In general, ocular pharmacokinetics have two routes, permeation and direct delivery [1,2,3,4,5,6,7].

  • Permeation:

    There are different mechanisms of permeation including:

    • Transcorneal permeation from the lacrimal fluid into the anterior chamber.

    • Non-corneal drug permeation across the conjunctiva and sclera into the anterior uveal tract.

    • Drug distribution from the bloodstream via the blood-aqueous barrier into the anterior chamber.

    • Drug elimination from the anterior chamber by the aqueous humor turnover to the trabecular meshwork and Schlemm’s canal.

    • Drug elimination from the aqueous humor into the systemic circulation across the blood-aqueous barrier.

    • Drug distribution from the blood into the posterior eye across the blood-retina barrier.

    • Drug elimination from the vitreous via the posterior route across the blood-retina barrier.

    • Drug elimination from the vitreous via the anterior route to the posterior chamber.

  • Direct delivery:

    There are two routes of the direct delivery of medications into intraocular structures:

    • Intravitreal drug administration.

    • Intracameral drug administration.