Abstract
The optical coherence tomography angiography (OCTA) is a noninvasive imaging technology which aims at imaging blood vessels in retina by studying decorrelation signals between multiple sequential OCT B-scans captured in the same cross section. Obtaining various vascular plexuses including deep and superficial choriocapillaris, is possible, which helps in understanding the ischemic processes that affect different retina layers. OCTA is a safe imaging modality that does not use dye. OCTA is also fast as it can capture high-resolution images in just seconds. Additionally, it is used in the assessment of structure and blood flow. OCTA provides anatomic details in addition to the vascular flow data. These details are important in understanding the tissue perfusion, specifically, in the absence of apparent morphological change. Using these anatomical details along with perfusion data, OCTA could be used in predicting several ophthalmic diseases. In this paper, we review the OCTA techniques and their ability to detect and diagnose several retinal vascular and optical nerve diseases, such as diabetic retinopathy (DR), anterior ischemic optic neuropathy (AION), age-related macular degeneration (AMD), glaucoma, retinal artery occlusion and retinal vein occlusion. Then, we discuss the main features and disadvantages of using OCTA as a retinal imaging method.
Highlights
Diabetic Retinopathy (DR), enlarged to 0.49 ± 0.19 mm2 in patients of diabetes with nonproliferative diabetic retinopathy (NPDR) and enlarged to 0.76 ± 0.16 mm2 in diabetic patients with PDR. This conforms with the findings of Bhanushali et al [59], who found out that foveal avascular zone (FAZ) area was 0.38 ± 0.01 mm2 in normal healthy controls, enlarged to 0.45 ± 0.03 mm2 in diabetic patients with mild NPDR, enlarged to 0.46 ± 0.01 mm2 in diabetic patients with moderate NPDR, enlarged to 0.46 ± 0.02 mm2 in diabetic patients with severe
optical coherence tomography angiography (OCTA) is an excellent imaging modality in these cases, perhaps even the best, as it can distinguish between inflammatory lesions with and without vessels and identify choroidal neovascularization (CNV) in areas of CSR pathology, when other imaging modalities are often unhelpful because these lesions cause leakage and OCTA abnormalities with or without CNV
Freund et al [132] used OCTA to study the location of the collateral vessels that are associated with BRVO. They are curvilinear, dilated channels that connect veins across the horizontal raphe or veins on opposite sides of an occluded venous segment inside the same hemisphere of the retina. This conforms with the findings of Arrigo et al [133] that the collateral vessels are located in the deep capillary plexus (DCP), representing retinochoroidal anastomosis starting from the superficial retinal capillaries and reaching the choriocapillaris and choroidal vessels to bypass the site of occlusion
Summary
Fatma Taher 1,† , Heba Kandil 2,† , Hatem Mahmoud 3 , Ali Mahmoud 2 , Ahmed Shalaby 2 , Mohammed Ghazal 4 , Marah Talal Alhalabi 4 , Harpal Singh Sandhu 5 and Ayman El-Baz 2, *.
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