Corneal wound healing: holographic stress-test analysis.

Double-exposure holograms are taken of the patient's cornea after a heartbeat. The resulting stress test, or holographic interferogram, shows sharply demarcated fringe patterns outlining structurally weak areas in the cornea. Wound strength in postoperative keratoplasties is now being evaluated on a routine basis to determine the effect of topical medications and surgical techniques. All grafts measured to date reveal "bulging" or weakness of the wound margin by holography even though clinically they are fully "healed." Only one patient had a vascularized region of the wound that was stronger than surrounding cornea. It is no longer necessary to resort to pulling the wound apart in animals for measurement of tensile strength.