Thickness changes in the epithelium and stroma of the cornea of a living rabbit eye were observed with the specular microscope. Previous experiments on the excised cornea using this technique have failed to show any thickening of the corneal epithelium due to anoxia at the anterior surface. In the living eye, the same result was obtained. The results confirm that corneal edema due to anoxia is caused almost entirely by swelling of the stroma, the epithelium undergoing very little thickness change.