Mechanical Microkeratomes

Abstract

During the last decade several techniques of lamellar keratoplasty (LK) have been developed with the purpose of retaining the advantages of penetrating keratoplasty (PK) while avoiding the removal of healthy portions of the cornea, thus selectively replacing the dysfunctional parts, limiting the rate of rejection, and increasing long-term graft stability. This chapter will review the different instruments and techniques to prepare donor tissue for endothelial keratoplasty (EK) and deep anterior lamellar keratoplasty (DALK). Descemet’s stripping automated endothelial keratoplasty (DSAEK) foresees the transplantation of a donor graft consisting of endothelium, Descemet’s membrane, and a variable amount of posterior stroma in case of eyes with decompensated endothelium. In order to optimize visual rehabilitation, the present trend is toward minimizing the amount of stroma transplanted, and this can be done with both single- and double-cut procedures. DALK has been gaining popularity as the optimal approach for treating non-endothelial disorders affecting Bowman’s layer and stroma. Hand dissection of the stroma is technically difficult, and the quality of the surfaces obtained is rarely compatible with optimal vision, while pneumatic dissection technique as the “big bubble” is difficult to learn and can be complicated by micro-macro perforations making a conversion to PK necessary. As an alternative, microkeratome-assisted LK has the advantage of being a standardized, technically easy procedure, yielding extremely smooth dissected surfaces, therefore compatible with 20/20 vision.