Vision correction technology changes drastically over 60 years

The human eye, like a fingerprint, has characteristics unique to each human being. However, these distinctions not only differentiate individuals from each other, they also may keep each person from achieving “optimum” vision after normal refractive or LASIK (Laser-Assisted In Situ Keratomileusis) surgeries.

In determining a prescription for glasses, doctors use standard measurements to correct vision, providing only a certain level of correction regardless of a person’s vision needs. A patient’s prescription is used for guidance during normal refractive and LASIK surgery.

A technology, approved by the FDA in the last three years, using wavefront-enhanced lasers, seems to be changing and improving the outcome of LASIK procedures. This new wavefront capability has the potential for better vision than is possible with glasses or contact lenses. This technology creates a map of the patient’s eyes, exhibiting any abnormalities, known as aberrations, which prevent maximum vision. Then the excimer laser corrects the vision accordingly, drawing on the wavefront data to create a custom surgical pattern for each individual.

Today’s refractive surgical procedures got their start approximately 60 years ago when Dr. Sato, a Japanese eye surgeon, noted that making radial cuts in the cornea flattened it, in effect making nearsighted people less nearsighted. In the early 1970s, Dr. Svyatoslav Fyodorov of the Soviet Union made improvements in the technique by refining the radial cuts on the “outside” surface of the cornea. Thus, Radial Keratotomy (RK), the first useable refractive surgical procedure of the cornea, was initiated.

By the mid-1980s two events were driving refractive surgery simultaneously: Dr. Richard Koplin and his associates took on the challenge of developing technology that would allow refractive surgeons to evaluate corneal shape; and the second was the development of laser systems that promised to refine and significantly improve refractive surgery. With the development of Corneal Modeling technology by Dr. Koplin and his associates and ablative lasers, modern day refractive surgery was born.

Unique to refractive lasers (those used to reshape the cornea), is the ablation of tissue exactly as the surgeon designed the procedure. This class of lasers, known as excimer lasers, makes tissue disappear precisely where the beam is aimed.

Each pulse of the cool ultraviolet beam of light removes a microscopic amount of central corneal tissue, doing it with amazing precision and predictability without affecting any other surrounding tissue.

Excimer lasers began their use in the United States in FDA-sponsored programs in the late 1980’s. Two laser procedures, photorefractive keratectomy (PRK) and LASIK, rapidly replaced RK because they were safer, more precise and longer-lasting. Hundreds of thousands of patients underwent laser procedures during the intervening years in Great Britain, Canada and Europe, well before approval was granted here in the States in late 1995.

Excimer laser companies have been refining and expanding offerings in an increasingly competitive marketplace. The manufacturers of excimer laser systems tied the wavefront diagnostic image of a patient’s eye directly to the surgical ablation map for excimer lasers. As a result, physicians can now customize the LASIK procedure according to each individual patient’s unique vision correction needs.

Wavefront technology was originally developed for use in high-powered telescopes to reduce distortions when viewing distant objects in space. The wavefront procedure is unique to each eye, just as a fingerprint is unique.

Custom ablations, Conductive Keratoplasty (CK) and accommodative intraocular lens (IOL) replacement are among the innovations announced in the last three years that are now available in northern Michigan.

CK is a very narrowly banded procedure intended for low or moderate farsighted patients or for those patients that just need reading glasses. CK uses the controlled release of radiofrequency energy to reshape the cornea. A small probe is applied in a circular pattern to the inner corneal tissue to make it shrink, steepening the curvature and increasing its focusing power.

The Crystalens, an accommodative IOL developed by eyeonics inc., received FDA approval in Nov. of 2003. This single piece IOL is designed to provide good vision at all distances by moving backward and forward along the axis of the eye. This movement is in response to pressure changes in the vitreous cavity and anterior chamber, resulting from relaxation and contraction of the eye’s ciliary muscle. BN

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