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Steven T Bailey, Simon S. Gao, Thomas S Hwang, Christina J Flaxel, Andreas Lauer, David Huang, Yali Jia; Quantitative OCT Angiography of Choroidal Neovascularization under Pro Re Nata Treatment. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2162.
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© 2017 Association for Research in Vision and Ophthalmology.
To use choroidal neovascularization (CNV) area as a metric to assess CNV response to treatment in age-related macular degeneration (AMD).
Prospective study of seven eyes from seven participants with treatment naïve CNV that underwent OCT angiography scans at baseline and monthly visits while under a pro re nata (PRN) anti-VEGF treatment regimen. Spectral OCT (RTVue-XR Avanti, Optovue) acquired 3×3 mm macular scans. Split-Spectrum Amplitude-Decorrelation Angiography (SSADA) algorithm was used to compute blood flow. The outer retinal angiograms were defined as the maximum flow projection between outer plexiform layer and Bruch's membrane. Projection artifacts in the outer retina were removed by subtracting a Gaussian filtered version of the inner retinal angiogram. CNV was automatically identified in outer retina using saliency detection, and CNV area was quantified by thresholding and a level set method to refine the CNV boundaries. Two scans were acquired at each visit and within-visit repeatability was assessed by coefficient of variation (CV).
Within-visit CNV area repeatability was 8.6% CV. Six of seven eyes showed initial reduction in CNV area while under treatment. In one eye, initial CNV area measurement was incomplete due to subretinal hemorrhage (SRH), and the apparent CNV area increased while under treatment; after resolution of SRH, CNV area stabilized (Fig. 1A). In another case, CNV area decreased during initial treatments and then remained stable without treatment (Fig. 1B). In a third example, CNV area increased preceding fluid accumulation on structural OCT (Fig. 1C).
CNV area can be automatically measured by saliency-based algorithm with excellent repeatability. This metric can be useful in monitoring treatment response. In some cases, increase in CNV area may precede recurrence of fluid on structural OCT, serving as an earlier indicator for the need for treatment.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
Figure 1. Changes in CNV area over time in 3 example cases of anti-VEGF PRN treatment regimen (bars = difference between 2 measurements made in the same visit). Shaded areas represent when treatment was given. A, CNV area increases after two months as SRH resolves, then stabilizes. B, CNV area decreases and remains static without treatment. C, CNV area initially decreases with treatment. Treatment is withheld and CNV growth precedes the need for treatment at month 6.
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