|
|
Future Vision Laser Center is extremely committed to providing the latest state of the art technology for our patients. The technology we offer is a critical component of our mission statement, ensuring we maintain the highest standards possible for all patients. Dr. Foulkes personally promises to continuously invest in the most current technology as it becomes available and to use this technology with safety as our primary focus.
Most other lasers have been adapted for LASIK from technology originally designed for PRK (Photorefractive Keratectomy). Some of these lasers use a modified broad beam of light while others deliver a narrower beam. The Visx laser uses a broad beam, designed for industrial use making computer chips, about 9 mm in diameter, with an aperture that controls the amount of the beam that is exposed to the eye during any single pulse. This laser, the Visx S2, leaves the outer edges of the corrected area too angular and too small (<6.0mm), creating the potential for undesired results such as glare and halos in some eyes. They have refined this technology with the S3 by splitting the single broad beam into seven smaller beams that are rotated around the treatment area. This is similar to how a showerhead splits the main water stream into smaller streams. These modified smaller beams are still not fully capable of smooth, well-blended edges. It is also limited to 6.5 and this may not be large enough in many people. Small spot lasers scatter a spot of ultraviolet laser light across the eye using a mirrored system. The spot size and contour is variable with two classes of profile. Gausian shaped beams have decreased energy around the rim of the circle to reduce the overlap effect in attempt to create a smoother profile. Flat top lasers use full energy across the profile. Though giving a slightly rougher profile on plastic this appears to not be visually significant on the eye. The overlap of gausian shaped profiles may use slightly less tissue but there is a thermal effect on the rim and the spot size becomes so small that the treatment time can be very slow. This has necessitated the use of very sophisticated tracking systems used on the Ladarvision laser to maintain some degree of accuracy and consistency in treatments that take twice as long. However, dehydration and other issues have made accurate nomagrams difficult and primary successes makes this a second choice laser in centers that have a flat top Bausch and Lomb and an Autonomous Ladarvision laser. The Bausch and Lomb will soon have two spot sizes with it's Zyoptics upgrade which will allow for the speed of larger area spots and the fine tuning and tissue sparing of a smaller spot, especially in custom or asymetric treatments.
We have studied the Bausch and Lomb tissue consumption and have found that it does not use as much tissue as predicted theoretically by the German engineers. This has allowed for the application of the better optics provided by ablations that extend out beyond the corneal edge. As lasers were designed to treat on a flat surface, a problem occurs when the laser works on a curved surface like your eye. When this short wavelength hits an angle it effectively decreases its power and this may be exaggerated in gausian shaped and smaller treatments. This slabing off effect may be a culprit in glare and halo. The effect on the eye is your treatment losing power away from the central 3 or so millimeters and leaving you with what is known as spherical aberration. This is your nearsightedness or astigmatism causing blur around the edges, which you might see as halo and decreased night vision. This effect may be the most reduced with a large spot full-powered 9 and greater zone of treatment provided only by the Bausch and Lomb laser. At Emory vision they have a device for showing undercorrection at the rim and have found this was the culprit in many patients night vision complaints. These problems can be fairly easily fixed soon with Zyoptics treatments, which would selectively treat around the rim avoiding the center. We recommend using the largest treatment zone possible to avoid this problem. Currently only the Bausch and Lomb laser can do this for you.
|
