Open-angle Glaucoma - Known and Possible Risk FactorsI. Influence of Elevated Intraocular Pressure and its Reduction on Glaucoma Progression

Overview

Open-angle glaucoma was defined as a progressive, multifactorial optic neuropathy. Elevatedintraocular pressure is considered to be the major risk factor. During the last years, sixmulticentric, randomized studies tried to evaluate the role of elevated intraocular pressure(IOP) and the optimal hypotensive treatment. The Ocular Hypertension Treatment Study foundthat there seem to be reasons for treatment in selected groups with high risk factors and noreason in the vast majority of ocular hypertensives (persons with elevated IOP but no anatomicor functional glaucoma damage). Similar design is applied in the ongoing European GlaucomaPrevention Study. The Early Manifest Glaucoma Trial evaluated the role of immediate IOPreduction compared to no initial reduction in patients with early glaucoma. The study supportsthe beneficial effect of IOP reduction on open-angle glaucoma, but did not prove that elevatedIOP is the primary cause of glaucoma. The Collaborative Initial Glaucoma Treatment Studycompared in an interim report medical and surgical lowering of IOP. Visual fields were stableover 48 months of follow up in both groups. The study will be continued. The CollaborativeNormal-tension Glaucoma Study showed a favourable effect of IOP reduction on progression ofvisual field changes in patients with glaucoma and IOP in normal statistical values.The Advanced Glaucoma Treatment Study, compared surgical and laser treatment in progessedopen-angle glaucoma with ineffective maximal medical treatment. In African-Americans lasertrabeculoplasty proved to be more efficient, whereas in white patients surgical trabeculectomywas better as first intervention. Low intraocular pressure was found to be associated withreduced progression of visual field defects, supporting a protective role of low intraocularpressure in visual field deterioration.

Key words:
open-angle glaucoma - intraocular pressure - risk factors.