APPARATUS AND METHOD FOR PERFORMING LASER THERMAL KERATOPLASTY WITH MINIMIZED REGRESSION
Apparatus and method for performing laser thermal keratoplasty capable of treating treatment areas with shapes that reduce regression. Both contact and non-contact apparatuses and methods are provided. The apparatus includes laser sources, a projection optical system, observation system, and control system. In some embodiments, the projection system uses two steering mirrors or a mask to control laser beam position on the cornea. This projection system enables precise control of the area of corneal heat shrinkage using relatively low-powered lasers, such as diode lasers. Desired changes in corneal refractive power are produced by selected patterns of photothermal shrinkage of corneal collagen tissue. The selected patterns are arrangements of oblong shapes that are preferably tapered at the ends of the long axis. The oblong shape and tapering distribute tension in the cornea over a wider area of collagen shrinkage and improve the stability of refractive correction. The long axes of the oblong treatment areas are preferably oriented radially for hyperopia correction and circumferentially for astigmatism correction.