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Laura Kuehlewein, Tudor Tepelus, Lin An, Mary K Durbin, Srinivas R Sadda; Depth-resolved imaging of the parafoveal capillary network in diabetic retinopathy using swept source OCT-microangiography. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):5918.
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© ARVO (1962-2015); The Authors (2016-present)
To characterize the foveal avascular zone (FAZ) and the parafoveal capillary network at different retinal layers using swept source OCT-microangiography (OMAG) in normal subjects and patients with diabetic retinopathy.
OMAG images were acquired in 15 eyes of 11 patients with diabetic retinopathy, and 19 eyes of 13 healthy individuals using a prototype swept source OCT (Carl Zeiss Meditec), with a central wavelength of 1050nm. Scans were taken in clusters of 4 repeated B-scans from 3x3x3mm cubes centered on the fovea. En-face images of the retinal vasculature were generated from the superficial and deeper inner retinal layer (SRL/DRL) using a proprietary intensity differentiation algorithm. The area of the FAZ was computed at each en-face level following manual segmentation of the FAZ border. In addition, the parafoveal vessel density in a ring with a distance of 500 microns from the border of the foveal avascular zone was computed following automatic extraction using the publically available GNU Image Manipulation Program GIMP 2.8.14 (http://gimp.org). Vessel density was expressed as percent retinal area occupied by vessels.
The values for mean ± SD area of the FAZ are shown in Table 1. The mean size of the FAZ was statistically significantly larger in patients with diabetic retinopathy for both the SRL and DRL (p<0.001 and p=0.002). The mean ± SD vessel density in the parafoveal ring is shown in Table 1. The mean parafoveal vessel density at the SRL was statistically significantly smaller in patients with diabetic retinopathy (p<0.001). At the DRL, however, there was no statistically significant difference in the vessel density when comparing patients with diabetic retinopathy and healthy individuals (p=0.552).
The foveal avascular zone was significantly larger in patients with diabetic retinopathy. The parafoveal vessel density was significantly smaller in patients with diabetic retinopathy at the superficial inner retinal layer. At the deeper inner retinal layer, however, the vessel density in patients with diabetic retinopathy was comparable to those in healthy subjects.
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