Endothelial cell loss following DMEK may be overestimated by standard calculation methods
AMSTERDAM — The amount of endothelial cell loss following Descemet membrane endothelial keratoplasty may be overestimated by the standard methods of measuring cell density, according to one speaker here at the European Society of Cataract and Refractive Surgeons meeting.
The decline in endothelial cell density (ECD) after DMEK has been quantified as a reproducible 34% in the first 6 months due to the traumatic insertion of the graft during the operation, followed by a stable rate of 7% per year.
According to Jack Parker, MD, following the introduction of the no-touch technique in DMEK, this initial decline can no longer be a consequence of surgical trauma. It is more likely that the changes in density are due to the distribution of the cells over a larger area.
“Inserting the graft deswells the posterior cornea and increases the posterior corneal surface. The same number of endothelial cells looks smaller because they are stretched over a larger area,” Parker said.
A mathematical model was formulated to calculate the posterior surface area of the cornea before and after the operation based on the postoperative changes in central corneal thickness (CCT).
In 25 eyes undergoing DMEK, ECD and CCT were measured before and after surgery. ECD in the first 6 months fell by 34% and CCT changed by 267µ.
“Taking into account the consequent increase in posterior corneal surface, the real endothelial cell loss goes down to 8.9%, while 25% of the total endothelial cell loss is attributable to the change in surface area of the cornea,” Parker said.
Disclosure: Parker has no relevant financial disclosures.