Eyeworld

OCTOBER 2020 | EYEWORLD | 67 C Contact Sorkin: nir.sorkin@gmail.com this necessitates having the patient lay down for 48 hours after the procedure. Considering cell loss The reason the cell loss tends to be less with the femtosecond technique is because the size of Descemet's membrane removed from the patient is the same as the graft. With manual DMEK a larger amount of tissue has to be stripped from the patient's eye to ensure that the donor tissue does not overlap the host's, which could lead to possible detachment if not adhered correctly. It also removes more of the patient's own endothelial cells in the process. "The more Descemet's you remove from the periphery, the more it works against you be- cause your purpose is not only to transplant the new cells, it's also to preserve the patient's cells," Dr. Sorkin said. "They still have good cells in the periphery." With the manual approach, even if the amount of tissue removed from the patient is oversized by just 0.25 mm in conjunction with the graft that is typically 8.25 mm, this increases the affected stripped area by 6%. "That means that the cells on the graft have to redistribute themselves over a larger area," Dr. Sorkin said. "They have to spread over an area that's 6% larger. That effectively reduces the cell density by 6%." In manual DMEK, it's also hard to create a perfect circle. Similar to tearing a piece of pa- per, it's not uncommon for this to inadvertently take off in another direction, Dr. Sorkin noted, adding that this results in removing a greater amount of tissue from the patient than was intended with more cell loss. The clinical advantages of the femtosecond approach translate into fewer graft detach- ments and a reduced rebubble rate, as well as potentially less endothelial cell loss. "We get these advantages without compromising the visual outcome," Dr. Sorkin said. One downside to the femtosecond approach is the expense because you'll need the laser and personnel to operate. Currently, manual DMEK is more com- monly performed. Though a good approach, Dr. Sorkin said with femtosecond technology showing fewer complications, it may come down to the patient's preference and whether they are willing to risk, for example, a higher chance of a rebubble. Overall, Dr. Sorkin views manual DMEK as an excellent surgery with great outcomes, both visually and mechanically, and low de- tachment rates. "The femtosecond laser gives us another tool, which can further reduce the complications, as well as improve long-term endothelial cell survivability," he said. Dr. Sorkin mentioned that their study group found reduced detachment and rebub- bling rates in a similar study that included patients with a failed penetrating keratoplasty graft who underwent DMEK, 2 and are currently conducting a prospective study to evaluate the femtosecond DMEK approach. References 1. Sorkin N, et al. Three-year outcome comparison between femtosecond laser-assisted and manual Descemet membrane endothelial keratoplasty. Cornea. 2019;38:812–816. 2. Sorkin N, et al. Comparison of manual and femtosecond laser-assisted Descemet mem- brane endothelial keratoplasty for failed penetrating keratoplasty. Am J Ophthalmol. 2020;214:1–8. Relevant disclosures Sorkin: None Intraoperative image following stripping of Descemet's membrane demonstrating the symmetric descemetorhexis circle created by the femtosecond laser with no remnant Descemet's islands or tags Source: Nir Sorkin, MD

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