An ophthalmically acceptable vehicle includes an aqueous suspension having a first viscosity. The suspension includes about 0.1% to about 6.5% by weight of a carboxyl-containing polymer prepared by polymerizing one or more carboxyl-containing monoethylenically unsaturated monomers and less than about 5% by weight of a cross-linking agent. The polymer has average particle size of not more than about 50 μm in equivalent spherical diameter. The vehicle includes a second polymer that allows the carboxyl-containing polymer to remain suspended. Upon contact with tear fluid, the vehicle gels to a second viscosity which is greater than the first viscosity. A method of administering a medicament to the eye of a subject includes applying a composition that includes this ophthalmically acceptable vehicle and a medicament contained for treatment of a disease or disorder for which ophthalmic delivery is indicated. The medicament is released from the vehicle in a sustained release manner.