The most traditional method of ocular drug delivery is through the use of eyedrops. However, by this method, the therapeutic concentration in deep ocular fluids and tissues can not be efficiently reached. Systemic administration presents poor access to the posterior segment of the eye due to ocular barriers. Subconjuntival and retrobulbar injections are not able to produce adequate levels of the drug, and intravitreal injection is an invasive and problematic procedure that may involve the risk of ocular perforation or retinal detachment. Thus, iontophoresis presents an alternative technique for the delivery of therapeutic drug doses to the posterior segment of the eye. Iontophoresis is a technique that consists of the administration of drugs to the body through tissues using an electric field involving a small potential difference. The active electrode, which is in contact with the drug, is placed at the site to be treated, and a second electrode, with the purpose to close the electric circuit, is placed at another site of the body. The electric field facilitates the transport of the drug that should be mainly ionized. Iontophoresis is considered to be a safe and noninvasive technique of drug delivery to specific sites of the eye. This technique, experimentally applied to the treatment of ocular diseases, has advanced in the last years and, at present, phase III clinical trials are in progress.
Iontophoresis; Eye diseases; Drug delivery systems; Eye; Technology; pharmaceutical