Hydrogels may be the ideal vitreous substitutes due to their wonderful physical features and biocompatibility. However, their drawbacks, short residence time, and biodegradation in vivo, have led to the fact that none of them have been approved for clinical use. In this study, we developed a novel approach of using a foldable capsular vitreous body (FCVB) injected with polyvinylalcohol (PVA) hydrogel as a vitreous substitute for long-term tamponade. The 3% PVA hydrogel that was cross-linked by gamma irradiation showed good rheological and physical properties and had no toxicity in vitro. After 180 days retention, the 3% PVA hydrogel inside FCVB remained transparent and showed good viscoelasticity without biodegradation and showed good biocompatibility and retina support. This new approach may develop into a valuable tool to improve the stability performance of PVA hydrogel as a vitreous substitute and to extend the application function of FCVB for long-term implantation in vitreous cavity.

The objective of this study was to produce a porcine corneal acellular matrix (ACM) and assess its possibility for biomedical applications. Porcine corneas were treated with various concentrations of sodium dodecylsulfate for different lengths of time. Optimal conditions for processing the ACM were noted regarding removal of all cellular components and retention of the spatial arrangement of the corneal stroma. The physical characteristics (including water absorption and light transmittance), biomechanics, and cytotoxicity of the ACM were also found to be conserved. Subsequently, ACM was transplanted into the interlaminar stroma of rabbit corneas. The transparency and structures of the collagen fibers were determined. By immersing corneal tissues in isotonic buffer containing 0.1% sodium dodecylsulfate for 7 hours, we were able to produce an ACM whose cells were completely removed, without disrupting collagen layer structure. Although water absorption and light transmittance of the ACM decreased when compared with natural corneal stroma, ACM showed similar biomechanical properties and biocompatibility as natural ones. After xenotransplantation into rabbit corneal stromal layers for 4 weeks, both ACM and rabbit corneas showed complete transparency. Almost 1 year postoperatively, the corneas remained transparent with regular stromal structures and ACM appeared stable in situ without deliquescence or immunological rejection. A simple and valid method to produce decellularized corneal matrix has been successfully developed. These acellular matrices similar to natural corneas in structure, strength, and transparency have tremendous potential for corneal transplantation as ideal implants for donors and for tissue engineering applications as suitable scaffolds.

Purpose.: To determine the flexibility, efficacy, and safety of a novel foldable capsular vitreous body (FCVB) in the treatment of severe retinal detachment in human eyes. Methods.: The study involved 11 patients with 11 severe retinal detachments. A standard three-port pars plana vitrectomy was performed, and the FCVB was triple-folded and implanted into the vitreous cavity. Balanced salt solution was then injected into the capsule of the FCVB to support the retina. The treated eyes were examined by ophthalmoscopy, fundus photography, and tonometry during a 3-month implantation period. B-scan ultrasonography, optical coherence tomography (OCT), ultrasound biomicroscopy (UBM), and electroretinogram (ERG) were also performed. The FCVB was removed and examined in the laboratory at the end of the 3-month treatment time. Results.: The FCVB was easily implanted into the vitreous cavity through a 3-mm incision and was easily removed through a 2-mm scleral incision. Retinal reattachment was found in 8 (73%) of 11 eyes at the end of the 3-month treatment time. The fundus, B-scan, and OCT showed that the FCVB was well distributed in the vitreous cavity and evenly supported the retina. IOP and visual acuity in the FCVB-treated eyes did not show a significant difference when compared with the preoperative measurements. UBM showed that the FCVB smoothly contacted but did not crush the ciliary body. Laboratory examinations showed no significant inflammatory cells in the balanced salt solution, no decrease in spectral transmittance, and no blocking of tiny apertures from the FCVB after a 3-month implantation period. Conclusions.: The FCVB was shown to be flexible, effective, and safe as a vitreous substitute over a 3-month implantation time. (ClinicalTrials.gov number, NCT00910702.)

The natural vitreous body has a fine structure and complex functions. The imitation of the natural vitreous body by vitreous substitutes is a challenging work for both researchers and ophthalmologists. Gases, silicone oil, heavy silicone oil and hydrogels, particularly the former two vitreous substitutes are clinically widely used with certain complications. Those, however, are not real artificial vitreous due to lack of structure and function like the natural vitreous body. This article reviews the situations, challenges, and future directions in the development of vitreous substitutes, particularly the experimental and clinical use of a new artificial foldable capsular vitreous body.