Optical coherence angiography

Abstract

Background:Retinal vascular diseases are one of the most common causes of blindness in the developed world. Optical Coherence Tomography Angiography (OCT-A) is a new noninvasive method that uses several algorithms to detect blood movement. This enables the creation of high-resolution vascular images with contrast depicting motionless tissue.Methods:This review presents the results of articles relevant to age-related macular degeneration (AMD), diabetic retinopathy (DR), and OCT-A. The OCT-A technique can successfully be used in the diagnosis of neovascularization, retinal vein occlusion (RVO) and retinal artery occlusion (RAO), vessel abnormalities and even anterior segment neovascularization. OCT-A can also be applied to compute data such as vessel density, and flow index in both superficial and deep plexuses.Results:Many studies have compared fluorescein angiography with OCT-A. Other studies have reported differences in vascular density in AMD patients and have compared them with people having healthy eyes. Although OCT-A offers rapid picture acquisition, high repeatability and resolution, it also has many drawbacks. The most common are: motion artifacts, projections from overlying vessels and limited field of view.An interesting new application is the possibility to assess changes during antivascular endothelial growth factor (anti-VEGF) therapy. Another function of OCT-A is the possible application in the study of choriocapillaries in many fields of ocular pathology.Conclusion:OCT-A is a new promising method that allows the visualization of the retinal vascular network and the counting of blood flow parameters. This technique provides reliable images useful in clinical routines.

Dental Applications of Optical Coherence Tomography (OCT) in Cariology

“…The method, which is based on low coherence interferometry, was first presented by Huang et al [18]. In medicine, OCT is currently primarily used in ophthalmology for evaluating the pathological changes in retinal layers and the optic nerve [19][20][21][22]. Further applications are found in dermatology [23,24] and cardiology [25].…”

The Importance of VRI and AOR Segmentations in Optical Coherence Tomography Angiography

“…In a healthy eye, the VRI has no vascular structure though the ganglion cell layer of the retina has the superficial retinal capillary plexus based on vitreo-retinal histology and VRI segmentation of OCTA ( Figure 1, VRI) [1][2][3][4][5][6][7][8]. Preretinal neovascularization (PNV) is characterized by networks of vessels lying on the surface of the retina and invading the cortical vitreous gel and extending into the vitreous cavity.…”

“…Using by OCTA, the vasculature and blood flow of retina and choroid can be visualized in detail through detecting motion contrast of erythrocytes in the vessel, using serial optical coherence tomography B-scans. OCTA has an ability to perform the separate segmentations including the vitreoretinal interface (VRI), the superficial retinal layer, the deep retinal layer, avascular outer retina (AOR), the choriocapillaris and the choroid (Figure 1) [1][2][3][4][5][6][7][8].…”

“…AOR is the layer between the outer plexiform layer (OPL) in the inner border and ellipsoid zone in the outer border. The outer retina segmentation between the OPL and Bruch membrane by OCTA show no vascular blood flow in a normal eye (Figure 1, Avascular) [1][2][3][4][5][6][7][8]. Choroidal neovascularization (CNV) defines the development of the new blood vessels derived the choroid and the invasion into sub-retinal pigment epithelium (RPE) or subretinal space via a break in Bruch membrane.…”

“…Using by OCTA, the vasculature and blood flow of retina and choroid can be visualized in detail through detecting motion contrast of erythrocytes in the vessel, using serial optical coherence tomography B-scans. OCTA has an ability to perform the separate segmentations including the vitreoretinal interface (VRI), the superficial retinal layer, the deep retinal layer, avascular outer retina (AOR), the choriocapillaris and the choroid (Figure 1) [1][2][3][4][5][6][7][8].In a healthy eye, the VRI has no vascular structure though the ganglion cell layer of the retina has the superficial retinal capillary plexus based on vitreo-retinal histology and VRI segmentation of OCTA (Figure 1, VRI) [1][2][3][4][5][6][7][8]. Preretinal neovascularization (PNV) is characterized by networks of vessels lying on the surface of the retina and invading the cortical vitreous gel and extending into the vitreous cavity.…”