Eyeworld

82 | EYEWORLD | FALL 2024 G UCOMA Reference 1. Shah A, et al. Three techniques for guidewire-assisted sulcus glaucoma tube shunt place- ment. Am J Ophthalmol Case Rep. 2024;34:102009. Another pearl Dr. Kanter offered is to use viscoelastic to deepen the sulcus (as he would with anterior chamber placement as well). Dr. Kanter said bevel direction is traditionally pos- terior for sulcus placement to avoid iris clogging the tube, but some surgeons still bevel anteri- orly as they would for anterior chamber place- ment. An anterior bevel helps the tube go into the sclerotomy a little easier, Dr. Kanter said. He said he's never seen iris block a sulcus tube that was beveled anteriorly, unless it was actually sticking into the iris. "As long as it's parallel to the iris, you can get away with an anterior bevel in the sulcus," he said. Pars plana placement Dr. Han will use pars plana placement when she wants the tube to be even farther away from the cornea or in the setting of anterior segment dysgenesis when there is limited space in the anterior chamber or sulcus. If a patient is at high risk for corneal dam- age or if they've had prior corneal surgery, Dr. Misra said the sulcus or pars plana are options for tube placement, but she personally sees ben- efits to pars plana. "Sometimes with the sulcus, you don't have a sense of what happened there (what their cataract surgery was like, if there is any scarring, etc.)." Dr. Misra said she finds the pars plana also a bit safer if a patient has already had tube ex- posure episodes because the tube entry into the eye is farther back from the limbus. "Tube expo- sure risk is a big reason why we decide to place the tube in the posterior chamber," she said. The physicians interviewed for this article emphasized the importance of a thorough vit- rectomy by retina colleagues prior to pars plana tube placement to avoid vitreous clogging the tube. Dr. Misra also said leaving the tube a little bit longer into the posterior cavity could help for postop visualization. Tube management Dr. Han said for sulcus tube placement, she sees postoperative patients at 1 day, 1 week, and 1 month postop. Most of the time she doesn't need to see the tube postop in exams. "The key point is during surgery, you need to see the tip of the tube clearly before you finish the case. I had one case where we were not sure if the tube was clearly visualized in the sulcus intraoperatively. The next day the patient had an IOP spike, and the tube was stuck in the ciliary body. Since then, I know I need to clearly see the tip of the tube before I close the case. That's intraoperatively. Postop, if you don't see the tube, that's fine, it's behind the iris," she said, adding that she thinks in sulcus placement, the tube should be bevel down, away from the iris. An indentation in the iris postop combined with an IOP spike could indicate that the iris has been sucked into the tube. Dr. Han said she uses a long-term steroid postop for a few months. This prevents scar formation. She also uses mitomycin-C at 1 week and sometimes 1 month to prevent scar forma- tion. "In general, tube management is easier than trabeculectomy. The key to success of the tube shunt surgery is to prevent scar formation, including controlling the inflammation to pre- vent the hypertensive phase," Dr. Han said. Dr. Misra said she watches out for how quickly a patient encapsulates the bleb over the plate itself. If IOP starts to increase early, she suspects early encapsulation and utilizes aque- ous suppression early. DECLARE trial It's unknown whether sulcus placement of tubes actually results in less endothelial cell loss compared to anterior chamber place- ment, but the Glaucoma Drainage Device and Endothelial Cell Loss Compare Trial (DECLARE) aims to provide some data for this debate. The prospective, multicenter, outcome-masked, randomized clinical trial is enrolling patients who will be randomized 1:1 to receive either sulcus or anterior cham- ber tube placement. Endothelial cell density and IOP will be measured at 12 months and 24 months of follow up. "Because we don't know which tube placement is better, we're conducting the DECLARE trial. We're hoping it will provide more information about endothelial cell count and outcomes, so stay tuned," Dr. Han said. continued from page 81 Contact Han: Ying.Han@ucsf.edu Kanter: jkanter2@jh.edu Misra: Pmisra1@northwell.edu

• Cover