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Sayoko Eileen Moroi, Diana Burnett, Jesse Gilbert, David M Reed, Arthur J Sit, Jay W McLaren, Vikas Gulati, Donna G Neely, Carol B Toris, David C Musch; Mechanisms of Glaucoma Drug Response Variations: Description of a Multi-Center Study of Aqueous Humor Dynamic Phenotypes. Invest. Ophthalmol. Vis. Sci. 2014;55(13):150.
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© ARVO (1962-2015); The Authors (2016-present)
We describe preliminary measurements of a new study designed to test the hypothesis that individual aqueous humor dynamic (AHD) variables can predict a patient’s glaucoma medication response.
Our prospective, randomized clinical trial aims to determine AHD phenotypes in patients with glaucoma and normal subjects at the University of Michigan, University of Nebraska, and Mayo Clinic. In 8 visits, we will measure intraocular pressure (IOP; iCare, Ocular Response Analyzer® (ORA®), Goldmann applanation, and pneumatonometry), biometry, cataract (Lens Opacities Classification System III, LOCS), aqueous humor flow rate, episcleral venous pressure, and outflow facility before and after treatment with timolol 0.5%, and latanoprost 0.005%. Physical measurements, medical history, and physical activity will be determined by using PhenX Toolkit, version 4. To date, we examined relationships among lens autofluorescence, age, central corneal thickness (CCT), topical anesthetic, and IOP. Relationships were examined by Spearman’s rank correlation (ρ) and Wilcoxon signed rank tests.
We examined 26 healthy subjects with a mean age of 56 ± 12 years. This sample was limited to low grades of cataract (LOCS classification >90% NO1-2, C1-3, and P1-2). Both anterior and posterior lens autofluorescence increased with age (ρ=0.75, p=0.019 and ρ=0.82, p=0.003 respectively) while lens transmittance decreased with age (ρ=-0.67, p=0.048). CCT was correlated between eyes (ρ=0.96). High CCT was associated with high IOP when measured by using iCare (ρ=0.44, p=0.034) and Goldmann applanation tonometers (ρ=0.46, p=0.028), but there was no relationship between CCT and IOP when measured by pneumatonometry (ρ=0.23) or the ORA® (ρ=0.35). There was no difference in IOP as measured by iCare or ORA® with or without proparacaine.
Our multi-center study provides a mechanism to explore ocular physiology. Our preliminary results suggest that, in normal subjects, lens autofluorescence increases and transmittance decreases with age. IOP is not influenced by CCT when measured by pneumatonometry or ORA® or by the use of topical anesthetic when measured by iCare or ORA®. These preliminary measurements will be the basis of our study to explore the relationship between AHD phenotypes and variations in response to glaucoma medications.
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