David Shield

Date of Award

7-26-2010

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

First Advisor

Jimmy K. Lee, M.D.

Second Advisor

Z. Jimmy Zhou, Ph.D

Third Advisor

Aryan Shayegani, M.D.

Abstract

Several challenges prohibit Descemets Membrane Endothelial Keratoplasty (DMEK) from becoming widely adopted as the next generation of corneal transplant for corneal endothelial dysfunction. To date, there have been no evaluations of donor cornea attributes associated with tissue harvest for DMEK. The aim of this study was to describe a method for harvesting the Descemets membrane and endothelial graft and to evaluate a series of dissections of human corneas for factors associated with successful harvest. Forty human donor corneas were obtained from tissue and eye banks. Endothelial surfaces were stained with trypan blue dye and then scored with 8.5 mm disposable trephines. Harvesting of Descemets membrane-endothelial graft was attempted using smooth forceps and hydrodissection with application of balanced salt solution (BSS) to the interface between tissue graft and adherent stroma. Donor cornea variables (sex, age, time from death to preservation, time from death to dissection) and factors such as warming donor tissue to room temperature were recorded for each harvest attempt. Twenty-eight of forty (70%) Descemets membranes were peeled successfully with this technique. After adjusting for donor cornea age, sex, and time from death to preservation, soaking the donor tissue for 60 minutes in ambient temperature BSS was found to be the only factor significantly associated with successful membrane harvest (p=0.044). Twenty-six of 32 corneas (81.3%) that had been warmed were successfully peeled, whereas on 2 of 8 (25.0%) of unwarmed corneal peels were successful. These results highlight the importance of warming and rehydrating the donor cornea for an hour or more in BSS prior to dissection. However, additional challenges trouble the remaining steps of Descemets membrane endothelial keratoplasty; future directions for the field are presented, including possibilities for refinement of the DMEK technique and hybrid DSAEK/DMEK techniques. We have developed one such hybrid technique using thin-cut grafts (40-70 microns) to combine the advantages of DMEK (topical anesthesia, clear corneal incision, less induced hyperopia) with the ease of graft manipulation allowed by thicker endothelial grafts used in traditional DSAEK.

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This is an Open Access Thesis.

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