Real-time measurements of vascular permeability in the mouse eye using vitreous fluorophotometry

Breakdown of blood-retinal barrier integrity underpins pathological changes in numerous ocular diseases, including neovascular age-related macular degeneration (nAMD) and diabetic macular edema (DME). Whilst anti-vascular endothelial growth factor (VEGF) therapies have revolutionised disease treatment, novel therapies are still required to meet patients' unmet needs. To help develop new treatments, robust methods are needed to measure changes in vascular permeability in ocular tissues in animal models. We present here a method for detecting vascular permeability using fluorophotometry, which enables real-time measurements of fluorescent dye accumulation in different compartments of the mouse eye. We applied this method in several mouse models with different increased vascular leakage, including models of uveitis, diabetic retinopathy and choroidal neovascularization (CNV). Furthermore, in the JR5558 mouse model of CNV, we observed with anti-VEGF post-treatment a longitudinal reduction in permeability, in the same animal eyes. We conclude fluorophotometry is a useful method for measuring vascular permeability in the mouse eye, and can be used over multiple time points, without the need to sacrifice the animal. This method has the potential to be used in both basic research for studying the progression and factors underlying disease, but also for drug discovery and development of novel therapeutics.