At Cleveland Clinic’s Cole Eye Institute, which has more than eight years of progressive experience with Descemet’s stripping automated endothelial keratoplasty (DSAEK), corneal surgeons say the procedure represents a dramatic leap forward in the treatment of corneal endothelial disease. DSAEK allows them to replace only the portion of a cornea that is dysfunctional instead of performing a full-thickness penetrating keratoplasty (PK).
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“This has been a game-changer for corneal endothelial disease that allows the surgeon and the patient to see the fruits of their labors much more quickly,” says William J. Dupps, MD, PhD, one of several Cole Eye Institute surgeons offering DSAEK. “It is our first choice for any patient with endothelial disease.”
DSAEK cases surpass PK
At the Cole Eye Institute and across the specialty of corneal transplantation, the number of DSAEK cases has now exceeded the number of transplants performed using the traditional full-thickness approach, also known as penetrating keratoplasty (PK).
“For the right patients, DSAEK is a wonderful procedure,” he says. “These include eyes in which the corneal endothelium is no longer functioning, such as Fuchs’ corneal dystrophy and bullous keratopathy.”
Eye conditions in which PK is still preferable include conditions associated with scars through the center of the cornea, infections, and corneal melts that threaten to perforate, he explains.
Quick visual acuity return
DSAEK has many benefits in the right patient, including much faster recovery of visual acuity. Sutures can be removed within a month of surgery, which is at least five months earlier than suture removal can begin after PK. Induced astigmatism and other refractive error usually is negligible, allowing many patients to see well with glasses, or sometimes without them.
“With PK, patients often begin with very high astigmatism that limits their vision in glasses for several months before we can even begin to address the astigmatism,” says Dr. Dupps. “After six months, we can start with selective suture removal and achieve good short-term results, but the astigmatism can return as remaining sutures erode and break away over time. Patients can still be left with very high levels of astigmatism. This is a situation that almost never occurs with DSAEK.”
These PK patients then have to face the possibility of additional corrective surgery or wearing much stronger glasses or even rigid gas-permeable lenses, which can be a huge adjustment, especially considering that the typical patient is well over 60 years of age and has never worn contact lenses before.
Astigmatism after PK also can be worsened by the often unavoidable and unpredictable mechanical mismatches that exist between the donor and the recipient eyes, notes Dr. Dupps. With DSAEK, the front of the cornea, where optics are centered, isn’t affected.
Concurrent DSAEK/cataract surgeries
He says that DSAEK is most frequently done on eyes that are pseudophakic (eyes that have had a cataract removed and a lens implant placed). When the procedure is planned concurrently with or shortly after cataract surgery, careful intraocular lens selection can leave even more patients spectacle-free. Photorefractive keratectomy (PRK) or laser-assisted-in-situ keratomileusis (LASIK) are other options to help achieve this goal after DSAEK, and the results of laser surgery may be more predictable than after PK.
Another benefit of DSAEK is that there may be less risk of graft rejection, since it only requires transplantation of corneal endothelium and a small amount of stromal tissue. The small incision size also reduces the risk of serious intraoperative complications such as expulsive chorodal hemorrhage. The small incision in DSAEK is far less risky than the ‘open sky’ required for PK,” says Dr. Dupps.
Furthermore, if a repeat procedure becomes necessary, repeat DSAEK is much less invasive and risky than repeat PK, as it simply involves slipping out the failed disc of tissue and replacing it with a new one. “Each time you do PK, you face increased difficulty and risk,” says Dr. Dupps.
If DSAEK is unsuccessful or impossible because of coexisting eye conditions, the surgeon can still perform a PK, he adds.
Dr. Dupps notes that earlier forms of endothelial keratoplasty required surgeons to perform manual dissection of the donor tissue. The introduction of a microkeratome technique for preparing the donor tissue has made the procedure technically accessible to more surgeons and has improved visual outcomes because of smoother tissue interfaces. Also, most eye banks now are able to prepare the tissue for facilities that don’t have microkeratome access.
Cole Eye Institute improves technique
Dr. Dupps and colleagues at the Cole Eye Institute instituted one of the first academic DSAEK centers in 2005, and the group has been active in improving the surgical technique. Advances have included developing specialized approaches to promoting successful attachment of the graft to the recipient cornea, and performing intraoperative imaging to study these interventions and assess their impact on surgical outcome.
Corneal surgeons today are fortunate to have access to this greatly improved surgical approach for endothelial disease, concludes Dr. Dupps.
“However,” he adds, “it is much more technically demanding than PK, so proper training and experience are essential.”