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Kamden R. Kopani, Michael A. Page, Jeffrey D. Holiman, David Davis-Boozer, Chris Stoeger, Winston D. Chamberlain; Femtosecond Laser Assisted Keratoplasty: Comparing Full and Partial-thickness Cut Wound Burst Pressure and Endothelial Cell Loss Across a Variety of Wound Patterns. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6059.
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To evaluate wound strength properties and effects on corneal endothelium when partial-thickness and full-thickness femtosecond laser-assisted keratoplasty (FLAK) wounds are made in cadaveric corneas.
Eighteen cadaveric human corneoscleral rims were mounted on an anterior chamber maintainer and cut with the femtosecond laser programmed to one of six possible wound patterns. Three corneas each were assigned to one of the following 6 groups: A1 (full-thickness "zig-zag"), A2 (partial-thickness "zig-zag" with posterior 70 µm tissue bridge left intact), B1 (full-thickness "mushroom"), B2 (partial thickness "mushroom"), C1 (full-thickness "top hat"), and C2 (partial-thickness "top hat"). The intracameral pressure required to produce leakage from the corneal wound was then measured in each case. Six additional cadaveric corneas were cut with the "zig-zag" pattern: 3 full-thickness and 3 partial-thickness. The full-thickness corneal buttons were floated in optisol and shipped to a remote site per eye bank protocol for tissue distribution of pre-cut donor FLAK tissue. The buttons were then shipped back and analyzed for endothelial cell loss with vital dye staining and digital image analysis. The partially-cut corneas were analyzed for endothelial cell loss from laser effect alone.
Mean leakage pressure in mm Hg for group A1 was 110 (SD 94); group A2, 1180 (SD 468); group B1, 978 (SD 445); group B2, 987 (SD 576); group C1, 710 (SD 474); group C2, 1290 (SD 231). There was a borderline statistically significant difference in leakage pressure between groups A1 and A2, p=0.05; between group A1 and B1 (p=0.05), and between group A1 and C1 (p=0.05). Mean percentage endothelial cell damage in corneas with full-thickness cuts was 17.25 compared with 8.48 in partial-thickness cuts.
Partial-thickness FLAK wounds with a 70 µm posterior tissue bridge demonstrate excellent resistance to rupture by direct intracameral pressurization, for a variety of programmed wound patterns. Full-thickness laser trephination and current eye bank handling protocol for donor FLAK buttons leads to moderate peripheral endothelial cell loss in donor tissue.
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