Corneal transplantation in the modern era

Abstract

Corneal blindness is one of the major causes of reversible blindness, which can be managed with transplantation of a healthy donor cornea. It is the most successful organ transplantation in the human body as cornea is devoid of vasculature, minimizing the risk of graft rejection. The first successful transplant was performed by Zirm, and since then, corneal transplantation has seen significant evolution. It has been possible because of the relentless efforts by researchers and the increase in knowledge about corneal anatomy, improvement in instruments and advancements in technology. Keratoplasty has come a long way since the initial surgeries wherein the whole cornea was replaced to the present day where only the selective diseased layer can be replaced. These newer procedures maintain structural integrity and avoid catastrophic complications associated with open globe surgery. Corneal transplantation procedures are broadly classified as full-thickness penetrating keratoplasty and partial lamellar corneal surgeries which include anterior lamellar keratoplasty [sperficial anterior lamellar keratoplasty (SALK), automated lamellar therapeutic keratoplasty (ALTK) and deep anterior lamellar keratoplasty (DALK)] and posterior lamellar keratoplasty [Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK)] broadly.

Keywords: Corneal blindness; corneal transplantation; eye banking; graft rejection; keratoplasty; visual acuity.

Fig. 1

Diagrammatic representation of anatomical layers of the cornea (Drawn by the authors based on the theoretical knowledge of the corneal anatomy).

Fig. 2

Flowchart showing the evolution of corneal transplantation. Source: Ref. .

Fig. 3

Flowchart depicting a stepwise approach while planning surgical management in a case of corneal opacity. SALK, superficial anterior lamellar keratoplasty; HALK, hemi-automated lamellar keratoplasty; ALTK, automated lamellar therapeutic keratoplasty; DALK, deep anterior lamellar keratoplasty, DSAEK, Descemet stripping automated endothelial keratoplasty, DMEK, Descemet membrane endothelial keratoplasty.

Fig. 4

Diagrammatic representation of the type of keratoplasty depending the on the level of corneal opacities along with endothelial function (Drawn by the authors based on the practical knowledge utilized for decision making in cases of corneal opacity). SALK, superficial anterior lamellar keratoplasty; ALTK, automated lamellar therapeutic keratoplasty; DALK, deep anterior lamellar keratoplasty.

Fig. 5

Diagrammatic representation of the type of keratoplasty to be chosen for cases of corneal decompensation with compromised endothelium with and without stromal scarring. (Drawn by the authors based on the practical knowledge utilized for decision making in cases of corneal decompensation).

Fig. 6

Post-operative clinical photograph of sutureless superficial anterior lamellar keratoplasty (SALK) for healed keratitis with superficial opacity involving anterior 200 μm of cornea. The photograph demonstrates a well apposed clear lamellar graft.

Fig. 7

Intra-operative pictures showing use of automated microkeratome for host dissection (A) and donor dissection (B) in case of automated lamellar therapeutic keratoplasty (ALTK).

Fig. 8

Post-operative clinical photographs of a patient operated using automated lamellar therapeutic keratoplasty for right eye nebulomacular opacity.

Fig. 9

Clinical pictures showing post-operative diffuse (left) and slit images (right) of automated lamellar therapeutic keratoplasty (with sutures). 10-0 nylon monofilament=0.020-0.029 mm thickness.

Fig. 10

Intra-operative sequential steps of manual deep anterior lamellar keratoplasty in case of advanced keratoconus. (A) Keratoconus with paracentral ectasia; (B) lamellar dissection with the aid of intra-operative optical coherence tomography; (C) donor preparation; (D) at the end of surgery intra-operative optical coherence tomography showing well-apposed donor graft to host bed. OCT, optical coherence tomography.

Fig. 11

Post-operative day 1 clinical picture of operated Descemet stripping automated endothelial keratoplasty (DSAEK) showing well-apposed lenticule to host cornea.

Fig. 12

Clinical photographs (A) showing operated penetrating keratoplasty with failed graft; (B) post-operative day one picture with clear graft and well-apposed graft-host junction.

Fig. 13

Clinical photograph of a child with left eye congenital corneal opacity along with an intra-operative photograph showing a very well-defined posterior corneal defect confirming the diagnosis of Peter's anomaly.

Fig. 14

Intra-operative photograph showing the well-apposed Descemet membrane endothelial keratoplasty (DMEK) lenticule on intra-operative optical coherence tomography.

Fig. 15

Clinical picture showing operated keratoprosthesis (K-pro) with operated membranectomy for retroprosthetic membrane.