The technology of laser eye surgery continues to evolve and improve. One of the newest advances in laser eye surgery is a procedure known as Wavefront. This technique customizes treatment for each patient and perfects the LASIK procedure, resulting in a higher quality of vision for LASIK patients.
How Does Laser Eye Surgery Correct Vision?
Light travels thru the cornea, the clear front part of the eye, onto the retina located in the back of the eye. When the image focuses directly on the retina we see clearly. When we can’t see clearly it’s because the image is focusing in front of or behind the retina.
When the image focuses in front of the retina it results in blurry distance vision, a condition that we commonly call nearsightedness, or myopia. Nearsightedness is caused by a cornea that is too steep or an eye that is too long to focus properly.
When the image focuses behind the retina, a condition called farsightedness, or hyperopia, it is because the eye is too flat. This makes it difficult to see things up close, although it may also affect distance vision as well.
Laser eye surgery is primarily useful in correcting nearsightedness, or myopia. Since nearsightedness is often caused by a cornea that is too steep, the laser is used to take off tissue and reshape the cornea. By removing tissue and shortening the distance from the cornea to the retina, images can focus on the retina instead of in front of it, resulting in clearer distance vision.
The Evolution of Laser Eye Surgery
To appreciate the advances in refractive surgery, it is helpful to understand the steps that have led to the current technology. Before laser eye surgery, there was a corrective procedure known as Radial Keratotomy (RK). The goal of RK surgery, like LASIK, is to correct refraction by changing the shape of the cornea. With RK, a scalpel is used to make eight spoke-like incisions into the cornea so it will flatten and thus correct nearsightedness. Although RK was once the most frequently performed surgical eye procedure for nearsightedness, it is rarely used anymore because it not as effective as LASIK.
The next step in the evolution of laser eye surgery is a procedure known as Photorefractive Keratectomy (PRK). This is the first refractive surgery to reshape the cornea of the eye using a laser. PRK, like LASIK, uses a excimer laser to reshape the cornea. Unlike LASIK, PRK does not involve cutting a flap into the cornea. Instead, the laser goes thru the outer surface of the eye and removes tissue from the central cornea. The outer layers of the eye (epithelium) regenerate during the healing process. Because a flap is not cut into the cornea with PRK, there is not the risk of dislocated corneal flaps, but the procedure can also be more painful and recovery time slower than with LASIK.
The Development of Conventional LASIK
LASIK laser eye surgery emerged with the combination of two separate and sophisticated techniques of surgery. The first technique was to use an automated instrument called a microkeratome to cut a thin layer of corneal tissue that could be folded out of the way, exposing the part of the cornea that needed to be reshaped by the laser. The flap improved upon PRK by reducing discomfort and speeding up recovery after surgery. The second technique was to use the excimer laser, the same laser used in PRK, to reshape the cornea and thus correct the refractive error. After the laser is done reshaping the cornea, the flap is repositioned in the eye.
With conventional LASIK, laser correction basically treats all eyes the same. The routineness of this type of procedure can help bring down costs and be effective for many patients. All eyes are not the same, however, and this is the benefit of Wavefront technology, one of the newest advances in LASIK technology. Many people can have the same eye prescription, but a persons Wavefront measurement is unique.
The Improvements of Wavefront LASIK
Wavefront technology allows the laser treatment to be customized to each LASIK patient based on 3-dimensional measurements of the eye. The Wavefront procedure, which is performed before surgery, maps the surface of the cornea using a beam of light. The process shows where the laser correction needs to be performed and how much tissue needs to be taken off during surgery. While the procedure is similar to conventional LASIK, it differs in the amount of corneal tissue that is removed.
When Wavefront technology is combined with LASIK, the overall quality of vision can be improved. This is because there are less “higher order” aberrations such as visual glare and halos with Wavefront LASIK than with conventional LASIK. While many people may benefit from Wavefront technology, your doctor may not recommend it if you have thin corneas, high degrees of aberration, or severely dry eyes because it usually removes more tissue than conventional LASIK eye surgery.