To determine the size and characteristics of the superficial and deep foveal avascular zone (FAZ) in healthy adults by using optical coherence tomography angiography (OCT-A), and to ascertain the effects of demographic and ocular parameters on the FAZ size.In a prospective cohort study of 117 healthy volunteers, foveal-centered 3 × 3-mm OCT-A scans were manually graded by certified graders to determine the size of the superficial and deep FAZ. Multiple linear regression analyses were performed to evaluate the impact of demographics and ocular factors, including central retinal thickness (CRT), choroidal thickness, axial length (AL), and spherical equivalent (SE) on superficial and deep FAZ areas.The mean age of the participants was 22.5 years, with mean AL of 25.4 mm and mean SE of -4.3 diopters. The mean CRT was 262.8 μm (range, 220-316 μm). The mean superficial FAZ area was 0.24 mm2, while the deep FAZ area was 0.38 mm2 (P < 0.001). Females had a larger superficial (P < 0.001) and deep FAZ (P < 0.001). On univariate linear regression, both superficial and deep FAZ areas had significant correlations with CRT, sex, AL, and SE, but not with age. By multiple linear regression analysis, in normal eyes, superficial FAZ area varied significantly with CRT and sex. Among eyes with high myopia, both superficial and deep FAZ varied significantly with CRT, sex, and choroidal thickness.The superficial and deep FAZ areas varied significantly among healthy eyes. Factors such as CRT, sex, SE, AL, and choroidal thickness influence the size of the FAZ.
Background: Corneal lenticules can be banked and retrieved for vision-restoring surgeries. Extended transportation logistic delays from the lenticule bank to the clinic could be a concern. This study investigated the effects of transportation on the lenticules. Methods: Lenticules were cryopreserved at a Ministry of Health-licensed lenticule bank for 1 year and were transported at 4 o C. The transparency was measured daily until significant degradation was notable, compared to fresh lenticules from donor corneas (n=3). The molecular and ultrastructural integrity of lenticules after 1 day in transport (n=3) and on the day of transparency deterioration (n=3) was evaluated by histochemistry and transmission electron microscopy (TEM). In addition, 6 rabbits were implanted with these lenticules to assess the difference in postoperative outcomes by corneal imaging, immunofluorescence staining, and TEM. Results: Lenticules showed a significant transparency reduction after 6 days in transit (p=0.002). The change was not caused by molecular alterations but by a greater distribution shift in the interfibrillar distance (IFD) (Z=4.419; p<0.001) and fibrillar diameter (FD) (Z=6.435; p<0.001). Post-implantation, day 6 lenticules exhibited greater haze and slower recovery of clarity compared to fresher lenticules, despite corneal imaging and immunofluorescence staining showing no fibrosis, inflammation, or vascularization in either group. With TEM, the discrepancy was revealed due to the difference in the recovery of IFD and FD distribution. Conclusions: Banked lenticules can maintain transparency for up to 5 days of transportation at 4 o C. Further delays compromise their ultrastructural integrity and postoperative clarity, emphasizing the need to factor in transportation in lenticule banking logistics.
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