Cryogenic Treatment of Herpes Simplex Keratitis.

DURING the early stage of our experiments on the use of low temperature for cataract extraction (Krwawicz, 1961, 1963), we had several opportunities of observing the effects of accidentally touching the cornea with the cryoextractor refrigerated to about -79°C. This accident proved to be quite harmless in all cases as no lasting effect on the clarity of the cornea could be seen after the tissue had been separated from the instrument. The ability of the cornea to return to its normal condition after coming into contact with the refrigerated metal suggested the possibility of the therapeutic application of low temperature to the cornea itself. A series of experiments on animal eyes was then carried out, and it was found that when the cornea was touched with an appropriate instrument refrigerated to -79'C., there occurred an immediate freezing of the epithelium and superficial layers of the corneal stroma. Repeated refrigeration of a delimited area of corneal tissue had no ill effects on its transparency and did not produce any noteworthy fall in the temperature measured in the anterior chamber (Krwawicz, 1964). This cryogenic procedure was then used to treat corneal lesions in patients suffering from herpes simplex keratitis, with highly satisfactory results.