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Refinements continue to be made in endothelial keratoplasty, transplantation techniques
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Lamellar keratoplasty has now passed penetrating keratoplasty as the predominant form of corneal surgery.
While deep anterior lamellar keratoplasty is becoming more popular, PK is still performed more frequently for keratoconus. However, for endothelial pathology, including Fuchs’ dystrophy, aphakic and pseudophakic bullous keratopathy, and other forms of endothelial failure, including those occurring following prior transplant failure, a form of endothelial keratoplasty dominates as the preferred choice of corneal surgeons.
Eye banks worldwide are now preparing high-quality thin donor tissue for the more commonly utilized Descemet’s stripping endothelial keratoplasty, and leading eye banks are beginning to provide tissue for Descemet’s membrane endothelial keratoplasty, as well. This tremendous advance in keratoplasty technique has been driven by innovative corneal surgeons selflessly training their colleagues and a strong effort by eye banks, led by the Eye Bank Association of America, to make quality tissue readily available to U.S. surgeons, allowing keratoplasty to be scheduled as an elective procedure, much to the benefit of patients and their families.
While the incidence of vision loss from corneal pathology varies from country to country, if the U.S. rate of keratoplasty were extrapolated to the rest of the world, one would calculate that approximately 1 million corneal transplants of one type or another would be performed each year. The actual number is estimated to be less than 200,000. The great unmet need is multifactorial, including an inadequate number and distribution of trained corneal surgeons, but even more so an underdeveloped network of global eye banks, resulting in inadequate corneal donor tissue, even in countries where trained surgeons are available.
The Eye Bank Association of America has committed to help reduce the global burden of corneal blindness by working with interested parties worldwide to increase the number and quality standards of eye banks outside the U.S. A positive example of this effort is the collaboration between SightLife eye bank in Seattle and the corneal and the eye banking community in India. It is hoped that the necessary financial and human resources will continue to be supplied because the miracle of a corneal transplant in a patient with bilateral corneal blindness is extraordinary to observe. Of course, similar needs exist for the treatment of cataract, glaucoma, age-related macular degeneration and diabetic retinopathy worldwide, with an ever expanding backlog of patients needing treatment, but corneal transplantation is unique in its requirement for a live donor cornea and a well-functioning eye bank to approach the problem.
In advanced countries, we can expect corneal surgeons to slowly transition toward thinner DSEK and DMEK because visual outcomes appear superior in early clinical trials. In countries with less advanced networks of corneal surgeons and eye banks, efforts to strengthen donor tissue availability by strengthening the eye banking sector offer great promise.
Research continues into transplantation of replacement endothelial cells themselves, and evidence suggests this is a potentially viable approach. In addition, the elusive goal of a synthetic cornea continues to attract investigators as well as investment capital, and with advances in polymer science, we are learning how to get a synthetic cornea to heal into place and re-epithelialize in a stable fashion.
Finally, it is possible to imagine the day when an unlimited number of donor corneas might be created using cloning techniques. Instead of harvesting, processing, preserving and transporting donor corneas, the day may come when a global network of eye banks actually creates corneas, perhaps from the donors’ own stem cells, eliminating the risk of graft rejection.