Recent advances in polymeric vitreous substitutes

The vitreous humor occupies two thirds of the volume of the eye and is the major component behind the lens. The human vitreous is a gelatinous substance predominantly composed of water (98–99%). Its functions include holding the retina in place and circulating metabolites throughout the eye. The vitreous liquifies with age, facilitating posterior vitreous detachment, which can lead to retinal tears, intravitreal hemorrhage or retinal detachment. Vitreous substitutes are needed to tamponade the retina or during vitrectomies for treatment of retinal detachments. Gases, perfluorocarbon liquids and silicone or fluorosilicone oils are currently used as vitreous substitutes; however, none of these substitutes can be used long term due to the short retention time of the gaseous substitutes, cell toxicity or other complications, such as glaucoma or cataracts. Vitreous substitutes, both experimental and clinical, will be reviewed, along with promising experimental artificial vitreous; polymeric hydrogels.