Grid-based Analysis of Three-Dimensional Choroidal Sattler's and Haller's Layer Vascularity Volume Index and its Relation to Age and Axial Length in Adults by Ultra-Widefield Swept-source Optical Coherence Tomography Angiography

Background. This study was to evaluate the features of choroidal Sattler’s and Haller’s layer (CSHL) vessels in adults and explore its relationship with factors such as age, axial length (AL) and body mass index (BMI) by using ultra-widefield swept-source optical coherence tomography angiography (ultra-widefield SS-OCTA). Methods. 24mm×20mm fovea centered rectangular SS-OCTA scans were acquired. Theywere divided into 9 identical grids, with each equal size of 8mm×6.7mm. OCTA artifacts were evaluated.Three-dimensional choroidal vascularity volume index (CVI) and choroidal vascular volume per unit area (CVV/a or CVV) of CSHL were calculated. The correlations of CVI and CVV with age, AL, and BMI were analyzed. Results. Artifacts account for 19.30%, 18.60%, 30.23% of three inferior grids, respectively. CVI and CVV of left eyes were 30.82 ± 0.28% and 76.76 ± 2.19μm, respectively. Similary, CVI and CVV of right eyes were 31.16 ± 0.34% and 80.49 ± 3.10μm. Strong relationships of CVI (0.877, P=0.000) and CVV (0.866, P=0.000) were found between the two eyes in the same individual. The covariance of CVI is lower than that of CVV. Higher CVI was associated with younger age and shorter AL. Neither CVI nor CVV has association with BMI. Conclusions.CVI can be a more stable parameter for describing choroidal medium and large-sized vessels compared to CVV. Aging and longer AL were associated with attenuated CSHL’s vascularity. Taken together, these findings may provide helpful and referential CSHL vascular parameters for retinal specialists to reveal risk factors of choroidal diseases.