Eyeworld

68 | EYEWORLD | SEPTEMBER 2023 G UCOMA COMPLICATED CASES by Liz Hillman Editorial Co-Director About the physicians Inas F. Aboobakar, MD Instructor in Ophthalmology Massachusetts Eye and Ear/ Harvard Medical School Boston, Massachusetts Matt Schlenker, MD Associate Professor University of Toronto Toronto, Canada Devesh Varma, MD Assistant Professor of Ophthalmology University of Toronto Toronto, Canada Malignant glaucoma: why it happens and its management "Despite these things, in general, XEN intraoperatively is a very safe procedure. I tell patients they're going to hear me talking about positioning and repositioning during the proce- dure because I want it perfect before we leave," Dr. Sheybani said. "Repositioning at the time of surgery is not a worrisome thing for me because the intraop complications are so unlikely. … There is hypotony that can occur within the first 1–2 weeks, and there can be choroidals. There can be hyphema, less likely but possible. The advantage of XEN is that the long-term issues are less likely compared to the other filtration procedures." Prevention In general, with all of these complications, pre- vention is key. Here are some points Dr. Shah provided to help prevent complications: • Make sure you're choosing the right patients for any given procedure. • Ensure you have an en face view for angle procedures and operate in reverse Trendelenburg. • Know your landmarks, using trypan blue to stain the trabecular meshwork and Schlemm's canal if needed. • Use OVDs appropriately (a dispersive OVD to protect the endothelium and cohesive in the nasal angle); cohesive OVD can displace blood away from your view. In his interview with EyeWorld, Dr. Shah also emphasized making sure incisions are wa- tertight and potentially leaving a bit of cohesive viscoelastic in the anterior chamber for extra pressurization for eyes at risk of complications from decompression, such as choroidals or ante- rior chamber shallowing. "To realize the promise of MIGS, we have to continue to put safety above all else. These procedures are safe when the proper steps are taken, when we take the time to get good visu- alization, when we recognize the right patient for the right process, when we're meticulous with surgical technique," Dr. Shah said. "The onus is on all of us as practitioners to maintain that high vigilance to be exacting in our tech- nique, in our fundamental principles to live that promise that MIGS are meant to provide." continued from page 67 W hen it comes to malignant glau- coma, why it occurs, its manage- ment, and if possible, its preven- tion, Matt Schlenker, MD, and Devesh Varma, MD, both think it's important to first discuss some of the misun- derstanding that has surrounded this topic. The term "malignant glaucoma" was coined by Albert von Graefe in 1869 when he published a paper on acute angle closure glaucoma in pa- tients after peripheral iridotomy, with shallow- ing of the anterior chamber and high intraocular pressure. 1 Dr. Varma and Dr. Schlenker said there is a history of malignant glaucoma being described as aqueous misdirection. As Dr. Varma put it, "In the early days, malignant glaucoma was de- scribed as the shallowing of the peripheral and central anterior chamber with high pressure. People weren't sure what the cause was. They thought maybe aqueous was going in the wrong direction and called it aqueous misdirection." Dr. Varma and Dr. Schlenker said this is not what's happening. The seminal paper in 2009 by Harry Quigley, MD, cleared up what's hap- pening in these cases and began to change what Dr. Varma said is a misnomer. 2 In the abstract of the paper, Dr. Quigley wrote: When the pupil dilates, the iris typically decreases its volume by losing extracellular fluid. Eyes with angle-closure lose less iris volume with pupil dilation, contributing to obstruction of the trabecular meshwork. Expansion of choroidal volume is a dynamic phenomenon and is a major risk factor in angle-closure. The mechanism of malignant glaucoma seems likely to result from poor

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