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SUMMARY
It is now established that there is a destructive biophysical interaction between a plastic intraocular lens and the corneal endothelium during intraocular lens implantation. In the present study, Na-hyaluronate was placed into the anterior chamber of one eye of 20 rabbits, after lens extraction and prior to pseudophake implantation, in an attempt to protect the corneal endothelium. The other eye of each rabbit was subjected to a lens extraction and pseudophake implantation in the conventional manner. During the 4-week postoperative period, it was observed that the eye treated with Na-hyaluronate showed significantly less corneal edema as well as less iris engorgement and edema.
INTRODUCTION
Kaufman and Bourne1 have reported significant damage to the corneal endothelium following intraocular lens insertion. Kaufman and Katz2 then showed that biophysical interaction between the intraocular lens and the corneal endothelium produced extensive cell damage. These findings are in keeping with the popular clinical observation that, after intraocular lens implantation, more corneal edema is present than after conventional cataract surgery.
Thus, we felt that instillation of a non-toxic, clear, viscous material into the anterior chamber, after cataract removal, but prior to intraocular lens implantation, might maintain the anterior chamber and protect the endothelial surface of the cornea during implantation.
The material we chose was a Na-hyaluronate3 obtained from human umbilical cord and rooster comb (Healon, Pharmacia Laboratories, Piscataway, N.J.). This material has been used as replacement vitreous since 1970, in cases of complicated retinal detachment surgery in several hospitals in Europe. Reports from these hospitals4"8 confirm that the material is pyrogen free, sterile, remains in the eye about two weeks, and usually induces only a mild inflammatory response, not unlike that induced by the injection of sterile saline. Laboratory tests have also shown that the material is non-antigenic, and can be used after repeated injections.3'9 Because it is about 99% water, it does not present a serious barrier to aqueous outflow.
Na-hyaluronate is a large polymer with a molecular weight of 1.1 - 1.8 ? 106 and contains less than 1% protein. The viscosity of 1% solution of Na-hyaluronate is 30,000 to 100,000 centipoise (measured at 25°C). It is classified as a visco elastic polymer which means it has...