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Title	Illustration of tissue harvesting for pre-Descemet’s Endothelial Keratoplasty: Pearls and pitfalls learned from a series of ex-vivo pneumodissections
Abstract Nr.	1053

Purpose	The aim of this study was to demonstrate surgical pearls and pitfalls in type 1 big bubble (BB) formation in pre-Descemet’s endothelial keratoplasty (PDEK) and to correlate these findings with optical coherence tomography (OCT) imaging and histology.
Methods	50 cadaveric human corneal tissue specimens consented for research and not suitable for transplantation were obtained in an eyebank. A BB was formed after intrastromal injection of air into the donor corneoscleral button. The production of type 1, type 2 and type 3 BB’s were recorded. Selected specimens were submitted for imaging with OCT or light microscopy.
Results	We obtained 31 type I BB’s (63.3%), 12 type II BB’s (24.5%) and 6 type III BB’s (12.2%). Key points illustrated by video analysis included the enlargement of a type 1 BB by injecting storage medium or viscoelastic into the air bubble, and the potential of perforation by increasing its size beyond 8.0mm. The salvage maneuver for a small type 1 BB with a peripheral perforation was viscoelastic injection at the perforation site, and subsequent further pneumodissection. The different methods to prevent a type 2 or type 3 BB formation were highlighted. Histology and OCT confirmed the anatomy of the 3 distinct BB types.
Conclusion	We present the video analysis of tissue harvesting with pneumodissection for PDEK. The principal points illustrated include the use of storage medium and viscoelastic to enlarge a type 1 BB and to seal peripheral perforation sites. We demonstrate techniques to prevent the formation of a type 2 and type 3 BB.

Authors 1

Last name	TERMOTE
Initials	K
Department	University Hospitals Brussels
City	Brussels

Authors 2

Last name	White
Initials	VA
Department	University of British Columbia
City	Vancouver

Authors 3

Last name	McCarthy
Initials	JM
Department	University of British Columbia
City	Vancouver

Authors 4

Last name	Holland
Initials	SP
Department	University of British Columbia
City	Vancouver