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Nicole Koulisis, Alice Yon Kim, Zhongdi Chu, Anoush Shahidzadeh, Ruikang K Wang, Carmen A Puliafito, Amir H Kashani; Quantitative Microvascular Analysis of Retinal Venous Occlusion by Optical Coherence Tomography Angiography. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5505.
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© ARVO (1962-2015); The Authors (2016-present)
To quantitatively and noninvasively evaluate the retinal microvasculature in human subjects with retinal venous occlusions (RVO) using optical coherence tomography angiography (OCTA).
This was a retrospective study of adult human subjects with RVO. OCTA was performed on a prototype, SD-OCTA system (Carl Zeiss Meditec, Dublin, CA, USA) in a 3 mm x 3 mm region centered on the fovea. Retinal vasculature was quantified within a single horizontal slab extending from the internal limiting membrane to the retinal pigment epithelium. Quantitative analysis with custom MATLAB software was used to transform the OCTA retinal segment into binarized and skeletonized images, from which fractal dimension (FD), vessel density (VD), skeletal density (SD), and vessel diameter index (VDI) were calculated using previously described protocols (Reif et al., Int J Biomed Imag). These parameters were compared to those from a cohort of healthy eyes, as well as the contralateral eyes of patients with RVO.
Thirty-nine eyes from 22 patients with retinal venous occlusions (12 branch, 10 central; 14 females, 8 males) were analyzed. Mean age was 65.5 years (range 36-80). Twelve of 22 subjects had RVO greater than one year duration. Three of 22 had RVO less than two months old. Collectively, RVO eyes demonstrated decreased FD (1.66 vs 1.72; p<0.0001), decreased VD (0.33 vs 0.41; p<0.0001), decreased SD (0.08 vs 0.1; p<0.0001) and increased VDI (4.3 vs 4.1; p<0.0001) when compared to normal eyes. These trends held when compared to the other eye (p<0.0001 for FD, VD and SD; p<0.05 for VDI). Figure 1 illustrates representative images from one subject with RVO.
RVO causes quantifiable changes in the retinal vascular parameters as measured by OCTA. These findings support previously described qualitative findings of decreased capillary perfusion, vessel dropout, and dilated vessels noted qualitatively on OCTA and fluorescein angiography (Kashani et al., Retina). This algorithm provides a quantitative and reproducible tool for monitoring microvascular disease.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
Depth-encoded OCTA image of a subject with RVO involving the supra-temporal quadrant, left eye (A). Binarized image, skeletal image, mid-laminar phase fluorescein angiogram, and fundus image of the corresponding occlusion (B-E).
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