Ocular Drug Delivery

Traditionally, medication is delivered to the eye by three main mechanisms: Topical ocular administration, systemic administration, and intraocular or periocular injection. Each of these methods has significant disadvantages. Topical ocular solutions or ointments have less than a 1% penetration, have rapid dilution and tear washout, and rely substantially on owner compliance to administer the medication. Systemically administered medications, in general, have limited ocular penetration and may require high peripheral drug levels with the potential of toxicity. Ocular or periocular injection of medication is traumatic and invasive, is rapidly diluted, and may require repeat procedures for adequate drug levels. Because of these limitations, especially for chronic internal ocular diseases of large animals, we have studied methods to deliver medications to the eye through the use of constant-release drug delivery devices.