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Joshua H Hou, Peter Bedard; Impact of bubbling pressure on endothelial cell quality in Pre-Descemet’s endothelial keratoplasty (PDEK) preparation.. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5696.
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© ARVO (1962-2015); The Authors (2016-present)
PDEK offers numerous advantages over Descemet’s membrane endothelial keratoplasty (DMEK). Unlike DMEK, PDEK grafts can be obtained from very young donor tissue. Furthermore, PDEK grafts are thin enough to be optically similar to DMEK, but thick enough to be easier to manipulate intraoperatively. Adoption of PDEK, however, has been limited due concerns over post-processing graft quality. Factors that affect graft quality are poorly understood. The purpose of this study is to evaluate the impact of inflation pressure on endothelial cell quality after PDEK preparation.
Donor corneas with adequate endothelium for transplantation were obtained for PDEK processing. Samples were evaluated for endothelial cell quality using specular microscopy and trypan blue vital dye staining. Samples were then randomized for bubble inflation with either air or Optisol. PDEK preparation was performed under continuous pressure monitoring using an in-line pressure gauge (DPI 705 series). Bubble type (1 vs 2), peak inflation pressure (PIP) during bubble formation, and mean expansion pressure (MEP) during bubble enlargement, were obtained. Post-processing endothelial cell quality was then evaluated with trypan blue vital dye staining and graded as acceptable (<25% global cell loss) or unacceptable.
In total, 25 corneas were processed. A type 1 or type 2 bubble was obtained in 56.0% and 32.0% of cases, respectively. No bubble was obtained in 12.0% of cases. Mean PIP was statistically higher for type 1 (1030.5mmHg) vs type 2 (593.1mmHg) bubbles (p=0.012). Mean MEP trended higher for type 1 (667.3mmHg) vs type 2 (449.6mmHg) bubbles (p=0.056). There was no statistical difference in mean PIP or MEP when using air (706.0mmHg, 510.7mmHg) compared to Optisol (852.9mmHg, 653.0mmHg). 29% of type 1 bubbles had acceptable endothelial cell quality post processing compared to 88% for type 2 bubbles (p=0.012). The percentage of PDEK preparations with acceptable endothelium post-processing declined significantly as a function of increasing PIP and MEP (Fig 1).
PDEK processing can induced significant endothelial cell damage during bubbling. Type 1 bubbles are associated with higher inflation pressures and more endothelial cell loss compared to type 2 bubbles. Both PIP and MEP correlate with endothelial cell loss and should be minimized in future PDEK preparation techniques.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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