Lamellar keratoplasty techniques

Abstract

Lamellar keratoplasty (LK) has revolutionized corneal graft surgery in several ways. Deep anterior LK (DALK) has eliminated risk of failure due to endothelial rejection. Endothelial keratoplasty (EK) has almost eliminated induced astigmatism and the "weak" graft-host junction as seen with penetrating keratoplasty (PK) and also reduced the risk of endothelial rejection. LK provided new insights into posterior corneal anatomy that led to better understanding and performance of DALK and to the development of another EK procedure, namely pre-Descemet's EK (PDEK). Surgical procedures for LK were further refined based on the improved understanding and are able to deliver better surgical outcomes in terms of structural integrity and long-term patient satisfaction, reducing the need of further surgeries and minimizing patient discomfort. In most specialist centers, anterior lamellar techniques like DALK and EK techniques like Descemet's stripping EK (DSEK) and Descemet's membrane EK (DMEK) have replaced the full-thickness PK where possible. The introduction of microkeratome, femtosecond laser, and PDEK clamp have made LK techniques easier and more predictable and have led to the innovation of another LK procedure, namely Bowman membrane transplant (BMT). In this article, we discuss the evolution of different surgical techniques, their principles, main outcomes, and limitations. To date, experience with BMT is limited, but DALK has become the gold standard for anterior LK. The EK procedures too have undergone a rapid transition from DSEK to DMEK and PDEK emerging as a viable option. Ultrathin-DSEK may still have a role in modern EK.

Keywords: Deep anterior Lamellar keratoplasty; Descemet's membrane endothelial keratoplasty; Descemet's stripping endothelial keratoplasty; Lamellar keratoplasty; pre-Descemet's endothelial keratoplasty.

Figure 1

Deep anterior lamellar keratoplasty with a Type-1 big bubble. (a) Postoperative day 1 clear graft diffuse slit-lamp view. (b) Optical coherence tomography showing normal graft thickness centrally and thickening at the graft–host junction as also occurs with penetrating keratoplasty. The pre-Descemet's layer is closely applied to the donor stroma

Figure 2

Endothelial keratoplasty: Postoperative slit-lamp and optical coherence tomography images of patients who had undergone Descemet's stripping endothelial keratoplasty (a and b), Descemet membrane endothelial keratoplasty (c and d), and pre-Descemet's endothelial keratoplasty (e and f). The edges of the grafts are visible (arrows). The Descemet's stripping endothelial keratoplasty graft is the thickest on optical coherence tomography. Descemet membrane endothelial keratoplasty and pre-Descemet's endothelial keratoplasty graft show similar outcomes in terms of graft thickness and visual outcome