Corrective laser eye surgery has come a long way, but there are still just two basic types of laser surgery. Photo Refractive Keratectomy (PRK) involves removal of the cornea’s outer most layer of tissue, called the epithelium and reshaping the cornea with an excimer laser. LASIK is a second type of eye surgery involving a cutting technique to create a cornea “flap,” reshaping the eye using the excimer laser and replacing the flap.
There are pros and cons in both techniques. LASIK penetrates more deeply into the cornea to create the cornea flap, which results in a thinned corneal wall and carries some surgical risk. The corneal wall in PRK loses only 5 – 10% of its thickness. There is, however, a longer and more uncomfortable recovery period with PRK while the epithelium grows back. LASIK is painless for most people, and vision is immediately corrected (with some blurriness for a few weeks). But LASIK permanently thins and weakens the cornea, which may lead to progressive steepening or bulging (ectasia) of the cornea, with associated deterioration of vision.
Both types of surgery have developed newer, improved techniques which have reduced risks and complications. For instance, LASEK (with an “e”) is an advanced form of PRK that uses alcohol in solution to first soften the epithelium and then cuts it in a thin sheet that retains its “hinge” on the eye. After the laser reshapes the eye to correct the vision, the epithelium is replaced. Healing is faster while still not using a cutting blade to create a corneal flap. But there is a possibility of a reaction from the alcohol which can kill epithelial cells.
Epi-LASIK was developed to solve some of the problems with both LASIK and LASEK. Rather than using alcohol to loosen the epithelium before removal, the surgeon uses an epithelial “separator” (a blunt, plastic oscillating blade) to separate the epithelium from the eye. However, some eye surgeons do still use alcohol with the Epi-LASIK procedure to improve the quality of the epithelial flap and hinge.
There are several newer LASIK techniques as well. Custom Vue Lasik surgery uses the same hardware as conventional LASIK, but the excimer laser is guided by advanced software called Wavefront. In this procedure, vision is measured by mapping the optical system using technology that is 25% more accurate than traditional methods.
Custom Vue IntraLasik surgery combines the best of all worlds. It uses a laser to create a cornea flap, and Custom Vue’s Waterfront technology to guide the excimer laser for the best possible results. But this type of eye surgery is also the most expensive.
Laser surgeries are contraindicated in most patients with high refractive errors. Refractive Lens Exchange may be a better option for patients with presbyopia (age-related gradual thickening and loss of flexibility of the natural lens in the eye) and high hyperopia. Patients with moderate to high myopia or thin corneas may be good candidates for Vision ICL. And Phakic Intraocular lenses are designed to correct high myopia. They are called “phakic” because the eye’s natural lens is left untouched.
Refractive Lens Exchange (RLE) replaces the patient’s natural lens with an artificial intraocular lens. RLE corrects conditions such as presbyobia and extreme farsightedness (hyperopia). The procedure is virtually identical to cataract surgery, except that the natural lens being replaced is clear, unlike the cloudy lens with cataracts.
The VisianTM ICL is inserted through a small micro-opening, placing it inside the eye just behind the iris in front of the eye’s natural lens. The Visian ICL is designed to stay in position with no special care.
Implantable Collamer Lens (ICL) technology uses a soft, flexible gel-lens to treat a range of refractive error. ICL lenses can treat myopia, hyperobia and astigmatism, but the VisianTM ICL to treat hyperopia is not yet available in the United States. The lens is small and of highly biocompatible material to reduce the eye’s reaction to the lens, and is a permanent corrective solution for most patients. VisianTM ICL promotes its lens as adding visual quality to visual acuity for a sharper, clearer vision, with greater depth and dimension.
Phakic intraocular lenses (PIOL) are a special kind of intraocular lens, implanted behind the cornea and attached on top of the iris. The PIOL does not replace the natural lens. It gives your eye a second focusing lens that provides a high quality, high-def vision. The procedure is reversible if desired or necessary.
We encourage our patients to ask many questions before proceeding with eye surgery. Not everyone is a good candidate for a particular type of eye surgery or any eye surgery at all. And keep in mind that while eye surgery is considered safe, it is still surgery, and there are risks involved.