Abstract
Purpose :
To characterize age-related alterations of retinal microcirculation, microvascular network and microstructure in healthy subjects.
Methods :
Seventy-four healthy subjects with age from 18 to 82 years were recruited and divided into 4 groups with an interval of 15 years. There were 25 subjects with age < 35 years (G1), 25 subjects aged from 35 to 49 years (G2), 18 subjects aged from 50 to 64 years (G3) and 18 subjects with age ≥ 65 years (G4). Custom ultra-high resolution OCT (UHR-OCT) was used to acquire three dimensional volumes of the macula and six intraretinal layers in a diameter of 6 mm centered on the fovea were segmented. OCT angiography (OCTA) with a Cirrus AngioplexTM (Carl Zeiss Meditec, Dublin, CA) was used to image retinal microvasculature in the macula. The vessel density was quantitatively analyzed using fractal analysis with box counting method (Dbox). In addition, retinal blood flow velocities of both arterioles and venules in a field of 7.3 × 7.3 mm2 centered on the fovea were measured using Retinal Function Imager (RFI).
Results :
Compared to G1, G2 showed significant decreases of retinal vessel density in total retina and deep vascular plexus measured in an annulus (from 0.6 to 2.5 mm, P < 0.05) and thinning of RNFL (P < 0.05). G3 showed significant decreases of retinal vessel density in retinal vascular network in the annulus (0.6 – 2.5 mm, P < 0.05) and thinning of RNFL and GCIPL (P < 0.05), in addition to thickening of OPL and PR (P < 0.05). Interestingly, G3 showed an increase of arteriolar blood flow velocity (P < 0.05), compared to G1. G4 showed significant decreases of retinal vessel density in retina, superficial and deep vascular plexuses in both fields of 3 mm and 6 mm and thinning of RNFL, GCIPL and INL, in addition to thickening of OPL and PR (P < 0.05). Furthermore, G4 showed a significant decrease of venular blood flow velocity (P < 0.05). Age was negatively related to retinal vessel densities of retinal microvascular network, superficial and deep vascular plexuses, inner retinal layers including RNFL, GCIPL and INL and retinal blood flow velocity in venules.
Conclusions :
This is the first study to analyze changes of retinal microvasculature, microcirculation and microstructure in healthy subjects over a wide age distribution. Significant decreases with age in retinal vessel density, inner retinal layer thickness and venular blood flow velocity were found.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.