Surgical treatment for glaucoma is usually undertaken when medical therapy is not appropriate, not tolerated, not effective, or not properly used by a particular patient, and the glaucoma remains uncontrolled with either documented progressive damage or a high risk of further damage. Surgery encompasses both laser and incisional procedures.
Laser surgery is used as primary, adjunctive, or prophylactic treatment in various types of glaucoma. For primary angle closure, the most frequent surgeries are laser iridotomy and laser iridoplasty to widen the angle and, less commonly, laser trabeculoplasty and cyclodestruction to lower intraocular pressure (IOP). In open-angle glaucoma, laser trabeculoplasty is most frequently used to lower IOP, but cyclodestruction can also be used in select cases.
Incisional surgery is the first-line treatment for primary congenital glaucoma. For most other types of glaucoma, a trial of medication and/or laser surgery is first attempted to control IOP. The clinician must exercise caution when recommending incisional surgery because potential adverse effects (infections, hypotony, cataracts) can result in vision loss. Early studies of trabeculectomy as initial therapy for glaucoma, which were performed before the introduction of contemporary glaucoma medications, suggested that trabeculectomy might offer some advantages—better control of IOP, reduction in the number of patient visits to the physician, and possibly better preservation of the visual field, for example. The results of the Collaborative Initial Glaucoma Treatment Study (CIGTS; see Chapter 4) confirmed that initial surgical therapy achieves better IOP control than does initial medical therapy. However, this finding did not translate to better visual field stabilization on average because subjects who received initial surgical treatment had a higher risk of cataract in the long term. In both groups, there was a low incidence of visual field progression. However, the 9-year follow-up data showed that initial surgery led to less visual field progression than did initial medical therapy in subjects with advanced visual field loss at baseline, whereas subjects with diabetes mellitus had more visual field loss over time if treated initially with surgery. Based on the results of this study and on current practice, most clinicians defer incisional surgery for primary open-angle glaucoma (POAG) unless initial treatment with medical and/or laser therapy fails. Surgical treatment can be accelerated in patients with advanced visual field loss at presentation.
When surgery is indicated, the clinical setting must guide selection of the appropriate procedure. Each of the many possible procedures is appropriate in specific conditions and clinical situations.