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Vision correction research began in earnest over 50 years ago. Back then, the surgeries involved cutting the clear window on the front of the eye (the cornea) in order to reshape it. Dr. Jose Barraquer in Columbia and Dr. Svyatoslav Fyodorov in what was then the USSR worked on perfecting techniques to change the cornea’s curvature with blades. Dr. Fyodorov gets the credit for developing the technique of modern radial keratotomy, known more commonly for its acronym “RK.” RK became pretty popular during the 1980s and into the early 1990s, because people with difficulty seeing in the distance (i.e. they were nearsighted) had good results for improvement of distance vision. But something better was on the way…
Dr. Stephen Trokel was the one of the first to pursued the idea of using an excimer laser for vision correction. Excimer lasers were used throughout the 1970s to etch silicone chips used in computers. In 1982, Dr. Trokel and colleagues began testing the laser on living tissue and were amazed by its ability to remove precise amounts of tissue with no collateral damage. This unique ability was a result the 193 nanometer wavelength of this laser, which vaporizes carbon-carbon bounds in protein without causing thermal (heat) damage. Scientists were amazed to see electron micrograph photos of precise steps cut into a human hair. Precision like this had never before been seen in surgery.
Now aided by a tool that allowed for such extreme precision, refractive surgeons developed a technique called photorefractive keratectomy (PRK). Drs. Marguerite McDonald, Stephen Trokel, and Charles Munnerlyn worked to solve the surgical and mathematical formula to use PRK to reshape the cornea to correct distance vision. The first procedure was performed by Dr. McDonald in 1987. It was limited in scope to correct only nearsightedness, but over the next few years correction for astigmatism and farsightedness was developed. It was an exciting time in refractive surgery. But something better was on the way…
Now that vision could be corrected with lasers, scientist sought to find a way to do it painlessly. Since PRK was performed by removing the epithelium off the surface of the eye before laser ablation, the eye was uncomfortable for several days and sometimes took several weeks for the vision to improve. By 1991, a laser procedure was performed under a protective corneal flap for the first time. It was name Laser-assisted In Situ Keratomileusis (LASIK). Using a blade called a microkeratome, the surgeon was able to create a small flap on the surface of the eye, perform the ablation, and then “hide” the ablation zone by replacing the corneal flap in its original position. This procedure was FDA approved in 1999. Around this time, most everyone heard about LASIK and many had the procedure. People who had LASIK had a 95% satisfaction rate, which is almost unheard of for medical procedures. But something better was on the way…
In 2002, the femtosecond laser was approved by the FDA to replace the blade used in LASIK procedures. This meant that LASIK could now be a bladeless procedure. However, it wasn’t until five years later that Drs. Daniel Durrie and Stephen Slade introduced a new and better form of LASIK that took advantage of the precision offered by bladeless technology. By using the femtosecond laser to create a layer of bubbles to separate the natural layers of the cornea, a thinner and smaller flap was able to be consistently reproduced in a way that blades could not achieve. This minimally-invasive technique was termed Sub-Bowman’s Keratomileusis (SBK) because it separates the natural layers of the cornea just beneath the very top plane of tissue named Bowman’s layer. For the first time, recovery from surgery could be quick and painless, but also adverse effects sometimes seen with LASIK (dry eyes, dangerous corneal weakening) could be minimized to almost zero. The evolution of laser surgery achieved a new level with this procedure, but something better was on the way…
The technique used in SBK is now standard practice for most high-end centers. However, diagnostic technology used to evaluate the eye, and excimer laser technology used to reshape the eye have improved dramatically over the last five years. With 3D imaging technology, the most subtle nuances of the human eye can be captured - down to 1000th of a millimeter. In kind, excimer lasers that used to use a 6 millimeter broad beam to shape the cornea, can now be focused down to a 0.9 millimeter beam that distributes the energy more evenly across the entire corneal surface. This allows a 3D approach that can preserve the natural corneal curvature of the eye in a unique way. Using SBK for safety, 3D imaging technology for accuracy, and 3D laser technology for precision, 3D LASIK has set a new standard in vision correction.
© Hunter Vision 2012
