Eyeworld

84 | EYEWORLD | DECEMBER 2021 G UCOMA References 1. Trubnik V, et al. Evaluation of risk factors for glaucoma drain- age device-related erosions: A retrospective case-control study. J Glaucoma. 2015;24:498–502. 2. Liu KC, et al. Recurrent tube erosions with anti-vascular en- dothelial growth factor therapy in patients with age-related macular degeneration. Ophthal- mol Glaucoma. 2020;3:295–300. 3. Gedde SJ, et al. Postoperative complications in the Tube Versus Trabeculectomy (TVT) study during five years of follow-up. Am J Ophthalmol. 2012;153:804–814. 4. Oana S, Vila J. Tube exposure repair. J Curr Glaucoma Pract. 2012;6:139–142. 5. Chaku M, et al. Risk factors for tube exposure as a late com- plication of glaucoma drainage implant surgery. Clin Ophthal- mol. 2016;10:547–553. 6. Muir KW, et al. Risk factors for exposure of glaucoma drainage devices: a retrospective observational study. BMJ Open. 2014;4:e004560. 7. Levinson JD, et al. Glauco- ma drainage devices: risk of exposure and infection. Am J Ophthalmol. 2015;160:516–521. 8. Einan-Lifshitz A, et al. Repair of exposed Ahmed glaucoma valve tubes: long- term outcomes. J Glaucoma. 2018;27:532–536. 9. Grover DS, et al. Forniceal conjunctival pedicle flap for the treatment of complex glaucoma drainage device tube erosion. JAMA Ophthalmol. 2013;131:662–666. more, without a patch graft." The switch to this approach has been more recent. "A lot of us switched to that when CMS stopped reimburs- ing the surgery center for patch grafts," he said. "I think that was about 3 years ago, and since it often takes years to develop an erosion, I'm not sure if I can say that definitively makes a difference." Managing the complication If it's in the early postop period, Dr. Razegh- inejad said revision surgery is mandatory if the tube is exposed. If the patch is exposed and still covering the tube, topical antibiotics and lubricants (drops and gels) usually help with conjunctivalization of the patch, he said. With late tube exposure, Dr. Razeghinejad said the need for revision is urgent because the chance of endophthalmitis is high. The conjunctiva around the area of the tube exposure is usually friable and congested. "I do inject lidocaine plus epinephrine to balloon the conjunctiva and decrease the bleeding," he said. "It also helps me to delineate the boundaries of free and scarred conjunctiva. I dissect the conjunctiva posteriorly, and due to the tissue expansion effect of the plate on the conjuncti- val tissue, there is enough conjunctiva over the plate to undermine and pull forward toward the limbus." Generally, Dr. Razeghinejad said the con- junctiva at the area of tube exposures is not a good tissue to cover the new patch and tube, and it's necessary to bring fresh conjunctiva from superior or the sides to close the defect area. He added that free conjunctival grafts or rotational flaps, double-layer amniotic mem- branes, and buccal membrane transplants may be used for superficial coverage in the event of conjunctival scarring. 4,8 If the tube is inserted anteriorly (close to the limbus or at the limbus), Dr. Razeghinejad prefers to relocate it more posterior and close the original tube entry with Vicryl sutures. "When you close the tract, you have to over tighten the suture to stop the leak, which usual- ly leads to astigmatism," he said. "Vicryl sutures dissolve within 4–6 weeks, but nylon lasts lon- ger and you have to deal with the astigmatism postoperatively if you use nylon sutures." When you see the tube is exposed, wheth- er it's the plate or tube itself, Dr. Smith said it's important to start antibiotics, manage the early infection if present, and seek the help of a retina specialist if indicated as in the case of endophthalmitis. The approach to an exposed tube also depends on what section of the tube is exposed, she said. If the plate is exposed, the whole tube usu- ally has to come out because it's hard to get the continued from page 83 Exposure of tubing material Source (all): Oluwatosin Smith, MD Exposure of plate with partial extrusion

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