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L.D. Hubbard, T.Y. Wong, N.J. Ferrier, B.E. K. Klein, R. Klein, B.A. Esser, C.T. Hannan; Computerized Measurement of Retinal Vascular Caliber Abnormality in Studies of Systemic and Ocular Diseases . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2435.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To review technological implementation and current research application of the ARIC (Parr/Hubbard) procedure for summarization of caliber of the retinal arterioles, venules, and arterio–venous ratio. Methods: In an automated (technician supervised) computerized procedure, all arterioles and venules coursing through a measurement zone between ½ and 1 disc diameter of the optic disc in a retinal image are detected, identified, and their caliber measured. As reported by the Atherosclerosis Risk in Communities (ARIC) Study, results are summarized into the "central retinal arteriolar equivalent" (CRAE) and "central retinal venous equivalent" (CRVE), which can yield an arterio–venous ratio (AVR) if desired. Lower AVR is commonly interpreted as an indicator of generalized arteriolar narrowing, although in retinal vascular disease arterioles and venules should be considered separately. Results: Arteriolar and venular calibers have been considered, among other things as indicators of autoregulation of retinal blood flow and degree of retinal tissue oxygenation, respectively. Vascular caliber varies with blood pressure – the correlation between AVR and BP ranges from as low as 0.3 in elderly subjects to over 0.8 in young adults. In ARIC, the Cardiovascular Health Study, and the Beaver Dam Eye Study, arteriolar narrowing has been reported as an independent and significant prospective risk factor for various systemic disease outcomes, as will be reviewed. In the Wisconsin Epidemiological Study of Diabetic Retinopathy, baseline vascular caliber in the 4th quartile (broadest) was a risk factor for 4–yr retinopathy progression in persons with type 1 DM. Possible use of vascular measurement to explore development of other diseases (e.g., retinal vein occlusion, AMD) and response to treatment (e.g., scatter photocoagulation, VEGF–inhibition, and cortico–steroids) will be explored. Recent technological developments in implementation of the method will be presented. Conclusions: Computerized retinal vascular measurement may be a useful tool for study of a variety of retinal diseases and treatments, but further careful work needs to be done (1) on the method itself to improve it and (2) in epidemiological and clinical studies of ocular diseases to determine its value.
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