Quantitative Assessment of Macular Vascular Density in Healthy Human Eyes Using Optical Coherence Tomography Angiography

Abstract

Purpose : The human retina is composed of morphologically distinct vascular networks that can be visualized separately using optical coherence tomography angiography (OCTA). Quantification of vascular networks in healthy eyes is important for understanding vascular pathobiology with potential clinical implications. We intended to quantify density of macular vascular networks over regions of interest in healthy subjects using OCTA.

Methods : Subjects with no known systemic disease and without retinal pathology were included. OCTA was performed on a 3×3-mm region centered on the macula and en face angiograms of the superficial and deep vascular networks were acquired. Vascular density was calculated using an automated image thresholding method over foveal and parafoveal regions of interest. The differences between vascular networks, genders, fellow eyes and correlation between vascular density and age as well as reproducibility of measurements were evaluated.

Results : A total of 163 eyes of 122 subjects were included. In the parafoveal region, deep vascular density was significantly higher than the superficial (52 ± 2.4% vs. 46 ± 2.2%; P<0.001) whereas the opposite was found in the foveal region (27 ± 5.2% vs. 32 ± 3.2%; P<0.001). All vascular density measurements were statistically similar in fellow eyes and there was no gender difference (P>0.05). There was a negative correlation between vascular density and age that persisted upon adjusting for signal strength (Figure 1). Vascular density measurements were highly correlated between separate imaging sessions with intraclass correlation coefficients of over 0.85 for all assessments.

Conclusions : Calculation of vascular density using OCTA is a reproducible and non-invasive method to quantitate vascular regions of interest and individual networks within the macula. Understanding normal values and their correlations could affect clinical evaluation of the macula in healthy patients and disease states.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

 

The relationship between foveal (left panel) and parafoveal (right panel) vascular density and age. Black and gray circles represent values from the superficial and deep vascular networks respectively. The solid black and dashed gray lines are their corresponding linear regression lines with respect to age. Unadjusted (r) and signal strength-adjusted (r_a) correlation coefficients and P-values are shown.