Choroidal Microcirculation

CVI showed substantial intraindividual variation over time, with the largest increases appearing in patients with the highest APACHE2 scores. EDI-OCT may detect micron-scale temporal changes in choroidal anatomy that could reflect perfusion pressure, fluid balance, vascular leakage, or systemic disease severity, though this remains speculative. Highly myopic eyes lose choroidal vascular density faster than healthy controls in the cited Zhang et al study. Baseline CVI was negatively associated with APACHE2 score (r = -0.68), albuminaemia (r = -0.68), haematocrit (r = -0.68), and haemoglobin (r = -0.76). CVI showed positive monotonic associations with cumulative fluid input (Spearman r = +0.57) and cumulative fluid output (Spearman r = +0.55). The trial's primary outcome is 12-month change in choroidal vascular density and choroidal vessel volume index. The Choroidal Vascular Index represents the proportion of choroidal volume occupied by vascular spaces. Excessive axial elongation is proposed to stretch and thin the choroid, reducing capillary density and perfusion. Choroidal haemodynamic changes may precede structural atrophy in high myopia. Reduced choroidal perfusion is linked t…