Age-Related Alterations in the Retinal Microvasculature, Microcirculation, and Microstructure

PURPOSE. To characterize age-related alterations in the retinal microcirculation, microvascular network, and microstructure in healthy subjects. METHODS. Seventy-four healthy subjects aged from 18 to 82 years were recruited and divided into four age groups (G1 with age < 35 years, G2 with age 35 similar to 49 years, G3 with age 50 similar to 64 years, and G4 with age >65 years). Custom ultra-high resolution optical coherence tomography (UHR-OCT) was used to acquire six intraretinal layers of the macula. OCT angiography (OCTA) was used to image the retinal microvascular network. The retinal blood flow velocity (BFV) was measured using a Retinal Function Imager (RFI). RESULTS. Compared to G1, G2 had significant thinning of the retinal nerve fiber layer (RNFL) (P < 0.05), while G3 had thinning of the RNFL and ganglion cell and inner plexiform layer (GCIPL) (P < 0.05), in addition to thickening of the outer plexiform layer (OPL) and photoreceptor layer (PR) (P < 0.05). G4 had loss in retinal vessel density, thinning in RNFL and GCIPL, and decrease in venular BFV, in addition to thickening of the OPL and PR (P < 0.05). Age was negatively related to retinal vessel densities, the inner retinal layers, and venular BFV (P < 0.05). By contrast, age was positively related to OPL and PR (P < 0.05). CONCLUSIONS. During aging, decreases in retinal vessel density, inner retinal layer thickness, and venular BFV were evident and impacted each other as observed by simultaneous changes in multiple retinal components.