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The Place of Trabeculectomy in the Treatment of Glaucoma

1981; Elsevier BV; Volume: 88; Issue: 3 Linguagem: Inglês

10.1016/s0161-6420(81)35051-9

1549-4713

Peter Watson, Ian Grierson,

Retinal Diseases and Treatments

The purpose of treating glaucoma is to reduce intraocular pressure throughout the 24 hours to a level at which no further damage is done to the optic nerve head. We have reviewed the results of 424 trabeculectomies performed at our clinic from 1967 to 1977. We have found that although initial control of intraocular pressure was achieved in 74% with medical therapy, only 40% remained under adequate control over a five-year period. Trabeculectomy alone controlled the intraocular pressure in 86% of the 424 eyes requiring surgery. This percentage was increased to 98% by the use of additional medical and/or surgery. Regression analysis of the results showed that the intraocular pressure can be predictably reduced to a level approaching the episcleral tissue pressure. A detailed discussion of recent knowledge of the functional anatomy of the outflow system and the morphologic basis of drug actions on the trabecular meshwork indicates that the continued use of strong miotics or drugs that give rise to underperfusion of the outflow system can lead to progressive damage of the trabecular meshwork. Because of this, and because of the low complication rate of trabeculectomy, we feel that surgery should be undertaken as soon as simple medication (ie, pilocarpine 2% tid; timolol 0.5% bid or a combination of these) fails to control the intraocular pressure, or at any time, regardless of the intraocular pressure, that progressive field loss is confirmed. The purpose of treating glaucoma is to reduce intraocular pressure throughout the 24 hours to a level at which no further damage is done to the optic nerve head. We have reviewed the results of 424 trabeculectomies performed at our clinic from 1967 to 1977. We have found that although initial control of intraocular pressure was achieved in 74% with medical therapy, only 40% remained under adequate control over a five-year period. Trabeculectomy alone controlled the intraocular pressure in 86% of the 424 eyes requiring surgery. This percentage was increased to 98% by the use of additional medical and/or surgery. Regression analysis of the results showed that the intraocular pressure can be predictably reduced to a level approaching the episcleral tissue pressure. A detailed discussion of recent knowledge of the functional anatomy of the outflow system and the morphologic basis of drug actions on the trabecular meshwork indicates that the continued use of strong miotics or drugs that give rise to underperfusion of the outflow system can lead to progressive damage of the trabecular meshwork. Because of this, and because of the low complication rate of trabeculectomy, we feel that surgery should be undertaken as soon as simple medication (ie, pilocarpine 2% tid; timolol 0.5% bid or a combination of these) fails to control the intraocular pressure, or at any time, regardless of the intraocular pressure, that progressive field loss is confirmed.