Although atropine is one of the oldest drugs known to man and has been widely used as a mydriatic agent, information concerning its penetration into the eye has been gauged, more or less, by the onset of its cycloplegic action and gross effects on the pupil. Two common methods for introducing atropine into the eye are by topical application to the cornea and conjunctiva and by subconjunctival injections.
The passage of drugs through the cornea into the globe is generally considered to be a process of simple diffusion.1 However, since there is a difference in the penetration of chemical compounds with polar and nonpolar constituents there may be an active transport of drugs through the cornea.2 In this transport the pH of the solution seems to be an important factor.3 Identification of chemical compounds after their ingression into the eye has been made in a few instances.
JANES RG, STILES JF. The Penetration of C14-Labeled Atropine into the EyeA Comparison of Methods of Application. AMA Arch Ophthalmol. 1959;62(1):69-74. doi:10.1001/archopht.1959.04220010073007