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Wei Wang, Han Xiaotong, Xinxing Guo, Wei Xiao, Mingguang He; Two-Year Changes of Iris Parameters and Related Factors in a Chinese Population. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4988.
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© ARVO (1962-2015); The Authors (2016-present)
Previous anterior segment optical coherence tomograhy (AS-OCT) studies revealed that iris parameters were strongly associated with angle closure. However, the longitudinal changes in these parameters have not been well studied. We determined the longitudinal changes in iris parameters and their related factors in a Chinese population.
Subjects aged 35+ years in Guangzhou, China were recruited and underwent standard ophthalmic examinations in December 2008 and December 2010. The iris parameters [iris thickness at 750 μm from the scleral spur (IT750), iris area, and curve (Iarea, Icurve)], angle parameter [angle opening distance and trabeculo-iris space area at 500 μm from the scleral spur (AOD500, TISA-500), anterior chamber angle (ARA)], anterior chamber width (ACW) were obtained from AS-OCT imaging in the dark. The axial length (AL) and anterior chamber depth (ACD) were measured by partial coherence laser interferometry. The right eye was used for analysis. Kolmogorov-Smirnov test was used to confirm the distribution of normality. The paried t test was used to assess the two years changes in these parameters. Univariate and multivariate linear regression were used to assess the relationship between the baseline demorgraphic and ocular parameters and the changes in iris parameters.
A total of 699 subjects completed all the examinations in 2008 and 2010 (Mean baseline age 52.6±11.4 years; 46.1% were male). Mean Iarea increased from 1.50±0.26 mm2 to 1.58±0.77 mm2 (Mean difference: 0.08; 95% confidential enterval [95%CI] 0.03 to 0.14; P=0.004). The Icurve increased from 0.27±0.17 mm to 0.28±0.16 mm (Mean difference:0.01; 95%CI: 0.006 to 0.02; P=0.036). In the multivariate analyses, baseline height (β=0.01; 95%CI: 0.001 to 0.02; P=0.022) and ARA (β=0.33; 95%CI: 0.01 to 0.66; P=0.041) were associated with changes in Iarea, while ACD (β=0.04; 95%CI: 0.01 to 0.07; P=0.023), AOD500 (β=0.36; 95%CI: 0.23 to 0.49; P<0.001), TISA500 (β=-0.54; 95%CI: -0.93 to -0.15; P=0.006), ARA (β=-0.11; 95%CI: -0.22 to -0.00; P=0.042), and ACW (β=-0.04; 95%CI: -0.06 to -0.02; P<0.001) were associated with changes in Icurve.
This longitudinal study provides evidence for changes of iris parameters with aging in a Chinese population. Demographic and biometric factors such as height, angle parameters may be used to predict changes in iris parameters.
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