Nonpenetrating filtering surgery in glaucoma.

Since 1967, trabeculectomy has been the standard drainage operation for most cases of medically uncontrolled glaucoma. It is associated with significant risk of hypotony, hyphema, choroidal effusion or hemorrhage, and bleb failure. Toward the goal of a safer and more reproducible glaucoma filtering surgery, nonperforating filtering surgeries are now performed in primary open-angle glaucoma, normal-pressure glaucoma, and most cases of secondary glaucoma. The site of highest resistance to outflow, the juxtacanalicular trabecular meshwork, is bypassed with avoidance of penetration into the anterior chamber. Different techniques of nonpenetrating filtering surgeries are discussed here.