Effect of Active Transport and Loss to Choroidal Blood Flow on Transscleral Drug Delivery to the Posterior Eye

Delivering drugs to the posterior eye has been a challenge for many years. Systemic delivery of drugs is not a viable option because the eye does not receive enough blood supply, because of its small size, for the drug delivery process to be effective. Topical delivery in the form of eye drops is also ineffective in generating therapeutic concentrations in the posterior eye, because of the resistance offered by the corneal epithelium to the transport of drugs, and rapid elimination due to aqueous humor flow and tear dilution. Intravitreal delivery of drugs through implants and injections has been associated with serious side effects like endophthalmitis, hemorrhage, and retinal detachment. In recent years, transcleral delivery of drugs has received attention due to the relatively high permeability of the sclera.