The role of optical coherence tomography angiography in fundus vascular abnormalities

Abstract

BackgroundTo evaluate the role of optical coherence tomography angiography (OCTA) in observation of fundus vascular abnormalities.MethodsPatients (n = 50, 10 in each group) with fundus disorders including branch retinal vein occlusion (BRVO), non-proliferative diabetic retinopathy (NPDR), proliferative diabetic retinopathy (PDR), exudative age-related macular degeneration (AMD), and polypoidal choroidal vasculopathy (PCV) were examined. They underwent imaging of OCTA and fluorescein angiography/indocyanine green angiography. The split-spectrum amplitude-decorrelation angiography algorithm was employed to obtain angiography within a 6 × 6 mm scanning area at the posterior retina. Segmentation algorithm was used to obtain 2-dimensional images from arbitrary layers. The OCTA features were analyzed and compared with the findings of conventional angiography. The contralateral eyes of the patients with BRVO and the eyes of 20 healthy volunteers served as controls.ResultsOCTA showed precise images of normal and abnormal vasculature in the posterior retina and choroid by the given layers. Vascular abnormalities such as enlarged foveal avascular zone (FAZ), non-perfusion area of retina, microaneurysm, retinal neovascularization, choroidal neovascularization (CNV), branching vascular network and polypoidal lesions in choroid were clearly displayed by OCTA.ConclusionsOCTA provided a better projection of vascular pathologies of the posterior retina and choroid and could determine the precise location of the vascular lesion. The noninvasive OCTA can benefit the diagnosis of vascular abnormalities in the posterior retina and choroid.

OCT angiography and visible-light OCT in diabetic retinopathy

“…Studies show that NV lesions are similar in shape and size in OCTA compared to FA (Yu, et al, 2016). Furthermore, quantitative evaluation of NV is possible on OCTA, which could be an objective way to follow patients and evaluate treatment response (Ishibazawa et al, 2015).…”

Optical coherence tomography angiography in uveitis

“…Although FFA is capable of demonstrating retinal NV, it cannot separately illustrate the major retinal capillary networks (superficial and deep) and may fail to reveal retinal ischemia in some of the aforementioned diseases [105]. OCTA is the imaging modality that provides detailed delineation of the microvascular structures and their potential abnormalities [105][106][107]. Furthermore, OCTA facilitates assessment of the precise spatial extent (depth and size) and morphological features of these intraretinal abnormalities that cannot be clearly visualized on FFA [106,108].…”

Can Foveal Avascular Zone (FAZ) Assessment By OCT Angiography, Used For Grading Of Diabetic Retinopathy?

“…The FAZ was first described in vivo by FA [7]. The FAZ shape is identical in the OCTA and FA, and the FAZ size was correlated in both [8]. The OCTA believed to be more accurate than the FA to demarcate and measure the FAZ; as it is not obscured by leakages, pooling or staining from fluorescein.…”

“…In diabetics, the FAZ is enlarged due to vasculture disintegrity [9]. The FAZ often appeared to be asymmetrical due to gaps, holes or interruption of the capillary networks which form an irregular circles with hypo reflection that demarcates the enlarged FAZ [8,9].…”

“…Our center reviewed literature regarding the OCTA applications in diabetics which is going to be published soon. Available reports are few, but interesting facts regarding the FAZ is published [7][8][9][10][11][12][13][14][15][16][17][18]. The FAZ in normal individual was described in the OCTA as an intact well-demarcated round or oval area of reduced capillary density with a border without gaps, holes or interruption of the capillary network in both superficial and deep plexuses.…”