The Blood-Brain Barrier (BBB) is a vital physiological barrier in the central nervous system that regulates the movement of ions and molecules from circulating blood into the brain and protects the brain from invading pathogens and toxic agents. However, the BBB is also presents a challenge for treating brain disease—most drugs are blocked by the BBB. More than 95% of drugs cannot reach a therapeutic dose in the brain and the BBB is the bottleneck.

The leading causes of vision impairment and blindness are posterior segment-related diseases including Leber Hereditary Optic Neuropathy (LHON), age-related macular degeneration, diabetic macular edema, glaucoma, endophthalmitis etc. However, blood-ocular barriers, similar to the blood-brain barrier, block most drugs from being transported into the eye, especially to the posterior-segment. The characteristics of MSN such as the nanoparticle size, surface charge, and constitution, etc., can be modulated to increase penetration of static and dynamic barriers of the eyes improving ocular bioavailability.