| The human vitreous is a natural hydrogel predominantly composed of water. Vitreous substitutes are needed for treatment of retinal detachments by reapproximating the retina to the back of the eye, or during vitrectomies for maintenance of ocular volume. None of the current substitutes can be used long-term due to their short retention time, toxicity, or due to complications such as glaucoma or cataracts. In addition, all of the current compounds have a specific gravity less than water and are not appropriate for inferior retinal detachments; in general, their physical and mechanical properties are unlike the natural vitreous. The viscoelastic properties of the porcine vitreous were analyzed to develop a model for biomimetic vitreous substitutes. Synthetic polymers that form hydrogels in situ were researched for the development of artificial vitreous. One biomimetic hydrogel formulation was analyzed in vivo in a rabbit study, and the results were promising. Statistical experimental design was then used to optimize various in vivo gelling polymer formulations. The feed ratios of crosslinker, hydrophobic monomer, and polymer concentration were varied, and the viscoelastic properties, swelling properties, and refractive index of each formulation were analyzed. Additionally, the osmotic pressure exerted by these hydrogel vitreous substitutes was modeled using Flory-Rehner theory. It was shown that these vitreous substitutes are capable of exerting small osmotic pressures and should be capable of tamponading the retina for treatment of a retinal detachment. |
