Lysosomal Enzymes in Corneal Storage Media and Corneal Graft Outcome

Abstract

The purpose of this study was to relate lysosomal enzyme activities in corneal storage media to the outcome of the transplanted corneas. Corneal storage media from 358 transplanted corneas were frozen at -70 degrees C and kept for enzyme analysis. Corneas were stored in K-Sol (28), CSM (35), Dexsol (80), Index medium (five), Optisol (158), and Optisol GS (52). Activities of alpha-D-mannosidase, beta-glucuronidase, alpha-glucosidase, and N-acetyl-beta-glucosaminidase were assayed fluorometrically. Mayo Clinic records were examined for donor information, including cause of death and 2-month graft follow-up data. For all corneas, there was a low but significant correlation between activities of each enzyme and storage time (rs = 0.13-0.35; p = 0.02-0.0001), and donor age (rs = -0.14 to -0.23; p = 0.009-0.0001). There was no significant correlation of enzyme activity with 2-month endothelial cell density, structure, cell loss, or corneal thickness. Enzyme activities for four primary donor failures and six grafts with > 65% 2-month endothelial cell loss were not significantly different from those for the rest of the transplanted corneas. Enzyme activities were higher for corneas from donors with renal failure but not from those with diabetes mellitus. There was no significant difference in graft outcome for different cause-of-death groups. The activities of lysosomal enzymes released into corneal storage media are not useful as predictors of graft outcome.