Precise prediction of size of a foldable capsular vitreous body via computerized three-dimensional ocular reconstruction in severe retinal detachment

BACKGROUND

This study aimed to precisely predict the size and silicone oil injection of a foldable capsular vitreous body (FCVB) via computerized three-dimensional (3D) ocular reconstruction in the treatment of severe retinal detachment in China.

METHODS

The 3D software Unigraphics NX was applied to determine the volume of the inner cavity with 16-30 mm axial length, assigning the anterior and posterior chambers, the FCVB sizes, and the silicone oil injection volume, and modeling the data between the axial length and the FCVB size. In clinical practice, IOL Master was applied to accurately measure the axial length of the contralateral healthy eye to anchor the anterior-posterior and horizontal diameters of the operated eye in horizontal position CT, and compared with the model to recommend the FCVB size and silicone oil amount, and the clinical effect was validated in cases across five hospitals in China.

RESULTS

For the axial length of 16-30 mm, the volume of the inner cavity is 1.2 ml-8.4 ml. FCVB size and silicone oil volume were recommended based on this volume of the inner cavity. Of 253 cases, we noted 11 cases implanted with AV-10P and 1.05 ± 0.21 ml of silicone oil, 41 with AV-12P and 1.58 ± 0.18 ml of silicone oil, 163 with AV-13.5P and 2.48 ± 0.29 ml of silicone oil, 31 with AV-15P and 3.57 ± 0.39 ml of silicone oil, and 7 with AV-17P and 5.71 ± 0.81 ml of silicone oil. There was no significant difference in postoperative visual acuity scores compared with preoperative (P = 0.097), postoperative IOP(10.29 ± 0.57mmHg)was slightly higher than preoperative IOP (9.76 ± 0.48 mmHg), but there was still no statistically significant difference between the two comparisons (P = 0.405).

CONCLUSION

Three-dimensional reconstruction prediction is a good solution for eyeballs with obvious individualized changes in severe retinal detachment, and this method helps doctors standardize FCVB size selection and the silicone oil amount for patients.

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.

Study on maintenance of eyeball morphology by foldable capsular vitreous body in severe ocular trauma

OBJECTIVES

To explore the feasibility and safety of using a foldable capsular vitreous body (FCVB) in managing severe ocular trauma and silicone oil-dependent eyes.

METHODOLOGY

This is a retrospective study of 61 ocular trauma patients (61 eyes) who presented to the Department of Eye Emergency, Hebei Eye Hospital from May 1, 2018, to May 31, 2019, including 51 male patients (51 eyes) and 10 female patients (10 eyes) with an average age of 44.98 ± 14.60 years old. The oldest patient was 75 years old, and the youngest was 8 years old. These cases represented 51 eyes with severe eyeball rupture and 10 eyes with severe, complicated ocular trauma, which became silicone oil-dependent after the operation. These patients received FCVB implants, and data regarding their visual acuity, intraocular pressure, changes in eye axis, cornea, retina, and FCVB state were recorded after the operation.

RESULTS

In all patients, the FCVB was properly positioned and well supported with the retina. All 61 patients cleared a follow-up window of 1-36 months with no reports of important changes in their visual acuity. Among the patients, 91.8% reported normal intraocular pressure, the retinal reattachment rate reached 100%, and the eyeball atrophy control rate reached 100%. There was no report of rupture of the FCVB, allergies to silicone, intraocular infection, intraocular hemorrhage, silicone oil emulsification, or sympathetic ophthalmia.

CONCLUSIONS

Foldable capsular vitreous bodies (FCVBs) designed to mimic natural vitreous bodies are suitable as long-term ocular implants that can provide sustained support for the retina without the need for any special postoperative postures. Their barrier function may effectively prolong the retention time of the tamponade and prevent various complications caused by direct contact of the eye tissues with the tamponade.

Foldable capsular vitreous body indications, complications, and outcomes: a systematic review

PURPOSE

Foldable capsular vitreous body (FCVB) is an emerging vitreous substitute that has been recently introduced to treat various advanced vitreoretinal conditions including severe ocular trauma, complicated retinal detachment (RD), and proliferative vitreoretinopathy.

METHODS

Review protocol was prospectively registered at PROSPERO (CRD42022342310). A systematic literature search using PubMed, Ovid MEDLINE, and Google Scholar for articles published until May 2022 was performed. The search included the following keywords: foldable capsular vitreous body, FCVB, artificial vitreous substitutes, and artificial vitreous implants. Outcomes included indications of FCVB, anatomical success rates, postoperative intraocular pressure (IOP), best-corrected visual acuity (BCVA), and complications.

RESULTS

A total of 17 studies that utilized FCVB up to May 2022 were included. FCVB was used intraocularly as a tamponade or extraocularly as a macular/scleral buckle for various retinal conditions including severe ocular trauma, simple and complex RD, silicone oil-dependent eyes, and highly myopic eyes with foveoschisis. FCVB was reported to be successfully implanted in the vitreous cavity of all patients. Final retinal reattachment rate ranged from 30 to 100%. Postoperative IOP improved or was maintained in most eyes, with low postoperative complication rates. Improvement in BCVA ranged from 0 to 100% of subjects.

CONCLUSION

Indications of FCVB implantation have recently widened to include multiple advanced ocular conditions such as complex RD, but also include simpler conditions as uncomplicated RD. FCVB implantation showed good visual and anatomical outcomes, few IOP fluctuations, and a good safety profile. Larger comparative studies are required to further evaluate FCVB implantation.

Advances in Polysaccharide- and Synthetic Polymer-Based Vitreous Substitutes

The vitreous humour is a gel-like structure that composes the majority of each eye. It functions to provide passage of light, be a viscoelastic dampener, and hold the retina in place. Vitreous liquefaction causes retinal detachment and retinal tears requiring pars plana vitrectomy for vitreous substitution. An ideal vitreous substitute should display similar mechanical, chemical, and rheological properties to the natural vitreous. Currently used vitreous substitutes such as silicone oil, perfluorocarbon liquids, and gases cannot be used long-term due to adverse effects such as poor retention time, cytotoxicity, and cataract formation. Long-term, experimental vitreous substitutes composed of natural, modified and synthetic polymers are currently being studied. This review discusses current long- and short-term vitreous substitutes and the disadvantages of these that have highlighted the need for an ideal vitreous substitute. The review subsequently focuses specifically on currently used polysaccharide- and synthetic polymer-based vitreous substitutes, which may be modified or functionalised, or employed as the derivative, and discusses experimental vitreous substitutes in these classes. The advantages and challenges associated with the use of polymeric substitutes are discussed. Innovative approaches to vitreous substitution, namely a novel foldable capsular vitreous body, are presented, as well as future perspectives related to the advancement of this field.

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

Vitreous substitutes are indispensable tools in vitreoretinal surgery. The two crucial functions of these substitutes are their ability to displace intravitreal fluid from the retinal surface and to allow the retina to adhere to the retinal pigment epithelium. Today, vitreoretinal surgeons can choose among a plethora of vitreous tamponades, and the tamponade of choice might be difficult to determine in the ever-expanding range of possibilities for a favorable outcome. The currently available vitreous substitutes have disadvantages that need to be addressed to improve the surgical outcome achievable today. Herein, the fundamental physical and chemical proprieties of all vitreous substitutes are reported, and their use and clinical applications are described alongside some surgical techniques of intra-operative manipulation. The major upcoming developments in vitreous substitutes are extensively discussed, keeping a translational perspective throughout. Conclusions on future perspectives are derived through an in-depth analysis of what is lacking today in terms of desired outcomes and biomaterials technology.

Study on the efficacy and safety of foldable capsular vitreous body in the severe retinal detachment eyes

BACKGROUND

This study was to evaluate the efficacy and safety of the implantation of foldable capsular vitreous body (FCVB) in severe retinal detachment eyes.

METHODS

A retrospective study in retinal detachment eyes was performed at Shandong Provincial Hospital Affiliated to Shandong First Medical University. A standard three-port pars plana vitrectomy was performed, and the FCVB was triple folded and implanted into the vitreous cavity. The silicone oil (SO) was then injected into the capsule of the FCVB to support the retina and eye. During the follow-up period, The treated eyes were examined by ophthalmoscopy, fundus photography, and tonometry. B-scan ultrasonography, optical coherence tomography (OCT), and computed tomography (CT), were also performed.

RESULTS

From May 2020 to November 2021, 31 cases with severe retinal detachment were enrolled in the study. The postoperative follow-up time gradient ranged from 1 to 72 weeks, At various observation time points during the 72 weeks after surgery, The postoperative IOP was maintained at around 10 mmhg at various time points, with a slight decrease compared to the preoperative IOP (14.2 ± 4.6 mmHg n = 18), and was statistically significant. 9 of 31 patients had clear refractive media, both fundus and OCT showed retinal reattachment, OCT showed the 200 μm thick FCVB capsule support retina. The remaining 22 patients with unclear refractive media, B-scan showed arcuate hyperechoes in front of the retina. There was also no significant difference in visual acuity compared to preoperative. The FCVB was well positioned in the vitreous cavity, and no serious complications such as endophthalmitis, glaucoma, silicone oil emulsification, product exposure, or sympathetic uveitis were found.

CONCLUSIONS

FCVB has retinal support with certain ability to maintain IOP and eye morphology and avoid eye removal in patients with severe retinal detachment during the 72-week observation period.

Clinical Application of Foldable Capsular Vitreous Bodies in the Treatment of Severe Ocular Trauma and Silicone Oil Dependent Eyes

Purpose

This study aimed to assess the application of a foldable capsular vitreous body (FCVB) in the treatment of severe ocular trauma and silicone oil (SO) dependent eyes.

Methods

A retrospective analysis was performed on the clinical application of FCVB in the treatment of severe ocular trauma and SO dependent eyes. The results of best-corrected visual acuity and intraocular pressure (IOP) evaluation, B-scan ultrasonography or color Doppler ultrasonography, ultrasound biomicroscopy, and anterior segment photography were recorded during follow-up. A paired t-test was used to compare the difference in IOP before and after FCVB implantation.

Results

Seven eyes of seven patients were included in the 6-month follow-up. In all cases, B-scan ultrasonography and ultrasound biomicroscopy showed that FCVB adapted closely to the globe wall and ciliary body, thus supporting the retina. Visual acuity did not improve, except in one case from LP to HM. The mean ± SD IOP was 8.5 ± 1.90 mm·Hg prior to FCVB implantation and 10.43 ± 0.98 mm·Hg after implantation, with no significant difference between these measurements (P=0.095). Five of the seven patients developed differing degrees of corneal opacity and keratopathy.

Conclusions

FCVB implantation may be a safe and effective method for the treatment of severe ocular trauma and SO dependent eyes. However, FCVB cannot prevent the phthisis of the traumatic eyes. In addition, corneal opacity and keratopathy are potentially serious complications after surgery. Appropriate case selection and proper surgical timing are required for further investigation.

Reattachment After Foldable Capsular Vitreous Body Implantation in Severe Retinal Detachment Eyes

Purpose

To evaluate the clinical effectiveness and safety of foldable capsular vitreous body (FCVB) implantation for severe retinal detachment.

Methods

A retrospective analysis was performed on 26 patients with severe ocular trauma and one with recurrent retinal detachment. Clinical data-including surgery success, complications, retinal reattachment, vision, and intraocular pressure (IOP)-were analyzed for patients who underwent 23G pars plana vitrectomy and FCVB implantation combined with silicone oil tamponade.

Results

The mean follow-up period was 10.44 ± 2.68 months. All surgeries were smooth; the FCVBs were properly positioned and supported the retina well, and the retinal reattachment rate reached 92.59%. At the six-month follow-up, preoperative (1.30 ± 1.20) and postoperative (0.63 ± 0.79) vision was significantly different (t = 3.03, P = 0.005), and the postoperative IOP (7.93 ± 3.57 mm Hg) was lower than the preoperative IOP (13.98 ± 10.72 mm Hg) (t = 2.74, P = 0.01). Among 20 patients followed up for >12 months, preoperative (1.20 ± 0.95) and postoperative (0.75 ± 0.91) visions were significantly different (t = 1.831, P = 0.005), and the postoperative IOP (9.85 ± 6.48 mm Hg) was lower than the preoperative IOP (14.85 ± 12.17 mm Hg) (t = 1.82, P = 0.01). No endophthalmitis, sympathetic ophthalmia, and rejection of FCVB occurred during follow-up.

Conclusions

FCVB combined with silicone oil tamponade showed good efficacy and safety in severe retinal detachment treatment during the follow-up period.

Translational Relevance

Vitreous substitution is deemed a highly challenging and interesting research topic in ophthalmology. Traditional method such as silicone oil tamponade often causes various complications such as silicone oil emulsification, silicone oil migration, and corneal degeneration. The foldable capsular vitreous body as a novel vitreous substitute combined silicone oil injection into it can stay in the eyeball for a long time without obvious complications.

Foldable capsular vitreous body implantation for treatment of traumatic retinal detachment: two case reports

Retinal detachment caused by severe ocular trauma is a type of refractory vitreoretinal disease. Current treatment methods include vitrectomy combined with silicone oil tamponade. However, long-term use of silicone oil tamponade has various complications, including a risk of silicone oil dependence that eventually leads to eyeball atrophy and enucleation. Foldable capsular vitreous bodies (FCVBs) offer a good solution for these problems. However, FCVBs have not been used in large-scale clinical applications and few cases have been reported in the published literature. The main use of FCVBs, based on current evidence, is in the treatment of the relatively few (but important) patients whose eyes have no visual potential; the aim of treatment in these patients is globe preservation, rather than restoration of vision. Here, we describe two patients who underwent FCVB implantation. The findings in these patients indicated that FCVBs can effectively support the vitreous cavity and detached retina. FCVB implantation may thus offer a safe and effective method for treatment of severe retinal detachment, avoiding the inconvenience caused by silicone oil dependence and enucleation. To confirm its long-term usefulness in clinical applications, many additional case reports are needed.

Implantation of Foldable Capsular Vitreous Body for the Treatment of Acute Retinal Necrosis Syndrome: A Case Report

The authors present the case of a 35-year-old male who was diagnosed with acute retinal necrosis syndrome that evolved into retinal detachment (RD), even after immediate treatment with systemic antiviral medications, as well as intravitreal injection and laser photocoagulation. Pars plana vitrectomy plus silicone oil tamponade was performed, but silicone oil emulsified 22 months later. Due to the widespread necrosis lesions and defects of the peripheral retina, RD was highly likely to reoccur after silicone oil removal; thus, foldable capsular vitreous body was implanted to support the retina. No recurrent RD was observed afterward. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:653-657.].

Macro- and Microscale Properties of the Vitreous Humor to Inform Substitute Design and Intravitreal Biotransport

Research on the vitreous humor and development of hydrogel vitreous substitutes have gained a rapid increase in interest within the past two decades. However, the properties of the vitreous humor and vitreous substitutes have yet to be consolidated. In this paper, the mechanical properties of the vitreous humor and hydrogel vitreous substitutes were systematically reviewed. The number of publications on the vitreous humor and vitreous substitutes over the years, as well as their respective testing conditions and testing techniques were analyzed. The mechanical properties of the human vitreous were found to be most similar to the vitreous of pigs and rabbits. The storage and loss moduli of the hydrogel vitreous substitutes developed were found to be orders of magnitude higher in comparison to the native human vitreous. However, the reported modulus for human vitreous, which was most commonly tested in vitro, has been hypothesized to be different in vivo. Future studies should focus on testing the mechanical properties of the vitreous in situ or in vivo. In addition to its mechanical properties, the vitreous humor has other biotransport mechanisms and biochemical functions that establish a redox balance and maintain an oxygen gradient inside the vitreous chamber to protect intraocular tissues from oxidative damage. Biomimetic hydrogel vitreous substitutes have the potential to provide ophthalmologists with additional avenues for treating and controlling vitreoretinal diseases while preventing complications after vitrectomy. Due to the proximity and interconnectedness of the vitreous humor to other ocular tissues, particularly the lens and the retina, more interest has been placed on understanding the properties of the vitreous humor in recent years. A better understanding of the properties of the vitreous humor will aid in improving the design of biomimetic vitreous substitutes and enhancing intravitreal biotransport.

Study on the effectiveness and safety of Foldable Capsular Vitreous Body implantation

Background

Foldable capsular vitreous body (FCVB) was designed to treat severe retinal detachment. The aim of this study was to evaluate the efficacy and safety of the implantation of foldable capsular vitreous body in 1-year follow-up.

Methods

A retrospective analysis was conducted for 20 patients with severe ocular trauma or silicone oil (SO) dependent eyes underwent vitrectomy and FCVB implantation in a 1-year follow-up. All treated eyes were peformed clinical examinations involved the visual acuity (VA) examination, Goldmann applanation tonometer, noncontact specular microscopy, fundus photography, B-Scan examination and optical coherence tomography (OCT). The groups were compared with t-test and the McNemar - Bowker test.

Results

In 1-year follow-up, 20 eyes were evaluated in the study. FCVB well supported the vitreous retina in all treated eyes, and 6 treated eyes achieved retinal reattachment 12 months after FCVB implantation. There were no significant differences in VA before and after FCVB implantation (P = 1.000). In addition, the postoperative IOP markedly elevated from the preoperative IOP of 12.90 ± 7.06 mmHg to 15.15 ± 3.36 mmHg (P = 0.000017). The intraocular pressure (IOP) of 10 eyes maintained at a normal level after surgeries. The other 10 eyes showed slightly lower IOP within the acceptable level. Though two patients developed keratopathy and ocular inflammation respectively, other treated eyes were symmetric with fellow eyes showing satisfactory appearance. Moreover, there was no SO emulsification or leakage happened in the observation.

Conclusions

FCVB implantation was an effective and safe treatment in the eyes with severe retinal detachment.

Risk Factors for Trauma-Related Eviscerations: Analysis of 821 Cases

Evisceration is the end therapeutic approach for the treatment of severe ocular trauma cases, and it is a tremendous loss for patients. In this study, we explored the changing trends in the number of surgeries performed, demographic data and ocular features, and risks for early evisceration, aiming to provide more data for the additional prevention and management strategies for this catastrophic problem. This was a retrospective study that included patients who underwent ocular evisceration at the Zhongshan Ophthalmic Center between January 2013 and December 2017. A total of 1229 evisceration cases were reviewed, and only trauma-related eviscerations were analyzed. Etiology, demographic data, ocular features, and hospitalization time were evaluated. The total number of trauma-related eviscerations recorded in the past five years was 821 cases. The number of surgeries performed was almost constant each year (164 ± 17 cases); 35% of the patients were less than ten years old at the time of the original ocular injury and 69% of them were male. Endophthalmitis led to significantly early evisceration compared with cases without endophthalmitis (P < 0.05). The group with a history of silicone oil tamponade showed a significantly longer surgical interval between trauma and evisceration than did the nonsilicone oil tamponade group (P < 0.05). Day-case hospitalization for evisceration increased from 0% to 32% over the past five years. The results of the present study show that the number of ocular trauma-related eviscerations performed in the past five years was almost unchanged and boys under ten are highly susceptible. This study also demonstrates that endophthalmitis leads to significantly early evisceration, and silicone oil tamponade may postpone ocular atrophy. Based on the study data, day-case surgery is safe for evisceration management.

Extended release of dexamethasone from oleogel based rods

HYPOTHESIS

Topical and systemic methods are not able to deliver ophthalmic drugs for treatment of retinal diseases. Consequently, invasive monthly intravitreal injections through the eyeball are required to deliver retinal drugs. A reduction in the frequency of the injection through extended release of the drugs could have significant clinical benefits.

EXPERIMENTS

Oleogels containing ethyl cellulose as the gelator at 10% (wt%) in soybean oil were loaded with dexamethasone above the solubility limit and expunged from a syringe to create cylindrical rods for extended drug delivery. The devices were imaged to explore particle distribution and drug release was measured under sink conditions in buffer. A model was developed and fitted to data to determine effective drug diffusivity.

FINDINGS

Dexamethasone is released slowly due to the presence of the drug particles that serve as drug depots. The release increases from 600 to 3000 h as the drug loading is increased from 3% to 28%. The release profiles can be modeled by considering drug dissolution and diffusion, as well as the tortuosity of the matrix due to the presence of the voids formed after the drug particles have dissolved. The proposed approach is promising as the release profiles of the drug are comparable to commercial devices.

Vitreous substitutes: challenges and directions

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.

Preliminary study on retinal vascular and oxygen-related changes after long-term silicone oil and foldable capsular vitreous body tamponade

Silicone oil has been the only long-term vitreous substitute used in the treatment of retinal detachment since 1962 by Cibis. Nevertheless, its effects on retinal vascular morphology and oxygen supply to the retina are ambiguous in current research. We previously invented a foldable capsular vitreous body (FCVB) to use as a new vitreous substitute in the treatment of severe retinal detachment, but its effects on the retinal vessel were unknown. Therefore, in this study, a standard three-port pars plana vitrectomy (PPV) was performed on the right eye of each rabbit and then silicone oil and FCVB were injected into the vitreous cavity as vitreous substitutes. After 180 days of retention, the retinal vascular morphology did not display any distinct abnormalities, and hypoxia-induced factor-1alpha (HIF-1α) and vascular endothelial growth factor (VEGF) did not vary markedly during the observation period in silicone oil tamponade- and FCVB-implanted eyes. This study may suggest that silicone oil and FCVB tamponade in rabbit eyes did not cause retinal vascular pathologic changes or retinal hypoxia for 180 days.

A study of the dexamethasone sodium phosphate release properties from a periocular capsular drug delivery system

The aim of this study was to investigate whether a periocular capsular drug delivery system (DDS) can release dexamethasone sodium phosphate (DEXP) in vitro and in vivo to the posterior segment of rabbit's eye. In vitro, the periocular capsular DDS containing 2 mg/ml or 5 mg/ml DEXP was immersed in modified Franz diffusion cell. Four-hundred microliters of liquid was aspirated at 0.5, 1, 2, 4, 8, 24 and 48 h for determination. In vivo, the DEXP-filled periocular capsular DDS was implanted into the sub-Tenon's sac of the New Zealand rabbit. DEXP concentration at the serum aqueous humor, cornea, iris, lens, ciliary body, vitreous, retina, choroids and sclera was quantified at 1, 3, 7, 14, 28 and 56 d after implantation. The DEXP concentration was determined by ultra-performance liquid chromatography-tandem mass spectrometry. In vitro, the periocular capsular DDS released the DEXP in time-dependent manner from 1/2 to 48 h. In vivo, the concentrations of the DEXP at the retina, choroids, ciliary body and iris were 123.11 (91.23, 732.61) ng/g, 362.46 ± 330.46 ng/g, 71.64 (71.35, 180.21) ng/g and 192.50 ± 42.66 ng/g, respectively, at 56 d after implantation. Minimal DEXP was found in the aqueous, serum and vitreous. Our results demonstrated that DEXP could be sustained released from the periocular capsular DDS, which indicated that the periocular capsular DDS might be a potential candidate of transscleral drug delivery for the management of posterior segment diseases.

A novel vitreous substitute of using a foldable capsular vitreous body injected with polyvinylalcohol hydrogel

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.