Eyeworld

60 | EYEWORLD | JULY 2023 C ORNEA Contact Deng: deng@jsei.ucla.edu Sorkin: nir.sorkin@gmail.com References 1. Gagnon MM, et al. Corneal endothelial cell density in glau- coma. Cornea. 1997;16:314–318. 2. Alshaker S, et al. Four-year survival comparison of endothe- lial keratoplasty techniques in patients with previous glaucoma surgery. Cornea. 2021;40:1282– 1289. 3. Aravena C, et al. Outcomes of Descemet membrane endo- thelial keratoplasty in patients with previous glaucoma surgery. Cornea. 2017;36:284–289. 4. Bonnet C, et al. Long-term out- comes of Descemet membrane endothelial keratoplasty in eyes with prior glaucoma surgery. Am J Ophthalmol. 2020;218:288–295. Relevant disclosures Deng: None Sorkin: Beyeonics In addition to medication considerations, Dr. Sorkin said that if the glaucoma patient has a tube, the position of that tube in the anterior chamber should be considered because it could interfere with the graft. If it's too long, it should be trimmed prior to or in combination with DMEK surgery. The tube could also be reposi- tioned to put it posteriorly, Dr. Sorkin said. He said there is speculation that when the tube is too close to the graft, aqueous flow could damage the endothelium, reducing the length of graft survival. Other factors also negatively affect the long-term survival of corneal trans- plants in eyes with prior trabeculectomy and shunt, Dr. Deng said. Surgical considerations When it comes to DMEK surgery in patients with glaucoma, Dr. Deng said that eyes with prior tube shunts or trabeculectomy might have anterior or posterior synechiae that needs to be lysed during the DMEK procedure. Dr. Sorkin said both of these filtration procedures could also filter out the air that is needed for the graft attachment more quickly. He said a bigger air fill might be needed or the patient can be positioned afterward in such a way to reduce this chance. Dr. Deng said that she doesn't change much of what she does preop, intraop, or postop for patients who have had prior MIGS vs. trab/tube. Postop considerations Both Dr. Deng and Dr. Sorkin emphasized the importance of regular IOP monitoring in the postop period for DMEK patients who have glaucoma. Dr. Deng said she will check IOP 1–2 hours after DMEK surgery in the postop area, and she has a low threshold to burp the para- centesis to lower the IOP if it is over the mid- 20s at the bedside using a portable slit lamp. Dr. Sorkin also cautioned against a high IOP in the early postop period, due to the air bubble potentially blocking the trab and/or causing pupillary block. "If I see a big air fill, especially a couple of hours after surgery when I check these patients, I will have a lower threshold for removing some of the air at the slit lamp to avoid reaching the status of pupillary block because I don't want them to have an IOP spike," he said. He also said that when measuring IOP in the early postop period, try to use a low to no-contact tonometer to avoid potentially dislo- cating the graft. Later in the postop period, IOP needs con- tinued monitoring due to the prolonged steroid use. Dr. Deng and Dr. Sorkin said that the cor- nea specialist and glaucoma specialist, which in some cases might be the same surgeon, should collaborate and communicate on whether a steroid drop needs to be reduced or postponed or if additional glaucoma management should be added. "If the IOP is not controlled by medication, additional glaucoma surgery might be neces- sary," Dr. Deng said. Finally, Dr. Sorkin said that glaucoma patients need to be counseled about some different things. First, he said it should be very clear that they need to continue their glauco- ma regimen even after the addition of steroid drops; he said patients can sometimes become confused and discontinue one for the other. Second, he said there is a need to understand the high long-term failure rate of grafts when patients have a trab or tube. "They need to know there is a high chance the graft will fail every few years, and they'll need to get repeat grafts. You need to have that conversation with the patient so that they know what to expect," Dr. Sorkin said. continued from page 59 A phakic patient with two prior shunts 1 week after DMEK Source: Sophie Deng, MD, PhD

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