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W. Vilser, E. Nagel; Functional Imaging of Retinal Vessels by Means of Rva . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4912.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: RVA measures and analyzes diameter changes in relation to time and position along the vessel. The ability for dilation or constriction and dynamic responses of different local regulations can be studied by means of different provocation methods (100% O2 breathing, flicker light etc.) for single very small vessel segments. Aim of functional imaging of retinal vessels is the clear pictured overview about different functional abilities of single vessel segments along the vessel image. Methods: Functional parameters (FP) like maximum of dilation or constriction due to a used provocation methods and defined examination procedure are calculated from measuring values of the RVA for each small examined vessel segment. These values of FP are then assigned along the vessel due to its measuring position and pictured presented along the vessel image. To demonstrate this principle 100% oxygen breathing was used to examine the FP: Segmental Ability for Constriction (SAC). Vessel diameters were measured on-line and automatically by the RVA before (baseline: 2 min) , during (5 min) and after (5 min) 100% oxygen breathing. SAC is defined as the difference between the mean diameter during the last two minutes of 100% oxygen breathing to mean baseline diameter. Results: Efficiency of function imaging is presented by examples for SAC. Local differences of the SAC along the vessel can be seen clearly in healthy and patients. In case of patients with systemic hypertension pathological changes in SAC can be shown and demonstrate the segmental loss of ability to constrict during 100% oxygen breathing. Conclusions: Functional Imaging is able to present pictured and clearly local changes of functional behavior of small vessel segments along vessels. It reduces the giant amount of dynamic measuring values to a clear and easy image.
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