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Qisheng You, Yukun Guo, Thomas S Hwang, Yali Jia; Normative data of inter-capillary distance and vessel density in temporal retina assessed by OCT angiography. Invest. Ophthalmol. Vis. Sci. 2020;61(7):5250.
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To characterize normative data and associations of inter-capillary distance (ICD) and retinal vessel density (VD) of superficial vascular complex (SVC) in macula and temporal 6x6-mm OCT angiography (OCTA).
One eye of each healthy subject underwent high-definition (400x400) 6x6-mm OCTA scans centered on fovea and temporal retina consecutively with ~0.5mm overlap (Figure 1) using a commercially available spectral-domain OCT system. A custom algorithm created en face angiograms of the SVC. The shadow areas due to vignetting or vitreous floaters were removed using a deep learning algorithm. We calculated the ICD and VD on the regions free of artifact with sufficient signal strength and analyzed the variation in relation to their distance from the foveal center.
Fifty-three healthy adults with a mean age of 49-year old were enrolled. Compared to central macular 6x6-mm region, the temporal retina had a significantly longer ICD (0.036 vs. 0.029mm, P<0.001) and lower VD (34.5% vs. 41.8%, P<0.001). The difference remained significant for both ICD and VD after adjustment with SSI and inner retinal thickness (P<0.001), suggesting the inner retina in the temporal region may have less metabolic demand than in the central macular region. Multivariate analysis demonstrated the ICD significantly increased with age (slope=0.33, P=0.005), but decreased with signal strength index (SSI) (slope=-0.41, P<0.001) and inner retinal thickness (slope=-0.32, P=0.002). It is not significantly associated with mean arterial pressure (MAP, P=0.21), intraocular pressure (IOP, P=0.28) or axial length (AL, P=0.24). In parallel, the temporal retinal SVC VD significantly decreased with age, increased with SSI and inner retinal thickness, but not significantly associated with MAP, IOP or AL.Regional variation analysis demonstrated, from nasal to temporal, the mean ICD increased while the mean VD and ganglion cell complex (GCC) thickness decreased. Interestingly, the GCC thickness remains stable from 3 mm to 7.8 mm temporal to the foveal center even as the ICD increased and VD decreased through this region (Figure 2).
In a healthy population, the ICD increases and VD decreases as the distance from the foveal center increases. This may provide a useful normative data for interpreting vascular metrics obtained with extended field OCTA.
This is a 2020 ARVO Annual Meeting abstract.
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