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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.

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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PurposeThe purpose of this study was to compare imaging of choroidal neovascularization (CNV) using swept-source (SS) and spectral-domain (SD) optical coherence tomography angiography (OCTA).MethodsOptical coherence tomography angiography was performed using a 100-kHz SS-OCT instrument and a 68-kHz SD-OCTA instrument (Carl Zeiss Meditec, Inc.). Both 3 × 3- and 6 × 6-mm2 scans were obtained on both instruments. The 3 × 3-mm2 SS-OCTA scans consisted of 300 A-scans per B-scan at 300 B-scan positions, and the SD-OCTA scans consisted of 245 A-scans at 245 B-scan positions. The 6 × 6-mm2 SS-OCTA scans consisted of 420 A-scans per B-scan at 420 B-scan positions, and the SD-OCTA scans consisted of 350 A-scans and 350 B-scan positions. B-scans were repeated four times at each position in the 3 × 3-mm2 scans and twice in the 6 × 6-mm2 scans. Choroidal neovascularization was excluded if not fully contained within the 3 × 3-mm2 scans. The same algorithm was used to detect CNV on both instruments. Two graders outlined the CNV, and the lesion areas were compared between instruments.ResultsTwenty-seven consecutive eyes from 23 patients were analyzed. For the 3 × 3-mm2 scans, the mean lesion areas for the SS-OCTA and SD-OCTA instruments were 1.17 and 1.01 mm2, respectively (P = 0.047). For the 6 × 6-mm2 scans, the mean lesion areas for the SS-OCTA and SD-OCTA instruments were 1.24 and 0.74 mm2 (P = 0.003).ConclusionsThe areas of CNV tended to be larger when imaged with SS-OCTA than with SD-OCTA, and this difference was greater for the 6 × 6-mm2 scans.