The present technology provides a nanoparticulate in-situ gelling vitreous substitute, which is a liquid at room temperature to aid easy administration, such as e.g. through a small needle incision, and forms a gel within the eye, which is hydrophilic in nature, similar to the natural vitreous. The vitreous substitute formulation may include a water-soluble natural or synthetic polymer and a gelling-agent which are blended together in the presence of a cross linker, to form a gel having the properties of the vitreous humor. The process of cross linking and gelation may occur in-situ. This can be achieved by dispensing to the eye, different components of the vitreous substitute in liquid state, along with the cross linking agent.