Phakic Intraocular Lenses
For patients who have extreme myopia or hyperopia it may be possible to implant a lens in the eye to correct the refractive error without removing the natural lens. This will allow patients who are not yet presbyopic, to retain their normal focusing ability for near vision. A small lens can be inserted through extremely small incisions in front of the natural lens to correct nearsightedness or farsightedness. One type of lens for correcting extreme myopia or nearsightedness is called Verisyse. This is a tiny but rigid lens that has received FDA approval and is slowly gaining acceptance among Ophthalmologists. Another, possibly better approach is to use a flexible or foldable lens implant to correct nearsightedness or farsightedness. Once implanted in the eye, the foldable lens expands to its full size, allowing the eye to remain relatively un-traumatized, thus reducing astigmatism and recovery time.
What are Phakic Intraocular Lenses?
A phakic intraocular lens (PIOL) is a lens implanted inside the eye for the correction of either extreme nearsightedness or extreme farsightedness. In effect, the lens becomes an internal contact lens rather than contact lenses on the surface of the eye. It is usually recommended for patients whose visual correction is outside the range that can safely be treated with LASIK surgery. Because of the slightly increased risk of more serious complications, the PIOL is reserved for high amounts of nearsightedness or farsightedness–above the current limits of LASIK. In places where this technology is available, surgeons are implanting the PIOL in patients with myopia greater that 12.00 to 15.00 diopters and hyperopia greater than 4.00 to 6.00 diopters. Despite the excellent outcomes in most cases, complications associated with the implants are currently the biggest concern. Specifically, in the early studies a small percentage of patients developed cataracts shortly after implantation of the lens. There is also a small risk of endophthalmitis (infection within the eye) because the surgical incision actually enters the eye. This rare complication could lead to complete loss of vision. Endothelial cell loss with some lens designs is also a concern and is being studied rigorously. The Versyse Lens is already FDA approved and some Ophthalmologists in the United States are currently performing this procedure with other lenses as part of an FDA clinical trial. The procedure holds a lot of promise for extremely nearsighted or farsighted individuals. Ophthalmologists are anxious to see how the implantable lenses fare in current studies using newer lens designs and implantation techniques. These lenses are currently being used in Europe and South America with very high success rates. The results will be presented to the Food and Drug Administration with the hope that the FDA will authorize other eye surgeons to use this exciting new technology.