From Medical to Surgical Therapy


For both the patient and the clinician, the decision to advance from medical therapy to surgery in glaucoma is an important one. Thoughtful consideration and assessment of the benefits and risks are essential. Although a lower intraocular pressure (IOP) following glaucoma surgery is generally considered beneficial to the eye, the risk of vision loss without surgery must outweigh the risk of vision loss with surgery. For this reason, medical therapy is the preferred initial treatment in most circumstances. With medical therapy, one or more drugs in the form of eye drops are prescribed to achieve a target IOP—the level below which the optic nerve function is stable and not expected to worsen. However, some clinicians have advocated early surgical intervention when glaucoma is first diagnosed.

Proponents of early surgery, and particularly those who advocate the benefits and success of glaucoma surgery as the initial therapeutic measure for primary open-angle glaucoma, cite the limitations of medical treatment. These include ocular and systemic side effects of medical treatment, cost of medication, poor compliance, and loss of visual function despite presumed adequate medical treatment. Under these conditions, early surgical intervention clearly is warranted in some patients. In particular, early surgery should be considered in those patients who are unlikely to comply with medical therapy, who require an unusually low target IOP, and in whom adequate IOP control is unlikely to be achieved with medical treatment.

In addition to these indications for early surgery, it has been suggested that patients not treated previously with a medical regimen have a better chance of success with trabeculectomy than do those who have received medical therapy. In this regard, some topical medications have been associated with an adverse effect on subsequent trabeculectomy because of deleterious effects, particularly of their preservatives, on the conjunctiva or Tenon's capsule. Without definitive data, however, most ophthalmologists view the potential complications of glaucoma surgery as serious enough that other therapeutic modalities should be employed first. Therefore, for most patients, surgery should be performed only when medical therapy has failed or is likely to fail. In other words, surgery to lower IOP is generally indicated for glaucoma patients on maximum tolerable medical therapy who have had maximal laser benefit and whose target IOP is exceeded.

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