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Newer keratoplasty procedures changing the field of corneal transplant surgery
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 Richard L. Lindstrom |
The rapidly growing return to lamellar keratoplasty to treat most patients who require corneal transplant surgery is nothing short of amazing.
Penetrating keratoplasty has been the dominant method used to treat corneal opacities, dystrophies and ectasia for more than 50 years. For decades, we corneal surgeons have debated graft size, suture material and pattern, and similar minor surgical nuances with only minimal incremental improvement in outcome, complication rate, patient morbidity or rate of visual recovery. Meaningful advances have included great improvements in eye banking and corneal preservation, including the development of advanced preservation media such as Optisol-GS (Bausch & Lomb) in the U.S. for 4°C storage and sophisticated methods of organ culture in Europe for 34°C storage.
These media have allowed longer-term corneal preservation, catalyzing the development of a very productive network of eye banks worldwide. The Eye Bank Association of America, along with other global organizations, has worked tirelessly to continuously improve both the quantity and the quality of corneal donor tissue available to the patient suffering corneal blindness or visual disability. Major clinical trials, such as the Cornea Donor Study, have advanced our knowledge of which donor corneas are appropriate for transplantation. For example, this still-ongoing study has shown us that donor corneas from elderly patients can generate equivalent results to those from younger donors. Exciting to many, the PK surgeon’s holy grail of reducing surgically induced astigmatism may also be positively affected by application of the femtosecond laser to donor and recipient bed creation, enhancing visual restoration.
Still, PK, while a miracle for many, requires a major commitment from the patient and the surgeon to achieve visual rehabilitation. To the rescue comes an ever-increasing alphabet of lamellar refractive procedures that are destined to overtake PK as the most common form of corneal transplant. The most important of these are the methods to replace the corneal endothelium alone for the large number of patients with Fuchs’ dystrophy, aphakic and pseudophakic bullous keratoplasty, and the like. These endothelial transplantation procedures now dominate the corneal surgeon’s practice.
Almost an oxymoron a few years ago, we now have an approach to corneal transplantation that can be considered “minimally invasive.” The results with DSAEK/DSEK and promise of DMAEK/DMEK are amazing to a senior corneal surgeon like me. While there was a learning curve incorporating the DSAEK procedure into my practice, it is definitely learnable with minimal patient morbidity, thanks to the outstanding training available from our colleague innovators in the field.
One significant concern to me is intraoperative surgically induced endothelial cell loss and possible more rapid continuous annual endothelial cell loss reported by many. Advances in surgical technique should help here, but we may be facing a high incidence of regrafts in a decade as we operate on younger and younger patients with longer life expectancies.
Years ago, I did research on techniques to enhance the endothelial cell count of a donor with growth factors or cultured endothelial cell seeding, and today this approach remains a topic of active research around the world. It is easy to imagine the day when our ever-more sophisticated eye banks not only cut us a donor customized to our patients needs, but also supplement the donor cornea with additional viable endothelial cells, offering a greater reserve to moderate those cells lost from surgical trauma.
The resurgence in interest and capability for lamellar keratoplasty is not limited to the posterior cornea. Equally innovative work is advancing the quality of outcomes achieved with anterior lamellar keratoplasty. In my early years as a corneal transplant surgeon, I rarely chose lamellar keratoplasty for visual rehabilitation, reserving it primarily for tectonic indications. My experience with lamellar keratoplasty was: “The eye looks good, but the patient sees bad.” Advances such as DALK and more superficial lamellar keratoplasty done with the femtosecond laser or microkeratome, in select cases without suturing (another example of “minimally invasive corneal transplant surgery”), while technically quite demanding, are yielding very good visual outcomes. These eyes not only look good but see great as well.
So, joining our colleagues in glaucoma who for decades passed the nuances of trabeculectomy and tube shunts from one generation to the next and are now in the middle of developing a plethora of new and minimally invasive ways to surgically treat glaucoma, we corneal surgeons are in the middle of a similar revolutionary change in corneal transplantation. As always, a society’s access to trained surgeons and ability to afford the costs associated with these life-changing surgical procedures remain a major challenge. One can only dream of a world where these procedures will be available to all in need, but where available now, they are making a significant and positive impact, and it is definitely more fun being a corneal surgeon today than at any other time in my career.