Topical cyclosporine in high-risk corneal transplants

Topical corticosteroids with topical cyclosporine A versus topical corticosteroids alone for immunological corneal graft rejection

PURPOSE

To assess the efficacy and safety of supplementing topical cyclosporine A (CsA) to topical corticosteroids (CS), in the prophylaxis and treatment of corneal graft rejection following penetrating keratoplasty (PK).

METHODS

Meta-analysis. Search was performed in PubMed, CENTRAL, ClinicalTrials.gov, reference lists of articles and conference proceedings. Primary outcomes: 1-year rejection-free survival rate (prophylaxis); resolution rate of rejection episodes (treatment). Secondary outcomes: 6- and 24-month rejection-free graft survival rate, number of rejection episodes during follow-up, time-to-resolution of rejection episode, 12- and 24-months graft survival rate, adverse events. Subgroup analyses were planned for high-risk grafts; primary vs. secondary prophylaxis of graft rejection episodes; and CsA concentrations of 0.05%, 1%, and 2%.

RESULTS

Five studies of moderate methodological quality were included (one retrospective, four RCT), assessing 459 eyes (CS + CsA 226, CS 233). In the prophylaxis setting, supplemental CsA was associated with a higher rejection-free survival rate at 12-months (RR 1.25, 95% CI: 1.00-1.56, p = 0.05) and 24-months post-PK (RR 1.56, 95% CI: 1.15-2.11, p < 0.01), though no differences were found at the 6-months timepoint (p = 0.93). This effect was mostly verified using CsA 2% in the high-risk subset of patients. In the treatment setting, no differences were found in the resolution rate of rejection episodes (p = 0.23). No differences existed on drug-related adverse events.

CONCLUSION

In the prophylaxis of rejection episodes post-PK, the combined regimen of CS + CsA was associated with a higher 1- and 2-year rejection-free graft survival rate. Subgroup analysis mostly supported the use of CsA 2% for high-risk grafts. Further studies are needed to validate these results.

Real-world experience of using ciclosporin-A 0.1% (Ikervis) in the management of ocular surface inflammatory diseases

PURPOSE

To report the real-world experience of using topical ciclosporin, Ikervis, in the management of ocular surface inflammatory diseases (OSIDs).

METHODS

This was a retrospective study of patients treated with Ikervis for OSIDs at the Queen's Medical Centre, Nottingham, between 2016 and 2019. Relevant data, including demographics, indications, clinical parameters, outcomes and adverse events, were collected and analysed for patients who had completed at least 6 months follow-up. For analytic purpose, clinical outcome was categorised as 'successful' (resolved or stable disease), 'active disease' and 'drug intolerance'.

RESULTS

463 patients were included; mean age was 51.1±21.6 years, with a 59.0% female predominance. Mean follow-up was 14.6±9.2 months. The most common diagnosis was dry eye disease (DED; 322, 69.5%), followed by allergic eye disease (AED; 53, 11.4%) and ocular mucous membrane pemphigoid/Steven-Johnson syndrome (OMMP/SJS; 38, 8.2%). Successful treatment was achieved in 343 (74.1%) patients, with 44 (9.5%) requiring additional treatment and 76 (16.4%) reporting drug intolerance. The efficacy of Ikervis was highest in DED (264, 82.0%), followed by OMMP/SJS (25, 65.8%) and post-keratoplasty (7, 50.0%; p<0.001). Logistic regression analysis demonstrated age <70 years (p=0.007), AED (p=0.002) and OMMP/SJS (p=0.001) as significant predictive factors for Ikervis intolerance. AED and post-keratoplasty were 8.16 times (95% CI, 2.78 to 23.99) and 13.98 times (95% CI, 4.22 to 46.28), respectively, more likely to require additional treatment compared with DED.

CONCLUSIONS

Ikervis is a useful steroid-sparing topical treatment for managing OSIDs in the real-world setting. Preparations with improved tolerability are needed to benefit a larger number of patients.

Corneal xenotransplantation: Where are we standing?

The search for alternatives to allotransplants is driven by the shortage of corneal donors and is demanding because of the limitations of the alternatives. Indeed, current progress in genetically engineered (GE) pigs, the introduction of gene-editing technology by clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9, and advanced immunosuppressants have made xenotransplantation a possible option for a human trial. Porcine corneal xenotransplantation is considered applicable because the eye is regarded as an immune-privileged site. Furthermore, recent non-human primate studies have shown long-term survival of porcine xenotransplants in keratoplasty. Herein, corneal immune privilege is briefly introduced, and xenogeneic reactions are compared with allogeneic reactions in corneal transplantation. This review describes the current knowledge on special issues of xenotransplantation, xenogeneic rejection mechanisms, current immunosuppressive regimens of corneal xenotransplantation, preclinical efficacy and safety data of corneal xenotransplantation, and updates of the regulatory framework to conduct a clinical trial on corneal xenotransplantation. We also discuss barriers that might prevent xenotransplantation from becoming common practice, such as ethical dilemmas, public concerns on xenotransplantation, and the possible risk of xenozoonosis. Given that the legal definition of decellularized porcine cornea (DPC) lies somewhere between a medical device and a xenotransplant, the preclinical efficacy and clinical trial data using DPC are included. The review finally provides perspectives on the current standpoint of corneal xenotransplantation in the fields of regenerative medicine.

Literature review and suggested protocol for prevention and treatment of corneal graft rejection

Effective prophylaxis and treatment of corneal graft rejection are essential to improve outcomes in corneal transplantation. To date, there has been no standardized protocol published that outlines the optimal prophylactic and therapeutic approaches and, furthermore, the published controlled trials on this subject are limited. Likewise, no study has addressed how the level of antigen exposure varies between different types of keratoplasties. The aim of this paper is to provide a simple evidence-based protocol for the prevention and treatment of corneal graft rejection.

The Risk of Microbial Contamination in Multiple-Dose Preservative-Free Ophthalmic Preparations

Multiple-dose ophthalmic preparations that do not contain preservatives carry high risks of microbial contamination. However, there are various types of hospital preparations, with different physicochemical properties. In the present study, we evaluated the association between physicochemical properties and microbial contamination in ophthalmic preparations. The investigated hospital preparations included ophthalmic preparations of physiological saline, 0.2% fluconazole, 0.5% vancomycin hydrochloride, and 2% cyclosporine. We investigated the microbial dynamics of each ophthalmic preparation and microbial contamination in ophthalmic preparations used by patients. Remarkable growth of Pseudomonas aeruginosa, Burkholderia cepacia, and Serratia marcescens was observed in ophthalmic preparations of physiological saline and 0.2% fluconazole. All tested microorganisms displayed decreased counts after inoculation in 0.5% vancomycin hydrochloride. In 2% cyclosporine, all investigated microorganisms were below the limit of detection after inoculation for 6 h. The microbial contamination rates of ophthalmic preparations used by patients were 16.7% (3/18 samples) for 0.5% vancomycin hydrochloride and 0% (0/30 samples) for 2% cyclosporine. All detected contaminants in 0.5% vancomycin hydrochloride were Candida spp., one of which was present at a level of 1×10⁴ colony-forming units/mL. The storage method for in-use ophthalmic preparations should be considered on the basis of their physicochemical properties.

Update on the Management of High-Risk Penetrating Keratoplasty

PURPOSE OF REVIEW

In this article, we review the indications and latest management of high-risk penetrating keratoplasty.

RECENT FINDINGS

Despite the immune-privilege status of the cornea, immune-mediated graft rejection still remains the leading cause of corneal graft failure. This is particularly a problem in the high-risk graft recipients, namely patients with previous graft failure due to rejection and those with inflamed and vascularized corneal beds. A number of strategies including both local and systemic immunosuppression are currently used to increase the success rate of high-risk corneal grafts. Moreover, in cases of limbal stem cell deficiency, limbal stem cells transplantation is employed.

SUMMARY

Corticosteroids are still the top medication for prevention and treatment in cases of corneal graft rejection. Single and combined administration of immunosuppressive agents e.g. tacrolimus, cyclosporine and mycophenolate are promising adjunctive therapies for prolonging graft survival. In the future, cellular and molecular therapies should allow us to achieve immunologic tolerance even in high-risk grafts.

Systemic Immunomodulatory Strategies in High-risk Corneal Transplantation

The cornea is the most commonly transplanted tissue in the body. Although corneal grafts generally have high success rates, transplantation onto inflamed and vascularized host beds, or so-called high-risk corneal transplantation, has a high rate of graft rejection. The management of this high-risk corneal transplantation is challenging and involves numerous measures. One of the key measures to prevent graft rejection in these cases is the use of systemic immunosuppressive agents. In this article, we will review the systemic immunosuppressive agents most commonly used for high-risk corneal transplantation, which include corticosteroids, cysclosporine A, tacrolimus, mycophenolate mofetil, and rapamycin. Benefits, risks, and published data on the use of these medications for high-risk corneal transplantation will be detailed. We will also summarize novel immunoregulatory approaches that may be used to prevent graft rejection in high-risk corneal transplantation.

Management of high-risk corneal transplantation

The cornea is the most commonly transplanted tissue in medicine. The main cause of corneal graft failure is allograft rejection. The incidence of graft rejection depends on the presence of high-risk characteristics, most notably corneal neovascularization. Although corneal grafting has high success rates in the absence of these risk factors, high-risk keratoplasty is associated with low success rates because of a high incidence of immune-mediated graft rejection. To improve the survival of high-risk corneal transplantation, various preoperative, intraoperative, and postoperative measures can be considered; however, the key step in the management of these grafts is the long-term use of local and/or systemic immunosuppressive agents. Although a number of immunosuppressive agents have been used for this purpose, the results vary significantly across different studies. This is partly due to the lack of an optimized method for their use, as well as the lack of a precise stratification of the degree of risk in each individual patient. New targeted biologic treatments, as well as tolerance-inducing methods, show promising horizons in the management of high-risk corneal transplantation in near future.

[Current treatments for corneal neovascularization]

The extension of blood vessels into the normally avascular stroma defines corneal neovascularization. Though this phenomenon, pathophysiological and clinical features are well characterized, therapeutic modalities have been hindered by a lack of safe, efficacious and non-controversial treatments. In this literature review, we focus on available therapeutic options in light of recent evidence provided by animal and clinical studies. First, this review will focus on pharmacological treatments that target angiogenesis. The low cost and market availability of bevacizumab make it the first anti-angiogenic therapy choice, and it has demonstrable efficacy in reducing corneal neovascularization when administered topically or subconjunctivally. However, novel anti-angiogenic molecules targeting the intracellular pathways of angiogenesis (siRNA, antisense oligonucleotides) provide a promising alternative. Laser therapy (direct photocoagulation or photo-dynamic therapy) and fine needle diathermy also find a place in the treatment of stabilized corneal neovascularization alone or in association with anti-angiogenic therapy. Additionally, ocular surface reconstruction using amniotic membrane graft or limbal stem cell transplantation is essential when corneal neovascularization is secondary to primary or acquired limbal deficiency.

Prevention and treatment of corneal graft rejection: current practice patterns of the Cornea Society (2011)

PURPOSE

To analyze current practice patterns in the prevention and treatment of corneal graft rejection for both penetrating keratoplasty (PK) and endothelial keratoplasty (EK) and to compare these patterns with previously reported practices.

METHODS

In 2011, an electronic survey was sent to 670 members of the Cornea Society worldwide addressing the routine postoperative management of corneal transplants at different time points, treatment of various manifestations of corneal graft rejection, and preferred surgical techniques.

RESULTS

A total of 204 of 670 surveys (30%) were returned and evaluated. All respondents used topical corticosteroids for routine postoperative management and treatment of endothelial graft rejection. Prednisolone was the topical steroid of choice in all clinical scenarios, similar to previous surveys from 1989 to 2004. Use of subconjunctival and systemic steroids increased for many scenarios of probable and definite graft rejection. Routine use of prednisolone decreased by approximately 10% from previous surveys, whereas difluprednate was used in 13% of high-risk eyes during the first 6 months. Dexamethasone, fluorometholone, and loteprednol use remained stable. Adjunctive topical cyclosporine use increased significantly for PK and EK. EK was the preferred technique for endothelial dysfunction, whereas PK and deep anterior lamellar keratoplasty were both used for keratoconus and anterior scars. Most respondents (75%) felt that graft rejection occurs more frequently after PK than after EK.

CONCLUSIONS

Prednisolone remains the treatment of choice for management and treatment of graft rejection; however, since the introduction of difluprednate, its use has declined slightly since the introduction of difluprednate. Despite perceived differences in rejection rates, there were no differences in prophylactic steroid treatment for PK and EK.

Gene therapy in corneal transplantation

Corneal transplantation is the most commonly performed organ transplantation. Immune privilege of the cornea is widely recognized, partly because of the relatively favorable outcome of corneal grafts. The first-time recipient of corneal allografts in an avascular, low-risk setting can expect a 90% success rate without systemic immunosuppressive agents and histocompatibility matching. However, immunologic rejection remains the major cause of graft failure, particularly in patients with a high risk for rejection. Corticosteroids remain the first-line therapy for the prevention and treatment of immune rejection. However, current pharmacological measures are limited in their side-effect profiles, repeated application, lack of targeted response, and short duration of action. Experimental ocular gene therapy may thus present new horizons in immunomodulation. From efficient viral vectors to sustainable alternative splicing, we discuss the progress of gene therapy in promoting graft survival and postulate further avenues for gene-mediated prevention of allogeneic graft rejection.

Topical cyclosporine for severe dry eye disease in liver-transplanted Portuguese patients with familial amyloidotic polyneuropathy (ATTRV30M)

PURPOSE. Evaluation of the use of topical cyclosporine eyedrops in the treatment of severe dry eye disease in liver transplanted patients with familial amyloidotic polyneuropathy (FAP) unresponsive to therapy with artificial tears and lacrimal plugs.

METHODS

A prospective clinical study of 5 patients (10 eyes) admitted to the Ophthalmology Department of the Centro Hospitalar do Porto with severe dry eye disease refractory to artificial tears and lacrimal plug treatments. Evaluation of the patients included best-corrected visual acuity, corneal punctuate fluorescein staining, tear break-up time, Schirmer test without anesthesia, and Ocular Surface Disease Index. Patients were observed at time 0, and at 3, 7, and 11 months.

RESULTS

Treatment with topical cyclosporine improved all studied parameters from baseline, and in all the patients (p<0.001). The safety profile was excellent, without topical or systemic adverse events.

CONCLUSIONS

Topical cyclosporine was beneficial in the treatment of severe dry eye disease in liver transplanted patients with FAP.

Corneal Allograft Rejection: Immunopathogenesis to Therapeutics

Corneal transplantation is among the most successful solid organ transplants. However, despite low rejection rates of grafts in the ‘low-risk’ setting, rejection can be as high as 70% when grafted into ‘high-risk’ recipient beds. Under normal homeostatic conditions, the avascular cornea provides a unique environment that facilitates immune and angiogenic privilege. An imbalance in pro-inflammatory, angiogenic and lymphangiogenic mediators leads to a breakdown in corneal immune privilege with a consequent host response against the donor graft. Recent developments in lamellar and endothelial keratoplasties have reduced the rates of graft rejection even more, while providing improved visual outcomes. The corneal layer against which an immune response is initiated, largely determines reversibility of the acute episode. While epithelial and stromal graft rejection may be treated with topical corticosteroids with higher success, acute endothelial rejection mandates a more aggressive approach to therapy due to the lack of regenerative capacity of this layer. However, current immunosuppressive regimens come with the caveat of ocular and systemic side effects, making prolonged aggressive treatment undesirable. With the advent of biologics, efficacious therapies with a superior side effect profile are on the horizon. In our review we discuss the mediators of ocular immune privilege, the roles of cellular and molecular immune players in graft rejection, with a focus on human leukocyte antigen and antigen presenting cells. Furthermore, we discuss the clinical risk factors for graft rejection and compare rates of rejection in lamellar and endothelial keratoplasties to traditional penetrating keratoplasty. Lastly, we present the current and upcoming measures of therapeutic strategies to manage and treat graft rejection, including an overview of biologics and small molecule therapy.

Treatments for corneal neovascularization: a review

Corneal neovascularization (CNV) may be a physiological response to various stimuli, but a chronic and persistent upregulation of neoangiogenesis can result in pathological CNV. Pathological blood vessels are immature and lack structural integrity, predisposing the cornea to lipid exudation, inflammation, and scarring. CNV can therefore become a potentially blinding condition. In this review, we frame CNV in an epidemiological perspective, consider risk factors for CNV, provide an overview of CNV pathogenesis, and consider the impact of CNV on corneal transplantation. We consider treatments that are of largely historical interest, before reviewing contemporary medical and surgical treatments. Within medical treatments, we report on steroids, nonsteroidal anti-inflammatory agents, antivascular endothelial growth factor agents, and cyclosporine. Within surgical treatments, we report on the use of lasers, photodynamic therapy, superficial keratectomy, and diathermy/cautery-based treatments.

Long-term use of topical tacrolimus (FK506) in high-risk penetrating keratoplasty

PURPOSE

To evaluate the long-term efficacy and side effects of off-label topical tacrolimus 0.03% ointment (Protopic; Fujisawa Health, Deerfield, IL) as a sole second-line immunosuppressive agent in the management of high-risk corneal grafts.

METHODS

Four consecutive patients underwent high-risk penetrating keratoplasty (4 grafts) with a prior diagnosis of corneal scar secondary to herpetic keratitis, keratoconus, acanthamoeba keratitis, and Fuchs endothelial dystrophy, respectively. All 4 patients developed steroid-induced glaucoma and failed traditional immunosuppressant therapy. Patients were started on topical tacrolimus ointment 0.03%, twice daily, which was tapered to the lowest possible therapeutic dose that maintained its antirejection efficacy. Patients were monitored for adverse treatment effects. The mean follow-up was 33 months (range, 26-48 months), and the mean treatment duration was 22.6 months (range, 13-32 months).

RESULTS

All 4 high-risk corneal transplant patients experienced episodes of acute rejection that was successfully reversed with topical tacrolimus treatment. During tacrolimus treatment, there were no further episodes of graft rejection and no incidents of herpes simplex virus infection or reactivation, with the longest follow-up being 4 years. Two patients have been successfully tapered off tacrolimus, and 2 patients are currently on once-daily dosing. No adverse effects were observed.

CONCLUSIONS

Topical tacrolimus 0.03% ointment seems to be a promising second-line immunosuppressant in management of high-risk grafts.

Uses and safety profile of ciclosporin in ophthalmology

Ciclosporin is a calcineurin inhibitor that acts by primarily inhibiting the action of T cells. Clinical trials in the early 1980s demonstrated that systemic ciclosporin was a promising steroid-sparing agent and was also effective in patients who are refractory to treatment with corticosteroids. However, recent years have witnessed the emergence of safer immunosuppressive agents due to the poor side-effect profile of systemic ciclosporin. Topical ciclosporin, however, has a much improved safety profile and is still used to treat a variety of ocular surface disorders including dry eye syndrome, vernal and atopic keratoconjunctivitis, severe blepharitis and high-risk corneal graft patients. This article reviews the uses and safety profile of systemic and topical ciclosporin in ophthalmology, as well as discussing alternative therapeutic agents available.

Topical 2% cyclosporine A in preservative-free artificial tears for the treatment of vernal keratoconjunctivitis

BACKGROUND

A double-masked, placebo-controlled trial to evaluate the short-term efficacy and safety of topical 2% cyclosporine A in preservative-free artificial tears for patients with vernal keratoconjunctivitis.

METHODS

Twenty patients with severe vernal keratoconjunctivitis were included in the study. All were treated with topical 2% cyclosporine A eye drops. One eye of each patient was administered 2% cyclosporine A in preservative-free artificial tears; the fellow eye received the placebo (vehicle) for the first 2 weeks, in a double-masked, placebo-controlled trial. Thereafter, the placebo eye received cyclosporine A (open trial). Symptoms and signs were scored on the day of enrollment and at the end of week 2, 4, and 14.

RESULTS

At the end of week 2, no statistically significant decrease was noted from baseline in mean scores of either signs (p = 0.18) or symptoms (p = 0.50) in the eyes that received placebo. On the other hand, a statistically significant decrease was observed in both sign and symptom scores (p < 0.001, for both) of eyes that received cyclosporine A. Significant differences were also noted at 2 weeks in mean scores of both signs and symptoms (p < 0.001, for both) between the eyes that received cyclosporine A and those that received placebo. At week 4 and 14, statistically significant decreases in both sign scores and symptom scores were noted compared with baseline in the eyes that received cyclosporine A and in the eyes that had initially received placebo (p < 0.001, for all).

INTERPRETATION

Topical 2% cyclosporine A in preservative-free artificial tears is effective in alleviating signs and symptoms of patients with severe vernal keratoconjunctivitis and had no observed side effects over the course of the study.

Prevention and Treatment of Corneal Graft Rejection

PURPOSE

This study was designed to analyze current practice patterns in the prevention and treatment of corneal graft rejection and to compare these patterns with previously reported practices.

METHODS

In January 2004, a survey addressing the routine postoperative management of corneal transplants and the treatment of various manifestations of corneal graft rejection was sent to members of The Cornea Society.

RESULTS

Of the 396 surveys, 111 (28%) were returned and analyzed. All respondents used topical corticosteroids for routine postoperative management and treatment of endothelial graft rejection. Prednisolone, in brand or generic form, was used by 37 to 90% for routine management in various clinical scenarios and 81 to 91% for various manifestations of graft rejection at all time points; however, after 6 months, 12 to 26% used loteprednol etabonate for routine management. For routine management of high-risk grafts, 48% used topical cyclosporine in addition to prednisolone. Compared with previous surveys, the use of oral steroids significantly decreased for the routine management of high-risk corneal transplants, and the use of subconjunctival steroids decreased for the management of graft rejection.

CONCLUSIONS

Topical prednisolone remains the mainstay for the prevention and treatment of corneal graft rejection; however, the role of newer agents, loteprednol etabonate and topical cyclosporine, is expanding.

Étude de la cytotoxicité de différents collyres à base de ciclosporine A buvable (Sandimmun®)

INTRODUCTION

Cyclosporine is a molecule used in ophthalmology for the prevention of corneal graft rejection. The systemic use of this product can lead to serious adverse side effects that can be avoided using the topical formulation of cyclosporine. However, cyclosporine application can induce ocular irritation.

MATERIAL AND METHODS

The aim of this study is to evaluate the cytotoxicity of four formulations of 2% cyclosporine eye drops: Sandimmum intravenous solution diluted with NaCl 0.9%, Sandimmun oral solution diluted in castor oil or corn oil after ethanol evaporation, and Sandimmun oral solution diluted in castor oil without previous ethanol evaporation. Two tests--the Draize test and the evaluation of cytotoxicity of adherent alive cells with cold light cytofluorimetry on microplates--were used in this study.

RESULTS

These tests demonstrated that the aqueous solution shows more toxicity than the other formulations, and the type of oil and ethanol concentration influence cell viability.

CONCLUSION

These results helped the Pharmacy unit choose the vehicles for a safe cyclosporine eye drop formulation and thus decrease the side effects of cyclosporine eye drop instillation with a decrease in ethanol concentration compared to published formulations.

An Implantable Immunosuppressive Cyclosporine Drug Delivery System

In the article a kind biodegradable drug carrier (glycolide-co-lactide-co-caprolactone) tricomponent copolymer (PGLC) was synthesized by ring opening copolymerization of glycolide (GA), lactide (LA) and ε-caprolactone (CL), and was used to manufacture an implantable drug preparation---Cyclosporine-PGLC drug delivery system (Cs-PGLC DDS).The Cs could slowly release from the Cs-PGLC DDS near linearly and last for a long time in vitro. A clinically significant Cs concentration in the cornea and anterior chamber could be achieved by implanting the Cs-PGLC DDS in anterior chamber. It was demonstrated that the Cs-PGLC DDS is a long-effective intraocular immunosuppressive agent for remaining corneal allograft clear and significantly prolong its survival time.

Ocular Pharmacokinetics and Safety of Ciclosporin, a Novel Topical Treatment for Dry Eye

Ciclosporin is a potent immunomodulator that acts selectively and locally when administered at the ocular surface. 0.05% ciclosporin ophthalmic emulsion has recently been approved by the US FDA for treatment of keratoconjunctivitis sicca (KCS) [dry-eye disease]. After topical application, ciclosporin accumulates at the ocular surface and cornea, achieving concentrations (>/=0.236 microg/g) that are sufficient for immunomodulation. Very little drug penetrates through the ocular surface to intraocular tissues. Ciclosporin is not metabolised in rabbit or dog eyes and may not be prone to metabolism in human eyes. Cultured human corneal endothelial and stromal cells exposed to ciclosporin in vitro exhibited no adverse effects and only minor effects on DNA synthesis. No ocular or systemic toxicity was seen with long-term ocular administration of ciclosporin at concentrations up to 0.4%, given as many as six times daily for 6 months in rabbits and 1 year in dogs. Systemic blood ciclosporin concentration after ocular administration was extremely low or undetectable in rabbits, dogs and humans, obviating concerns about systemic toxicity. In 12-week and 1-year clinical safety studies in dry-eye patients, the most common adverse event associated with the ophthalmic use of ciclosporin emulsion was ocular burning. No serious drug-related adverse events occurred. These data from in vitro, nonclinical and clinical studies indicate effective topical delivery of ciclosporin to desired target tissues along with a favourable safety profile, making 0.05% ciclosporin ophthalmic emulsion a promising treatment for KCS.

Préparation d’un collyre de ciclosporine à 2 %

PURPOSE

Cyclosporine administration is very effective in the case of immunological diseases of the cornea, conjunctive or uvea. Moreover, it is widely used in the case of high-risk rejection corneal transplantation. We present a preparation of cyclosporine 2% eye drops.

METHODS

Cyclosporine 2% eye drops are prepared following a particular formulation including one part commercially available cyclosporine oral solution (Sandimmun) diluted in four parts of sterile castor oil. Manufacturing procedures maintain the sterile state of the preparation with a laminar airflow hood placed in a particulate controlled room, with pharmacists, technicians and clerical personnel wearing sterile clothes. Physical and chemical monitoring during and after manufacture for each batch guarantees the process and minimizes the risk of batch rejection. Chemical analysis of cyclosporine is conducted using a validated stability-indicating high-performance liquid chromatographic assay (reverse-phase). Blood dosages taken after the first administration at the 24th hour (after administration of the 6th drop) check for systemic integration.

RESULTS

Cyclosporine 2% eye drops are fairly stable: 12 months after manufacturing, concentrations result in levels not statistically different from concentrations measured the day of preparation. After a daily regimen of six drops in the eye, cyclosporine 2% eye drops have a very low systemic bioavailability, because the blood concentrations only reach the detection limit of the fluorescence polarization immunoassay used for cyclosporine drug monitoring. This explains the absence of systemic toxicity.

CONCLUSION

Cyclosporine 2% eye drops can be available in the hospital pharmacy. The eye drops are stable at room temperature and can be delivered up to 12 months after manufacture. No local adverse effects have been noted, probably in relation with the very low concentration of ethanol in the ocular preparation.

Lacrimostimulants and lacrimomimetics

A thorough understanding of tear film physiology and the clinical manifestations of tear film abnormalities enables the veterinarian to diagnose and treat quantitative (decreased aqueous layer) and qualitative (decreased mucin or lipid layers) tear film abnormalities accurately and to monitor the responses to lacrimostimulatory and lacrimomimetic therapy. This article reviews the embryology,anatomy, and physiology of the lacrimal glands; glands of the nictitating membrane; goblet cells; and tarsal glands as well as the pathophysiology of tear film deficiencies. We also review lacrimo-stimulants, including cyclosporine, tacrolimus, sirolimus, pilocar-pine, and lacrimomimetics (tear film replacements).

Topical cyclosporine in the management of shield ulcers

PURPOSE

To report our experience with 0.05%-2% topical cyclosporine in the treatment of 4 cases of severe, corticosteroid-resistant, vernal keratoconjunctivitis with shield ulcers.

METHODS

Four patients with shield ulcers not responding to medical treatment with topical steroids, antihistamines, and mast-cell stabilizers were treated with 0.05%-2% topical cyclosporine. The frequency of application was 4 times daily in all cases, and the concentration was adjusted according to the clinical status starting with 2%.

RESULTS

Healing of ulcers with no epithelial defect occurred in 10 days with the 2% concentration in all cases. The patients experienced no side effects except for a burning sensation during administration. Recurrences occurred when the concentration was decreased to 0.05% in 3 cases. The recurrences were effectively treated with 1% concentration in all cases, and patients were stable with this concentration for at least 6 months.

CONCLUSIONS

Topical cyclosporine is an effective treatment alternative in the management of shield ulcers in patients with vernal keratoconjunctivitis. The 1% concentration seems to be the minimal effective concentration in such cases in our experience, but further controlled studies are needed to support our findings.

Use of thermokeratoplasty for treatment of ulcerative keratitis and bullous keratopathy secondary to corneal endothelial disease in dogs: 13 cases (1994-2001)

OBJECTIVE

To evaluate the outcome of thermokeratoplasty for treatment of ulcerative keratitis and bullous keratopathy secondary to corneal endothelial disease in dogs.

DESIGN

Retrospective study.

ANIMALS

13 dogs.

PROCEDURES

Medical records from 1994 to 2001 for dogs evaluated because of ulcerative keratitis and bullous keratopathy and treated with thermokeratoplasty were reviewed.

RESULTS

There were 7 spayed females, 5 castrated males, and 1 sexually intact male, ranging from 6 to 16 years of age. Ten dogs had endothelial degeneration, and 3 dogs had breed-related endothelial dystrophy. All dogs had bullous keratopathy, characterized by microbullae formation that was detected via biomicroscopy. Recurrent or nonhealing corneal ulcers were detected unilaterally in 5 dogs and bilaterally in 8 dogs. Mean +/- SD duration from thermokeratoplasty until ulcerations were healed for all dogs was 2.2 +/- 1.1 weeks. All dogs that underwent thermokeratoplasty for nonhealing corneal ulceration secondary to endothelial disease and corneal edema had epithelial wound healing and resolution of corneal ulceration. Mean duration of treatment (ie, topical treatment required until resolution of ulceration) was significantly less after thermokeratoplasty than duration of treatment (with multiple treatments) prior to referral.

CONCLUSIONS AND CLINICAL RELEVANCE

It may be necessary to perform thermokeratoplasty of the entire cornea to prevent recurrence of ulcerations in areas that have not been treated with thermokeratoplasty.

Systemic cyclosporin A in high risk penetrating keratoplasties: a case-control study

AIM

To examine the efficacy of systemic cyclosporin A (CSA) in preventing rejection and graft failure in high risk keratoplasty (PK).

METHODS

A retrospective case-control study with 49 patients in both the CSA group and the control group. The patients receiving CSA were at high risk of graft rejection and failure. Controls were identified from surgical audit books and had high risk characteristics.

RESULTS

There was no statistical difference in preoperative risk factors and the use of postoperative topical steroids between the two groups. The median follow up in the CSA group was 22 months and 27 months in the control group. One or more rejection episodes occurred in 18 out of 49 (36.7%) cases in the CSA group and 26 out of 49 (53.1%) in the control group. Graft failure from all causes occurred in 16 (32.7%) CSA patients and 18 (36.7%) control patients. Four (8.2%) of the CSA group compared to eight (16.3%) in the control group failed because of rejection. 22 (44.9%) out of 49 patients in the CSA group had side effects. In five (10.2%) patients, CSA was stopped because of the side effects; eight patients had elevated serum urea and creatinine and four developed hypertension. Minor side effects reported include gum hyperplasia, increased sweating, backache, nausea, feeling unwell, oral candidiasis, cramps, and paraesthesia of the extremities.

CONCLUSION

These results suggest that the benefit of CSA over conventional therapy in preventing rejection episodes and subsequent graft failure is only moderate and did not reach statistically significant levels in this study. Considering the high frequency of side effects and the cost of CSA, a randomised control trial may be necessary to determine the true value of CSA in high risk penetrating keratoplasty.

Tacrolimus (FK506) in the management of high-risk corneal and limbal grafts

OBJECTIVE

To assess the efficacy and side effects of tacrolimus in the management of patients with high-risk corneal and limbal grafts.

DESIGN

Noncomparative case series.

PARTICIPANTS

Seventeen patients (23 grafts) were treated with tacrolimus; 15 patients (20 host corneas) had two or more quadrants of stromal vascularization, 6 patients had stem cell deficiency, and 6 patients had glaucoma. Seven patients had received one previous graft, six patients had two previous grafts, and four patients had three previous grafts.

INTERVENTION

Patients with high-risk corneal and limbal grafts were treated with systemic tacrolimus at a mean optimum dosage of 4.4 mg daily (range, 2-12 mg daily).

MAIN OUTCOME MEASURES

Graft survival, visual acuity.

RESULTS

No patient has had irreversible graft rejection while receiving tacrolimus. The follow-up period ranges from 12 to 46 months, with a mean of 24 months. Three patients have had reversible graft rejection associated with low tacrolimus levels. Nine patients have stopped treatment; two had reversible rejection within 2 months of stopping, and five grafts remain clear. The other four patients stopped treatment because of graft failure, which was not considered to be rejection related. Eight patients remain on treatment, and all have clear grafts.

CONCLUSIONS

Tacrolimus (FK506) is effective in prevention of rejection in patients with high-risk corneal and limbal grafts.

Prolongation of corneal allograft survival using cyclosporine in a polylactide-co-glycolide polymer

PURPOSE

To test for prolongation of corneal transplant survival with cyclosporine in a polymer placed in the anterior chamber of corneal allograft recipients.

METHODS

Wistar inbred rats with vascularized corneas were recipients of corneal allografts from Sprague-Dawley donor rats. Grafted rats were randomized into six groups: untreated control animals, cyclosporine-polymer anterior chamber recipients, cyclosporine-polymer subconjunctival recipients, cyclosporine-olive oil drop recipients, polymer-only anterior chamber recipients, and autografted Wistar rats. Grafts were examined by slit lamp every 3 days and the clinical condition scored. The cyclosporine concentration in the aqueous humor was assayed at 1, 2, and 4 weeks. At 2 and 4 weeks after transplantation, the eyes were collected for histopathologic evaluation of the grafts.

RESULTS

The median survival time of untreated corneal allografts was 8.2 +/- 1.48 days for grafts treated with topical cyclosporine, 8.5 +/- 1.50 days for polymer-only anterior chamber implants, 10.6 +/- 1.90 days for 1% cyclosporine drops, 11.4 +/- 2.50 days for grafts given subconjunctival cyclosporine-polymer, 17 +/- 3.05 days for grafts given cyclosporine-polymer implants in the anterior chamber, and more than 3 months in autografted rats. There was a statistically significant difference ( p < 0.05) between the survival time of the allografts in the animals treated with the cyclosporine-polymer in the anterior chamber compared with the other groups of graft recipients. Significantly higher concentrations of cyclosporine were found in the eyes given an anterior chamber implant of cyclosporine-polymer than in the other treatment groups or the untreated rats. The cyclosporine-polymer implants placed in the anterior chamber induced a transient inflammatory response in transplanted eyes.

CONCLUSIONS

Cyclosporine-polymer placed in the anterior chamber significantly prolongs corneal allograft survival in a high-risk corneal graft rejection. This intraocular delivery system may be a valuable adjunct for the suppression of immune graft rejection in high-risk recipients of corneal transplants.

Immunologic rejection of the central graft after limbal allograft transplantation combined with penetrating keratoplasty

PURPOSE

To study the incidence and prognosis of immunologic rejection of the central graft after limbal allograft transplantation (keratolimbal allograft transplantation [KLAT]) combined with penetrating keratoplasty (PKP).

METHODS

Endothelial rejection in central penetrating graft after simultaneous KLAT and PKP using the same donor cornea was retrospectively studied. Incidence, reversibility, prognosis, and changes in limbal grafts were examined.

RESULTS

Forty-five eyes underwent simultaneous PKP and KLAT. Endothelial rejection of the central graft was found in 16 eyes (35.6%). At last examination, 10 grafts (62.5%) restored clarity after immunosuppressive therapy. During rejection episodes, four eyes showed engorgement of vessels in limbal grafts, which existed before the episodes. Only one eye developed neovascularization with mild edema of the limbal grafts; however, no other limbal grafts showed abnormalities on biomicroscopy. No epithelial changes were noted, and 14 grafts (87.5%) were covered by corneal epithelium after the rejection.

CONCLUSION

Approximately one third of eyes had endothelial rejection in the central graft after simultaneous KLAT and PKP. Abnormalities suggestive of rejection in the limbal grafts were seldom observed in these eyes, suggesting that immunologic response was different in central and limbal grafts.

The profile of repeated corneal transplantation

PURPOSE

To evaluate the primary indications for corneal transplantation in patients with repeated keratoplasties, graft survival, the causes and risk factors for failure.

SETTING

Tertiary referral care center.

DESIGN

Retrospective, noncomparative case series.

METHODS

Charts of all patients who underwent repeated corneal transplantation between 1985 and 1998 were reviewed. Eighty patients underwent repeated corneal transplantation, of which six underwent repeated corneal transplantation in both eyes, totaling 86 eyes. A total of 208 keratoplasties were performed in this group; 86 primary and 122 repeated keratoplasties. The most common primary indications for corneal transplantation were vascularized corneal scar in 31 of the 86 eyes (36%), followed by pseudophakic and aphakic bullous keratopathy (PBK, ABK). Of the repeated transplants, 55 eyes (64%) had one repeated graft, 27 eyes (31.4%) had two repeated grafts, three (3.5%) had three repeated grafts, and one (1.2%) had four repeated transplants.

MAIN OUTCOME MEASURES

Final visual outcome and clarity of corneal graft.

RESULTS

At the end of the follow-up period, 44 of the 86 eyes (51%) had clear grafts, but only 39.5% had good visual outcome. The mean survival periods of the repeated transplants decreased gradually with the number of regrafting procedures, from 14.3 to 8.7 months. The mean survival period was longer for patients with ABK, PBK, and secondary glaucoma, and shorter for patients who experienced graft ulcer or surface disorders. Graft failure was unrelated to graft size, but was associated with vascularization (P = 0.025), additional surgical procedures (P < 0.0001), and postoperative complications (P < 0.0001). There was a constant tendency for decrease in visual acuity with time. Final visual acuity was 20/20 to 20/40 in 13 of the 86 eyes (15%), 20/80 to 20/200 in 23 eyes (27%), and less than 20/200 in 50 eyes (58%). The most common complication was immune rejection, which occurred in 65 of the 208 transplants (31%), followed by secondary glaucoma in 48 eyes (23%) and cataract in 19 eyes (9%). Graft survival decreased remarkably after the third and forth regrafts, to 25% and 0%, respectively, compared with the first and second regrafts, 37% and 43%, respectively.

CONCLUSIONS

"High-risk" preoperative conditions, postoperative complications, and the need for additional surgical interventions may decrease graft survival. Close follow-up, extended use of antiinflammatory, antiviral, and immunosuppressive drugs, and avoiding additional surgical interventions as much as possible may decrease graft failure and the need for repeated keratoplasties.

Prolonged survival of corneal allografts incubated in alloantibody fragments

BACKGROUND

In this study, we determined the binding characteristics of F(ab')2 alloantibody fragments to corneal antigens and assessed the capacity of these antibody fragments to protect corneal allografts from immune attack.

METHODS

Goat anti-rabbit alloantibodies were pepsin-digested and labeled with 125I, and the time course of association and dissociation of the F(ab')2 fragments was determined. Corneal allografts were incubated in unlabeled F(ab')2 fragments and transplanted into allogeneic recipients, and the graft survival times were recorded.

RESULTS

Binding of radiolabeled F(ab')2 fragments to rabbit cornea cells reached a maximum at 12 hr. At 32 degrees C (rabbit corneal temperature), the radiolabel eluted rapidly from the cornea, reaching baseline at 72 hr. At 4 degrees C (corneal graft storage temperature), significant amounts remained associated with the cornea at 96 hr. Mean survival time for grafts incubated in F(ab')2 anti-rabbit fragments was significantly greater than that of grafts incubated in nonimmune F(ab')2 fragments. Three of the corneal allografts incubated in goat F(ab')2 anti-rabbit fragments survived for 100 days, whereas the longest surviving control allograft incubated in goat F(ab')2 nonimmune fragments was rejected on day 24. Preincubation of corneas in unlabeled, immune F(ab')2 fragments followed by incubation in radiolabeled, immune F(ab')2 fragments suggested that antigen masking was not a factor in the prolongation of graft survival.

CONCLUSION

Based on the binding and release kinetics and the graft survival times, it appears that the protective effect of immune F(ab')2 fragments extends well beyond the binding interval of the antibody fragments to corneal cell membranes.

The use of combined intravenous pulse methylprednisolone and oral cyclosporin A in the treatment of corneal graft rejection: a preliminary study

PURPOSE

Oral cyclosporin A used in addition to high-dose intravenous pulse methylprednisolone has been shown to have an adjunctive effect in reversing the rejection of liver and renal transplants. The aim of this prospective study was to evaluate the benefits and risks of this combined drug therapy in acute corneal graft rejection.

METHODS

Eleven patients with acute corneal graft rejection received the combined regimen of a single pulse of intravenous methylprednisolone (500 mg) and a low dose of oral cyclosporin A (to maintain a trough blood level of 100-200 micrograms/l).

RESULTS

At a mean follow-up of 16.5 months (range 8-22 months) from the presentation of the graft rejection, reversal of graft rejection was achieved in 10 of 11 cases (90.9%). No recurrence of graft rejection was encountered during the study period. One patient developed a duodenal ulcer, which healed after medical treatment. No other complications were encountered.

CONCLUSIONS

The high efficacy and low risk of the combined regimen demonstrated in this preliminary study call for a larger-scale prospective double-masked study to confirm the value of this treatment protocol.