To achieve effective ophthalmic therapy, an adequate amount of ingredients must be delivered and maintain at the site of action with in the eye. The anatomical structure and the protective physiological process of the eye exert a formidable defense against ophthalmic drug delivery. The most frequently used dosage forms i.e. ophthalmic solutions and suspensions are compromised in their effectiveness by several limitations, leading poor ocular bioavailability. This review deals with topical ophthalmic drug delivery systems as a means to localize and prolong drug activity at its site of action by use of a novel in-situ gel approach. These gels are instilled as drops into the eye and undergoes a sol to gel transition in the cul-de-sac, improved ocular bioavailability by increasing the duration of contact with corneal tissue, there by reducing the frequency of administration required in case of conventional ophthalmic solutions, thus optimizing ocular therapy.
