Use of a hydrogel sealant in epithelial ingrowth removal after laser in situ keratomileusis

Progress of tissue adhesives based on proteins and synthetic polymers

In recent years, polymer-based tissue adhesives (TAs) have been developed as an alternative to sutures to close and seal incisions or wounds owing to their ease of use, rapid application time, low cost, and minimal tissue damage. Although significant research is being conducted to develop new TAs with improved performances using different strategies, the applications of TAs are limited by several factors, such as weak adhesion strength and poor mechanical properties. Therefore, the next-generation advanced TAs with biomimetic and multifunctional properties should be developed. Herein, we review the requirements, adhesive performances, characteristics, adhesive mechanisms, applications, commercial products, and advantages and disadvantages of proteins- and synthetic polymer-based TAs. Furthermore, future perspectives in the field of TA-based research have been discussed.

Tissue Adhesives for the Management of Corneal Perforations and Challenging Corneal Conditions

Corneal perforations are ophthalmological emergencies which can have serious and detrimental consequences, if not managed timely and appropriately. These are a significant cause of ocular morbidity and can result in decreased vision, blindness, and even loss of the eye. Corneal perforations can be managed using a range of treatment approaches, including temporary solutions such as the application of corneal glue and bandage contact lens, as well as definitive treatment such as corneal transplantation. Tissue glues/adhesives were developed as substitutes for sutures in ophthalmic surgery. Unlike sutures, these glues are associated with shorter overall surgical times and reduced inflammation, thus improving postoperative comfort without compromising wound strength. The available tissue adhesives can be broadly classified into two types: synthetic (eg, cyanoacrylate derivatives) and biological (eg, fibrin glue). Cyanoacrylate glue is chiefly used as a corneal patch to manage acute corneal perforations and improve visual outcomes. Fibrin glue can be used instead of cyanoacrylate glue in many conditions with the benefits of reduced conjunctival and corneal inflammation and reaction. Apart from this, each type of adhesive is distinct in terms of its benefits as well as limitations and is accordingly used for different indications. The present review focuses on the two main types of tissue adhesives, their applications in the management of corneal perforations, the associated complications, safety and efficacy data related to their use available in the literature and the need for newer adhesives in this field.

Assessment of the Retinal Toxicity and Sealing Strength of Tissue Adhesives

PURPOSE

The purpose of this in vitro prospective nonrandomized study is to compare the toxicity and strength of cyanoacrylate and hydrogel adhesives on human retinal pigment epithelium (RPE) cells and porcine retina, respectively.

METHODS

The toxicity of cyanoacrylate (histoacryl, dermabond, superglue), ReSure PEG, and Tisseel fibrin glue on human RPE cells was determined by growing RPE cells in vitro, applying the different adhesives to the cells, and monitoring for disruption of growth over 3 days. The relative strength of these adhesives was tested by gluing a 3 mm piece of foam to a porcine retina and determining the amount of force needed to break the attachment.

RESULTS

0.085 N of force was required to break the porcine retinal tissue (p = .913). Histoacryl adhesive exhibited high strength (0.247 N) and high RPE toxicity (0.55 mm inhibition zone after 24 hrs). The strength of Tisseel fibrin glue was 0.078 N while that of ReSure was only 0.053 N. Both Tisseel and ReSure were nontoxic to the RPE cells.

CONCLUSIONS

Tisseel VH fibrin sealant may provide the best option for sealing retinal breaks because of its high strength and low retinal toxicity.

Adhesive Tissue Engineered Scaffolds: Mechanisms and Applications

A variety of suture and bioglue techniques are conventionally used to secure engineered scaffold systems onto the target tissues. These techniques, however, confront several obstacles including secondary damages, cytotoxicity, insufficient adhesion strength, improper degradation rate, and possible allergic reactions. Adhesive tissue engineering scaffolds (ATESs) can circumvent these limitations by introducing their intrinsic tissue adhesion ability. This article highlights the significance of ATESs, reviews their key characteristics and requirements, and explores various mechanisms of action to secure the scaffold onto the tissue. We discuss the current applications of advanced ATES products in various fields of tissue engineering, together with some of the key challenges for each specific field. Strategies for qualitative and quantitative assessment of adhesive properties of scaffolds are presented. Furthermore, we highlight the future prospective in the development of advanced ATES systems for regenerative medicine therapies.

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.

Hydrogel sealant to prevent recurrent epithelial ingrowth in the setting of a LASIK flap buttonhole

Purpose

To report the first case of hydrogel sealant to prevent the recurrence of epithelial ingrowth in a LASIK flap buttonhole.

Observations

A 67-year-old female presented ten years after undergoing bilateral LASIK with diffuse lamellar keratitis and flap dislodgement after blunt trauma to the right eye. She was found to have epithelial ingrowth with diffuse debris and striae, so her flap was lifted and the epithelial ingrowth was removed. However, a central buttonhole was noted intraoperatively. Once all the epithelium was removed, the flap was repositioned and hydrogel sealant (ReSure, Ocular Therapeutix, Bedford, MA) was used to fill the buttonhole as well as seal down the edges of the flap. Sixteen months postoperatively, the patient's uncorrected visual acuity was 20/50-2 and there was no recurrence of the epithelial ingrowth at the edges of the buttonhole.

Conclusions and importance

Preventing the recurrence of epithelial ingrowth is a challenging situation, especially in the setting of a LASIK flap buttonhole. The use of hydrogel sealant in the buttonhole and around the edges of the flap may offer an elegant and effective solution.

Ocular adhesives: Design, chemistry, crosslinking mechanisms, and applications

Closure of ocular wounds after an accident or surgery is typically performed by suturing, which is associated with numerous potential complications, including suture breakage, inflammation, secondary neovascularization, erosion to the surface and secondary infection, and astigmatism; for example, more than half of post-corneal transplant infections are due to suture related complications. Tissue adhesives provide promising substitutes for sutures in ophthalmic surgery. Ocular adhesives are not only intended to address the shortcomings of sutures, but also designed to be easy to use, and can potentially minimize post-operative complications. Herein, recent progress in the design, synthesis, and application of ocular adhesives, along with their advantages, limitations, and potential are discussed. This review covers two main classes of ocular adhesives: (1) synthetic adhesives based on cyanoacrylates, polyethylene glycol (PEG), and other synthetic polymers, and (2) adhesives based on naturally derived polymers, such as proteins and polysaccharides. In addition, different technologies to cover and protect ocular wounds such as contact bandage lenses, contact lenses coupled with novel technologies, and decellularized corneas are discussed. Continued advances in this area can help improve both patient satisfaction and clinical outcomes.

Management of Complex Epithelial Ingrowth After Laser In Situ Keratomileusis Using Fibrin Tissue Glue

OBJECTIVES

To evaluate the efficacy and safety of adjunctive fibrin tissue glue in the treatment of complex epithelial ingrowth after laser in situ keratomileusis (LASIK).

METHODS

A retrospective review was performed of 12 eyes in 12 patients treated for clinically significant epithelial ingrowth after LASIK with mechanical debridement of the ingrowth and placement of fibrin tissue glue. Primary outcome measurements including recurrence of ingrowth, visual acuity, and manifest refraction were evaluated at each postoperative examination. Changes in higher-order aberrometry were also evaluated.

RESULTS

After epithelial ingrowth removal with adjunctive fibrin tissue glue, 11 eyes (91.7%) had no recurrence of ingrowth at the final follow-up examination. Uncorrected distance visual acuity changed from 20/20 or better in 3 eyes (25%) and 20/40 or better in 6 eyes (50%) preoperatively to 20/20 or better in 5 eyes (41.7%) and 20/40 or better in 10 eyes (83.3%) postoperatively. Nine eyes (75%) gained one or more lines of best-corrected distance visual acuity (CDVA). No eyes lost any lines of CDVA. There was no significant change in mean spherical equivalent (P=0.22) or mean cylinder (P=0.26) before and after surgery. Higher-order aberrations also remained stable with no significant change in root-mean-square error, coma, trefoil, and spherical aberration. There were no complications associated with the treatment.

CONCLUSIONS

Adjunctive fibrin tissue glue seems to be a safe and effective treatment for epithelial ingrowth after LASIK. This therapy may be particularly useful in managing challenging cases of complex or recalcitrant ingrowth.

Flap-Lift LASIK 10 or More Years After Primary LASIK

PURPOSE

To evaluate the safety and efficacy of flap-lift LASIK performed 10 or more years after the original LASIK procedure.

METHODS

All patients who were treated with flap-lift LASIK 10 or more years after primary LASIK for whom records of the primary treatment could be obtained and at least 45-day follow-up refractions after re-treatment were available were included in this study. A total of 23 eyes of 20 patients were identified. The median time between primary LASIK and flap-lift LASIK was 13.9 years (range: 10 to 18.7 years).

RESULTS

A total of 22 of 23 eyes (96%) retained the same corrected distance visual acuity (CDVA) postoperatively that was present preoperatively. One of 23 eyes (4%) experienced a loss of CDVA from 20/20 to 20/25 as the result of clinically significant epithelial ingrowth requiring multiple treatments followed by photorefractive keratectomy (PRK) treatment. One additional eye experienced clinically significant epithelial ingrowth that required a single surgical treatment. Fourteen of 20 eyes with a goal of plano achieved uncorrected distance visual acuity (UDVA) of 20/20 or better and 6 eyes achieved UDVA of 20/25 (2 of these eyes had preoperative CDVA of 20/25). For the eyes with a goal of plano, 16 of 20 eyes (80%) achieved UDVA equal to the preoperative CDVA.

CONCLUSIONS

Flap-lift LASIK is an effective treatment for refractive error when performed between 10 and 18.7 years after the initial flap was created. Epithelial ingrowth is the major complication, occurring to a clinically significant degree in 9% of the eyes. [J Refract Surg. 2018;34(9):604-609.].

Epithelial ingrowth following laser in situ keratomileusis (LASIK): prevalence, risk factors, management and visual outcomes

The number of laser in situ keratomileusis (LASIK) procedures is continuing to rise. Since its first application for correcting simple refractive errors over 25 years ago, the role of LASIK has extended to treat other conditions, including postkeratoplasty astigmatism/ametropia, postcataract surgery refractive error and presbyopia, among others. The long-term effectiveness, predictability and safety have been well established by many large studies. However, due to the creation of a potential interface between the flap and the underlying stroma, interface complications such as infectious keratitis, diffuse lamellar keratitis and epithelial ingrowth may occur. Post-LASIK epithelial ingrowth (PLEI) is an uncommon complication that usually arises during the early postoperative period. The reported incidence of PLEI ranged from 0%–3.9% in primary treatment to 10%–20% in retreatment cases. It can cause a wide spectrum of clinical presentations, ranging from asymptomatic interface changes to severe visual impairment and flap melt requiring keratoplasty. PLEI can usually be treated with mechanical debridement of the affected interface; however, additional interventions, such as alcohol, mitomycin C, fibrin glue, ocular hydrogel sealant, neodymium:yttriumaluminum garnet laser and amniotic membrane graft, may be required for recurrent or refractory cases. The aims of this review are to determine the prevalence and risk factors of PLEI; to describe its pathogenesis and clinical features and to summarise the therapeutic armamentarium and the visual outcome of PLEI.