DEX-NP or CON-NP Injections.

DEX-NPs or CON-NPs were prepared as described (28). Briefly, PB copolymer of PGA−PCL−PEG−PCL−PGA) was synthesized by sequential ring-opening polymerization reaction. DEX-loaded PB copolymer NPs were prepared in the size range of ∼110 nm by oil-in-water single-emulsion solvent evaporation method. DEX-NPs or CON-NPs were diluted in PBS to a final NP concentration of 50 µg/µL, vortexed for 10 min, and then sonicated for 10 min. Mice were anesthetized with 100 mg/10 mg/kg of ketamine/xylazine. Then 20 µL of the NP suspension, containing 1 mg of NPs with ∼23 µg of DEX (or no DEX in control eyes), were slowly injected into either the superior or inferior subconjunctival or periocular spaces of a single eye or both eyes of mice using a 30-gauge needle with a Hamilton glass microsyringe (50-µL volume; Hamilton Company). Specifically, the initial two injections were subconjunctival, while subsequent injections were periocular to avoid complication of leaks following repeated subconjunctival injections. In experiments involving unilateral injections of DEX-NPs, a separate cohort of mice were used as controls, receiving unilateral injection of CON-NPs (SI Appendix, Fig. S2). After withdrawing the needle, Neomycin plus Polymyxin B Sulfate antibiotic ointment was applied to the eyes, and mice recovered on a warm pad.