Corneal hydration studied in stromal segments separated by interlamellar discs.

Interlamellar plastic discs inserted into cat corneas provide a means by which segments of the cornea can be studied with regard to swelling and water movement in vivo. The corneas are physiologically normal as demonstrated by their transparency, swelling properties, and histologic structure. The observation that one disc causes no change in the hydration of the stroma anterior or posterior to the disc is consistent with the hypothesis that active movement of water occurs across both the epithelium and the endothelium. The middle stromal segment which is created by inserting two interlamellar discs also remains transparent and physiologically normal. This raises the possibility that the stroma itself is a site of metabolic activity which is sufficient to sustain a normal state of stromal hydration. It further indicates that metabolic interaction between the stroma and the overlying epithelium or the underlying endothelium is not essential to the normal state of corneal tissue.