Clinical experience with N-butyl cyanoacrylate (Nexacryl) tissue adhesive

A hyperdry amniotic membrane patch using a tissue adhesive for corneal perforations and bleb leaks

PURPOSE

To evaluate the efficacy of hyperdry amniotic membrane (AM) patching attached using a tissue adhesive for corneal perforations and glaucoma filtering bleb leaks.

DESIGN

Prospective, noncomparative, interventional case series.

METHODS

Five eyes of 5 patients (glaucoma bleb leaks, 2 eyes; corneal perforations, 3 eyes) were treated with a single-layer patch of dried AM using a biological tissue adhesive. The dried AM was prepared with consecutive far-infrared rays and microwaves (hyperdry method) and was sterilized by gamma-ray irradiation. The dried AM was cut to the desired size and shape, and the tissue adhesive was applied to the amniotic epithelial side of the dried membrane. After applying the tissue adhesive, the dried membrane with glue applied then was positioned to cover the conjunctival bleb leak site or corneal perforation lesion using forceps. A therapeutic hydrogel contact lens then was installed as a bandage.

RESULTS

Bleb leaks or corneal perforations were repaired successfully within 21 days in all 5 cases. There were no remarkable adverse effects, and there was no recurrence of bleb leak or corneal perforation.

CONCLUSIONS

The hyperdry AM is a useful substrate, and this surgical procedure is a promising method to treat glaucoma filtering bleb leak or corneal perforation, which may result in serious vision-threatening ocular complications.

Fibrin Glue as a Suture Substitute: Histological Evaluation of Trabeculectomy in Rabbit Eyes

PURPOSE

To describe the outcome of the use of fibrin adhesive (Quixil) in penetrating trabeculectomy in a rabbit model.

METHODS

Fibrin adhesive was used experimentally to attach the conjunctiva and the scleral flap in two groups of 17 New Zealand albino adult rabbits (34 eyes). In the first experiment (20 eyes), the fibrin adhesive was used to reattach the tissue after conjunctival peritomy and scleral flap only in 14 eyes (experiment I). In 6 eyes (controls), the conjunctiva was attached with nylon sutures. In the second experiment (14 eyes), the fibrin adhesive was used after conjunctival peritomy, scleral flap, and penetrating trabeculectomy in 8 eyes (experiment II). In a control group of 6 eyes, nylon sutures were used to attach the scleral flap and the conjunctiva after penetrating trabeculectomy. Biomicroscopy and histopathological examinations were performed on postoperative days 1, 3, 7, 14, 21, and 30. Intraocular pressure was measured before and after surgery in the second experiment. Main outcome measures are histological presence of adhesive in the tissue, degree of capillary congestion, inflammatory reaction, collagen density [scar formation] and clinical (IOP measurements before and after surgery, conjunctival chemosis, anterior chamber reaction, presence of filtering bleb and wound leakage).

RESULTS

In experiments I and II, the adhesive was well identified histologically in the tissue as an amorphic eosinophilic substance for up to day 3 and nearly disappeared by day 7. An acute inflammatory reaction was noted for up to 14 days, which converted to chronic inflammation with collagen deposits and scar formation by day 30. Similar inflammatory reaction was observed in the control group. The adhesive had no adverse effects on ocular tissue compared with sutures. One eye in experiment II demonstrated wound dehiscence. Intraocular pressure dropped from 17.35 mmHg preoperatively to 8.28 mmHg on postoperative day 1 in experiment II, and from 17.2 mmHg to 11.5 mmHg in the controls. No significant change in intraocular pressure was noted in experiment I.

CONCLUSIONS

The fibrin adhesive had no adverse effects on ocular tissue compared with sutures. It might serve as an effective substitute for conjunctival and scleral wound closure in trabeculectomy surgery.

Development of a biodegradable bioadhesive containing urethane groups

Surgical adhesives consist on an attractive alternative to suturing or stapling since they can accomplish other tasks, such as haemostasis and the ability to seal air leakages. The application of adhesives would also reduce the surgeries procedure time since they represent an easier and faster method to establish tissue adhesion. The aim of this work was the development of a biodegradable urethane pre-polymer that presents the capacity of reacting with the amino groups present in the biological molecules. Urethanes based on polycaprolactone diol (PCL) were synthesized by reaction of the molecule either with isophorone diisocyanate (IPD-isocyanate) or hexamethylene diisocyanate (HDI-isocyanate). The characterization of the materials was accomplished by: ATR-FTIR (Attenuated Total Reflectance-Fourier Transform Infrared), determination of swelling capacity, stability of NCO groups in the presence of humidity conditions, reaction with aminated substrates (as a simulation of the living tissues) and determination of surface energy by contact angle measurement. The haemocompatibility of the PU was also evaluated by thrombosis and haemolysis tests.

Development of a new photocrosslinkable biodegradable bioadhesive

Adhesives provide a needle-free method of wound closure and do not require local anaesthetics. Polymeric adhesives have been used for about 3 decades for joining several tissues of the organism. Also, they can accomplish other tasks, such as haemostasis and the ability to seal air leakages and have the potential to serve as delivery systems. PCL was modified with 2-isocyanatoethylmethacrylate to form a macromer that was crosslinked via UV irradiation using Irgacure 2959 by CIBA as the photoinitiating agent. The characterization of the materials was accomplished by: attenuated total reflectance-Fourier transform infrared (ATR-FTIR), swelling capacity determination, evaluation of adhesive capacity (by reaction with aminated substrates) and determination of surface energy by contact angle measurement. Thermal characterization of the adhesive was performed by dynamical mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA). The morphology of PCL networks was observed using scanning electron microscopy (SEM) both after crosslinking process and following biodegradation in human plasma. The haemocompatibility of the membranes was also evaluated by thrombosis and haemolysis tests.

Designing hydrogel adhesives for corneal wound repair

Today, corneal wounds are repaired using nylon sutures. Yet there are a number of complications associated with suturing the cornea, and thus there is interest in an adhesive to replace or supplement sutures in the repair of corneal wounds. We are designing and evaluating corneal adhesives prepared from dendrimers--single molecular weight and highly branched polymers. We have explored two strategies to form these ocular adhesives. The first involves a photocrosslinking reaction and the second uses a peptide ligation reaction to couple the individual dendrimers together to form the adhesive. These adhesives were successfully used to repair corneal perforations, close the flap produced in a LASIK procedure, and secure a corneal transplant.

Multifunctional chondroitin sulphate for cartilage tissue-biomaterial integration

A biologically active, high-strength tissue adhesive is needed for numerous medical applications in tissue engineering and regenerative medicine. Integration of biomaterials or implants with surrounding native tissue is crucial for both immediate functionality and long-term performance of the tissue. Here, we use the biopolymer chondroitin sulphate (CS), one of the major components of cartilage extracellular matrix, to develop a novel bioadhesive that is readily applied and acts quickly. CS was chemically functionalized with methacrylate and aldehyde groups on the polysaccharide backbone to chemically bridge biomaterials and tissue proteins via a twofold covalent link. Three-dimensional hydrogels (with and without cells) bonded to articular cartilage defects. In in vitro and in vivo functional studies this approach led to mechanical stability of the hydrogel and tissue repair in cartilage defects.

SURGICAL APPLICATIONS OF CYANOACRYLATE ADHESIVES: A REVIEW OF TOXICITY

Cyanoacrylate (CA) and its homologues have a variety of medical and commercial applications as biological adhesives and sealants. Homologues of CA are being widely promoted in surgery as a tissue adhesive to replace traditional suturing techniques. Potential benefits of using CA adhesives include better cosmetic results, more rapid wound closure, and perhaps most significantly, the potential for significant reductions in percutaneous injuries from suture needles, which would in turn also reduce the risk of transmission of infectious diseases. Nevertheless, certain concerns have been raised regarding the potential toxicity of CA within patients, as well as among health professionals who are occupationally exposed when using CA compounds. Reported toxicity of CA in the workplace may result in dermatological, allergic and respiratory conditions. To help reduce the occupational burden, therefore, medical staff using CA adhesives should avoid direct contact with the compound and use appropriate personal protective measures at all times. Maintaining higher levels of humidity, optimizing room ventilation and using special air conditioning filters in surgical suites and operating theatres may also be useful in minimizing the exposure to volatile CA adhesives.

Modification of the biopolymer castor oil with free isocyanate groups to be applied as bioadhesive

Surgical adhesives have been used for several applications, including haemostasis, sealing air leakages and tissue adhesion. The aim of this work was to develop a biodegradable urethane-based bioadhesive containing free isocyanate groups. This material presents the advantage of being biodegradable, biocompatible and having the capacity of reacting with amino groups present in the biological molecules. A urethane based on castor oil (CO) was synthesized by reaction of the molecule with isophorone diisocyanate (IPD). The characterization of the material was accomplished by different techniques: ATR-FT-IR (attenuated transmittance reflection-Fourier transform infrared), swelling capacity determination, evaluation of the moisture curing kinetics, reaction with aminated substrates and determination of surface energy by contact angle measurement. The study of the urethane thermal properties was performed by DMTA (dynamical mechanical thermal analysis) and TGA (thermogravimetric analysis). The haemocompatibility of the urethane was also evaluated by thrombosis and haemolysis tests.

In vitro toxicity test of ethyl 2-cyanoacrylate, a tissue adhesive used in cardiovascular surgery, by fibroblast cell culture method

BACKGROUND

The aim of this study was to evaluate the cytotoxicity of cyanoacrylate polymers (ethyl 2-cyanoacrylate) by an elution test system. In such systems, the material is extracted with a cell culture medium, which is subsequently added onto cultured cells, resulting in an indirect contact between the biomaterial and cells.

METHODS

A cell line commonly utilized for cytotoxicity experiments; L929 mouse fibroblasts were used in this study. The effects of extract dilutions on cells were evaluated by two experiments: (a) The cells were suspended and seeded in a medium containing the extract, followed by a short incubation to observe the effects on cell attachment; (b) cells were seeded in a normal medium. Following cell attachment, this was replaced with a medium containing the extract and long-term effects on cell proliferation were measured. The cytotoxicity was quantified using a cell viability assay, well established for use in the evaluation of cell-biomaterial interactions.

RESULTS

These results indicate that, in the test system utilized, a tenfold dilution of the extract results in an approximately 10% decrease in cells; this increases to between 30% and 45% in a 1:1 dilution. When a large number of cells (3000/well) were used, proliferation of cells overcame the cytotoxic effect and consistent results could not be observed.

CONCLUSIONS

In this study, the observed outcomes follow a similar trend on cell attachment and proliferation with acute effects (4 hours incubation) of the extracts on the cells, producing slightly higher toxicity. Our findings are parallel with the literature findings.

Ocular surface sealants and adhesives

Tissue adhesives, both synthetic and biologic, have a long history of use in ophthalmology. Cyanoacrylate-based glues have traditionally been the most widely used glues for various purposes. They have been specially useful for treating corneal perforations and have had significantly improved long-term outcomes. More recently, fibrin-based glues have gained a major role as a suture substitute for attaching biologic tissues and as surface sealants. The literature supports expanded use of fibrin glue in this fashion. Other new agents, such as polyethyelene glycols, have been underutilized and hold promise, especially as surface protectants. Numerous other glues are being developed and show promise as ocular surface sealants and protective membranes. Advances in knowledge about tissue adhesives are leading to more effective and efficient ophthalmic care.

Choroidal detachment in perforated corneal ulcers: frequency and management

AIMS

To determine the frequency of choroidal detachment (CD) in eyes with non-traumatic corneal ulcer perforation and, also, to assess the efficacy and safety of cyanoacrylate glue in sealing corneal perforations.

METHODS

18 eyes of 17 patients were studied. Inclusion criterion was any patient with a non-traumatic perforated corneal ulcer. All patients had a thorough history taken and complete ophthalmic examination including B-scan ultrasonography. Patient demographics, presence of CD, and efficacy of corneal gluing were assessed.

RESULTS

Eight of the 18 eyes (44%) were documented to have a CD. Among perforations of >2 mm2, six eyes (75%) were documented to have CD compared with two eyes (20%) with perforations of <or=2 mm2 (p = 0.054). No correlation could be determined between perforation duration and incidence of CD. Of the 15 eyes that underwent gluing, there were 13 successes (87%) and two failures (13%). Within the successes four patients (27%) required re-gluing because of infection (one patient) or progression of melt and glue loosening (three patients). Failure was the result of severe progression of melting (one patient) and a very large perforation (one patient).

CONCLUSION

Choroidal detachment following corneal ulcer perforation is common and is more likely in larger corneal perforations. Preoperative B-scan should be considered in cases of large corneal perforations requiring therapeutic keratoplasty to document choroidal detachment, which if large may require drainage. Cyanoacrylate glue is an effective and safe method for sealing small corneal perforations. A vigil must be maintained for infection while the glue and bandage contact lens are in situ.

Adal-1 bioadhesive for sutureless recession muscle surgery: a clinical trial

AIMS

To evaluate the efficacy and biotolerance of the Adal-1 adhesive for muscle sealing in strabismus surgery.

METHODS

27 eyes were included in the study: 17 in the control group and 10 in the study group. Surgery was performed on the recession of the horizontal rectus muscles. In the control group the muscle was joined to the sclera by a Vicryl 7/0 suture. In the study group, the Adal-1 adhesive was used instead. The efficacy of the sealing of the muscle to the sclera and the biotolerance of the surrounding tissues were evaluated.

RESULTS

The muscular recession in the control group was 8.17 (SD 2.38) with displacement of the sealing point of 0.02 (1.7) mm. In the group sealed with adhesive, the muscular recession was 9.09 (3.08) and the displacement was 0.15 (1.56) mm, with no significant differences between the techniques (p<0.05). The inflammation of the surrounding tissues in the immediate postoperative period was greater with the suture technique (p>0.05), but there were no differences in the other postoperative periods (Mann-Whitney U test).

CONCLUSION

Adal-1 was an effective and safe alternative to sutures in muscle recession for strabismus surgery in this study.

Scleritis

Scleritis is typically a severe painful inflammatory process centered in the sclera that may involve the cornea, adjacent episclera, and underlying uvea; it poses a significant threat to vision. Careful clinical history taking, detailed ocular examination, appropriate investigation for ocular disease with or without underlying systemic disease, and timely intervention with the use of immunosuppressant drugs when necessary, has improved the long-term outcome for patients with this disease.

[Other surgical therapies for cornea burns]

With limbal stem cell and amniotic membrane transplantations, penetrating keratoplasty is the most important treatment of severe corneal burns. In the acute stage, re-epithelialization failure and resultant stromal ulceration can induce corneal perforation. A lamellar or a full-thickness patch graft is indicated in order to preserve the eyeball. For small perforations, tissue adhesive can be used. In the early reparative stage, keratoplasty has its place, but corneal vascularization is a major risk factor for graft rejection. Lamellar keratoplasty is preferred because it provides tectonic support. After several graft failures, a keratoprosthesis is the last solution for these bilaterally affected patients, but evisceration cannot be always avoided.

Advances in the use of adhesives in ophthalmology

PURPOSE OF REVIEW

To summarize the known uses of available medical tissue adhesives in the management of diseases of the anterior segment, highlighting recent developments in the field.

RECENT FINDINGS

Human fibrin glues may be used in place of cyanoacrylate tissue adhesives in the treatment of progressive corneal thinning and small perforations, potentially resulting in less corneal and conjunctival inflammatory reaction. Additional currently proposed uses of fibrin glues in ophthalmic surgery include minimizing sutures in recurrent pterygium surgery, forniceal reconstruction, amniotic membrane transplantation, and lamellar corneal grafting.

SUMMARY

After reviewing the literature pertaining to the current use of tissue adhesives in ophthalmic surgery, the authors conclude that the main indication for cyanoacrylate tissue adhesives is for the treatment of progressive corneal thinning and small, uncomplicated corneal perforations. Human fibrin glues appear to be equally effective in such cases and have the advantage of biocompatibility, allowing application over a larger surface area and the use of a superficial covering layer such as amniotic membrane or conjunctiva for further reinforcement and promotion of rapid re-epithelialization. Other applications of human fibrin glues in ophthalmic surgery are evolving, but their widespread use is limited by concern over the theoretic risk of viral transmission and the complexity of their preparation and application in comparison with traditional sutures.

Clinical experience with butyl-2-cyanoacrylate adhesive in the management of canine and feline corneal disease

PURPOSE

To examine and evaluate clinical indications and postoperative outcome in a series of small animal patients in which corneal disease was managed by the application of butyl 2-cyanoacrylate adhesive.

MATERIALS AND METHODS

In this retrospective study all small animal patients were identified that presented to the Royal Veterinary College, University of London over a 2-year period, in which corneal disease was managed by the application of butyl 2-cyanoacrylate. Indications for application, complicating factors prior to gluing, glue retention time, postoperative comfort, and extent of subsequent corneal reaction and scarring were noted for each case. Long-term follow-up data concerning visual and cosmetic outcome were obtained from owners and referring veterinarians.

RESULTS

Thirty-seven patients (28 dogs and 9 cats), in which 39 eyes were treated, were identified. Indications for corneal gluing in this series included stromal ulceration (26/39 eyes); descemetocele (4/39 eyes); corneal laceration/foreign body (5/39 eyes); lamellar keratectomy (3/39 eyes) and superficial ulceration (1/39 eyes). At least one factor responsible for initiation, persistence or progression of the ulcer was identified in 66.7% of eyes prior to corneal gluing. These included keratomalacia; confirmed bacterial keratitis; corneal edema related to endothelial disease and keratoconjunctivitis sicca. Cyanoacrylate was generally well tolerated by patients with only 8/34 eyes demonstrating transient blepharospasm and increased lacrimation postoperatively. Retention time of cyanoacrylate varied widely from < 1 week to approximately 6 months, but was < 2 months in the majority (89%) of eyes. Exaggerated corneal vascularization was an infrequent postoperative complication, noted in only six canine eyes, and did not appear to be related to initial corneal disease, glue retention time or breed.

CONCLUSIONS

Butyl 2-cyanoacrylate offers a convenient, economical and effective alternative to other treatment modalities, such as conjunctival grafts, in the management of corneal defects in canine and feline patients.

Evaluation of a New Bioadhesive Copolymer (ADAL??) to Seal Corneal Incisions

OBJECTIVE

To evaluate the efficacy and clinical tolerance of a new acrylic copolymer tissue adhesive, ADAL, in corneal surgery.

METHODS

Corneal incisions were performed on 24 New Zealand albino rabbits. The incision was either sealed with ADAL bioadhesive, hydrated with balanced salt solution, or closed with 10-0 nylon surgical sutures. The incisions underwent weekly tensile strength testing and clinical, histopathologic, and confocal microscopy evaluations.

RESULTS

Clinical evaluation revealed good sealing and no incision leakage in any group. There was no anterior chamber reaction in any case. Compared with the hydrated group, there was somewhat more incisional vascularization and localized corneal opacity in the ADAL group, but there were no cases of severe corneal opacity or neovascularization. On histologic analysis, a slightly larger inflammatory reaction was noted in the ADAL group compared with the hydrated group. Tensile strength during the first week was statistically significantly greater in the ADAL group (2.93 Newtons) than in the control groups (1.40 Newtons, hydrated group; 1.43 Newtons, sutured group) (P < 0.001). Confocal microscopy study revealed a unique dendritic keratocyte shape and structure resembling shiny crystalline particles after disappearance of the adhesive from the cornea.

CONCLUSIONS

Corneal surgical incisions sealed with ADAL adhesive have superior tensile strength in the first postoperative week compared with incisions closed with sutures or hydrated with salt solution. Thereafter, findings in both groups became similar. The use of ADAL adhesive was not associated with any deleterious effects during the corneal incision-healing process compared with hydration or sutures.

Clinical experience with N-butyl cyanoacrylate tissue adhesive in fungal keratitis

PURPOSE

To evaluate the role of tissue adhesive in the management of corneal thinning or perforation associated with active fungal keratitis.

DESIGN

Retrospective noncomparative interventional case series.

METHODS

Seventy-three eyes of 73 patients with microbiologically proven keratomycosis associated with thinning or perforation participated in the study. N-Butyl cyanoacrylate tissue adhesive (medical grade) and bandage contact lens were applied in addition to topical and systemic antifungal therapy. Our outcome measures included resolution of the infiltrate and preservation of the structural integrity of the globe.

RESULTS

Outcome data were available for 66 eyes. The infiltrate resolved with scar formation in 42 (63.6%) eyes. In an additional eight (12.1%) eyes, tissue adhesive maintained the structural integrity of the globe while the patients awaited penetrating keratoplasty. Sixteen (24.2%) eyes showed progressive worsening or persistence of the infiltrate after application of tissue adhesive. Twenty-five (37.8%) eyes required multiple applications of tissue adhesive. The outcome was better in cases where the infiltrate measured less than 30 mm2 at the time of presentation and application of tissue adhesive (P < 0.01).

CONCLUSION

In view of the poor outcome of penetrating keratoplasty in active fungal keratitis, N-butyl cyanoacrylate tissue adhesive is a useful modality for the management of progressive thinning or perforation associated with active fungal keratitis. However, close observation is mandatory to assess the progression of disease.

Severe cough: a cause of late bleb leak

PURPOSE

To highlight coughing as a potential cause for late postoperative trabeculectomy bleb leaks.

METHODS

A retrospective study of 2 patients in whom late bleb leaks developed after a bout of severe coughing. Perioperative 5-fluorouracil was used at the time of the initial filtration procedure for one of the patients, while the second patient had had an ordinary trabeculectomy. Both patients required surgical repair of their bleb leak to manage the resultant hypotony.

RESULTS

Postoperatively, both patients had good intraocular pressure control and maintained their visual fields without topical medications. Both patients demonstrated bleb avascularity after leak repair.

CONCLUSIONS

Trabeculectomy bleb leaks are well recognized. Bleb leaks in the late postoperative period are more common after the perioperative use of antimetabolites, and spontaneous leaks after minimal trauma have been described. The authors describe 2 cases of late spontaneous bleb leaks after severe coughing, both of which responded well to surgical correction. The importance of inquiring about a history of coughing with late bleb leaks in the absence of other causative factors is stressed.

Fibrin glue versus N-butyl-2-cyanoacrylate in corneal perforations

OBJECTIVE

To compare the efficacy of fibrin glue and N-butyl-2-cyanoacrylate in corneal perforations.

DESIGN

Randomized, controlled clinical trial.

PARTICIPANTS

Forty-one patients (41 eyes) with corneal perforations up to 3 mm in diameter with a positive Seidel's test were randomly assigned to two groups (1 and 2).

INTERVENTION

Group 1 comprised 19 eyes treated with fibrin glue, and group 2 comprised 22 eyes treated with N-butyl-2-cyanoacrylate.

MAIN OUTCOME MEASURES

Number of eyes with successful healing, time required for healing, status of corneal vascularization, and complications were compared in the two groups. Power calculation was performed at alpha = 0.05.

RESULTS

Fifteen (79%) eyes had successful healing of corneal perforation in group 1, compared with 19 (86%) eyes in group 2 (P > 0.05) at 3 months' follow-up. The power to detect a difference between the two groups was 10%. Corneal perforation healed within 6 weeks in 12 (63%) eyes in group 1 and 7 (31.8%) eyes in group 2 (P < 0.05). Reapplication of glue was required in six (31.5%) eyes in group 1 and seven (31.4%) eyes in group 2 during the first 3 months of follow-up. The mean number of applications per eye was 1.37 in group 1 and 1.36 in group 2. An increase in deep corneal vascularization was observed in 2 (10.5%) eyes in group 1 and 10 (45.5%) eyes in group 2 (P < 0.05). Giant papillary conjunctivitis occurred in one (5%) eye in group 1 and eight (36.4%) eyes in group 2 (P < 0.05).

CONCLUSIONS

Fibrin glue and cyanoacrylate tissue adhesive are both effective in the closure of corneal perforations up to 3 mm in diameter. Fibrin glue provides faster healing and induces significantly less corneal vascularization, but it requires a significantly longer time for adhesive plug formation.

Intralamellar autopatch with lamellar keratoplasty for paracentral corneal perforations

PURPOSE

To report a new technique of tectonic intralamellar autopatch with lamellar keratoplasty (LK) for paracentral corneal perforations.

METHODS

A partial thickness lamellar dissection of the host was undertaken to remove the superficial epithelium and the anterior stroma. A second lamellar dissection began at the periphery to approximately 1 mm away from the perforation to fashion a hinge. The hinged autolamellar flap was reflected over the perforation and sutured to the host with interrupted sutures. Finally, the autolamellar patch graft was supported by a lamellar graft, which was secured in place with 16 interrupted sutures. This technique was undertaken in 4 eyes with paracentral perforation after trauma (2 eyes), after pterygium (1 eye), and inadvertent perforation during host bed dissection of large LK (1 eye).

RESULTS

All eyes achieved a stable ocular surface and a postoperative visual acuity of more than 6/60.

CONCLUSIONS

Intralamellar autopatch with lamellar keratoplasty provides adequate tectonic support in cases of paracentral corneal perforation and thereby maintaining the integrity of the globe. It also provides ambulatory visual acuity.

A photopolymerized sealant for corneal lacerations

PURPOSE

To determine whether a novel photocrosslinkable polymer synthesized from hyaluronic acid would seal experimental full-thickness corneal lacerations in a rabbit model.

METHODS

A solution of hyaluronic acid was modified with methacrylate groups (HA-MA), precipitated, dried, reconstituted in an aqueous solution, and sterilized before use. The viscous polymer solution was applied to 38 of 43 experimental corneal lacerations in rabbits and subsequently irradiated with a low-intensity argon laser beam to produce a clear flexible polysaccharide hydrogel patch. The ability of this sealant to repair corneal lacerations was evaluated in four types of full-thickness, 3-mm corneal wounds (linear, linear + epithelium removed, stellate, and stellate + epithelium removed). Slit-lamp examinations, measurements of intraocular pressure, Seidel tests, and histologic studies were performed at selected intervals to evaluate the wound and determine the rate of healing.

RESULTS

Corneal perforations were completely sealed and the anterior chambers had reformed by 6 hours in HA-MA-treated eyes. There was no evidence of leakage at this or later times in 37 of the 38 eyes. Intraocular pressure had risen to near-normal levels by day 7 in all four groups, and the sealant was still present in most eyes at day 7. In contrast, the anterior chambers did not re-form in control eyes (five) with untreated perforations because of aqueous leakage through the wounds. Minimal inflammation was observed clinically or in histologic sections of treated corneas. There was extensive proliferation of stromal cells and formation of new extracellular matrix at the wound edges, which became tightly adherent between days 4 and 7.

CONCLUSION

Our novel photocrosslinkable methacrylated hyaluronan polymer sealed 97% (37/38) of the experimental corneal lacerations. HA-MA may prove useful for sealing corneal lacerations in patients and for other sutureless ophthalmic surgical procedures.

Tolerance of the rabbit cornea to an n-butyl-ester cyanoacrylate adhesive (Vetbond)

OBJECTIVE

An n-butyl-ester cyanoacrylate adhesive available for veterinary surgery (Vetbond, 3M) was tested in rabbits for corneal irritation.

PROCEDURES

Two experimental procedures were used on 24 rabbits: injection of the adhesive into an intralamellar corneal pocket (n = 10) and application of the glue to a mid-stromal corneal defect (n = 14). In both experiments the eyes were examined for 20 days for evidence of corneal irritation and tolerance. At the end of each experiment, histopathologic studies were performed on all corneas.

RESULTS

The corneal reaction to the intrastromally injected cyanoacrylate was characterized clinically by slight edema and vascularization localized to the vicinity of the adhesive. A moderate foreign body-type reaction was found histologically. Following application of the adhesive to a central stromal defect, the treated corneas remained totally clear and histopathologic examination showed that the healing process was not altered compared to the controls. The mean retention time of the glue patch was 14 days.

CONCLUSIONS

Intrastromal injection and surface application to a corneal defect of n-butyl-ester cyanoacrylate to a corneal defect induced only a mild inflammatory response and did not interfere with the reparative process. These findings suggest that this surgical adhesive would be acceptable for treating corneal ulcerations in animals.

Use of isobutyl cyanoacrylate tissue adhesive to stabilize external eyelid weights in temporary treatment of facial palsies

PURPOSE

To describe a technique for stabilizing external eyelid load weights with isobutyl cyanoacrylate tissue adhesive for the temporary treatment of facial palsies.

METHODS

This was a nonrandomized, prospective study of six consecutive patients with unilateral facial paralysis treated with external eyelid load weights stabilized with isobutyl cyanoacrylate tissue adhesive instead of adhesive tape. Follow-up assessment included corneal exposure, patient comfort, amount of artificial tear usage, and complications associated with the weights.

RESULTS

Of the six patients studied, five had decreased corneal exposure, decreased artificial tear usage, and increased patient comfort with use of the weights. One patient had no improvement of symptoms. Weights were retained for a mean of 10.7 days. Two patients had difficulty with the weights; one was secondary to dermatochalasis and blepharoptosis obscuring his vision, and the other patient's weight fell off after 1 day. No weights were lost.

CONCLUSIONS

The use of isobutyl cyanoacrylate tissue adhesive is a simple, quick, and inexpensive method for placement of external eyelid weights for temporary treatment of ocular exposure associated with facial paralysis and for determining the correct weight for implantation. Furthermore, isobutyl cyanoacrylate tissue adhesive used to stabilize external eyelid weights is better tolerated and lasts longer than the previously described fixation method with adhesive tape.

2-Octyl cyanoacrylate medical adhesive in treatment of a corneal perforation

PURPOSE

To describe a case of successful treatment of a corneal perforation with 2-octyl cyanoacrylate.

METHODS

2-Octyl cyanoacrylate was applied at the slit lamp with topical proparacaine anesthesia to a cornea with an inferior perforation with iris plugging the defect.

RESULTS

After application of 2-octyl cyanoacrylate, the anterior chamber was noted to deepen, and visual acuity improved to 20/200. The glue remained intact for more than 6 weeks and eventually fell out. The underlying cornea healed without scarring, vascularization, or thinning.

CONCLUSION

We have described a case in which 2-octyl cyanoacrylate was used to treat a corneal perforation with excellent results. Further study of this adhesive will be useful in comparing the effectiveness and safety of 2-octyl cyanoacrylate with that of previously studied adhesives.

Cyanoacrylate glue for corneal perforations: a description of a surgical technique and a review of the literature

The effective early application of a cyanoacrylate glue corneal patch can aid in the management of small corneal perforations, corneal melts and wound leaks. Their use gives improved visual outcomes with reduced enucleation rates (6% vs 19%). It may also avoid the need for tectonic penetrating keratoplasty. Cyanoacrylate glue prevents re-epithelialization into the zone of damaged and naked stroma and prevents the development of the critical setting for collagenase production that leads to stromal melting. Cyanoacrylates also have significant bacteriostatic activity against gram-positive organisms. We describe a simple and easily reproducible method of cyanoacrylate corneal patch application, with neglible risk of inadvertent glue complications. It has the further advantage of a smooth corneal surface rather than an irregular surface as often occurs with direct application methods. With corneal application, the major concern is toxicity of cyanoacrylates through direct contact with the corneal endothelium and lens. Fibrin glues may be less toxic; however, they are not as readily available. The longer alkyl chains of currently available cyanoacrylate glues (e.g. Histoacryl) slows degradation significantly, limiting accumulation of histotoxic by-products to amounts that can be effectively eliminated by tissues. Vigilance in monitoring for infection/corneal infiltrate is necessary at all times, especially when the glue has been present for more than 6 weeks. Corneal patching with cyanoacrylate glue is a temporizing procedure only, buying time to allow healing secondary to medical treatment of the underlying condition, or allowing surgery to be elective and under more optimal conditions once inflammation has been reduced and the integrity of the globe restored.

Preliminary experience with 2-octylcyanoacrylate in a pediatric emergency department

OBJECTIVE

Documentation of use of octylcyanoacrylate adhesives in a pediatric emergency department with reference to patient selection, complications, and parent satisfaction.

DESIGN

Retrospective and concurrent chart review of the first 100 patients on which 2-octylcyanoacrylate (2-OCA, Dermabonda) was used in a pediatric emergency department. Additional telephone follow-up was performed for each patient.

RESULTS

The average patient age was 4.7 years, average laceration size 1.2 cm. Sixteen percent of wounds were repaired with 2-OCA. Three immediate complications involved a minor dehiscence and two eyelid adhesions. Two wound infections and a patient with hematoma and keloid formation were identified as later complications. The vast majority of parents preferred tissue adhesive repair to sutures. Time in department was reduced from 106 minutes to 69 minutes on average (P < 0.0001, CI 26-52).

CONCLUSIONS

Octylcyanoacrylate adhesives performed well in the daily practice of a pediatric emergency department, and were used for a significant percentage of laceration closures. Convenience, average infection rates, and good parental satisfaction make tissue adhesives a valuable addition to our wound closure techniques. Certain pitfalls occurring during early experience with these adhesives can be recognized and avoided.

The management of corneal trauma: advances in the past twenty-five years

Over the past quarter century, advances in our understanding of corneal anatomy, physiology, and wound healing have all played an integral role in the management of corneal trauma. As the etiologies of corneal trauma have changed, so has our understanding of the impact of injury on corneal function as it relates to visual rehabilitation. Numerous new classes of antibiotics, antiinflammatory agents, and tissue adhesives have emerged. Occlusive therapy has advanced from simple pressure patching bandage soft contact lenses and collagen shields. Surgical instrumentation, operating microscopes, viscoelastic substances, and suture materials have all improved the outcomes of corneal trauma repair. Improved understanding of the refractive properties of the cornea through topography and alternative suture techniques has helped us restore the natural corneal curvature and visual outcomes. Consequently, in the last quarter of this century our therapeutic approaches to cornea trauma, both medical and surgical, have improved.

Cytotoxicity of polymerized commercial cyanoacrylate adhesive on cultured human oral fibroblasts

Cyanoacrylate (CA) has been used as both a commercial and tissue adhesive. Dentists may have had the experience of patients repairing their own acrylic-based dentures using a cyanoacrylate (CA) adhesive known as 'super glue'. This study evaluated the cytotoxicity of commercial CA adhesives when fully polymerized, as well as the toxicity of substances released from polymerized commercial CA adhesives after incubation of these materials for various periods of time. Toxicity was tested on cultured oral fibroblasts. Dead cells found around the various CA-coated filter papers constituted inhibitory zones which varied from 200-1000 microns and which persisted for two weeks. Control oral fibroblasts grew to approach the wax-coated filter paper. Cell viability testing using MTT and crystal violet staining methods supported the conclusion that polymerized CA-coated filter paper released substances that are toxic to cells, while wax-coated filter paper gave the same result as the control. The crystal violet staining method was also used to investigate the cytotoxicity of various CA materials after incubation for one, three, seven and 14 days and showed that CA continued to release cytotoxic substances at about the same level for at least two weeks. It can be concluded that, if CA adhesive is used for repair of broken dentures, it will release substances which are toxic to human oral fibroblast cells. This release of substances may persist for at least two weeks.

Management of conjunctival cicatrizing diseases and severe ocular surface dysfunction

Physical or chemical injuries, infections, immunologic oculocutaneous disorders, drugs, and various systemic disorders may cause scarring of the conjunctiva and disturbances of the ocular surface. Trichiasis, lid margin malposition, and dry eye may result in persistent ocular irritation. The cornea may be primarily or secondarily involved. If severe, disturbances of the ocular surface may lead to significant visual impairment. Thorough evaluation of patients and of the underlying disease process is required for optimal management. Treatment may be challenging and should be comprehensive, combining medical measures and surgical correction of structural changes. Suppression of exogenous irritants, treatment of dry eye, antiinflammatory therapy, and immunosuppressants are paramount to control the underlying disease and allow optimal surgical results. Surgical correction of trichiasis and lid margin malposition, conjunctival grafting, mucous membrane transplantation, limbal stem cell transplantation, amniotic membrane transplantation, and penetrating keratoplasty help reestablish a physiologic ocular surface. Severe cases may require keratoprosthetics for visual rehabilitation. Corneal ulceration or perforation requires prompt attention to maintain ocular integrity. Special measures should be considered for patients who require cataract or glaucoma surgery.

Clinical experience with cyanoacrylate tissue adhesive

In this paper 385 cases treated with cyanoacrylate tissue adhesive during the years 1980-1995 are studied. The indications, outcomes and complications of cyanoacrylate adhesive are investigated and the results are analysed. It is encouraging that except for three cases of ocular hypotony and two cases of microbial infection no other complications occurred. Even in desperate cases with corneal perforation greater than 3 mm and ocular infection, enucleation was avoided. The early use of a bandage contact lens, inserted just after the glue application and the coverage with topical antibiotics switched every 15 days until the removal of the glue, may explain the small incidence of infection. Our experience from the use of cyanoacrylate tissue adhesive in cases with corneal perforation greater than 3 mm is very encouraging. In these cases a running 10.0 nylon suture was used to create a reticulum over the space of the corneal perforation upon which the glue was applied. The use of cyanoacrylate tissue adhesive offers to the clinician a safe technique for healing corneal wounds that avoids tectonic penetrating keratoplasty with its associated complications.

Management of the uncontrollable pulmonary air leak with cyanoacrylate glue

Massive pulmonary air leak from a ruptured bleb in a patient with emphysema may be uncontrollable by the usual methods. A technique is illustrated where fibrin glue, cyanoacrylate glue, and a bovine pericardial patch are used in combination to seal the leak.