Tissue adhesive arrests stromal melting in the human cornea

Surgical Management of Peripheral Ulcerative Keratitis: Update on Surgical Techniques and Their Outcome

Peripheral ulcerative keratitis (PUK) is an inflammatory, necrotic condition in the peripheral cornea which may end in corneal perforation and visual morbidity if not treated adequately. PUK can occur due to infectious or non-infectious causes. Early cases need medical therapy, both locally and systemically (for some cases). However, advanced PUK may necessitate surgical removal of inciting cause of the pathology and maintaining tectonic stability. Such surgical treatment, including corneal transplantations, may be used in an emergency setting or for visual rehabilitation following preliminary stabilization of the affected cornea. The outcome of these surgeries need to be analyzed to understand the long-term visual prognosis of such eyes. This is an attempt to analyze surgical modalities in the management of PUK and their outcomes.

Neurotization of the human cornea - A comprehensive review and an interim report

We present a comprehensive review of existing literature on surgical corneal neurotization (SCN) as a treatment modality for neurotrophic keratopathy (NK) with an interim report of seven cases where SCN was performed using the indirect approach and followed up till 18 months postoperatively to look for improvement in ocular surface, corneal sensations, and nerve regeneration by using in vivo confocal microscopy (IVCM). A literature search was performed for publications with keywords “corneal nerves,” “neurotization,” “esthesiometry,” “corneal anesthesia,” and “neurotrophic keratopathy.” All literature available till December 31, 2020 was reviewed and included to describe NK and its management options, particularly SCN. NK is associated with absent or reduced corneal sensations and is managed using a step-ladder algorithm ranging from medical management for symptomatic relief to surgical corneal neurotization. Both direct and indirect approaches of SCN have a favorable outcome with reduced surgical morbidity in the indirect approach using sural nerve graft. Post neurotization, corneal sensation recovery may take up to 3–6 months, while nerve regeneration on confocal microscopy can take as long as 6 months–1 year.

[Surgical management of infectious keratitis]

Infectious keratitis is one of the most common causes of blindness worldwide. Despite the existence of a wide arsenal of quite effective antimicrobial drugs, some forms of bacterial and viral keratitis are resistant. Advanced acanthamoeba and mycotic lesions of the cornea, as well as mixed forms of infection usually do not respond well to conservative treatment. In the absence of positive dynamics from the applied etiotropic therapy with observed further progression of the microbial process, there is a risk of corneal perforation and spread of infection to the sclera or deep ocular structures with a high probability of irreversible functional disorders or anatomical death of the eye. In such cases, a timely transition to surgical treatment is necessary in order to maintain structural integrity of the eyeball. For this purpose, corneal crosslinking, microdiathermocoagulation, tissue adhesive, autoconjunctival plasty, amniotic membrane, corneoscleral flap coating, various combinations of these methods, as well as therapeutic keratoplasty are used most often in clinical practice. The choice depends on the etiology, size and depth of the lesion, its localization, prognosis of visual outcomes, somatic status of the patient. Therapeutic keratoplasty is the most radical and effective method of surgical intervention that allows eradication of the infectious focus and best possible restoration of the structural integrity of the eyeball. However, in some cases due to inaccessibility of donor material or high risks of the surgery and non-transparent graft engraftment, it is advised to use alternative surgical approaches, and keratoplasty, if necessary, should be carried out for optical purposes at a further, "quiet" period.

Cyanoacrylate Tissue Adhesive for the Treatment of Corneal Thinning and Perforations: A Multicenter Study

PURPOSE

To examine the outcomes of cyanoacrylate tissue adhesive (CTA) application for impending or frank corneal perforations and assess for predictors of treatment response.

METHODS

A multicenter cohort study was conducted to assess the clinical outcomes of adult patients who underwent CTA gluing for impending or frank corneal perforations between 2013 and 2018. The primary outcome was the proportion of successful CTA applications, defined as tectonic stability of the globe without subsequent keratoplasty (KP). Secondary outcomes included visual acuity and success of subsequent surgical interventions, if performed.

RESULTS

Fifty-three eyes of 52 patients were included in this study [56% women; mean age at presentation 70 ± 13 years; median length of follow-up of 387 days (interquartile range: 191-704)]. Medical comorbidities were present in 62% of patients. The most common etiologies for perforations included infections (43%) and Sjogren disease (9%). Of the CTA-treated eyes, 22% had a complete resolution of the corneal lesion. Fifty-four percent of patients underwent KP. Longer duration of CTA treatment was associated with CTA success (P = 0.04). For patients requiring KP, 71% were successful and 29% failed. There is no significant difference in the median time delay between patients with successful and failed KPs (P = 0.4).

CONCLUSIONS

CTA may be considered a stand-alone treatment for corneal perforations. It yielded a success rate of 22%. Failed CTA treatment occurred quickly, largely because of the severity of presentation. In cases requiring KP, the delay between glue application and surgery did not influence the PK success.

CORNEAL NEUROTIZATION IN A PATIENT WITH SEVERE NEUROTROPHIC KERATOPATHY. CASE REPORT

PURPOSE

Neurotrophic keratopathy (NK) is a degenerative corneal disease caused by damage to the trigeminal innervation due to a decrease in corneal sensitivity or complete anaesthesia. Impaired corneal innervation leads to morphological and metabolic disorders of the epithelium. In addition, it also leads to the development of recurrent or persistent epithelial defects in corneal ulcers, which may progress to stromal lysis and corneal perforation. One possible solution for severe NK is reinnervation of the anaesthetic cornea (corneal neurotization) using the supraorbital nerve and an autologous sensory nerve graft (indirect neurotization). This article presents the results of corneal neurotization in a young male patient with persistent epithelial defects and corneal ulcers due to corneal denervation.

RESULTS

A 22-year-old man with a history of neurosurgery for astrocytoma of the cerebellum and trunk on the right side at the age of 2 years, was observed for postoperative paresis of the right facial nerve with lagophthalmos in his childhood. The presence of asymptomatic dysfunction of the right trigeminal nerve was also noted. At the age of 22 years, after right eyeball contusion, the vision of the right eye decreased and a persistent epithelial defect developed, followed by corneal ulceration. Due to the exhaustion of therapeutic options in a young patient with corneal anaesthesia, the cornea was reinnervated via the contralateral supraorbital nerve using an autologous sural nerve graft. Five months after the surgery, the sensitivity of the cornea of the right eye began to recover. After amniotic membrane transplantation, the extensive epithelial defect healed, and the opaque corneal stroma gradually cleared up.

CONCLUSION

The reinnervation of the anaesthetic cornea (corneal neurotization) using the supraorbital nerve and the autologous sensory nerve graft represents a new solution for severe NK treatment. The severe corneal condition in our patient healed after the surgery.

Management of corneal perforations: An update

Corneal perforation is a potentially devastating complication that can result from numerous conditions that precipitate corneal melting. It is associated with significant morbidity and prompt intervention is necessary to prevent further complications. Causes include microbial keratitis, ocular surface disease, and autoimmune disorders and trauma. Various management options have been described in the literature to facilitate visual rehabilitation. This rview discusses the treatment options that range from temporising measures such as corneal gluing through to corneal transplantation, with decision making guided by the location, size, and underlying aetiology of the perforation.

[Cyanoacrylate adhesive in surgrical treatment of corneal perforation (clinical case)]

In modern ophthalmological practice, three types of adhesives are most often used: synthetic (cyanoacrylate), biological (fibrin), and polyethylene glycol. Cyanoacrylate adhesive is very strong and polymerizes quickly, however, is generally more toxic compared to other types of adhesives, especially if applied to highly vascularized tissues. It is also believed to have bacteriostatic activity and suppress progressive stroma lysis within the area of ulceration by inhibiting polymorphonuclear leukocytes that exhibit collagenolytic and proteolytic activity. The article presents a clinical case of effective use of Russian-made cyanoacrylate (sulfacrylate) adhesive for the treatment of corneal perforation in a patient with neurotrophic keratopathy. The use of polymer glue can be an effective, affordable, and safe alternative to other methods of urgent treatment of corneal perforations and deep ulcers, as shown by this case and literature data. Depending on the lesion location and prognosis for vision, the method can be used either independently or become a treatment stage before keratoplasty. The latter would enable delayed transplantation with lower risk of complications.

Outcomes of Penetrating and Lamellar Corneal Patch Grafts

PURPOSE

To report the indications, long-term structural and functional outcomes, and prognostic factors for the success of penetrating and lamellar corneal patch grafts.

METHODS

This is a retrospective analysis of 49 patients who underwent the corneal patch graft procedure over 8 years. The baseline, preoperative, and postoperative characteristics along with their outcomes were evaluated.

RESULTS

Forty-nine eyes (49 patients) with a mean follow-up of 20.3 ± 3.27 months (range 6-48) were included. Thirty-one patients underwent full-thickness grafts for corneal perforation, and 18 underwent lamellar grafts for severe thinning. The most common indication was corneal thinning and/or perforation secondary to microbial keratitis (17 eyes, 34.7%). Anatomic success was achieved in 31 eyes (63.2%), in which no further surgical intervention was required for tectonicity. Functional success was achieved in 22 of 37 eyes (59.5%), where along with anatomic success, significant visual gain was also obtained. Absolute graft failure was noted in 12 eyes (24.5%), which developed recurrence of primary pathology requiring reintervention within the first 6 months. Good prognostic factor for success included sterile corneal perforations. The presence of microbial keratitis was noted to be a guarded prognostic factor for success.

CONCLUSIONS

Corneal patch graft can serve as a good therapeutic modality for corneal ulceration or thinning, not amenable to treatment with tissue adhesive application. Both anatomical success and functional success of 60% was achieved in our series. Those performed for immune-mediated conditions fared the best. Subsequent optical procedures may be performed for further visual rehabilitation at a later stage.

Surgical alternatives to keratoplasty in microbial keratitis

Penetrating keratoplasty is often required in microbial keratitis not responding to the standard treatments available or the development of complications like corneal perforation. Performing keratoplasty in microbial keratitis has several challenges, the major ones being the availability of donor corneal tissue and the poor success of the corneal graft performed in such a setting. For overcoming these challenges, several alternatives to keratoplasty have been described. Broadly, these options could be categorized into autologous tissues such as conjunctival and tenon tissue, synthetic products like tissue adhesives and therapeutic contact lenses, or biological tissues like amniotic membrane graft. These alternative modalities are not universal. They have their specific indications in microbial keratitis. Most of these alternatives are useful only for small corneal perforations. While autologous tissues are cost-effective and readily available, lack of tectonic support is a significant limitation. Tissue adhesives are excellent alternatives in terms of tectonic support, but surface irregularity and tissue reaction are their potential limitations. The amniotic membrane is useful for small corneal perforations, but availability, cost, and poor tectonic support restrict its use. Herein, we discuss these various alternatives to keratoplasty in microbial keratitis, their indications, advantages, disadvantages, and the various techniques of performing these procedures.

Post-herpes neurotrophic keratopathy: Aetiopathogenesis, clinical signs and current therapies

Neurotrophic keratopathy (NK) is a degenerative corneal disease caused by damage of trigeminal innervation. This leads to epithelial defects, ulceration and, eventually, perforation. Both herpes simplex and varicella zoster keratitis are reported to be the main causes of NK. Furthermore, prognosis in this type of NK is poor. Classic clinical findings in post-herpes NK are spontaneous epithelial breakdown, round and central epithelial defects with smooth edges, stromal melting and thinning, scarring, and neovascularisation. Although several medical and surgical treatments have been reported, no therapies are currently available to definitely restore corneal sensitivity. Therefore, NK remains a challenging disease to treat. In this review a summary is presented of the pathogenesis, manifestations, and current management of post-herpes NK. The role of antiviral treatment and varicella-zoster vaccination is also discussed. A description is also presented on both medical and surgical novel therapies, such as regenerative drugs and corneal neurotization.

Neurotrophic keratitis: current challenges and future prospects

Neurotrophic keratitis (NK) is a degenerative corneal disease caused by damage of trigeminal corneal innervation, which leads to spontaneous epithelial breakdown and corneal ulceration. The impairment of corneal sensory innervation causes the reduction of both protective reflexes and trophic neuromodulators that are essential for the vitality, metabolism, and wound healing of ocular surface tissues. A wide range of ocular and systemic conditions, including herpetic keratitis, ocular chemical burns, corneal surgery, diabetes, multiple sclerosis, and neurosurgical procedures, can cause NK by damaging trigeminal innervation. Diagnosis of NK requires careful investigation of any ocular and systemic condition associated with the disease, complete ocular surface examination, and quantitative measurement of corneal sensitivity. The clinical stages of NK range from corneal epithelial alterations (stage 1) to persistent epithelial defect (stage 2) and ulcer (stage 3), which may progress to corneal perforation. Management of NK is based on clinical severity, and the aim of the therapy is to halt the progression of corneal damage and promote epithelial healing. Although several medical and surgical treatments have been proposed, no therapies are currently available to restore corneal sensitivity, and thus, NK remains difficult and challenging to treat. The purpose of this review is to summarize available evidence on the pathogenesis, diagnosis, and treatment of NK. Novel medical and surgical therapies including the topical administration of nerve growth factor and corneal neurotization are also described.

Collagen cross-linking as an adjunct for repair of corneal lacerations: a cadaveric study

OBJECTIVE

To determine the efficacy of collagen cross-linking (CXL) as an adjunct to suturing in the repair of corneal lacerations.

METHODS

A cadaveric study was undertaken in which a linear 5 mm corneal laceration was created in the central cornea of 20 eyes. The eyes were then randomized to receive 1 (n = 8), 2 (n = 8), or 3 (n = 4) standard corneal sutures. The burst pressure of the wound was then measured. All eyes in the 1- and 2-suture group then underwent standard CXL, with burst pressure repeated afterward.

RESULTS

The initial wound burst pressure in the 1-, 2-, and 3-suture groups was 54.9, 74.0, and 201.2 mm Hg, respectively. After CXL, wound burst pressure increased by a mean of 3.2 and 62.3 mm Hg in the 1- and 2-suture groups, respectively. This change was statistically significant in the 2-suture group (p = 0.017). After CXL, the 2-suture group still had a significantly lower burst pressure compared with the 3-suture group (p = 0.011).

CONCLUSIONS

The study highlights a potential novel application for CXL to strengthen corneal wounds. Provided that suture density is sufficient to appose the wound edges, CXL may result in short-term wound strengthening. This could potentially allow for decreased corneal suture density and a corresponding decrease in suture-related complications.

Treatment of acute ocular chemical burns

Ocular chemical burns are an ophthalmic emergency and are responsible for 11.5%-22.1% of ocular injuries. Immediate copious irrigation is universally recommended in acute ocular burns to remove the offending agent and minimize damage. Conventional medical therapy consists of the use of agents that promote epithelialization, minimize inflammation, and prevent cicatricial complications. Biological fluids such as autologous serum, umbilical cord blood serum, platelet-rich plasma, and amniotic membrane suspension are a rich source of growth factors and promote healing when used as adjuncts to conventional therapy. Surgical treatment of acute ocular burns includes the debridement of the necrotic tissue, application of tissue adhesives, tenoplasty, and tectonic keratoplasty. Amniotic membrane transplantation is a novel surgical treatment that is increasingly being used as an adjunct to conventional treatment to promote epithelial healing, minimize pain, and restore visual acuity. Various experimental treatments that aim to promote wound healing and minimize inflammation are being evaluated such as human mesenchymal and adipose stem cells, beta-1,3 glucan, angiotensin-converting enzyme inhibitors, cultivated fibroblasts, zinc desferrioxamine, antifibrinolytic agents, antioxidants, collagen cross-linking, and inhibitors of corneal neovascularization.

Understanding the Pathogenesis of Neurotrophic Keratitis: The Role of Corneal Nerves

Neurotrophic keratitis (NK) is a rare degenerative disease of the cornea caused by trigeminal nerve damage, which leads to loss of corneal sensitivity, corneal epithelium breakdown, and poor healing. Though extremely uncommon, NK is increasingly recognized for its characteristics as a distinct and well-defined clinical entity rather than a rare complication of various diseases that can disrupt trigeminal innervation. Indeed, the defining feature of NK is loss of corneal sensitivity, and its clinical findings do not correlate with the wide range of systemic or ocular conditions that underlie trigeminal nerve damage. Despite increasing awareness of NK as a distinct condition, its management continues to be challenged by the lack of treatments that target nerve regeneration. This review focuses on the role of corneal nerves in maintaining ocular surface homeostasis, the consequences (such as alterations in neuromediators and corneal cell morphology/function) of impaired innervation, and advances in NK diagnosis and management. Novel therapeutic strategies should aim to improve corneal innervation in order support corneal renewal and healing. J. Cell. Physiol. 232: 717-724, 2017. © 2016 Wiley Periodicals, Inc.

Management of inflammatory corneal melt leading to central perforation in children: a retrospective study and review of literature

PURPOSE

To assess the outcome of early therapeutic penetrating keratoplasty (PKP) for corneal melt leading to perforation in children.

METHODS

Case notes of all the consecutive patients presenting with acute corneal perforation that underwent urgent therapeutic PKP between 2000 and 2010 to the practice of one of the authors, both NHS at Great Ormond Street Hospital for Children and private, were retrospectively reviewed. Onset of perforation, underlying cause, medical and surgical treatment, pre- and post-operative visual acuity, graft clarity, length of follow-up, and post-operative complications were recorded.

RESULTS

Four eyes of four consecutive patients (mean age of 9.5 years and median 8.5 years, range 4-17 years) were treated for acquired acute onset corneal perforations. There were three females and one male. Etiologies included herpes simplex keratitis secondary to immune recovery disease post bone marrow transplantation, acanthamoeba keratitis, recessive dystrophic epidermolysis bullosa, and blepharokeratoconjunctivitis with acne rosacea. Pre-operative visual acuity ranged from hand movements to 6/150. All the patients had severe anterior chamber inflammation. All eyes improved in visual acuity ranging from 6/9 to 6/18 with clear grafts at last follow-up. There was no recurrence of melt or perforation. Mean follow-up was 67 months (median 44 months).

CONCLUSION

PKP during the acute phase together with aggressive medical therapy and close follow-up may achieve good visual outcomes in children with corneal melt with perforation and should be considered. Waiting may sometimes allow the marked inflammatory response seen in children to cause irreversible structural and/or functional damage.

Lamellar corneal transplantation

Penetrating keratoplasty (PK) has been the gold standard for the surgical treatment of most corneal pathologies; lamellar keratoplasty that only replaces the diseased corneal layers has recently evolved as an alternative, however. Innovations in surgical technique and instrumentation provide visual outcomes comparable to PK. We review the indications and outcomes of various techniques of anterior lamellar surgery developed to treat stromal disorders. Similarly, we discuss posterior lamellar keratoplasty techniques such as Descemet stripping automated endothelial keratoplasty and Descemet membrane endothelial keratoplasty. Posterior lamellar keratoplasty provides faster visual rehabilitation than PK in cases of Fuchs endothelial dystrophy and pseudophakic bullous keratopathy. In addition, for medically unresponsive infectious keratitis, therapeutic anterior lamellar keratoplasty yields similar graft survival to PK without an increased risk of disease recurrence.

Superimposed fungal ulcer after fibrin glue sealant in infectious corneal ulcer

A healthy 27-year-old woman with a corneal ulcer underwent fibrin gluing with a bandage contact lens twice, due to an impending perforation. The ulcer lesion slowly progressed, unresponsive to topical antibiotics and amphotericin B. We removed the gluing patch and performed a corneal or scraping or biopsy with multiple amniotic membrane grafts to seal the thinned or perforated cornea. Three days after the surgery, the corneal cultures grew Fusarium, as well as Enterococcus faecalis. Three weeks after surgery, the outermost layer of amniotic membranes, serving as a temporary patch, was removed. The anterior chamber was clear without cells. The signs of infection clinically and symptomatically cleared up four weeks later. Two months after surgery, the lesion became enhanced by amniotic membranes. The use of fibrin glue in infectious keratitis should be avoided, because it not only masks the underlying lesion, but it also interferes with drug penetration into the underlying lesion.

The use of cyanoacrylate adhesives in the management of congenital vascular malformations

This article outlines the use of liquid acrylic adhesives in the management of congenital vascular malformations. Specifically, the chemical features of cyanoacrylates, including the physical and chemical properties, exovascular use of cyanoacrylates, and the techniques for use of these agents, are discussed.

A comparison of 2-octyl cyanoacrylate adhesives versus conventional suture materials for eyelid wound closure in rabbits

Purpose

To evaluate the clinical efficacy and histopathological tolerance of 2-octyl cyanoacrylate versus conventional suture materials for eyelid wound closure in rabbits.

Methods

We performed an experimental study on 16 eyes of eight New Zealand albino rabbits. Eyelid incisions of 15 mm were done 4mm from the upper eyelid margin in both eyes. The eyes of the rabbits were divided into two groups: eyelid incisions of the right eye were closed by a 2-octyl cyanoacrylate adhesive (group A) and eyelid incisions of the left eye were closed by 7-0 nylon sutures (group B). At 1, 2, 4, and 8 weeks after surgery, the rabbits were macroscopically examined and then sacrificed. The specimens of their eyelid tissues were stained by a hematoxylin and eosin stain and Masson-trichrome stain, and were observed under microscope.

Results

Both eyelid surgical closure methods were found to be equally efficacious in fixing the eyelids of groups A and B, and their clinical efficacy was similar. Histopathological findings of the hematoxylin and eosin stain of group A showed less inflammatory infiltration than group B at 2 weeks. There were no significant histopathological differences between the two groups at 1, 4, and 8 weeks. The degree of fibrosis of the Masson-trichrome stain was similar between the two groups at 8 weeks.

Conclusions

The 2-octyl cyanoacrylate adhesive proved to be an effective eyelid closure method and was very well tolerated by the skin surface. 2-Octyl cyanoacrylate could be used as an alternative tissue adhesive for eyelid wound closure along with conventional suture materials.

Pyoderma gangrenosum with necrotizing sclerokeratitis after cataract surgery

A 78-year-old man who had had uneventful extracapsular cataract extraction in the left eye 3 months earlier developed pyoderma gangrenosum (PG)-associated peripheral ulcerative keratitis (PUK) after suture removal. The patient had a 13-year history of PG associated with monoclonal immunoglobulin-A gammopathy. He presented with extensive, painful PUK at the incision site, with a descemetocele and a high risk for perforation. Fibrin glue tissue adhesive was used to stabilize the corneal ulcer as an adjunct to topical and systemic treatment. The patient had been treated with tapering doses of prednisone and cyclophosphamide (50 mg/day). High-dose human intravenous immunoglobulin (0.4 mg/kg/d for 4 days) was administered. The ulcer healed 1 month later with a loss of visual acuity. To our knowledge, this is the first reported case of PG-associated sclerokeratitis following cataract surgery. Early recognition of this rare ocular localization of PG is important to institute the appropriate therapy.

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.

Congenital Corneal Anesthesia

Congenital corneal anesthesia is a rare clinical entity that poses a diagnostic dilemma, particularly in the pediatric age group. The sensory deficit may be confined to the cornea, or extend to other divisions of the trigeminal nerve. The sensory deficit may occur as an isolated abnormality, as part of a complex neurological syndrome, or it may occur in association with multiple somatic abnormalities and congenital insensitivity to pain. This condition usually presents between the ages of 8 to 12 months. Poor vision, photophobia, conjunctival injection, and corneal ulceration in the absence of pain and distress in a child should alert the clinician to the possibility of anesthetic cornea. In the early stages of presentation, punctuate keratopathy is the main feature, which may progress to non-healing persistent corneal epithelial defects. This stage may progress to acute corneal lysis and perforation. In most patients, conservative approaches such as copious lubrication, prevention of self-harm and cautious use of bandage contact lenses are effective in preventing progressive corneal damage. Tarsorrhapy is effective in promoting epithelial healing and permanent lateral tarsorraphy may prevent further development of epithelial defects. Amniotic membrane graft may be considered in order to improve epithelial healing. Corneal grafts carry a poor prognosis. Accurate initial diagnosis, evaluation, and proper management are paramount to prevent visual loss due to long-term complications of corneal anesthesia. This review of the literature outlines the problems and approaches in diagnosis, evaluation, and management of this rare condition.

Antibacterial Analysis In Vitro of Ethyl-cyanoacrylate Against Ocular Pathogens

PURPOSE

To analyze the antimicrobial properties of ethyl-cyanoacrylate (Superbonder, Loctite, Brazil) in vitro in different microorganisms related to corneal infections.

METHODS

We analyzed the following microorganisms: (1) Staphylococcus aureus (multiresistant); (2) S. aureus (ATCC 25923); (3) coagulase-negative Staphylococcus; (4) Streptococcus pyogenes; (5) Streptococcus pneumoniae; (6) Pseudomonas aeruginosa (multiresistant); (7) P. aeruginosa (ATCC 27853); (8) Escherichia coli (ATCC25922); and (9) Enterococcus faecalis (ATCC 29212). One drop of the glue was dropped directly into the nutrient broth. The plates were incubated at 35 +/- 2 degrees C and its growth examined after 24 hours. Bactericidal activity of the glue was verified by sampling inhibition zones when present. The samples were plated in blood agar an analyzed after 24 and 48 hours.

RESULTS

The ethyl-cyanoacrylate inhibited the growth of every gram-positive microorganism tested and showed bactericidal effect over 70% for all of them. Among the gram-negative microorganisms, only the E. coli and the E. faecalis had its growth inhibited, and the bactericidal effect was 60% and 40%, respectively.

CONCLUSION

The ethyl-cyanoacrylate has bacteriostatic and bactericidal action in vitro, mainly against gram-positive microorganisms.

Amniotic membrane transplantation in acute chemical burns

PURPOSE

To evaluate the outcome of fresh amniotic membrane transplantation (AMT) for ocular surface reconstruction in acute chemical burns.

METHODS

A prospective study of 15 consecutive eyes with acute chemical burns was performed. In all, 10 eyes had lime burns and five eyes had acid burns. There were three eyes of grade II, four eyes of grade III and eight eyes of grade IV burns. AMT was performed within 3 weeks of injury.

RESULTS

Patients were followed up for 10.14 +/- 4.41 months. All patients had immediate relief of pain postoperatively. Of 15 eyes, nine (60%) showed epithelialization within 1-4 weeks (15.33 +/- 9.91 days). The final visual acuity improved in 10 of 15 eyes (66.66%). Eyes with burns of grade II and III showed more visual improvement than those with grade IV burns. None of the eyes showed perforation. Symblepharon was seen in nine of 15 eyes (60%). Of 15 eyes, 12 (80%) experienced limbal stem cell deficiency and showed superficial corneal vascularization.

CONCLUSIONS

Amniotic membrane transplantation with fresh amniotic membrane increases patient comfort and reduces inflammation. In mild burns, AMT alone restores corneal and conjunctival surfaces. In moderate to severe burns, it probably reduces conjunctival scarring sequelae, but does not prevent the sequelae of limbal stem cell deficiency that requires further limbal stem cell transplantation. In the acute stage, amniotic membrane transplantation probably has a protective role against the progressive melting and perforation.

Superior forniceal conjunctival advancement pedicles (SFCAP) in the management of acute and impending corneal perforations

OBJECTIVE/AIM

Corneal perforations can result from a wide variety of disorders and can lead to devastating visual sequelae. Various surgical procedures have been described to manage nontraumatic corneal perforation. Conjunctival flaps offer an important technique in dealing with such corneal emergencies. We report a modified conjunctival flap procedure referred to as superior forniceal conjunctival advancement pedicle (SFCAP) in the successful management of corneal perforation and impending corneal perforation.

PATIENTS AND METHODS

Out of 20 patients who underwent SFCAP for non-traumatic corneal perforation and impending perforation, 16 had corneal perforations. Perforations were secondary to acne rosacea (2), advanced bacterial keratitis (6), corneal anaesthesia(2), multiple retinal procedures (2), previous corneal grafts with a compromised ocular surface (3), and advanced Mooren's ulcer (1).

RESULTS

The globe was preserved in all patients. In 14 of the 16 eyes with perforated corneas the pedicle stabilised. One patient, who was a chronic alcoholic, rubbed the eye during sleep detaching the pedicle a week after surgery. However, the ulcer healed and the integrity of the globe was restored. None of these patients developed secondary glaucoma or ptosis.

CONCLUSION

SFCAP is an appropriate procedure to manage corneal perforations and impending corneal perforations where donor material is not available and transplantation of such tissue is not suitable.

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.

Neurotrophic keratitis

Neurotrophic keratopathy is a degenerative corneal disease induced by an impairment of trigeminal nerve. Impairment of loss of corneal sensory innervation is responsible for corneal epithelial defects, ulcer, and perforation. In the present report, we reviewed the pathogenesis, diagnosis, and therapeutic aspects of this disease. An accurate history and clinical examination, including the function of cranial nerves, together with the clinical features of the ocular surface are essential for a prompt diagnosis. The evaluation of the corneal sensitivity and tear film function are important diagnostic steps as well. Specific medical and surgical treatments, based on the clinical staging of the disease, are often able to halt its progression. Future developments in the medical treatment including the administration of neuropeptide and growth factors are presented.

Experimental anterior lens capsule transplantation for chronic corneal ulcers-Bowman's layer replacement?

PURPOSE

This study was designed to measure the value of allografted anterior lens capsule in the reepithelialization of recurrent corneal ulcers.

METHODS

Mechanical ulcers of uniform size were created with a 6-mm corneal trephine in both eyes of four Chinchilla male rabbits at one-third corneal depth. Following initial epithelial regrowth, an identical injury was created in the same area of each cornea a second time. In four eyes (treated group), an anterior lens capsule from a healthy donor rabbit was sutured into the ulcer bed followed by antibiotic/steroid drops three times daily for 1 week. The remaining four control eyes were allowed to heal without surgical intervention using the same antibiotic/steroid drops only. Slit-lamp examination and histopathology findings were recorded over a 6-month follow-up period.

RESULTS

The four treated eyes reepithelialized after the second injury at a faster rate than the control group eyes and had a lower percentage of corneal opacification at all follow-up exam dates. Histopathology revealed normal epithelium overlying the transplanted anterior lens capsule and no infiltration of inflammatory cells in the subepithelial stroma.

CONCLUSIONS

In experimental conditions, allotransplantation of anterior lens capsule speeds up reepithelialization after repeated mechanical trauma to the cornea. To our knowledge, this is the first experimental transplantation of an anterior lens capsule to create an artificial Bowman's layer in recurrent corneal ulcerations to aid reepithelialization and minimize corneal scarring.

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.

Failure of amniotic membrane transplantation in the treatment of acute ocular burns

AIM

To report the failure of amniotic membrane transplantation (AMT) for ocular surface reconstruction in patients with severe acute chemical and thermal burns.

METHODS

Four eyes of three patients who suffered severe chemical (n=3) and thermal (n=1) burns were studied. The aim of AMT was to prevent symblepharon formation, promote conjunctival regeneration, inhibit corneal melting by promoting epithelialisation, and to protect the ocular surface while associated lid burns were treated. AMT was used to cover the entire ocular surface of all the severely burnt and ischaemic eyes, 2-3 weeks after the injury. Where indicated, AMT was repeated by itself or in combination with other procedures in all patients.

RESULTS

Three of the four eyes developed symblepharon and progressive corneal melt requiring urgent tectonic keratoplasty. All four eyes had persistent epithelial defects. Less than 25% of conjunctival regeneration occurred in three eyes. Two eyes autoeviscerated, one patient underwent lid sparing exenteration for a painful blind eye and one eye became phthysical.

CONCLUSIONS

AMT did not help to restore the ocular surface or preserve the integrity of the eye in all our patients with severe acute burns, when used by itself or in combination with other surgical procedures. This reflects the extreme severity of the ocular burns in these patients and, in turn, draws attention to the fact that the current classification system does not adequately reflect such severity. In the current system such burns would be grouped under grade IV injuries to the eye (more than 50% limbal ischaemia). The prognosis of patients with 100% limbal ischaemia is much worse than patients with just over 50% limbal ischaemia. This inadequacy of the classification system probably also explains the difference between outcomes of management of grade IV burns (with AMT) in this series, compared with others.

Amniotic membrane, tear film, corneal, and aqueous levels of ofloxacin in rabbit eyes after amniotic membrane transplantation

PURPOSE

We evaluated ocular penetration and drug levels in tears after topical ofloxacin instillation in rabbit eyes with amniotic membrane transplantation (AMT).

METHODS

Forty-eight New Zealand White rabbits were used. In the first set of experiments, 24 rabbits (24 eyes) were divided into four groups according to the epithelial removal or AMT. Topical ofloxacin was instilled four times every 15 minutes. One hour after the last eyedrop, the concentration of ofloxacin in the amniotic membrane, cornea, and aqueous humor was evaluated. In the second set of experiments, 24 rabbits were divided into six groups according to AMT (transplantation of lyophilized or fresh amniotic membrane) or duration of application. Ofloxacin ointment or two drops of ofloxacin were applied to the right eye, and then tear samples were collected after 0.5, 1, 2, 4, and 6 hours for the analysis of ofloxacin concentration.

RESULTS

Mean ofloxacin concentrations in the cornea and aqueous humor were statistically higher in deepithelialized cornea regardless of AMT (p < 0.05). The mean tear levels of ofloxacin in the AMT groups were statistically higher than those in non-AMT groups (p < 0.05). There was no statistical significance in the tear level of ofloxacin between lyophilized amniotic membrane groups and fresh amniotic membrane groups nor between 1-hour amniotic membrane-attached groups and 6-hour amniotic membrane-attached groups.

CONCLUSION

Amniotic membrane transplantation seems to interfere with the ocular penetration of topical ofloxacin in normal rabbit corneas but enhances ofloxacin penetration in corneas with epithelial defects. The ofloxacin level in tears was higher in eyes with AMT up to 1 hour after topical ofloxacin use. Therefore, it seems that amniotic membrane has some potential to act as an effective drug delivery system.

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.

Nontraumatic corneal perforation

PURPOSE

To study the predisposing conditions, treatments, and visual outcomes of nontraumatic corneal perforations.

METHODS

A retrospective chart review was conducted of all nontraumatic corneal perforations seen between January 1992 and December 1998, with > or = 3 months of follow-up, at the Cornea Service Wills Eye Hospital.

RESULTS

A total of 40 nontraumatic corneal perforations was analyzed. Sixty-two percent of the cases were female. At presentation, 35 of 40 eyes (87.5%) had best corrected visual acuity of 20/200 or worse. The most common diseases associated with perforations were keratoconjunctivitis sicca (12 eyes, 30%), bacterial keratitis (6 eyes, 15%), exposure keratopathy (5 eyes, 12.5%), and herpes simplex virus (HSV) keratitis (4 eyes, 10%). Visual acuity improved > or = 2 Snellen lines in 3 of 8 eyes (37.5%) treated with penetrating keratoplasty, 5 of 14 eyes (35.7%) treated with tissue adhesive, and 1 of 12 eyes (8.3%) given medical treatment. After allowing for the different levels of presenting vision, treatment modality was not significantly related to final visual outcome.

CONCLUSION

Keratoconjunctivitis sicca is the most common underlying disease associated with nontraumatic corneal perforation. Corneal perforations were managed successfully using tissue adhesive, medical therapy, or penetrating keratoplasty. Treatment depended on the characteristics of the perforation and on the visual potential of the eye.

Management of neurotrophic keratopathy

Neurotrophic keratopathy is a degenerative corneal disease caused by an impairment of corneal sensitivity. Lack of the sensory nerve's trophic effect is responsible for the impairment in corneal healing and for the changes on the ocular surface that lead to corneal epithelial deficit, ulcer, and perforation. The etiology and recent advances in understanding of the pathogenetic mechanisms of neurotrophic keratopathy are reviewed here. An accurate history and a clinical examination that covers the function of cranial nerves often identify the cause of the disease. Clinical features and guidelines for the differential diagnosis and treatment are presented. Specific medical and surgical treatments, selected on the basis of clinical staging of the disease, can often halt disease progression. Future developments in medical treatment, including the use of neuropeptide and growth factors, are discussed. The identification of corneal anesthesia associated with an epithelial defect allows appropriate treatment and prevention of progression to stromal lysis and perforation.

Vasculitic peripheral ulcerative keratitis

The onset of peripheral ulcerative keratitis in the course of a connective tissue disorder, such as rheumatoid arthritis, relapsing polychondritis, or systemic lupus erythematosus, may reflect the presence of potentially lethal systemic vasculitis. Moreover, peripheral ulcerative keratitis may be the first sign of systemic necrotizing vasculitis in patients with Wegener's granulomatosis, polyarteritis nodosa, microscopic polyangiitis, or Churg-Strauss syndrome. Although the exact pathogenesis of this severe corneal inflammation and destruction is not well understood, evidence points to a dysfunction in immunoregulation with immune complexes formed in response to autoantigens or to some unknown microbial antigen depositing in scleral and limbal vessels. These events lead to changes that are mainly responsible for the resulting tissue damage. In pauci-immune vasculitides positive for antineutrophil cytoplasmic antibodies, cell-mediated cytotoxicity may play an important role in the pathogenesis of peripheral ulcerative keratitis. Untreated systemic conditions such as those mentioned above may carry a grave prognosis for the eye and may also be life-threatening. Immunosuppressive therapy with corticosteroids and cytotoxic agents is, we believe, mandatory in the treatment of these multisystem disorders associated with vasculitic peripheral ulcerative keratitis.

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.