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K.E. Kotliar, R. Schilling, J. Einzinger, I.M. Lanzl; Retinal Blood Flow Is Influenced by Age–Dependent Microirregularities in Retinal Arterial Walls. Biofluidmechanical Simulation . Invest. Ophthalmol. Vis. Sci. 2006;47(13):469.
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© ARVO (1962-2015); The Authors (2016-present)
By image analysis with Retinal Vessel Analyser it is possible to perceive vessels in their dynamic state online non–invasively along a given vessel segment. Previously we demonstrated changes in longitudinal vessel profiles of retinal arterial segments of 1 mm of length in healthy persons of different age. We found high–frequency waviness of retinal arterial walls (HFW) along vessel longitudinal sections increases significantly in anamnestically healthy volunteers with increasing age. In the elderly vessels assume a less regular profile, which might be an expression of endothelial damage. Whether these microirregularities influence hydraulic parameters of a vessel was investigated in this study using methods of computational fluid dynamics (CFD) in case of uniform Newtonian blood flow in a retinal vessel segment.
A C++ program was written in order to create 3–D geometry of a retinal arterial segment and corresponding computational grid. This allowed us to vary parameters of HFW. Finite Volume Modelling procedure was applied for further calculations with CFD–code NS3DV43C. Hydraulic resistance along an arterial segment was calculated depending on HFW in assumption that the volumetric flow through the vessel cross–section remains constant.
Hydraulic resistance along the arterial segment increased with increasing HFW. We did not find any significant difference between results calculated with laminar and turbulent flow in our model formulation for the whole considered range of vessel segment waviness.
Retinal branch vessels possess alternating vessel diameters which constitute the vessel longitudinal section profile. Increasing HFW worsens hydraulic conductivity of retinal arteries in anamnesticaly healthy volunteers with increasing age. The age–dependent microirregularities found in our previous clinical study and analysed here might be an indication for vascular endothelial alterations in elderly, leading to impaired perfusion and regulation.
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