Quarter-DMEK a promising solution to global shortage of donor tissue
Click Here to Manage Email Alerts
BARCELONA, Spain — Optimizing the use of donor tissue through hemi- and quarter-Descemet’s membrane endothelial keratoplasty can maximize the number of transplants per donor, according to a speaker here.
This approach can also help maintain favorable long-term outcomes in patients with endothelial diseases.
At the European Society of Cataract and Refractive Surgeons meeting, Lamis Baydoun, MD, PhD, of University Eye Hospital in Münster, Germany, and the ELZA Institute in Zurich, Switzerland, presented innovative strategies to address global corneal tissue shortages.
DMEK has been successful in achieving excellent visual outcomes and long-term graft survival. However, with the growing number of DMEK surgeries worldwide, concerns over donor tissue shortages have increased. To address this, Baydoun and her former colleagues at the Netherlands Institute for Innovative Ocular Surgery (NIIOS) pioneered modifications to the standard DMEK procedure.
“In regular DMEK, you trephine the central 8 mm to 9.5 mm of the cornea, and you discard the peripheral ring, which still contains viable corneal endothelial cells. We thought, if we just take the entire Descemet’s sheet and cut it into halves, we could create a hemi-DMEK, which could still cover the same surface as a standard graft,” Baydoun said.
Introduced in 2014, hemi-DMEK allows two patients to be treated from a single donor cornea. Early results were promising, with patients achieving good visual acuity and a low rate of complications. However, the technique raised concerns due to the lower endothelial cell density observed in hemi-DMEK patients compared with those who underwent full DMEK.
“This initially raised questions about the longevity of these grafts,” Baydoun said, but follow-up studies demonstrated stable vision over 5 years, with only one case of graft rejection.
Building on the success of hemi-DMEK, the NIIOS team developed quarter-DMEK, in which the donor cornea is divided into four segments. This procedure is reserved for patients with healthy peripheral endothelial cells, allowing for even greater tissue conservation.
“With quarter-DMEK, we perform a smaller descemetorhexis, about 6 mm to 7 mm, which reduces the bare stroma area and minimizes cell migration,” Baydoun said. Despite the smaller grafts, patients who underwent quarter-DMEK achieved visual outcomes comparable to those of standard DMEK, with no cases of graft rejection observed up to 5 years after surgery.
Baydoun noted that patient selection is key for quarter-DMEK, emphasizing the importance of guttate distribution in determining eligibility.
“If you look at the distribution of guttate under retroillumination, and if the periphery is clear and specular microscopy shows healthy peripheral endothelial cells, these patients could be good candidates for quarter-DMEK,” she said.
The logistical challenges of quarter-DMEK are notable, as multiple patients must be treated simultaneously to use all portions of the donor cornea.
“We’ve successfully performed surgeries where four patients were treated with quarters from the same donor, but it requires careful coordination,” Baydoun said.
Collapse
Baydoun L. Long term results of hemi and quarter DMEKs. Presented at: European Society of Cataract and Refractive Surgeons meeting; Sept. 6-10, 2024; Barcelona, Spain.
Read more about
Click Here to Manage Email Alerts