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K. Kamat, M. T. Bui, T. C. Prager, A. Z. Chuang, N. P. Bell, D. A. Lee, R. M. Feldman; The Effect of Age and Positional Changes on the Iris Angle. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3360.
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© ARVO (1962-2015); The Authors (2016-present)
Ultrasound biomicroscopy (UBM) has become an essential tool in the qualitative and quantitative assessment of the anterior chamber. Previously, the application of UBM was limited to a supine examining position, necessitating an open shell and gel. In this study, anatomic changes in superior and inferior angle configurations were compared in sitting and supine positions along with light or dark conditions in younger (<30 y.o.) and older (>40 y.o.) populations.
A ClearScanTM cover, a fluid-filled bag/balloon that allows for different positional examinations and a 35 MHz Sonomed VuMax II UBM were utilized to visualize the anterior chamber angles. The angle was manually determined using an angle caliber tool, with each arm extending 5 mm. The largest of three measurements was taken as datum in each test condition (light/dark x inferior/superior quadrants x sitting/supine x age group x 15 subjects). The order of each test condition was randomized. A dim red light was used in the scotopic test phase.
Older vs. younger patients•Angles significantly narrower in older patients regardless of position, quadrant or light condition by 4.50 (median), p=0.002•Angles narrower in the dark condition for entire cohort by 1.960, p=0.0002•Older patients, lights on, showed a significant difference (p=0.02) when sitting with larger angles than supine for the inferior quadrant by 2.140
Angles may be narrower in older people due to prevalence of phacomorphic lens thickening, but dim conditions always produce attenuated angles. Sitting vs. supine differences were small and only found in older patients.
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