Indications and Contraindications
Incisional glaucoma surgery is indicated when maximally tolerated medical therapy and laser treatments fail or are insufficient to prevent progressive damage. Failure of medical therapy may be the result of poor patient adherence. This can be an indication for surgery because further changes in medical therapy are unlikely to improve IOP control. Progression of visual field damage and uncontrolled IOP, even at low levels, are indications for surgery. Multiple visual field examinations may be required in order to confirm progression.
Because of the potential complications of incisional surgery, it is not reasonable to perform trabeculectomy in an eye with ocular hypertension and a low risk of developing functional loss. However, in less clear-cut situations—for example, when 1 eye has sustained significant glaucomatous damage, and the IOP is high in the fellow eye despite maximally tolerated medical therapy—some ophthalmologists recommend surgery prior to unequivocal evidence of damage. In eyes with severely elevated, medically uncontrollable IOP, surgery may be warranted in the absence of glaucomatous damage. In some cases without documented progression, the decision to proceed with surgery is based on clinical judgment that the IOP is too high for the stage of disease.
The absence of light perception is a contraindication for incisional glaucoma surgery. The risk of sympathetic ophthalmia should always be kept in mind when any procedure is considered in a blind eye or an eye with poor vision potential. Conditions that predispose to trabeculectomy failure, such as active anterior segment neovascularization or active anterior uveitis, are relative contraindications. The underlying problem should be addressed first, if possible, or a surgical alternative such as tube shunt surgery should be considered. It may be difficult to perform a successful trabeculectomy in an eye that has sustained extensive conjunctival injury (eg, from previous surgery or trauma). Patients with extremely thin or abnormal sclera (eg, from surgery, necrotizing scleritis, or degenerative myopia) have a higher likelihood of complications.
The success rate of trabeculectomy is lower in patients with diabetes; younger patients; patients with African, Asian, or Hispanic ancestry; and aphakic or pseudophakic patients who had prior cataract extraction through a scleral tunnel incision. However, with the advent of clear corneal incisions for cataract surgery and the use of antifibrotic agents during trabeculectomy, outcomes have improved in pseudophakic patients. Patients with certain types of secondary glaucoma, predisposition to an aggressive postoperative inflammatory response, or prior failed trabeculectomy have a higher risk of trabeculectomy failure. Use of topical fluorometholone for 1 month prior to surgery can reduce the need for postoperative interventions and the need for long-term postoperative glaucoma medications. Patients who are unwilling or unable to comply with postoperative care may not be good candidates for trabeculectomy.
Breusegem C, Spielberg L, Van Ginderdeuren R, et al. Preoperative nonsteroidal anti-inflammatory drug or steroid and outcomes after trabeculectomy: a randomized controlled trial. Ophthalmology. 2010;117(7):1324–1330.
Stiles MC. Update on glaucoma surgery. Focal Points: Clinical Modules for Ophthalmologists. American Academy of Ophthalmology; 2012, module 6.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.