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Shan Fan, tao guo, Baojiang Chen, Junqun Xiong, Fang Wang, Carol B Toris; Comparison of Aqueous Humor Dynamics Among Chinese and Caucasian Adults. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1063.
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© ARVO (1962-2015); The Authors (2016-present)
This study examines differences in aqueous humor dynamics (AHD) in healthy Chinese and Caucasian adults that may help to explain the difference in glaucoma prevalence in these ethnic groups.
Data from two studies were compiled and compared. Groups were comprised of young (between 20 and 30 years old, 32 Chinese and 39 Caucasians) and old adults (50 years and older, 37 Chinese and 46 Caucasians). Measurements included parameters of aqueous humor dynamics and ocular biometrics. A generalized estimating equation method was used to assess differences in AHD between groups by adjusting for the other variables. The ordinal GEE method was used to compare the ordinal variable, Shaffer Grade between groups.
In young Chinese compared to similarly-aged Caucasians, central cornea thickness (CCT) was greater (adjusted effect=-29.27, p<0.001); IOP was higher (adjusted effect=-2.33, p<0.001); anterior chamber volume (ACV) was smaller (adjusted effect=28.78, p<0.001) and uveoscleral outflow rate (Fu) was slower (adjusted effect=0.54, p=0.007). In old Chinese compared to Caucasians, the anterior chamber angle was smaller (Shaffer Grade, adjusted OR=3.06, p=0.016); IOP was higher (adjusted effect=-1.97, p<0.001); ACV was smaller (adjusted effect=33.15, p<0.001); and outflow facility was greater (adjusted effect=-0.05, p=0.013). All other parameters were not different between ethnic groups.
In Chinese compared to Caucasians, the cornea is thicker which may contribute in part to the higher IOP measurement. The smaller anterior chamber volume and narrower anterior chamber angle support a slower rate of drainage through the uveoscleral outflow pathway, despite faster aqueous flow. When separating young and old groups, the ethnic difference in aqueous flow occurs only in the old and in CCT occurs only in the young. The smaller AC volume and narrower angle in Chinese together with higher aqueous flow and lower uveoscleral outflow may increase their risk of narrow angle glaucoma. On the other hand, the smaller outflow facility in Caucasians might increase their risk of open angle glaucoma. Such information potentially could lead to improved screening and treatment options tailored towards specific ethnic groups.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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