A study of host corneal endothelial cells after non-Descemet stripping automated endothelial keratoplasty.

PURPOSE: To determine the short-term fate of the host endothelium and Descemet membrane after non-Descemet stripping automated endothelial keratoplasty (nDSAEK). METHODS: Eight unilateral DSAEK (n = 4) or nDSAEK (n = 4) surgeries were performed in the right eyes of 8 rabbits. Corneal transparency and thickness were followed-up by slit-lamp microscopy, and 2 weeks postoperatively, corneas were evaluated by immunohistochemistry and transmission electron microscopy. RESULTS: Corneas remained clear after both DSAEK and nDSAEK. One week after DSAEK, the stroma-to-stroma surgical interface was identifiable as a zone of fibrotic tissue a few microns thick, whereas in the nDSAEK group, the recipient corneal endothelium and Descemet membrane were clearly visible at the graft-host interface. The retained endothelial cells were positive for Na/K-ATPase but assumed a markedly different morphology from healthy endothelial cells, with cell processes extending into the graft stroma or engulfing strands of irregularly dissected grafted stromal tissue where they occasionally appeared to compartmentalize the transplanted matrix and became detached from the underlying Descemet membrane. CONCLUSIONS: Host endothelial cells 2 weeks after nDSAEK express markers of pump function, but appear to be morphologically altered, occasionally detaching from the adjacent Descemet membrane, extending into the graft stroma or engulfing strands of the grafted stroma at the interface. The short-term persistence and subsequent phenotypical alternation of residual endothelial cells, aligned to structural changes to Descemet membrane, might influence graft adherence after nDSAEK.

Changes in lactate dehydrogenase activity in bovine corneal stroma and epithelium in response to in vitro toxic challenges in the enucleated eye test.

PURPOSE: To assess whether changes in lactate dehydrogenase (LDH) activity, as a marker of cell damage, could be detected in corneal stroma and corneal epithelium after toxicity measurements using the enucleated eye test (EET). METHODS: The corneal surface of isolated bovine eyes was continuously wetted with commercial balanced salt solution (BSS) over 4 h at 37 degrees C and central corneal thickness (CCT) was measured. Initial 5-min challenges were made with dilute solutions of benzalkonium chloride (up to 0.032%) or NaOH (up to 0.4 M). The residual LDH activity in the corneal epithelium and corneal stroma were then assessed. RESULTS: Dose-dependent increases in CCT of up to 70% were measured. A strong correlation (r = -0.961) was found between increases in CCT and decreases in stromal LDH activity, but the correlation was much less (r = -0.512) for epithelial LDH activity. CONCLUSIONS: LDH activity can be used as one marker for cell integrity in the corneal stroma and epithelium, although dose-dependent correlations may not be high.

Localization and quantification of alpha-1-proteinase inhibitor in the human cornea.

alpha-1-Proteinase inhibitor, formerly called alpha-1-antitrypsin, was detected in human corneal epithelium, stroma, Descemet's membrane and endothelium using an indirect immunolocalization technique. The average alpha-1-proteinase inhibitor levels detected by an immunodot blot assay in the epithelium, stroma and Descemet's membrane-endothelium extracts per total human cornea were 29.5 micrograms, 54.3 micrograms and 3.5 micrograms, respectively. Immunolocalization on Western blots of SDS polyacrylamide electrophoresis gels revealed that all three layers contained a molecule with a molecular weight equal to the native alpha-1-proteinase inhibitor. Additionally, in the epithelial and stromal extracts minor bands at 75 kD and 110 kD were noted which are possibly due to complexes with proteases. The 110 kD band alternatively may be a dimer of the inhibitor. The epithelial extract contained bands at 40 kd and less than 30 kD indicating the presence of proteolysis products. alpha-1-Proteinase inhibitor probably plays a major role in the protection of the cornea from proteases released by inflammatory cells.