Abstract
Purpose: :
To evaluate the impact of baseline factors on subsequent measures of IOP response and IOP variability during long–term treatment for newly diagnosed, open–angle glaucoma.
Methods: :
607 patients with newly–diagnosed open–angle glaucoma were randomly assigned to receive initial medications or initial trabeculectomy for treating their condition. These patients underwent examination at six–month intervals by standardized testing, including Goldmann applanation tonometry. Regression analyses were conducted using SAS Proc GLM to develop predictive models for three IOP outcomes: mean, maximum, and variation (standard deviation, SD) of IOP over time. Analyses included follow–up data extending through 5 years post–randomization.
Results: :
Higher mean, maximum, and SD values of IOP over time were significantly associated with higher baseline IOP (0.01<p<0.05 for all 3 outcomes) and initial medical vs. surgical treatment (0.001<p<0.01 for all 3 outcomes). Black race (p=0.03) and higher baseline age (p=0.003) were significantly associated only with higher mean IOP. Race and baseline IOP showed significant interactions – although similar at lower baseline IOPs, blacks showed increasingly higher mean (p=0.02), maximum (p=0.03), and SD (p=0.06) values of IOP during treatment relative to non–blacks as baseline IOP increased. Initial treatment also showed significant interactions with baseline IOP – as baseline IOP increased, patients treated medically had increasingly higher mean (p=0.002), maximum (p=0.001), and SD (p=0.01) IOP values relative to surgically treated patients.
Conclusions: :
Three measures of IOP during long–term treatment – the IOP mean, maximum, and SD (which have been associated with an increased risk of visual field progression) – are significantly associated with baseline IOP, race, and initial treatment. Given consistent evidence that IOP control during treatment reduces the risk of glaucomatous progression, these baseline factors may well influence subsequent progression.
Keywords: clinical (human) or epidemiologic studies: risk factor assessment • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials • intraocular pressure