Compositions and methods for visualization of the vitreous

The invention provides compositions for rendering a vitreous cavity visible during a surgical procedure to alleviate a structural disorder caused by the vitreous in an eye, and methods of using the compositions. The compositions are vitreous delineating agents that comprise a hyaluronan binding peptide linked to an optically detectable moiety. Such compositions can be in a formulation that may be a solution, a suspension, or an emulsion, and would be injected into the vitreous shortly prior to use. The composition may additionally contain a therapeutic agent, a diagnostic agent, or a chemosensirig material, in use, the composition marks or delineates the vitreous by binding preferentially to the hyaluronan that permeates the vitreous humor and binding little or not at ail to surrounding tissues such as the retina. The interface between the labelled vitreous humor and the non-labelled surrounding vital tissues produces a visible signal, thereby allowing a surgeon to clearly visualize the entire vitreous cavity and distinguish it from vital ocular structures. Use of the method improves the accuracy and safety of a vitrectomy and thus prevents suboptimal outcomes or the need for repeated procedures. The compositions comprising chemosensing material are useful as long- lasting biosensors, which when used in the vitreous enable repetitive, non-invasive, in vivo measurements of metabolites or pharmacologic agents in the vitreous of animals or humans.