Mechanical stability of microkeratome-assisted intracorneal keratoprosthesis implantation.

OBJECTIVE To develop a laboratory model to study intracorneal keratoprosthesis implantation. METHODS A combination microkeratome and artificial anterior chamber system was used to create a hinged lamellar keratectomy on 13 human corneas. After reflecting the flap, the posterior stroma was trephined at either 2.5 or 3.0 mm. A model keratoprosthesis was positioned in the bed. The flap was sutured closed. Intrachamber pressure was increased, and wound leak pressure was recorded. The anterior corneal lamella was trephined at either 3.0 or 3.5 mm to expose the keratoprosthesis. Leak pressure was again determined. RESULTS After keratoprosthesis placement and prior to anterior trephination, all 13 corneas were watertight at maximum attainable intrachamber pressures. With posterior/anterior trephination combinations of 2.5/3.0 mm, 2.5/3.5 mm, or 3.0/3.5 mm, mean +/- SD wound leak pressure occurred at 95 +/- 12 mm Hg, 32 +/- 7 mm Hg, or 59 +/- 12 mm Hg, respectively (P<.01). CONCLUSIONS With a posterior trephination of 2.5 mm, there is significant keratoprosthesis-cornea interface destabilization between a 3.0- and 3.5-mm anterior trephination. For an anterior trephination of 3.5 mm, interface destabilization improves by increasing the posterior trephination to 3.0 mm. CLINICAL RELEVANCE An intracorneal keratoprosthesis may be implanted using microkeratome assistance. Our laboratory model provides a useful method for examining a range of posterior and anterior trephination diameters and their effects on the mechanical stability of intracorneal keratoprosthesis placement.