#Normal retina fluorescien angiography manual
In addition, fractal analyses are more easily performed automatically and may obviate the need for manual grading for the assessment of retinal vascular diseases. area of linear dimension), fractal analysis appears to be less dependent on the need for correcting peripheral distortion, which may be of importance where stereographic projection algorithms cannot be applied. Therefore, in contrast to the measurement of lesion size ( e.g. Error in fractal measurements due to retinal curvature was reported to be small (approximately 3%). Li et al found no evidence supporting any refractive axial magnification effect on fractal analysis.
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FD was observed not be affected by ocular magnification. Fractal analysis provides a global evaluation of the architecture of a vascular network using fractal dimension (FD), a single value between 1 and 2 on a 2-dimensional fundus image, with a higher value reflecting increased branching complexity as represented by the density of the space-filling pattern of the retinal vascular tree. The retinal vasculature harbors a branching pattern that presents the property of self-similarity which can be considered a fractal structure. In addition, stereographic projection techniques have allowed peripheral image distortion to be corrected, facilitating accurate measurement of lesions and features of interest such as retinal non-perfusion area (NPA) and vascular area in square millimeters. The Optos 200Tx scanning laser ophthalmoscope (SLO Optos PLC, Dunfermline, Scotland, UK) enables visualization of the entire fundus –. Ultra-wide field (UWF) fluorescein angiography (FA) has evolved into an important tool for the clinical care of patients with various retinal disorders –.
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