Why Full-Thickness Penetrating Keratoplasty and Not Deep Anterior Lamelar Keratoplasty for the Treatment of Keratoconus

Abstract

Over the past decade Deep Anterior Lamellar Keratoplasty (DALK) has been proposed as a preferred surgical option over Penetrating Keratoplasty (PKP) for the management of keratoconus (KC) and other anterior stromal diseases. However DALK is associated with a considerable number of problems which still prevent its acceptance by most corneal surgeons. DALK is a time consuming procedure, technically demanding, and is associated with a long and steep learning curve, even for experienced corneal surgeons. At the same time patients after DALK have comparable visual results to those of PKP, as well as comparable results in terms of refractive errors and residual astigmatism. In addition DALK is more costly compared to PKP as a result of the longer surgical time and higher number of follow-up visits. On a long-term follow-up PKP is associated with higher rates of graft rejection, while in DALK there is more interface haze as a result of retained host stroma. Whereas DALK is a procedure limited for anterior stromal corneal disorders with an intact descemet’s membrane, PKP can be used for all corneal pathologies that require replacement of the cornea, including descemet abnormalities such as hydrops in severe KC, penetrating trauma and herpetic infections where the endothelium is likely to be involved. The consistent reports of comparable visual outcomes for both PKP and DALK suggest there is no preference in choosing DALK over PKP. As long as more efficient, reproducible and easy to perform steps in DALK are developed, PKP will remain a valid and more popular option in corneal transplantation for keratoconus and other anterior stromal disorders.