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 in either of two locations in the eye:
Between the clear lens in front of the eye (cornea) and the iris (colored portion of the eye), or
Just behind the iris.
Unlike traditional contact lenses, you cannot feel a phakic IOL in your eye – like a dental filling, which you know is there but has no sensation. Also, phakic IOLs require no maintenance.
Implantable lenses are a surgical alternative to LASIK and, in some cases, produce better vision than 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 through the addition of an artificial lens to compensate for biological defects.
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 when other vision correction procedures aren’t a good option, such as when a person has thin corneas or myopia between -3.00 and -20.00 diopters. With some patients receiving phakic IOLs, LASIK may be used as a follow-up to refine vision correction.
Two Food and Drug Administration-approved implantable lenses are available in the United States:
Verisyse (Advanced Medical Optics, Santa Ana, Calif. Marketed as the Artisan outside the United States by Ophtec, Groningen, The Netherlands) In 2004 the Verisyse phakic IOL received FDA approval for correcting nearsightedness in moderate to severe ranges of -5.00 to -20.00 diopters. Patients receiving this lens must be 21 years or older. Made of a type of plastic called PMMA, this lens has been marketed for a number of years in Europe under the trade name Artisan
Verisyse phakic IOL.
Visian ICL (Staar Surgical, Monrovia, Calif.) The Visian ICL or Implantable Collamer Lens received FDA approval for marketing in the United States in 2005. The Visian ICL is made partly from collagen, a biocompatible material. The ICL is foldable, which means smaller surgical entry incisions and potentially quicker recovery times (in about one day, like LASIK). FDA approval is for patients older than 21 who are nearsighted in moderate to severe ranges of -3.00 to -20.00 diopters. Many years before FDA approval, the Visian ICL was approved and marketed in many countries outside the United States, including Europe
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The Visian ICL (Implantable Collamer Lens).
Both the Verisyse and the Visian ICL 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.
Clinical trials of the AcrySof phakic IOL (Alcon), a soft acrylic lens, are underway in the United States, Europe and Canada in nearsighted patients. In two-year follow-ups, researchers described a low rate of adverse events and excellent as well as stable visual acuity.
Alcon has announced plans to submit its application for FDA approval of the AcrySof phakic IOL in 2010 or later, according to the company’s Web site.
Techniqe:
Before surgery, numbing drops are placed in the eye. An instrument is attached to hold open the eyelids, and then an incision is made into the eye.
A different procedure is used for each approved lens:
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 after the procedure, which lasts about 15-30 minutes. The Verisyse IOL isn’t noticeable in the eye, though you may see it if you look very closely in the mirror.
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 unfolds to its full width after implantation, which requires no sutures. After the six-minute procedure, the Visian ICL is invisible to the naked eye because of its location behind the iris. It can be seen only with a microscope during eye exams.
After the procedure, vision often improves instantly, though you may have a feeling of mild scratchiness. You should rest at home for the remainder of the day and then return the next day for an eye examination in the office. It’s essential that you follow your eye surgeon’s postop instructions carefully to avoid any complications.
Most people are able to resume driving and return to work within a day. A series of follow-up visits with the eye doctor also are required.
Risks of Lens Implantation
As with any surgical procedure, complications are rare but can occur after implantation of phakic IOLs.
Possible complications include 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 also can develop with night driving and may 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. After surgery, your doctor will continue monitoring your endothelial cell counts, an indicator of how healthy your corneas are and how well they heal afterward.