Transcleral approach for closing retinal tears using DuraSeal™ hydrogel sealant

Advances in biomaterials as a retinal patch for the repair of rhegmatogenous retinal detachment

Rhegmatogenous retinal detachment (RRD) is the most common retinological emergency that can cause blindness without surgical treatment. RRD occurs when liquefied vitreous accumulates between the neurosensory retina and the retinal pigment epithelium via retinal breaks, which are caused by the separation of the vitreous from the retina with aging. Currently, the main treatment option is pars plana vitrectomy, which involves surgical removal of the vitreous and laser photocoagulation around retinal breaks to generate firm chorioretinal adhesion, as well as subsequent filling of the vitreous cavity with long-lasting substitutes (expansile gas or silocone oil) to prevent the connection between the subretinal space and the vitreous cavity via the breaks before the chorioretinal adhesion firm enough. However, the postoperative face-down position and the not very satisfactory first retinal reattachment rate place a heavy burden on patients. With the development of technology and materials engineering, researchers have developed biomaterials that can be used as a retinal patch to seal retinal breaks and prevent the connection of subretinal space and vitreous cavity via breaks, thus replacing the long-lasting vitreous substitutes and eliminating the postoperative face-down position. Preclinical studies have demonstrated that biomaterial sealants have enough biocompatibility and efficacy in the in vitro and in vivo experiments. Some sealants have been used in clinical trials on a small scale, and the results indicate promising application prospects of the biomaterial sealants as retinal patches in the repair of RRD. Herein, we review the recent advances in biomaterials as retinal patches for the repair of RRD, focusing on the biomaterial categories, methods, and procedures for sealing retinal breaks, as well as their biocompatibility and efficacy, current limitations, and development perspectives.

Potential Therapeutic Usage of Nanomedicine for Glaucoma Treatment

Glaucoma is a group of diseases characterized by progressive degeneration of retinal ganglion cells, leading to irreversible blindness. Currently, intraocular pressure reduction is the only established treatment available for glaucoma. With this treatment, the progression of the disease can only be delayed and there is no recovery. In addition, the commercially available eye drops have the disadvantage of low compliance and short therapeutic time, while glaucoma surgery always has the risk of failure due to wound fibrosis. Nanotechnology can overcome the limitations of the current treatment through the encapsulation and conjugation of drugs used for lowering intraocular pressure and antifibrotic agents using biodegradable or biocompatible nanoparticles for the sustained release of the drugs to protect the damaged ocular cells. Furthermore, using nanotechnology, treatment can be administered in various forms, including eye drops, contact lens, and ocular inserts, according to the convenience of the patients. Despite the promising results of delaying the progression of glaucoma, the regeneration of damaged ocular cells, including trabecular meshwork and retinal ganglion cells, is another critical hurdle to overcome. Bone marrow-derived mesenchymal stem cells and Müller glia cells can secrete neurogenic factors that trigger the regeneration of associated cells, including trabecular meshwork and retinal ganglion cells. In conclusion, this review highlights the potential therapeutic applications of nanotechnology- and stem cell-based methods that can be employed for the protection and regeneration of ocular cells.

Hydrogel-based ocular drug delivery systems: Emerging fabrication strategies, applications, and bench-to-bedside manufacturing considerations

The physiological barriers of the eye pose challenges to the delivery of the array of therapeutics for ocular diseases. Hydrogels have been widely explored for medical applications and introduce possible solutions to overcoming the medication challenges of the ocular environment. While the innovations in drug encapsulation and release mechanisms, biocompatibility, and treatment duration have become highly sophisticated, the challenge of widespread application of hydrogel formulations in the clinic is still apparent. This article reviews the latest hydrogel formulations and their associated chemistries for use in ocular therapies, spanning from external anterior to internal posterior regions of the eye in order to evaluate the state of recent research. This article discusses the utility of hydrogels in soft contact lens, wound dressings, intraocular lens, vitreous substitutes, vitreous drug release hydrogels, and cell-based therapies for regeneration. Additional focus is placed on the pre-formulation, formulation, and manufacturing considerations of the hydrogels based on individual components (polymer chains, linkers, and therapeutics), final hydrogel product, and required preparations for clinical/commercial applications, respectively.