Search

The ocular lens is the primary organ within the eye responsible for accommodation. During accommodation, the lens is subject to biomechanical forces. We previously demonstrated that stretching the porcine lens can increase lens epithelial cell proliferation. Although murine lenses are commonly employed in lens research, murine lens stretching has remained unexplored. Murine lens stretching thus represents a novel source of potential discovery in lens research. In the present study, we describe a method for stretching the murine lens by compressing the murine globe embedded in a hydrogel. We hypothesized that, as the eye is compressed along the optic axis, the lens would stretch through zonular tension due to the equatorial region of the eye bulging outward. Our results showed that this led to a compression-dependent increase in murine lens epithelial cell proliferation, suggesting that compression of the embedded murine globe is a viable technique for studying the mechanobiology of the lens epithelium., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Current experimental vitreous substitutes only replace the physical functions of the natural vitreous humor. Removal of the native vitreous disrupts oxygen homeostasis in the eye, causing oxidative damage to the lens that likely results in cataract formation. Neither current clinical treatments nor other experimental vitreous substitutes consider the problem of oxidative stress after vitrectomy. To address this problem, biomimetic hydrogels are prepared by free radical polymerization of poly(ethylene glycol) methacrylate and poly(ethylene glycol) diacrylate. These hydrogels have similar mechanical and optical properties to the vitreous. The hydrogels are injectable through small-gauge needles and demonstrate in vitro biocompatibility with human retinal and lens epithelial cells. The hydrogels and added vitamin C, an antioxidant, show a synergistic effect in protecting ocular cells against reactive oxygen species, which fulfills a chemical function of the natural vitreous. These hydrogels have the potential to prevent post-vitrectomy cataract formation and reduce the cost of additional surgeries., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Purpose: An in situ forming hydrogel was evaluated as a potential vitreous substitute in rabbits., Methods: The hydrogel used a disulfide cross-linker that was then reduced to produce an injectable thiol-containing polymer solution. The disulfide cross-links reformed by air oxidation of the thiols and produced a stable hydrogel once inside the eye. The polymer was clear, autoclavable, and could be stored easily in the presence of nitrogen gas. Capillary rheometry was used to measure the viscoelastic properties of the hydrogels and the porcine vitreous. Fourteen black rabbits underwent a pars plana, 25-gauge, three-port vitrectomy by a single surgeon with injection of a vitreous substitute., Results: The refractive indices of the hydrogels were measured by refractometry and were shown to be close to 1.33, and the 2% hydrogel matched the mechanical properties of the natural vitreous humor. The reduced polymeric hydrogel was easily injectable through a small-gauge needle into the vitreous cavity and did not show any fragmentation. The material underwent gelation within the eye, remained optically clear, and appeared well tolerated clinically. Slit lamp examination, dilated fundus examination, and electroretinograms showed no evidence of vitritis, uveitis, or endophthalmitis after 1 week. Histopathologic evaluation did not reveal any overt toxicity or gross morphologic changes in the retina., Conclusions: The fact that this process of in situ gelation gives rise to hydrogels that are biocompatible and physically and optically similar to the natural vitreous suggests its suitability as a permanent vitreous substitute. Hydrogel candidates will be further studied to evaluate long-term biocompatibility and degradation in vivo.