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P. A. Ple-plakon, J. S. Weizer, A. Goyal, A. Trzcinka, B. D. Strong, C. A. Bruno, J. Junn, I. Tseng, D. C. Musch, S. E. Moroi; Filtering Blebs With Microcysts and Less Vascularity Are Associated With Less Positional Intraocular Pressure Change. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1049.
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Large intraocular pressure (IOP) variation is an important risk factor for glaucoma progression. Positional IOP change (IOPsupine-IOPsitting) simulates nocturnal IOP variation. We hypothesized that filtering blebs are associated with smaller positional IOP change compared to medically treated eyes.
Sitting and supine IOP were measured by pneumotonometry in subjects having at least 6 months follow up after filtering surgery. Exclusion criteria were: completely scarred bleb, aphakia, penetrating keratoplasty, drainage implant, and cyclodestruction. For subjects with surgery in one eye and a medically treated fellow eye, positional IOP change was compared. Blebs were graded for height, extent, vascularity (using the Indiana Bleb Appearance Grading Scale), microcysts, and "ring of steel." Positional IOP change was analyzed using the paired t-test. Association of IOP change with bleb morphologies was evaluated using mixed regression models adjusting for inter-eye dependency.
Positional IOP change (6.1 vs. 4.6 mmHg, respectively; P=0.01) was larger in medically treated eyes (n=21) than in filtered eyes (n=115 of 78 subjects). Absence of microcysts (p=0.02) and increased bleb vascularity (p=0.02) were associated with larger positional IOP change, while bleb age, height, extent, and "ring of steel" were not.
Filtered eyes had less positional IOP change compared to medically treated eyes. Favorable bleb morphology associated with smaller positional IOP change included microcysts and less vascularity. Improving filtering surgery outcomes with specific bleb morphologies of microcysts and less vascularity may decrease IOP variation.
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