Estimating retinal vascular permeability from fluorescein videoangiography data despite signal saturation in large vessels in low-dynamic range systems

Fluorescein videoangiography is often used to visualize diabetic retinopathy (DR), a degenerative disease characterized by degradation of retinal blood vessels. However, more sensitive and quantitative measures of increased vessel permeability in the asymptomatic phase of DR (non-proliferative DR) could help identify patients who would benefit from therapeutic intervention to avoid vision loss. Here, a modified “adiabatic approximation to the tissue-homogeneity model” was shown in simulations and rat experiments to estimate extraction fraction within a 20%-error for physiological ranges of vascular permeability expected in nonproliferative DR, even in low-dynamic-range (8-bit) fluorescein imaging systems that are standard in many institutes.