Current Situation and Challenges in Vitreous Substitutes

Abstract

Vitreo‐retinal disorders constitute a significant portion of treatable ocular diseases. These pathologies often require vitreo‐retinal surgery and, as a consequence, the use of vitreous substitutes. Nowadays, the vitreous substitutes that are used in clinical practice are mainly divided into gases (air, SF6, C2F6, C3F8) and liquids (perfluorocarbon liquids, silicone oils, and heavy silicone oils). There are specific advantages and drawbacks to each of these, which determine their clinical indications. However, developing the ideal biomaterial for vitreous substitution continues to be one of the most important challenges in ophthalmology, and a multidisciplinary approach is required. In this sense, recent research has focused on the development of biocompatible, biodegradable, and injectable hydrogels (natural, synthetic, and smart), which also act as medium and long‐term internal tamponade agents. This comprehensive review aims to cover the main characteristics and indications for use of the extensive range of vitreous substitutes that are currently used in clinical practice, before going on to describe the hydrogels that have been developed recently and which have emerged as promising biomaterials for vitreous substitution.

The EyeFlowCell: Development of a 3D-Printed Dissolution Test Setup for Intravitreal Dosage Forms

“…Suitable systems for continuous dissolution studies, which provide a better preliminary understanding of how the dissolution might occur in vivo, are lacking so far. While there are several approaches for human vitreous body substitution in vivo, in vitro drug release in these has not been studied in detail so far [20,21]. Apart from the PAA gel by Loch et al used here, which has already been used for release studies, and another vitreous substitute developed by Awwad et al from hyaluronic acid and agar, which was used to determine the clearance of PLGA microparticles or antibodies, there is little literature on in vitro experiments.…”

Vitreous Substitutes from Bench to the Operating Room in a Translational Approach: Review and Future Endeavors in Vitreoretinal Surgery

“…Similarly to what happens with a gas tamponade, SiO is capable of blocking intravitreal fluid from migrating into the subretinal space so that, if retinopexy has been correctly applied, chorioretinal adhesion and scarring can occur [ 84 , 86 ]. Once the retinochoroidal adhesion has developed and there is no longer any retinal traction, SiO can be removed [ 168 ]. In contrast to gases, SiOs have a lower buoyancy, thus, the SiO bubble’s resting position cannot produce a high pressure against the retinal tear, and the sealing occurs almost exclusively as a result of the strong interfacial tension of the bubble over the break [ 86 ].…”

“…Similarly to what happens with a gas tamponade, SiO is capable of blocking intravitreal fluid from migrating into the subretinal space so that, if retinopexy has been correctly applied, chorioretinal adhesion and scarring can occur [ 84 , 86 ]. Once the retinochoroidal adhesion has developed and there is no longer any retinal traction, SiO can be removed [ 168 ].…”

“…During the last decade, new tamponade solutions have been developed in view of the existing limitations of the clinically used tamponades (hydrophobic materials such as SiO or HSiO). The development of biocompatible, biodegradable, and injectable hydrogels-based vitreous substitutes (natural, synthetic, and smart) that will also function as medium- and long-term tamponade agents has been the focus of recent studies and many such prototypes have been developed ( Table 2 a,b; [ 168 , 178 ]) [ 168 , 179 ]. Hydrogels-based biomaterials possess good physico-chemical properties such as high water content, optical transparency (visible range), appropriate refractive indices and density, adjustable rheological and porous properties, injectability, biocompatibility and the ability to tamponade retina on all sides through viscosity and swelling pressure [ 180 , 181 ].…”

Synthesis and characterization of hydrophilic functionalized organosilicon copolymers containing triazole and silylimidate/silylacrylate groups

“…Such hydrogels are mainly used in the production of modern third generation contact lenses, implants, and vitreous substitutes. [12][13][14][15][16][17] It is known in the literature to use silicone monomers in silicone hydrogel compositions, in particular, hydrophobic N,O-bis(trimethylsilyl)acrylamide, in combination with water-soluble monomers such as N-vinyl-2-pyrrolidone or N,N-dimethylacrylamide to obtain soft contact lenses with good performance characteristics, such as high oxygen permeability, and optical transparency. 18 (Cо)polymers of hydrophilic 1-vinyl-1,2,4-triazole arouse constant research interest.…”