Advances in Polysaccharide- and Synthetic Polymer-Based Vitreous Substitutes

Injectable self-assembling peptide hydrogel as a promising vitreous substitute

Vitreoretinal diseases pose significant threats to vision, often requiring vitrectomy and substitution of vitreous humor to restore ocular structure and visual function. However, existing substitutes have limitations that compromise patient outcomes. Supramolecular hydrogels, particularly peptide-based formulations, have emerged as promising alternatives due to their superior optical clarity, biocompatibility, and viscoelasticity. In this study, we designed and evaluated two peptide hydrogels, 3K-OX and 3E-OX, bearing positive and negative charges, respectively, as potential vitreous substitutes. Our in vitro findings revealed that the physicochemical properties of the negatively charged peptide hydrogel, 3E-OX, closely resembled those of the native vitreous body, exhibiting optimal light transmittance, refractive index, molecular permeability, and biocompatibility. Animal studies further confirmed the safety and biocompatibility of 3E-OX as a promising vitreous substitute. Notably, we introduced optical coherence tomography for retinal microvascular detection in non-pigmented rabbits, presenting a novel approach to evaluate the performance of intraocular tamponade materials. This work not only expands the utility of peptide hydrogels but also provides valuable insights into the design of vitreous substitutes.

Biopolymeric Innovations in Ophthalmic Surgery: Enhancing Devices and Drug Delivery Systems

The interface between material science and ophthalmic medicine is witnessing significant advances with the introduction of biopolymers in medical device fabrication. This review discusses the impact of biopolymers on the development of ophthalmic devices, such as intraocular lenses, stents, and various prosthetics. Biopolymers are emerging as superior alternatives due to their biocompatibility, mechanical robustness, and biodegradability, presenting an advance over traditional materials with respect to patient comfort and environmental considerations. We explore the spectrum of biopolymers used in ophthalmic devices and evaluate their physical properties, compatibility with biological tissues, and clinical performances. Specific applications in oculoplastic and orbital surgeries, hydrogel applications in ocular therapeutics, and polymeric drug delivery systems for a range of ophthalmic conditions were reviewed. We also anticipate future directions and identify challenges in the field, advocating for a collaborative approach between material science and ophthalmic practice to foster innovative, patient-focused treatments. This synthesis aims to reinforce the potential of biopolymers to improve ophthalmic device technology and enhance clinical outcomes.

Desired properties of polymeric hydrogel vitreous substitute

Vitreous replacement is a commonly employed method for treating a range of ocular diseases, including posterior vitreous detachment, complex retinal detachment, diabetic retinopathy, macular hole, and ocular trauma. Various clinical substitutes for vitreous include air, expandable gas, silicone oil, heavy silicone oil, and balanced salt solution. However, these substitutes have drawbacks such as short retention time, cytotoxicity, high intraocular pressure, and the formation of cataracts, rendering them unsuitable for long-term treatment. Polymeric hydrogels possess the potential to serve as ideal vitreous substitutes due to their structure-mimicking to natural vitreous and adjustable mechanical properties. Replacement with hydrogels as the tamponade can help maintain the shape of the eyeball, apply pressure to the detached retina, and ensure the metabolic transport of substances without impairing vision. This literature review examines the required properties of artificial vitreous, including the optical properties, rheological properties, expansive force action, and physiological and biochemical functions of chemically and physically crosslinked hydrogels. The strategies for enhancing the biocompatibility and injectability of hydrogels are also summarized and discussed. From a clinical ophthalmology perspective, this paper presents the latest developments in vitreous replacement, providing clinicians with a comprehensive understanding of hydrogel clinical applications, which offers guidance for future design directions and methodologies for hydrogel development.