The Dawn of a New Era
Colorado Custom LASIK Vision Correction Laser Eye Surgery with CustomVue Wavefront LASIK Technology in the Denver & Boulder Metro Area
Glasses have been in use for hundreds of years for correcting blurred vision. The first glasses were produced in Italy in the late 13th century. The first contact lenses were introduced in the 1880’s but were made of glass and were not comfortable and could only be worn for a few hours. Plastic , “hard contact lenses” became generally available starting in the 1950’s and soft contact lenses and “gas-permeable contact lenses” were successfully introduced in the 1970’s. The first surgical attempt to correct blurred vision began in the late 1970’s when a Russian Ophthalmologist, Sergiev Fyodorov introduced Radial Keratotomy (RK) as a procedure for reducing nearsightedness and Astigmatism. In Radial Keratotomy, the surgeon used a hand-held diamond knife to make deep radial incisions in the cornea. (When you cut a pizza you are making radial cuts. Unlike cutting a pizza, the cuts in Radial Keratotomy did not go all the way to the center of the cornea.) The surgeon would make four to sixteen radial cuts, depending on the amount of the patient’s nearsightedness. The goal of Radial Keratotomy was to flatten the cornea and decrease the patient’s nearsightedness. Radial Keratotomy flattened the cornea by structurally weakening and slightly collapsing the cornea. This is similar to cutting some of the support wires in a tent and then having the tent partially collapse.
Radial Keratotomy had two major drawbacks. First, the radial incisions would often cause visually-significant glare. The second problem with Radial Keratotomy was that the cornea was structurally weakened by the radial incisions. Short term, this weakness caused fluctuating unpredictable vision, often to the extreme that patients would see well without correction part of day and would require glasses to see clearly at other times of the day. Long term, the weakened cornea also continued to flatten, and patients were actually becoming farsighted. Even with these two major drawbacks, millions of patients underwent Radial Keratotomy and the vast majority were satisfied to be significantly less nearsighted. Radial Keratotomy is rarely being performed today. However, I feel some reassurance that although Radial Keratotomy was an imprecise procedure performed by making deep corneal cuts with a hand-held knife, Radial Keratotomy was well accepted by patients and has been shown to be reasonably safe long term. However, we now have a much more precise procedure, Laser Vision Correction, with computer-guided Lasers removing sub-microscopic amounts of corneal tissue. This technology provides much greater, reproducible accuracy and corneal stability than Radial Keratotomy.
In the mid 1980’s, IBM was looking for Laser technology to etch silicone computer chips. They discovered what we now call the Excimer Laser. The word Excimer is short for Excited-Diamer. The Excimer Laser uses two diamers, or gases, Argon and Fluoride, to generate the Laser energy. When I was in elementary school, I used a magnifying glass to focus the sunlight on a piece of paper, and burn a hole in the paper. A Laser functions on a principle similar to this. However, a Laser uses just one wavelength of light, whereas sunlight has a wide band of wavelengths. Also, Lasers have all the waves “in phase”, allowing for very high concentrations of focused energy. Each Laser wavelength has different physical properties. It happens that the Excimer Laser, which is in the ultra-violet range with a wavelength of 193 nanometers, breaks carbon-carbon bonds. This releases vaporized molecules, without cutting or damaging surrounding tissue. Each pulse of the Excimer Laser removes .25 microns, 0.00004 of an inch, or about 2000 molecules of tissue. A human hair is about 100 microns. The Excimer Laser removes 1/400 of a hair with each pulse of energy. Instead of making the radial cuts, as in Radial Keratotomy, the Excimer Laser flattens the cornea by removing thin layers of tissue from the surface of the cornea. The Excimer Laser actually reshapes the cornea, placing the glasses correction right on the surface of the eye. The more nearsighted the patient, the more tissue removed. The average patient has less than one-half hair’s thickness of tissue, 50 microns, removed in Laser Vision Correction. This does not structurally weaken the cornea as in Radial Keratotomy. Once the cornea is reshaped by the Excimer Laser, there is minimal long-term change in the shape of the cornea.
Rose Medical Plaza, 4545 East Ninth Avenue, #270, Denver, CO 80220