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E. Trastman-Caruso, S. Dorairaj, C. Tello, J. M. Liebmann, R. Ritch; Effect of Accommodation on Iris Thickness and Cross-Sectional Area and Ciliary Body Thickness in Pigment Dispersion Syndrome and Normal Controls. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1218.
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© ARVO (1962-2015); The Authors (2016-present)
To compare iris cross-sectional area and thickness in the accommodated and unaccommodated states in normals and patients with pigment dispersion syndrome (PDS) and to quantify the short-term response of the iris to accommodation.
Thirty-three patients diagnosed with PDS were examined with ultrasound biomicroscopy (UBM) and compared to 17 control subjects. A radial image of the iris and ciliary body was taken at the temporal quadrant before and after accommodation on a standardized target. Iris thickness was measured from a line perpendicular to the iris from points on the trabecular meshwork 500 µm and 1000 µm from the scleral spur (SS). Ciliary body thickness (CBT) was measured 500 µm posterior to the SS. Quantitative parameters and distances were measured using UBM Pro 2000 software. Independent sample t-tests compared mean iris thickness and cross-sectional area among patients with PDS and normal subjects.
Mean patient age was 45.6±15.7 years in the PDS group and 34.9±11.5 in the controls (p=0.017). Mean refractive error was -4.26±2.9 in the PDS group and -4.83±2.1 in the controls (p=0.499, t-test). All subjects were of European descent. There was no significant difference in iris cross-sectional area in the accommodated and unaccommodated states between groups (p values at 0-3 minutes were 0.617, 0.789, 0.786, and 0.916 respectively). Iris thickness at 500 µm (p=0.361) and 1000 µm (p=0.828) from the SS were comparable. CBT (878.3±344.7µm vs 793.5±159.5 µm) and area (0.98±0.27 mm2 vs 0.93±0.29 mm2) were similar between groups.
Iris cross-sectional area and thickness and CBT are similar in the accommodated and unaccommodated states in PDS and controls. This provides further suggestive evidence that properties of the iris pigment epithelium are inherently different in PDS compared to normals. Characterizing short-term dynamics of the iris furthers understanding of the mechanisms underlying PDS and glaucoma.
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