Figure 1. . Ocular structures and possible drug permeation/elimination routes.

(A) Transcorneal permeation, (B) noncorneal drug permeation, (C) drug from the blood to the anterior chamber, (D) drug elimination by aqueous humor turnover, (E) drug elimination to systemic circulation, (F) drug permeation across the blood–retinal barrier, (G) intravitreal drug administration, (H) drug elimination via blood–retinal barrier and (I) drug elimination via anterior route.

Adapted with permission from [9] © Elsevier (2006).