Abstract
Purpose::
Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) is new surgical procedure to address endothelial diseases without transplanting the full-thickness cornea. The purpose of the present study is to histopathologically determine which corneal layers (or portions thereof) are removed from the host cornea in a small surgical series of DSAEK procedures.
Methods::
: Corneal buttons from 5 patients (mean age 71, range 56-84) diagnosed with Fuchs’ Endothelial Dystrophy(FED) were immersed in 2% glutaraldehyde fixative immediately following excision. Tissues were processed, embedded in araldite, and sectioned for analysis with an Olympus BX51 light microscope(LM) and a FEI transmission electron microscope(TEM). Measurements of tissue thickness (from 3 points >200um apart and away from guttae) and the height of guttae (from the anterior face to the apex of 3 guttae >200um apart) were taken for each specimen utilizing LM and NIH Image 1.63.
Results::
TEM confirmed that the excised tissue contained both the diseased endothelium and the entirety of the posterior limiting lamina(PLL) including the abnormal posterior collagenous layer(PCL). No evidence of stromal collagen fibrils or lamellae were present at the surgical interface. Mean thickness of the removed PLL was 19.22um (SD= +/- 5.44um, n= 5) and the mean gutteal height was 23.74um (SD= +/- 6.66um, n= 15). It was noted that the tissue was prone to curling and that it could occur in either direction (endothelium in or out).
Conclusions::
The DSAEK technique, the endothelium and the entire thickened PLL, including the banded, non-banded, and abnormal PCL portions, are removed from the host eye without any adhering stroma. By exploiting the FED-weakened adhesion of the stroma and PLL, this surgery removes only around 20+um of tissue compared to the 500+um removed in Penetrating Keratoplasty. The tendency of the tissue to curl makes it important that surgeons take care when inserting the donor tissue to ensure that the endothelium is facing the anterior chamber. Histopathological analysis supports DSAEK as a promising and repeatable surgical technique for the selective removal of the pathological endothelium and its associated basement membrane.
Keywords: transplantation • cornea: endothelium • anatomy