Aging, macular oedema, retinal biopsies and many other conditions can result in removal of the native vitreous from the eye. Native vitreous is a 3D matrix consisting of collagen and hyaluronic acid. Current vitreous substitutes include silicone oil and gases. These may, in some cases, mimic the physical properties of the native vitreous, but have little or no biochemical resemblance to the native tissue. Further, these substances may require patients to lie face-down for days after implantation and have a different refractive index to native vitreous. Hydrogels represent an interesting new form of vitreous supplements having a 3D crosslinked structure and a high water content. Several biomaterials exist for hydrogel formation which may mimic the mechanical properties of the native vitreous. In this project we will focus on the suitability of hydrogels as vitreous substitutes from a patient focused viewpoint, investigating the transparency, refractive index, injectability and biocompatibility of the hydrogels. These factors have been identified by the academic supervisor as being important to patients through her patient and public involvement (PPI) work. The aim of this project is to identify an appropriate hydrogel for use as a vitreous substitute. The specific objectives will focus on formulating a number of biomaterial hydrogels based on alginate, celluloses and hyaluronic acid, characterising the mechanical properties of these hydrogels to identify lead candidates and then investigating the transparency, refractive index, injectability and biocompatibility of the hydrogel. The overall hypothesis is that by taking patient and clinical factors into account a hydrogel can be identified that could be successfully translated for clinical use as a vitreous substitute.