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Surgeons and eye banks partner for innovation in corneal transplant, regenerative medicine
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As corneal surgeons, we live in an era of great progress. Selective lamellar techniques have replaced the older penetrating keratoplasty technique, leading to less invasive surgery and a much lower rejection rate. For both anterior and posterior lamellar surgery, techniques are now well-established. Descemet’s stripping endothelial keratoplasty and deep anterior lamellar keratoplasty are now used worldwide as first-line treatments, and more sophisticated developments, such as Descemet’s membrane endothelial keratoplasty and femtosecond-assisted anterior lamellar keratoplasty, are gaining popularity.
The main advantage of lamellar techniques, both anterior and posterior, is that we are reducing damage to the eye and preserving more of its anatomy and strength. Because they are partially extraocular procedures, they also allow us to avoid most of the complications associated with intraocular “open sky” surgery. In addition, anterior techniques have the specific advantage of preserving the endothelium, thus greatly reducing the risk of immunological rejection and graft failure. Rejection episodes, which are mainly related to the endothelium, are now infrequent.
When lamellar techniques were first introduced, there was some resistance. They were difficult and lacked reproducibility, and results were highly surgeon-dependent. Over the years, however, the techniques have been greatly refined, surgical steps have been standardized, and although they still require more training than PK, they have become accessible to most surgeons.
Experience has taught us to accept the inherent limitations of these techniques. In DALK, it is objectively difficult to reach the dissection level that allows us to bare the Descemet’s membrane. In 10% to 20% of cases, we must accept that some posterior stroma is left. This still gives us the advantage of keeping the host endothelium. While DSAEK and ultra-thin DSAEK have practically no limitations, DMEK surgeons know well that manipulation of the Descemet’s roll in the anterior chamber might be challenging.
In the last 3 years, there has been an amazing trend toward selective lamellar procedures. There is almost no indication for PK when the problem is in the endothelium or the disease is limited to the anterior surface of the cornea. Ten years ago, we were treating 100% of our cases with PK; now, we are doing less than 20%.
A second area of great advancement is corneal restoration by cell therapy and tissue engineering. We are able today to expand cells in the laboratory and transfer them to the diseased cornea to restore structural integrity and transparency. Surface reconstruction by autologous limbal epithelial stem cell transplantation is a proven concept, and endothelial cell transplantation is increasingly becoming a reality, with the first human trial soon starting in Europe.
José L. Güell
In the near future, regenerative medicine and innovative corneal surgery will be successfully combined. We will be able to use our new surgical strategies — DMEK or DALK — with tissue-engineered grafts. The next step will be an artificial cornea made with autologous cultured cells. Basic research is stepping from bench to bedside.
In this exciting innovation process, eye banks play a central role. Posterior lamellar techniques have led eye banks to expand their services to the preparation of pre-cut endothelial grafts. Although some surgeons still prefer to dissect their own lamellae, eye banks all over Europe are gearing up to provide pre-cut tissue with increasingly high-quality standards, tailored to surgeons’ specific needs. They are becoming active partners in surgery. In addition, an increasing number of eye banks are broadening their scope to cell culture and research on tissue engineering and regenerative medicine.
This is the time for biologists, bioengineers, eye banks and surgeons to work together toward unprecedented achievements. It is a new momentum. As surgeons, we no longer regard eye banks as “shops” distributing eye tissues, but as professional partners and reference centers for a broad range of research activities aimed at developing innovative sight-saving strategies.
José L. Güell, MD, is director of the Cornea and Refractive Surgery Unit, Instituto Microcirugia Ocular of Barcelona, and associate professor of ophthalmology, Autonomous University of Barcelona. He can be reached at IMO, Carrer de Josep Maria Lladó, 08035 Barcelona, Spain; +34-932-53-15-00; email: guell@imo.es.
Disclosure: Güell has no relevant financial disclosures.