One of the possibilities of how to optimize bioavailability of drugs after topical ophthalmic administration is prolongation of the period of contact of the preparation with the eye tissue. The most usual way of achieving this gaol is an increase in the viscosity of the preparation by an addition of a suitable auxiliary substance. At pre-sent besides hydrogels and mucoadhesive substances, also polymers which produce the sol-gel phase change are employed for this purpose. This so-called in šitu gelation takés pláce in a very short period of time after contact with the eye tissue due to a change in temperature, pH, or interaction with physiological ions. The present páper aims to survey in šitu gelling polymeric substances, which are examined in relation to their use in ophthalmic administration.

        Key words: ophthalmic drops - gelation in šitu - polymers - polysaccharides