Combined microwave heating and surface cooling of the cornea.
We investigated a nonsurgical means of reshaping the cornea to correct hyperopia, keratoconus, or myopia. The object was to heat the central stroma of the cornea to the shrinkage temperature of collagen, 55-58 degrees C. The heating device was an open-ended, coaxial, near-field applicator driven at 2450 MHz; it incorporates cooling of the cornea surface by flow of saline. We investigated the system theoretically by computing the 2-D, axisymmetric temperature distribution with the finite element method. We investigated the system experimentally by heating excised steer corneas. Histology showed the system could shrink the stroma to a depth of 0.6 mm while sparing the epithelium in 75% of cases; the diameter of shrinkage was 1.3 mm. Theory predicted a significantly deeper and narrower region of shrinkage than was observed.
Trembly
B S
BS
Thayer School of Engineering, Dartmouth College, Hanover, NH 03755.
Keates
R H
RH
D000818:Animals; D002417:Cattle; D003080:Cold Temperature; D003315:Cornea / Q000528:radiation effects*; D006358:Hot Temperature; D008297:Male; D008872:Microwaves; D009216:Myopia / Q000532:radiotherapy