Refractive surgeries are procedures used to correct myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. The most common of these procedures include PRK, LASIK, and most recently phakic intraocular lenses.
There is always some degree of risk associated with any surgery, and refractive procedures are no different. Both corneal refractive surgery, LASIK and PRK for example, and the implantation of phakic intraocular lenses have individual and shared features and risks.
PRK and LASIK are grouped under the umbrella "laser eye surgery", but each is a little different when it comes to advantages and disadvantages. For example, LASIK and PRK share complications like dry eyes, but only LASIK has the risk of a corneal flap complication. Both are performed with a laser (Allegretto, Excimer, etc.), which precisely ablates tiny bits of corneal tissue to reshape its curvature. In PRK the corneal epithelium is removed, not cut and flapped, as in LASIK. LASIK patients have less discomfort and obtain good vision more quickly. PRK patients vision may take days, weeks or even months to fully rehabilitate. In the end the outcomes for both procedures are equal.
Similarly, The Visian ICL and the Verisyse (Artisan) P-IOL are both implanted into the eye, but each has a different lens placement. The Visian ICL is made from a soft flexable biocompatible Collamer while the Verisyse (Artisan) P-IOL is made from a rigid polymethylmethacrylate (PMMA) plastic. The Verisyse (Artisan) P-IOL clips onto the iris and is visible to everyone, while the Visian ICL is placed in the posterior chamber making it invisible to the naked eye. The Visian ICL requires a smaller incision with no sutures and therefore has a faster healing surgical wound with less risk of induced astigmatism.
Phakic Intraocular Lenses
Phakic intraocular lenses are an implantable lens that represents the latest evolution in refractive surgery. This procedure provides excellent visual outcomes, with minimal healing and postoperative restrictions. It corrects nearsightedness (myopia) between -3.00 D and -20.00 D and because of its superior quality of vision it is quickly becoming the procedure of choice for high myopic corrections. Phakic intraocular lenses bridge the gap for patients who are not good candidates for any other refractive procedure such as LASIK and PRK. They are not yet FDA approved for faresightedness and do not directly correct astigmatism though the process of surgery may reduce it.
The implantation procedure for the Visian ICL involves a procedure similar to that of cataract surgery. The main difference is that, unlike cataract surgery, the Visian ICL procedure does not require the removal of the eye's crystalline lens. And unlike the LASIK or PRK refractive procedures, the Visian ICL procedure does not involve the removal of corneal tissue.
The implantation procedure for the Verisyse (Artisan) P-IOL is also similar to cararact surgery in that it does not require the removal of the eye's crystalline lens, but it does require a larger incision in the cornea. Unlike the LASIK or PRK refractive procedures, the Verisyse (Artisan) P-IOL procedure does not involve the removal of corneal tissue. The Verisyse (Artisan) P-IOL is placed in the space in front of the iris and behind the cornea. It is centered in the pupil and is attached to the iris to hold it in place. The corneal incision is closed with stitches that dissolve over time.
LASIK, which is short for "laser-assisted insitu keratomileusis", is a refractive surgical procedure that uses a cool light laser (Allegretto, Excimer, etc.) to precisely ablate tiny bits of tissue from the cornea to reshape its curvature. It is the most commonly performed refractive surgical procedure. Its advantage over PRK is its relative lack of postoperative pain and the fact that good vision is usually achieved by the next day.
During this procedure a thin circular epithelial flap is created in the cornea. In the past a mechanical microkeratome was used to cut the flap. Now, a more accurate Femtosecond laser is used. After the flap is cut it is hinged back so the laser can remove the desired amount of corneal tissue underneath. The flap is then laid back into place, covering the area where the corneal tissue was removed.
PRK which is short for "photorefractive keratectomy", was once the most frequently performed refractive surgery. it was invented in the early 1980s. The first FDA approval of a laser for PRK was in 1995, but the procedure was practiced in other countries for years. In fact, many Americans had the surgery done in Canada before it was available in the United States.
During this procedure the corneal epithelium is removed, not cut and flapped as with LASIK. A cool light laser (Allegretto, Excimer, etc.) is then used to precisely ablate tiny bits of tissue from the cornea to reshape its curvature. A bandage contact lens is placed on the eye until the corneal epithelium, which was removed, heals.
For patients with thin corneas, PRK is still preferable over LASIK.