Objective To correlate images from swept source optical coherence tomography microangiography (SS-OMAG) with images from fluorescein angiography (FA) and indocyanine green angiography (ICGA) performed on asymptomatic eyes with intermediate age-related macular degeneration. Study Design and Methods A retrospective, observational, consecutive case series of patients with asymptomatic, intermediate AMD in one eye and neovascular AMD in their fellow eye. The patients underwent SS-OMAG, FA, and ICGA, and the images obtained from these three angiographic techniques were compared. Results Three patients were identified with intermediate AMD in one eye and symptomatic, neovascular AMD in their fellow eye. The three asymptomatic eyes had drusen and pigmentary abnormalities in the central macula and no evidence of macular fluid on OCT imaging. One patient presented with minimal leakage on FA from the asymptomatic eye. ICGA revealed the presence of central macular plaques, and SS-OMAG revealed type 1 neovascularization corresponding to the plaques. The type 1 neovascularization was visualized using en face slabs that extended from the border of the outer retina to the choriocapillaris (CC), 8 μm beneath Bruch’s membrane. Conclusions SS-OMAG identified type 1 neovascularization within ICGA plaques. The ability of OCTA to provide non-invasive, fast, detailed, depth-resolved identification of non-exudative neovascular lesions in eyes with intermediate AMD suggests the need for new terminology that distinguishes between non-exudative intermediate AMD and non-exudative, neovascular intermediate AMD. This distinction should prove useful for managing AMD patients at risk for conversion to late, exudative AMD once natural history studies are performed to better understand disease progression.

Purpose To investigate the changes of the retinal microvascular network and microcirculation in high myopia. Design A cross-sectional, matched, comparative clinical study. Participants Twenty eyes of twenty subjects with non-pathological high myopia (28 ± 5 Years) with a refractive error of −6.31 ± 1.23 Diopters (mean ± standard deviation) and twenty eyes of twenty age- and gender-matched control subjects (30 ± 6 years) with a refractive error of −1.40 ± 1.00 Diopters were recruited. Methods Optical coherence tomography angiography (OCTA) was used to image the retinal microvascular network, which was later quantified by fractal analysis (box counting, Dbox, representing vessel density) in both superficial and deep vascular plexuses. The retinal function imager (RFI) was used to image the retinal microvessel blood flow velocity (BFV). The BFV and microvascular density in the myopia group were corrected for ocular magnification using Bennett’s formula. Results The density of both superficial and deep microvascular plexuses was significantly decreased in the myopia group in comparison to the controls (P < 0.05). The decrease of the microvessel density of the annular zone (0.6 – 2.5 mm), measured as Dbox, was 2.1% and 2.9% in superficial and deep vascular plexuses, respectively. The microvessel density reached a plateau from 0.5 mm to 1.25 mm from the fovea in both groups, but that in myopic group was about 3% lower than the control group. No significant differences were detected between the groups in retinal microvascular BFV in either arterioles or venules (P > 0.05). Microvascular densities in both superficial (r = −0.45, P = 0.047) and deep (r = −0.54, P = 0.01) vascular plexuses were negatively correlated with the axial lengths in the myopic eye. No correlations were observed between BFV and vessel density (P > 0.05). Conclusions Retinal microvascular decrease was observed in the high myopia subjects, whereas the retinal microvessel BFV remained unchanged. The retinal microvascular network alteration may be attributed to ocular elongation that occurs with the progression of myopia. The novel quantitative analyses of the retinal microvasculature may help to characterize the underlying pathophysiology of myopia and enable early detection and prevention of myopic retinopathy.

ZEISS Angioplex™ optical coherence tomography (OCT) angiography generates high-resolution three-dimensional maps of the retinal and choroidal microvasculature while retaining all of the capabilities of the existing CIRRUS™ HD-OCT Model 5000 instrument. Angioplex™ OCT angiographic imaging on the CIRRUS™ HD-OCT platform was made possible by increasing the scanning rate to 68,000 A-scans per second and introducing improved tracking software known as FastTrac™ retinal-tracking technology. The generation of en face microvascular flow images with Angioplex™ OCT uses an algorithm known as OCT microangiography-complex, which incorporates differences in both the phase and intensity information contained within sequential B-scans performed at the same position. Current scanning patterns for en face angiographic visualization include a 3 × 3 and a 6 × 6 mm scan pattern on the retina. A volumetric dataset showing erythrocyte flow information can then be displayed as a color-coded retinal depth map in which the microvasculature of the superficial, deep, and avascular layers of the retina are displayed together with the colors red, representing the superficial microvasculature; green, representing the deep retinal vasculature; and blue, representing any vessels present in the normally avascular outer retina. Each retinal layer can be viewed separately, and the microvascular layers representing the choriocapillaris and the remaining choroid can be viewed separately as well. In addition, readjusting the contours of the slabs to target different layers of interest can generate custom en face flow images. Moreover, each en face flow image is accompanied by an en face intensity image to help with the interpretation of the flow results. Current clinical experience with this technology would suggest that OCT angiography should replace fluorescein angiography for retinovascular diseases involving any area of the retina that can be currently scanned with the CIRRUS™ HD-OCT instrument and may replace fluorescein angiography and indocyanine green angiography for some choroidal vascular diseases.

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