Dynamics of big bubble formation in deep anterior lamellar keratoplasty by the big bubble technique: in vitro studies.

Purpose: To examine the movement of air injected in the cornea in simulated deep anterior lamellar keratoplasty (DALK), from the needle tip to the formation of different types of big bubbles (BB) and to ascertain how air travels through the stroma and pre-Descemet's layer [Dua's layer (PDL)] to create a type-1 (air between PDL and deep stroma) and type-2BB (air between PDL and Descemet's membrane).

Methods: Air was injected in 57 sclerocorneal discs and the passage recorded. Leaking points and sites of commencement of type-1 and type-2BB were examined by scanning electron microscopy.

Endothelial cell loss following tissue harvesting by pneumodissection for endothelial keratoplasty: an ex vivo study.

Aims: To study ex vivo the difference in endothelial cell density (ECD) in tissue harvested by pneumodissection for pre-Descemet's endothelial keratoplasty (PDEK) and Descemet's membrane endothelial keratoplasty (DMEK).

Methods: Tissue for PDEK and DMEK were obtained from 10 eye bank sclerocorneal discs by trephination after air injection into corneal stroma and big bubble (BB) formation. PDEK tissue was prepared in five corneas after achieving a type 1 BB and DMEK after a type 2 BB in five corneas.