Towards an ideal biomaterial for vitreous replacement: Historical overview and future trends

Abstract

Removal of the natural vitreous body from the eye and its substitution with a tamponade agent may be necessary in cases of complicated retinal detachment. Many materials have been variously proposed and tested over the years in an attempt to find an ideal vitreous substitute. This review highlights the evolution of research in the field of vitreous replacement and chronicles the main advances that have been made in such a context. The suitability and limitations of vitreous tamponade agents and substitutes in current clinical use are examined, and the future promise of experimentally tested biomaterials are described and discussed. Future trends in research are also considered and, specifically, the great potential of polymeric hydrogels is emphasized, as they seem to be very effective in closely mimicking the features of the natural vitreous and they could successfully act as long-term vitreous substitutes without inducing clinical complications in the patient's eye.

Design of an Injectable in Situ Gelation Biomaterials for Vitreous Substitute

“…The SANS structural data are fairly well fitted to the model of hard-sphere interacting polymeric micelles, (1) where q is the length of scattering vector, and the micellar form factor, P mic , is given by 33 (2) where N agg is the micellar aggregation number, β s and β c , respectively, are the total excess scattering length of blocks in the core and in the chain, and R c the radius of the micellar core, which is described by the spherical form factor (3) The corona polymer chains are characterizes by the radius of gyration, R g and the form factor (4) The cross-correlation term between the micellar core and the corona chains attached to the surface of the core, S sc (q) is given by (5) where Φ(q,R) is the spherical form factor amplitude given in eq 3, while ψ(q,R g ) (6) is the chain form factor amplitude. The cross-correlation term between the two different chains in the corona, S cc (q), is correspondingly given by (7) The structure factor describing intermicellar correlations is calculated using the Percus−Yevick approximation with hardsphere interaction potential: 34 (8) G(2qR hs ,ϕ) is a trigonometric function of volume fraction, ϕ, and R hs being the hard-sphere interaction radius.…”

“…4,5 Body temperature transforms the polymer into a gel that completely fills the vitreous cavity. The gel does not leak, is entirely cohesive, and is expected to behave similar to the natural vitreous body.…”

A Novel Artificial Vitreous Substitute - Foldable Capsular Vitreous Body

“…It consists of about 99% water by weight, collagen fibers (types II, V/XI, VI, and IX), hyaluronic acid, opticin, fibrillin, and hyaluronan, which can maintain a certain spatial relationship with dipolar water molecules. 1,2 However, very few cells are found in the vitreous body. These cells are mostly phagocytes that clear useless cellular debris and hyalocytes mainly found at the periphery and that produce hyaluronic acid and collagen.…”

“…Artificial vitreous substitutes are one of the most interesting and challenging topics of research in ophthalmology. 2 A number of artificial vitreous substitutes, such as gas, silicone oil, heavy silicone oil, and hydrogels, have been used. 2,12 There are three major categories of currently available gas vitreous substitutes: air substitutes, expansile gas substitutes, and Xenon.…”

“…Currently, a number of cross-linked polymeric hydrogels have been proposed, such as poly (vinyl alcohol) (PVA), poly poly (1-vinyl-2-pyrrolidone), poly (acrylamide) (PAA), and poly (ethylene glycol) (PEG). 2,12,[31][32][33][34] Among these, the PVA and PAA hydrogels are the most promising candidates for long-term vitreous body replacement and are highly recommended for use. They show excellent biocompatibility, are biodegradable, and can closely mimic the physico-mechanical properties of natural vitreous bodies.…”