*2.5. Acellular Capillaries Quantification*

Trypsin digestion of the retina was performed according to a previously published protocol [32,33]. Briefly, eyeballs were enucleated and incubated in 4% paraformaldehyde overnight. Retinas were isolated, washed, and digested in elastase solution (40 Units elastase/mL; Sigma-Aldrich, St. Louis, MO, USA) to remove the non-vascular tissue. The vascular beds were mounted on glass slides followed by staining with periodic acid–Schi ff's base and hematoxylin. About 5–6 fields from the central to mid-periphery were imaged and the number of acellular capillaries per square millimeter were quantified.
