Experimental data in keratophakia.

With the aid of a thermistor, the temperature decrease in corneal stroma during keratophakia is measured. 1 min after the beginning of the freezing process the temperature is -15 degrees C, 1 min later it is -40 degrees C, and 4 min after the beginning of the freezing process it is -50 degrees C. This temperature course is programmed into the constant rate freezer, in which any number of tissue samples can be frozen at the same time and with a reproducible freezing curve. The preliminary results indicate that under the use of different cryoprotective agents the radioactivity after 35S incorporation is 50-70% of the non-frozen control cornea.