What is the aim of the review?
The aim of this Cochrane Review was to compare the effectiveness and safety of artificial corneal devices versus donor (human) corneas in people who had at least one donor cornea transplant that had failed.
The optimal management for people who have failed a donor corneal transplantation is unknown.
What was studied in the review?
There are several types of corneal transplants. The type of transplantation is defined by how much of the cornea is removed and replaced. Removal and complete replacement of the entire cornea is known as a full thickness penetrating keratoplasty (PK). Removing part of the cornea with replacement of the same part from a donor is based on the parts transplanted (e.g. endothelial keratoplasty refers to transplantation of the inner or endothelial layers of the cornea). Corneal transplantation is one of the most successful transplantations. However, sometimes the transplantation fails and the donor tissue becomes cloudy. No current guidelines are available as to how many donor corneal transplants can be performed in an eye that has failed a previous donor corneal transplantation.
Corneal transplantation with either a donor cornea or an artificial cornea (known as a keratoprosthesis) involves removal of the cloudy cornea and replacement with a clear cornea or corneal device. Some examples of keratoprostheses (KPro) are the Boston KPro (Types I and II), AlphaCor, osteo-odonto-keratoprosthesis, and Fyodorov-Zuev KPro.
What are the main results of the review?
We found no randomized clinical trials or controlled clinical trials in this review. There is no high-quality evidence to guide surgeons and patients as to the best treatment to use after failure of a donor transplant. A trial comparing the use of artificial versus human donor corneas after PK failure is therefore needed.
How up-to-date is this review?
We searched for studies published up to 4 November 2019.
The optimal management for those individuals who have failed a conventional corneal transplantation is unknown. Currently, in some centers, artificial corneal devices are routinely recommended after just one graft failure, while in other centers, they are not recommended until after multiple graft failures, or not at all. To date, there have been no controlled trials comparing the visual outcomes and complications of artificial corneal devices (particularly the Boston type 1 keratoprosthesis, which is the most commonly implanted artificial corneal device) with repeat donor corneal transplantation, in order to guide surgeons and their patients. Such a trial is needed and would offer significant benefit to an ever-increasing pool of people with visual disability due to corneal opacification, most of whom are still in productive stages of their lives.
Individuals who have failed one or more full thickness penetrating keratoplasties may be offered repeat corneal surgery using an artificial or donor cornea. An artificial or prosthetic cornea is known as a keratoprosthesis. Both donor and artificial corneal transplantations involve removal of the diseased and opaque recipient cornea (or the previously failed cornea) and replacement with another donor or prosthetic cornea.
To assess the effectiveness of artificial versus donor corneas in individuals who have had one or more failed donor corneal transplantations.
We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2019, Issue 11); Ovid MEDLINE; Ovid Embase; LILACS (Latin American and Caribbean Health Sciences Literature database); ClinicalTrials.gov; and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). We did not use any date or language restrictions in the electronic search for trials. We last searched the electronic databases on 4 November 2019.
Two review authors independently assessed reports from the electronic searches to identify randomized controlled trials or controlled clinical trials. Any discrepancies were resolved by discussion or consultation.
We used standard methodological procedures expected by Cochrane. For discussion purposes, we summarized findings from relevant comparative case series. We performed no data synthesis.
We did not identify any randomized controlled trials or controlled clinical trials comparing artificial corneas with donor corneas for repeat corneal transplantations.