10.22376/ijpbs.2019.10.1.p1-12 Volume 3 Issue 1 2012 (January - March) Environmentally sensitive polymers are smart materials that have gained importance in ophthalmic drug delivery because of their ability to undergo lessThan i greaterThan in-situ lessThan /i greaterThan gelation. This review presents the different polymers used for ophthalmic drug delivery covering the three basic mechanisms of lessThan i greaterThan in-situ lessThan /i greaterThan gelation such as temperature mediated, pH triggered and ion activated lessThan i greaterThan in-situ lessThan /i greaterThan gelation. The characteristics of the polymers, such as physicochemical properties and their pharmaceutical implications in ophthalmic delivery have been discussed exhaustively. This review showed that environmentally sensitive polymers can be utilized for prolonged drug delivery to the eye, because of their long retention time on the ocular surface resulting improved pharmacokinetic profile of the drug molecule.  Ikhwan Hadi Bin Suhaime, Minaketan Tripathy And Abu Bakar Abdul Majeed in situ gels, pH triggered, temperature mediated, ion activated. 586-608