ABSTRACT
Drug treatment of eye diseases can be carried out by local ocular drug application or by systemic drug administration. In the latter case the drug is distributed widely in the body after, for example, oral or intravenous administration. Only a very small fraction of the dose gains access to the eye. Therefore, most ocular drugs are given locally as eye drops. The eye drops are applied on the ocular surface and in most cases the drug absorbs into the inner tissues of the eye. Despite local administration, less than 5 per cent of the instilled dose absorbs into the eye (Maurice and Mishima, 1984). For this reason the drugs are often applied in high concentrations.
