Corneal Opacification: Diagnosis, Incidence, and Strategies for Keratoplasty.

Abstract

Corneal opacification has many causes; most commonly, diseases or injuries of the corneal endothelium lead to opacification and swelling. Corneal opacification usually manifests itself with painless loss of visual acuity and heightened sensitivity to glare. It can be treated surgically with layer-specific lamellar techniques of corneal transplantation (keratoplasty) that have become established in recent years. This narrative review is based on publications retrieved by a search in Medline, EMBASE, and the Cochrane Library for relevant clinical trials, systematic reviews, and meta-analyses of the different transplantation techniques. For endothelial diseases, which account for 55% of the nearly 9000 corneal transplantations performed in Germany every year, Descemet's membrane endothelial keratoplasty (DMEK) is associated with more rapid visual rehabilitation and a lower risk of rejection (2-3% vs.11-29%, according to a meta-analysis of 50 cohort studies) than penetrating keratoplasty (PKP). For opacification that is restricted to the stroma, deep anterior lamellar keratoplasty (DALK) has the advantage of full preservation of the recipient endothelium, so that endothelial rejection cannot occur, but it is a technically demanding procedure. In bilateral limbal stem-cell deficiency, PKP, including allogeneic limbal tissue (limbo-keratoplasty), can be effective but necessitates permanent systemic immunosuppression. Modern methods of keratoplasty enable targeted transplantation of only the affected corneal layers. As a result, postoperative complications are less common, and the transplants survive longer.