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Shan Fan, Tao Guo, Sruthi Sampathkumar, Fang Wang, Carol B Toris; Correlation among parameters of aqueous humor dynamics and biometrics in healthy Chinese adults. Invest. Ophthalmol. Vis. Sci. 2016;57(12):6423.
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© ARVO (1962-2015); The Authors (2016-present)
This study investigates correlations among and between parameters of aqueous humor dynamics and biometric measurements in young and old healthy Chinese adults.
This prospective, single center study of healthy Chinese volunteers was divided into young (between 20 and 30 years of age, n=32), and old (50 years of age and older, n=36) groups. Aqueous humor dynamics assessments were intraocular pressure (IOP), aqueous flow (Fa), episcleral venous pressure (EVP), outflow facility (C) and uveoscleral outflow (Fu). Biometric measurements included anterior chamber depth (ACD), anterior chamber volume (ACV), axial length and central cornea thickness (CCT). Parameters were analyzed using GraphPad Prism, and SPSS19- linear mixed effects model. Averaged values from both eyes of each volunteer were used to assess associations between two parameters by Pearson correlation analysis. Data are represented as mean ± SD. Statistical significance was set at p < 0.05.
Irrespective of age, a positive linear correlation was present between IOP and EVP [r (66)=0.43, p<0.001], Fa and Fu [r (62)=0.35, p=0.005], Fa and C [r (65)=0.28, p=0.02], EVP and Fu [r (56)=0.32, p=0.01] and Fa and ACV [r (65)=0.32, p=0.008]. Negative linear correlation occurred between Fu and C [r (56)= -0.6, p<0.001]. In the old group, correlations occurred between CCT and Fa [r (34) = -0.36, p = 0.03] and ACV and C [r (34)=0.4, p=0.02] but not in young heathy individuals.
The interplay among parameters of aqueous humor dynamics suggests the possible presence of autoregulatory mechanisms in the eye required for IOP maintenance. With higher EVP, IOP increases. When trabecular outflow facility is low, outflow favors the uveoscleral path of lesser resistance. The more aqueous humor produced, the more drains through the uveoscleral outflow pathway and the higher the outflow facility. With aging, correlations among parameters of AHD and ocular biometrics increase underlining the importance of ocular biometrics in the study of aqueous humor dynamics and aging.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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