[Histology and function of the cryopreserved corneal endothelium]

This work consists of a histological study of cryopreserved corneal endothelium before and after perfusion, and of measurements of the corneal thickness during perfusion. 1) Histoligical study: a) After 7 hours of perfusion, the endothelium of fresh corneas is unchanged. b) The preserving solutions used for freezing do not modify the histological structure of the endothelium. c) All the freezing and thawing processes described in this paper substantially alter the histological structure of the endothelium. Latent alterations are revealed during perfusion. 2) Pachymetric study: a) In the experimental conditions described, the fresh corneas keep their normal thickness for 7 hours of perfusion. b) The preserving solutions do not modify this property. c) After freezing and thawing the thickness of the perfused cornea increases rapidly. The thickness of the perfused cornea appears more slowly under the following conditions: 33 to 66 p. 100 of serum in the preserving solution, volume less than 1 ml; eutectic point between - 4 and - 6 degrees C; the duration of the plateau less than 4 min. speed of freezing after the plateau about 5 degrees C/min.