الفهرس 
I NTRODUCTIO NOnly 14 pages are availabe for public view
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Abstract
Retinal imaging techniques progress rapidly. In many cases, the diagnosis of retinal vascular diseases can be done by combination of fundus photography, OCT and FFA which remains useful when the other examinations are not conclusive. Other new investigation methods have been appeared such as OCTA which is a safe, rapid and three dimensional technique that obtains high resolution volumetric blood flow information in a matter of seconds challenging FFA. (93)
OCTA is a functional extension of OCT that can be used to visualize microvasculature by detecting motion contrast from flowing blood. The basis of OCTA is to repeatedly scan a region and then examine the resultant images for changes. Stationary tissue structures will show little change, while moving structures, in this case the flow of blood through vessels, can show changes from one image to the next. In contrast to FFA whose principle depends on Fluorescence which corresponds to the emission of light by cold bodies that have absorbed a particular photon. The glow stops immediately after the exciting light is removed. During FFA, intravenous fluorescein dye that reaches the retinal vessels will glow with stimulation by blue light at a wavelength varying between 465 and 490 nm and emits a yellowish-green light between 520 and 530 nm. (93and 94)
Recently, commonly available OCTA instruments allow quantification of