title: Physiology of aqueous humor dynamic in the anterior chamber due to rapid eye movement.
abstract: The nature of aqueous humor (AH) mixing in the anterior chamber (AC) of the human eye due to rapid eye movement (REM) has not been fully understood and has been somewhat a controversial issue. This study uses a computational modeling approach to shed light on this issue. For this purpose a numerical method was developed and used to solve the mathematical equations governing the flow and mixing of aqueous humor motion in the eye subjected to such movements. Based on the experimental measurements available in the literature for the average and maximum amplitudes of the eye movements, a harmonic model for the REM was developed. The corresponding instantaneous and time-averaged velocity fields were evaluated. The simulation results showed that, contrary to earlier reports, the REM led to complex flow structures and a 3-D mixing of AH in the anterior chamber. In addition, the mixing velocity increased in direct proportion to the REM amplitudes. Thus, the AC flow generated by REM could carry nutrients to the posterior surface of the cornea during the sleep. Furthermore, the shear stress acting on the corneal endothelial cells due to REM was computed and compared with that of buoyancy driven flow in the AC due to temperature gradient. It was found that the shear stress generated by REM is much higher than that introduced by the natural convection. A video file for providing a better understanding of the AH mixing process in the AC was also prepared. This video is available on the web.
authors.affiliation: School of Mechanical Engineering, Shiraz University, Shiraz, Iran.
authors.forename: SeyedAmirreza
authors.initials: S
authors.lastname: Modarreszadeh
authors.affiliation: School of Mechanical Engineering, Shiraz University, Shiraz, Iran. Electronic address: abouali@shirazu.ac.ir.
authors.forename: Omid
authors.initials: O
authors.lastname: Abouali
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, WI, USA.
authors.forename: Alireza
authors.initials: A
authors.lastname: Ghaffarieh
authors.affiliation: Department of Aeronautical and Mechanical Engineering, Clarkson University, Potsdam, NY, USA.
authors.forename: Goodarz
authors.initials: G
authors.lastname: Ahmadi
mesh_terms: D000867:Anterior Chamber / Q000502:physiology*; D001082:Aqueous Humor / Q000502:physiology*; D003198:Computer Simulation; D006801:Humans; D008954:Models, Biological; D012895:Sleep, REM / Q000502:physiology*
keywords: Anterior chamber; Aqueous humor; CFD; Eye; REM