Experimental research on intraocular aqueous flow by PIV method

Abstract

BackgroundAqueous humor flows regularly from posterior chamber to anterior chamber, and this flow much involves intraocular pressure, the eye tissue nutrition and metabolism.PurposeTo visualize and measure the intraocular flow regular pattern of aqueous humor.MethodIntraocular flow in the vitro eyeball is driven to simulate the physiological aqueous humor flow, and the flow field is measured by Particle Image Velocimetry(PIV). Fluorescent particle solution of a certain concentration was infused into the root of Posterior Chamber(PC) of vitro rabbit eye to simulate the generation of aqueous and was drained out at a certain hydrostatic pressure from the angle of Anterior Chamber(AC) to represent the drainage of aqueous. PIV method was used to record and calculate the flow on the midsagittal plane of the eyeball.ResultsVelocity vector distribution in AC has been obtained, and the distribution shows symmetry feature to some extent. Fluorescent particle solution first fills the PC as it is continuously infused, then surges into AC through the pupil, flows upwards toward the central cornea, reflecting and scattering, and eventually converges along the inner cornea surface towards the outflow points at the periphery of the eyeball. Velocity values around the pupillary margin are within the range of 0.008-0.012 m/s, which are close to theoretical values of 0.0133 m/s, under the driving rate of 100 μl/min.ConclusionsFlow field of aqueous humor can be measured by PIV method, which makes it possible to study the aqueous humor dynamics by experimental method. Our study provides a basis for experimental research on aqueous humor flow; further, it possibly helps to diagnose and treat eye diseases as shear force damage of ocular tissues and destructions on corneal endothelial cells from the point of intraocular flow field.

Numerical model to predict and compare the hypotensive efficacy and safety of minimally invasive glaucoma surgery devices

“…essentially interfere with each other due to the disparity between the scales of their velocity and pressure fields. The radial flow does not significantly modify the velocity field of the natural convection, and this convection does not, as assumed by previous studies, alter the IOP [21,31,[43][44][45]. Table 3 and Fig 4 show the post-operative IOP values in the different scenarios.…”

“…Interestingly, the two flows described above do not essentially interfere with each other due to the disparity between the scales of their velocity and pressure fields. The radial flow does not significantly modify the velocity field of the natural convection, and this convection does not, as assumed by previous studies, alter the IOP [ 21 , 31 , 43 – 45 ].…”

Fluid and structure coupling analysis of the interaction between aqueous humor and iris

“…The flow field in anterior chamber is measured by particle image velocimetry technology. The pivotal device in our study is image velocimetry system, provided by Beijing Institute of Technology, which can be found in Yang et al [20]. …”

One-year natural course of corneal densitometry in high myopic patients after implantation of an implantable collamer lens (model V4c)

“…However, in the present study, although we detected a significant decrease in corneal densitometry between post-operative Day 1 and postoperative Month 12, we did not detect any remarkable changes in endothelial cell density. We suggest that changes in corneal densitometry may be caused by various factors, including the density and function of endothelial cells, the balance between the stromal swelling pressure and the endothelial pump rate [31,32], the corneal wound healing reaction and even the quality of tear film [33]. Additional studies are needed to determine the primary cause of a decrease in corneal densitometry.…”