Foveal avascular zone (FAZ) metrics suggest heightened sensitivity of the peripheral capillary free zone (pCFZ) in relation to age-related retinal vascular changes, according to research results published in Scientific Reports.
In the current study, researchers sought to understand 3 aspects of normal aging: remodeling and size increases in the pCFZ zone, individual differences in perivenule CFZ, and mean differences in the periarteriole and perivenule CFZ in cognitively unimpaired older adults.
Researchers recruited 20 cognitively unimpaired younger adults (mean age, 26±3 years; 10 men) and 20 cognitively unimpaired older adults (mean age, 64±6 years; 8 men). All participants had refractive errors of ≤5.00 D. Older adults were recruited from a single center in Rhode Island as part of the Atlas of Retinal Imaging in Alzheimer Study (ATLAS).
Investigators collected optical computed tomography angiography (OCT-A) imaging of all participants. In older adults, the superficial vascular plexus was identified as the vascular layer of interest.
In older adults, investigators found that the periarteriole CFZ width was significantly larger compared with the perivenule CFZ (78.8±12.3 µm vs 61.5±11.3 µm); the mean difference between these measurements — 17.3 µm — was significantly less than the difference found in younger adults — 24.5 µm. These results, researchers noted, indicate that the perivenule CFZ remodeled “to a greater extent, on average, in normal aging.”
ANCOVA results indicated that mean periateriole CFZ width in older adults was significantly larger compared with younger adults (78.8±12.3 µm vs 67.2±12.8 µm). Mean perivenule CFZ width was also significantly larger (61.5±11.3 µm vs 42.7±5.17 µm).
Individual perivenule CFZ widths in older adults was also greater than predicted values and 1-tailed 95% CI of the predicted values of younger adults who had similar vessel parameters.
Investigators did find that the FAZ area did not differ significantly between older and younger adults (0.34±0.127 mm2 vs 0.368±0.114 mm2). Similarly, FAZ effective diameter in adults did not differ significantly (647±123 µm; median, 649 µm vs 674±120 µm; median, 700 µm).
No significant associations between periarteriole and perivenule CFZ and FAZ area were found (r=0.08), and similarly, no significant associations were noted between periarteriole and perivenule CFZ width and FAZ effective diameter (r=0.10).
Study limitations include the limits of lateral resolution in OCTA technology, the limited age range of young adult participants, and the covariates and associations that should be investigated in future research.
“Findings of the FAZ metrics indicate that the pCFZ may be more sensitive to age-related retinal vascular changes than the FAZ,” the research concludes. “Beyond showing the remodeling of the pCFZ in normal aging, the next steps of research would include demonstrating its applicability in [Alzheimer disease] and cerebral amyloid angiopathy.”
Arthur E, Alber J, Thompson LI, Sinoff S, Snyder PJ. OCTA reveals remodeling of the peripheral capillary free zones in normal aging. Sci Rep. 2021;11(1):15593. doi:10.1038/s41598-021-95230-0