New Lasik
New Lasik treatment uses the same kind of laser used in PRK or photorefractive keratectomy. PRK is the first surgical procedure developed to reshape the cornea by sculpting using the laser. It was only later that new Lasik was developed. The major difference between the two surgeries lies in the way that the stroma, the middle layer of the cornea is exposed before vaporized with the laser.
In PRK, the top layer of the cornea called epithelium is scraped away to expose the stromal layer. In new Lasik, a flap is cut in the stromal layer and then the flap is folded back. The first refractive laser systems approved by the FDA were excimer lasers for use in PRK to treat myopia and later on to treat astigmatism. Later, doctors began using these lasers for new Lasik to treat other refractive errors. Over the last several years, new Lasik treatment has been used by doctors to treat myopia, hyperopia and astigmatism.
Over the past ten years, there have been major developments in laser vision correction technology and the understanding of the procedure. The improvements include improved eye tracking systems during the laser procedure, larger treatment zones, and improved mechanical and laser microkeratomes which reduce flap complications. However no development has caused more excitement than the recent FDA approval (June, 2003) of CustomVue LASIK from VISX utilizing wavefront guided treatment. This will be the predominant form of new LASIK treatment.
Wavefront guided custom new LASIK differs from conventional LASIK treatment in the way the eye's optics is measured. Accurate measurement of the optics of each eye is essential for a good visual outcome from the new LASIK procedure. It is this series of numbers/calculations that is used to program the laser for reshaping the cornea. Before wavefront guided new LASIK, the surgeon objectively measured the eye with a handheld instrument or an automated measuring device then asked the patient to subjectively refine the measurement. The reality is that the eye's optical system is not uniform throughout the central 6mm of measurement. The new Lasik wavefront can precisely measure the optics of light from minute areas over the central 6mm of the cornea.
While conventional LASIK was and still is very effective treatment, the wavefront guided new LASIK procedure has given surgeons the ability to provide patients with improved visual results than conventional LASIK. Custom wavefront guided new LASIK uses a waveprint of the eye's optical system as the guide for laser reshaping. The waveprint is 25 times more precise than an averaged measurement because data about the eye's optical system is collected from hundreds of separate points over the central 6mm area of the cornea. Rather than using an averaged measurement from the central 6mm to reshape the entire cornea, the cornea reshaping is customized at each of the hundreds of points from which measurements are taken.
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