Use of Evicel Fibrin Sealant in Optic Disc Pit-Associated Macular Detachment

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.

Fibrin glue for treatment of optic disc maculopathy

We describe clinical and anatomical outcomes of optic disc maculopathy using internal limiting membrane (ILM) peeling and fibrin glue application over the optic nerve in this retrospective, interventional case series of five eyes. Extent of neurosensory detachment and foveoschisis along with foveal thickness at baseline and follow-up were evaluated. The mean age was 29 ± 10.6 years. The most common location of disc pit was temporal (3 eyes). All eyes underwent peripapillary laser with 532 nm green laser before surgery with a mean interval of 4.9 ± 1.9 months. The mean baseline and final vision was 0.68 ± 0.23 and 0.61 ± 0.33 logMAR, respectively, with a mean follow-up of 7.2 ± 3.5 months. Three eyes showed complete resorption of serous detachment, while the remaining two had reduction in schisis and subretinal fluid. None of the eyes had any complications. Glue application in addition to ILM peeling improves the visual prognosis in optic disc pit maculopathy with restoration of macular anatomy.

Reattachment of Rhegmatogenous Retinal Detachment via Fibrin Tissue Adhesive

Purpose

To manage reattachment of rhegmatogenous retinal detachment using tissue adhesive (fibrin glue) in five patients.

Methods

Five eyes of five patients with rhegmatogenous retinal detachment were treated with 23-gauge pars plana vitrectomy and the application of fibrin glue (Tisseel Lyo) into the break under air without laser photocoagulation or cryopexy.

Results

The median age of patients was 64 (range, 46–82) years, and the median duration of symptoms was 15 (range, 7–60) days. Three eyes had inferior and two had superior rhegmatogenous retinal detachments. Successful retinal reattachment was achieved in all cases and maintained during the followıng 10 to 24 months. The median best-corrected visual acuity improved from 2 / 100 preoperatively to a Snellen visual acuity of 20 / 50 by 6 months postoperatively. No postoperative complications were detected during the follow-up period.

Conclusions

Excellent adhesive effects of fibrin glue with respect to sealing retinal tears with no side effects were seen in our study. With further prospective studies, this technique could be an alternative method to conventional retinopexy.

Surgical Options for Optic Disc Pit Maculopathy: Perspectives and Controversies

Optic disc pit (ODP) is a rare congenital optic nerve head abnormality, which can be complicated by intraretinal and subretinal fluid at the macula (ODP-maculopathy) with progressive visual loss. The source of this fluid remains unclear and the most dominant hypotheses have pointed to vitreous cavity or cerebrospinal fluid. Although spontaneous resolution has been reported, the majority of untreated cases of ODP-maculopathy result in final visual acuity less than 20/200 or worse. A wide array of interventions, either individually or in combination with adjuvant treatments, have been tried with varying degrees of success. Recently, different surgical procedures to fill the ODP by self-sealing materials in combination with pars plana vitrectomy have been reported as an effective adjuvant treatment. However, given the relative rarity of this condition, the majority of reports describe a small retrospective case series, making it difficult to compare among different treatments options and create a consensus regarding the optimal treatment for ODP-maculopathy. In this situation, a mini-review about surgical treatment modalities and their results can be a useful approach to identify the most effective surgical option in the management of ODP-maculopathy.

Comparison and application of commercially available fibrin sealants in ophthalmology

Fibrin glues carry many advantages over traditional suture as a tissue adhesive and have been increasingly used in a variety of ophthalmic procedures over the past 15 years. Several fibrin sealants are commercially available worldwide, each of which differs slightly in its composition and mechanism of delivery. The focus of our review is to briefly discuss the reported uses of fibrin in ophthalmic surgery and provide a broad overview of the properties associated with each commercially available fibrin sealant.

Surgical applications of intracorporal tissue adhesive agents: current evidence and future development

Introduction: Traditional mechanical closure techniques pose many challenges including the risk of infection, tissue reaction, and injury to both patients and clinicians. There is an urgent need to develop tissue adhesive agents to reform closure technique. This review examined a variety of tissue adhesive agents available in the market in an attempt to gain a better understanding of intracorporal tissue adhesive agents as medical devices.Areas covered: Fundamental principles and clinical determinants of the tissue adhesives were summarized. The available tissue adhesives for intracorporal use and their relevant clinical evidence were then presented. Lastly, the perspective of future development for intracorporal tissue adhesive were discussed. Clinical evidence shows current agents are efficacious as adjunctive measures to mechanical closure and these agents have been trialed outside of clinical indications with varied results.Expert opinion: Despite some advancements in the development of tissue adhesives, there is still a demand to develop novel technologies in order to address unmet clinical needs, including low tensile strength in wet conditions, non-controllable polimerization and sub-optimal biocompatibility. Research trends focus on producing novel adhesive agents to remit these challenges. Examples include the development of biomimetic adhesives, externally activated adhesives, and multiple crosslinking strategies. Economic feasibility and biosafety are limiting factors for clinical implementation.

Fibrin hydrogels are safe, degradable scaffolds for sub-retinal implantation

Retinal pigment epithelium (RPE) transplantation for the treatment of macular degeneration has been studied for over 30 years. Human clinical trials have demonstrated that RPE monolayers exhibit improved cellular engraftment and survival compared to single cell suspensions. The use of a scaffold facilitates implantation of a flat, wrinkle-free, precisely placed monolayer. Scaffolds currently being investigated in human clinical trials are non-degradable which results in the introduction of a chronic foreign body. To improve RPE transplant technology, a degradable scaffold would be desirable. Using human fibrin, we have generated scaffolds that support the growth of an RPE monolayer in vitro. To determine whether these scaffolds are degraded in vivo, we developed a surgical approach that delivers a fibrin hydrogel implant to the sub-retinal space of the pig eye and determined whether and how fast they degraded. Using standard ophthalmic imaging techniques, the fibrin scaffolds were completely degraded by postoperative week 8 in 5 of 6 animals. Postmortem histologic analysis confirmed the absence of the scaffold from the subretinal space at 8 weeks, and demonstrated the reattachment of the neurosensory retina and a normal RPE–photoreceptor interface. When mechanical debridement of a region of native RPE was performed during implantation surgery degradation was accelerated and scaffolds were undetectable by 4 weeks. These data represent the first in situ demonstration of a fully biodegradable scaffold for use in the implantation of RPE and other cell types for treatment of macular degeneration and other retinal degenerative diseases.

Fibrin Glue and Internal Limiting Membrane Abrasion for Optic Disc Pit Maculopathy

BACKGROUND AND OBJECTIVE

To describe a novel surgical technique using pars plana vitrectomy (PPV), internal limiting membrane (ILM) abrasion, and intravitreal fibrin glue for the treatment of optic disc pit maculopathy.

PATIENTS AND METHODS

Surgical case series technique with scanning electron microscopy (SEM) of human post-mortem eyes.

RESULTS

Using SEM, the authors demonstrate the persistent adherence of vitreous fragments to the optic disc following induction of posterior vitreous detachment in human postmortem eyes. The authors describe a surgical technique using PPV, Tano Diamond Dusted Membrane Scraper for an ILM abrasion, intravitreal fibrin glue (Tisseel), and gas-air exchange to seal optic disc pits. The authors report successful long-term visual and anatomical outcomes in three patients.

CONCLUSIONS

Intravitreal fibrin glue, when combined with ILM abrasion, may be a viable treatment option for optic disc pit maculopathy with good short- and long-term visual acuity outcomes. SEM shows that ILM abrasion removes vitreous fragments, which are persistently adherent and may lead to failure with other interventional techniques. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:e271-e277.].

Surgical adhesives in ophthalmology: history and current trends

Tissue adhesives are gaining popularity in ophthalmology, as they could potentially reduce the complications associated with current surgical methods. An ideal tissue adhesive should have superior tensile strength, be non-toxic and anti-inflammatory, improve efficiency and be cost-effective. Both synthetic and biological glues are available. The primary synthetic glues include cyanoacrylate and the recently introduced polyethylene glycol (PEG) derivatives, while most biological glues are composed of fibrin. Cyanoacrylate has a high tensile strength, but rapidly polymerises upon contact with any fluid and has been associated with histotoxicity. Fibrin induces less toxic and inflammatory reactions, and its polymerisation time can be controlled. Tensile strength studies have shown that fibrin is not as strong as cyanoacrylate. While more research is needed, PEG variants currently appear to have the most promise. These glues are non-toxic, strong and time-effective. Through MEDLINE and internet searches, this paper presents a systematic review of the current applications of surgical adhesives to corneal, glaucoma, retinal, cataract and strabismus surgeries. Our review suggests that surgical adhesives have promise to reduce problems in current ophthalmic surgical procedures.

Fibrin hydrogels as a xenofree and rapidly degradable support for transplantation of retinal pigment epithelium monolayers

Recent phase 1 trials of embryonic stem cell and induced pluripotent stem cell (iPSCs) derived RPE transplants for the treatment of macular degeneration have demonstrated the relative safety of this process. However, there is concern over clumping, thickening, folding, and wrinkling of the transplanted RPE. To deliver a flat RPE monolayer, current phase 1 trials are testing synthetic substrates for RPE transplantation. These substrates, however, cause localized inflammation and fibrosis in animal models due to long degradation times. Here we describe the use of thin fibrin hydrogels as a support material for the transplantation of RPE. Fibrin was formed into a mechanically rigid support that allow for easy manipulation with standard surgical instruments. Using fibrinolytic enzymes, fibrin hydrogels were degraded on the scale of hours. The rate of degradation could be controlled by varying the fibrinolytic enzyme concentration used. RPE cells degraded fibrin spontaneously. To preserve the fibrin support during differentiation of iPSCs to RPE, media was supplemented with the protease inhibitor aprotinin. iPSC-RPE on fibrin gels remained viable, generated monolayers with characteristic cobblestone appearance and dark pigmentation, and expressed mRNA and protein markers characteristic of RPE in the eye. Following differentiation of the cells, addition of fibrinolytic enzymes fully and rapidly degraded the fibrin support leaving behind an intact, viable iPSC-RPE monolayer. In conclusion, human fibrin hydrogels provide a xeno-free support on which iPSCs can be differentiated to RPE cells for transplant which can be rapidly degraded under controlled conditions using fibrinolytic enzymes without adverse effects to the cells.

STATEMENT OF SIGNIFICANCE

Stem cell-derived retinal pigment epithelial (RPE) cell transplantation is currently in phase 1 clinical trials for macular degeneration (MD). A major obstacle in these studies is delivering the RPE as a living, flat sheets without leaving behind foreign materials in the retina. Here we investigate the suitability of using hydrogels made from human blood-derived proteins for RPE transplant. Our data shows that these fibrin hydrogels are rigid enough for use in surgery, support growth of stem cell-derived RPE, and are easily degraded within hours without damage to the RPE sheet. These fibrin hydrogels offer a promising solution to transplant RPE for patients with MD.