many countries outside the United States, including in Europe.

The Visian ICL (Implantable Collamer Lens).

Both the Verisyse and ICL implantable lenses are FDA-approved for treating nearsightedness only. Clinical trials for the two lenses are continuing for potential FDA approval for treating near vision defects (farsightedness, or hyperopia). A version of the Visian ICL (toric) also is being studied for correction of higher levels of astigmatism.

Look for other types of phakic IOLs eventually to become available in the United States, including additional foldable styles that can be implanted with smaller incisions. Research also continues on multifocal phakic IOLs that potentially could simultaneously correct vision defects in near, middle, and distant ranges — similar to the functionality of multifocal eyeglasses and contact lenses. [See also: Multifocal Contact Lenses]

Prior to surgery, drops are placed in the eye to reduce pupil size. An instrument is attached to hold open the eyelids during the procedure, and a local anesthetic is given to numb the eye's surface. An incision then is made into the eye. The Verisyse phakic IOL is inserted and attached to the colored portion of the eye (iris). Tiny, dissolvable stitches are used to close the wound. An eye shield will need to be worn for a short time following the procedure, which lasts about 15-30 minutes.

The folded Visian ICL is inserted just behind the eye's iris and in front of the natural lens. After being placed through the microincision, the artificial lens then unfolds to its full width following implantation, which requires no sutures. Once inserted during about a six-minute procedure, the Visian ICL is invisible to the naked eye because of its location behind the iris. It can only be seen with a microscope during eye examinations.
 

After the procedure, vision often is instantly improved, though there may be a feeling of mild scratchiness. Patients should rest at home the remainder of the day and then return the next day for an eye examination in the office. Most patients are able to resume driving and return to work within a day. A series of routine, follow-up visits with the eye doctor also are required.

After the lenses are inserted, patients cannot feel them (unlike traditional contact lenses). Because these lenses are designed to be permanently added to the eye, they have the added advantage of never requiring removal for cleaning, as occurs with traditional contact lenses.

In one study preceding FDA approval of the Verisyse lens, about 92 percent of 662 myopic patients who received an implant achieved 20/40 or better eyesight.

FDA studies demonstrated that about 95 percent of 294 myopic patients receiving the Visian ICL implant achieved 20/40 or better vision, which enables driving without glasses if no other vision defects are present.

Reversibility appears to be one of the procedure's main advantages over laser vision correction such as LASIK. The implant simply can be removed if the eye changes, complications occur, or the phakic IOL correction no longer is effective.

As with any surgical procedure, complications are rare but can occur following implantation of phakic IOLs such as increased chance of retinal detachment, loss of cells in the thin layer inside the cornea (endothelium), inflammation, infection and cataracts.

The FDA warns of other potential complications such as sometimes severe vision loss, problems with night driving that can include halos, increased eye pressure (intraocular pressure) that can damage the eye's optic nerve, and inadequate lens power that may not properly correct vision.

Because phakic IOLs represent a relatively new technology, long-term effects and potential risks of lens implantation are unknown.