Graft failure in human donor corneas due to transmission of herpes simplex virus

Quality assurance in corneal transplants: Donor cornea assessment and oversight

The cornea is the most frequently transplanted human tissue, and corneal transplantation represents the most successful allogeneic transplant worldwide. In order to obtain good surgical outcome and visual rehabilitation and to ensure the safety of the recipient, accurate screening of donors and donor tissues is necessary throughout the process. This mitigates the risks of transmission to the recipient, including infectious diseases and environmental contaminants, and ensures high optical and functional quality of the tissues. The process can be divided into 3 stages: (1) donor evaluation and selection before tissue harvest performed by the retrieval team, (2) tissue analysis during the storage phase conducted by the eye bank technicians after the retrieval, and, (3) tissue quality checks undertaken by the surgeons in the operating room before transplantation. Although process improvements over the years have greatly enhanced safety, quality, and outcome of the corneal transplants, a lack of standardization between centers during certain phases of the process still remains, and may impact on the quality and number of transplanted corneas. Here we detail the donor screening process for the retrieval teams, eye bank operators. and ophthalmic surgeons and examine the limitations associated with each of these stages.

PCR testing for herpesviruses in aqueous humor samples from patients with and without clinical corneal endothelial graft rejection

To compare prevalence of positive PCR tests for herpesviruses between patients with and without a history of clinical corneal endothelial allograft rejection (AGR). Retrospective cross-sectional study with two-group comparison. A total of 307 aqueous humor (AH) samples from 235 Patients and 244 eyes who underwent penetrating keratoplasty or Descemet membrane endothelial keratoplasty or had a diagnostic AH aspiration due to clinical AGR between 2019 and 2023 were tested for DNA of herpes simplex virus (HSV), varicella-zoster virus (VZV), cytomegalovirus (CMV), and Epstein-Barr virus (EBV). PCR test results were compared between the two groups (with/without AGR). Another sub-analysis examined the results of patients without a history of herpetic keratitis. A total of 8% of eyes with clinical AGR (9/108) had a positive PCR result for one of the herpesviruses (HSV:3, CMV:3, EBV:2, VZV:1). All patients in the group without AGR had negative PCR results for all previous viruses (0/136). The difference was statistically significant (p < 0.001). The sub-analysis of eyes without a history of herpetic keratitis also revealed significantly more positive herpes PCR results (7/87) in eyes with AGR than in eyes without AGR (0/42, p = 0.005). Clinical AGR after keratoplasty shows a significant correlation to viral replication. Herpetic infection and AGR could occur simultaneously and act synergistically. Timely differentiation between active herpetic infection and/or AGR is pivotal for proper treatment and graft preservation.

Prevalence of Herpes Simplex and Varicella-Zoster Virus DNA in Corneal Grafts Is Higher than Expected

PURPOSE

(1) To determine the prevalence of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), varicella-zoster virus (VZV), and cytomegalovirus (CMV) DNA in donor corneas; (2) To evaluate the clinical outcome of the grafts with viral DNA and to compare donors with and without viral DNA.

METHODS

We analyzed data from all donors and recipients who underwent penetrating keratoplasty (PK) or Descemet membrane endothelial keratoplasty (DMEK) between September 2022 and March 2023. Donor corneoscleral rims and excised recipients' corneal buttons were tested for the presence of HSV-1, HSV-2, VZV, and CMV DNA by polymerase chain reaction (PCR). The results were known 2-3 days after the surgery. We closely followed up on patients whose grafts tested positive for viral DNA. We compared the medical histories of donors with and without viral DNA.

RESULTS

We included 85 corneas from 67 donors. Seven (8.2%) donor corneas tested positive for HSV-1 (n = 3) or VZV (n = 4) DNA. We did not detect any HSV-2 or CMV DNA. In the postoperative follow-up of patients with positive PCR, a graft failure was observed in one and infections in two eyes. Re-operation was necessary in three of these cases (42.9%). Patients without herpes DNA in the donor cornea needed reoperation in 7.7% of the cases. Cultural duration, the cause of the donor's death, and the death-to-explantation interval did not differ significantly between donors with and without viral DNA. Additionally, 3 of the 7 (42.9%) donors with positive PCR were in a septic status at the time of death, compared to 21 of the 78 (26.9%) donors with negative PCR (p = 0.52).

CONCLUSIONS

The prevalence of herpes DNA in the donor corneas was 8.2% and thus higher than previously reported. We did not notice any evidence for a donor-to-host transmission, but a higher rate of postoperative complications in recipients of the grafts with viral DNA. The donors with and without herpetic DNA did not differ significantly regarding systemic diagnoses or cultural conditions, but sepsis was more frequent in the group with viral DNA.

Occurrence of Herpes Viruses in Morphologically Normal Corneas

PURPOSE

The purpose of this study was to detect the occurrence of herpes simplex virus (HSV) types 1 and 2 and varicella zoster virus (VZV) DNA in transplanted corneas using polymerase chain reaction (PCR) and to determine the relationship between latent HSV and VZV and herpetic eye disease in recipients.

METHODS

This was a retrospective, interventional case series. Samples from 88 donor corneoscleral buttons (CSBs) were collected from the conjunctiva, iris, and endothelium and tested for HSV-1, HSV-2, and VZV DNA using PCR. All transplanted eyes were evaluated and followed up. The main outcome measures were HSV-1, HSV-2, and VZV DNA positivity rates in donor CSBs and the occurrence of herpetic eye disease or graft failure in recipients of positive corneas.

RESULTS

HSV-1 DNA was detected in 5 (5.7%) of 88 CSBs. HSV-2 was not detected in any CSBs, and VZV was found in 1 (1.2%) of the 82 examined CSBs. One recipient (16.7%) developed dendritic epitheliopathy and keratouveitis typical of HSV 12 months after transplantation, although the graft remained clear after treatment. One cornea was used for a tectonic graft and stayed edematous at the 20-month follow-up. The remaining corneas remained clear.

CONCLUSIONS

Morphologically normal donor corneas may be PCR-positive for herpes viruses, especially HSV-1. Recipients of herpes-positive corneal grafts could be at risk for herpetic eye disease. Further studies using viral RNA by reverse transcriptase PCR are needed to provide more information on HSV and VZV latency and active replication in donor corneas.

Herpes simplex virus PCR in 2230 explanted corneal buttons

PURPOSE

To determine herpes simplex virus (HSV) DNA prevalence and mean cycle threshold of polymerase chain reaction (PCR) in corneal tissue of patients with penetrating keratoplasty (PKP), with (HSK+) and without (HSK-) previous clinical herpetic keratitis history.

METHODS

Retrospective review of recipient corneal buttons which were explanted through PKP between March 2010 and September 2018 at the Department of Ophthalmology, Saarland University Medical Center in Homburg/Saar, Germany. Corneal tissue samples were analysed by real-time PCR for the presence of HSV DNA. For each subject, clinical data, including patients' demographics and clinical diagnoses, were collected.

RESULTS

In total, 2230 corneal samples (age at the time of the surgery 57.3 ± 19.2 years) of 1860 patients were analysed. HSV PCR was positive in 137 (6.1%) corneal samples, with a 30.57 ± 6.01 (range 14-39) mean cycle threshold (Ct) value. Two hundred ninety-eight (13.4%) corneas of 266 patients were clinically HSK+, and 1932 (86.6%) corneas of 1600 patients were clinically HSK-. HSV DNA was detected significantly more frequently (p < 0.0001) in HSK+ corneal samples (108 corneal samples; 36.2%), than in HSK- corneal samples (29 corneal samples; 1.5%). Ct value was significantly lower in HSK+ than in HSK- corneal samples (29.8 ± 5.8 versus 32.6 ± 5.9; p = 0.008).

CONCLUSION

Our data demonstrate that a positive clinical history of HSK is related to HSV PCR positivity in about every 2.8th patient. In addition, about every 66th explanted corneal tissue is HSV PCR-positive despite the lack of clinical suspicion. These patients may need additional local/systemic antiviral treatment to avoid newly acquired HSK following penetrating keratoplasty.

The incidence and influence of the donor corneas positive for herpesviridae DNA in keratoplasty

Purpose

We detected the DNA of herpes simplex virus type 1 (HSV-1), herpes simplex virus type 2 (HSV-2), varicella-zoster virus (VZV), cytomegalovirus (CMV), and Epstein-Barr virus (EBV) in donor corneas and assessed the clinical outcomes of recipients who received virus-positive grafts.

Method

All donor corneas were analyzed for the presence of HSV-1, HSV-2, VZV, CMV, and EBV by real-time PCR from April 2017 to July 2019. The medical records of the transplant patients who received virus-positive grafts were reviewed.

Result

Twenty-three (2.44%) donor cornea buttons tested positive for herpesviridae DNA. The positivity rates of HSV-1, CMV, VZV, and EBV were 0.74%, 0.85%, 0.64%, and 0.21%, respectively.

Conclusion

We suggest that the corneas from donors who had cancer, donors who were inpatients, and donors who had immunodeficiency or who were on immunosuppressive therapy should be tested for herpesviridae DNA before transplantation. Finally, HSV-1 can be transmitted from graft to recipient, but that CMV cannot be transmitted according to our observations. The donor corneas found to be HSV-1-positive have to be discarded and not used for keratoplasty.

Clinical consequences of herpes simplex virus DNA in donor corneas: Different prognosis and management of endothelial keratoplasty and deep anterior lamellar keratoplasty

BACKGROUND

There is still controversy over the necessity of screening donor corneas for herpes simplex virus (HSV). Currently, no study reported the outcomes of different types of keratoplasty with HSV-positive donor corneas.

OBJECTIVES

To describe the clinical consequences of four patients who underwent keratoplasty by sharing double corneas from a single donor, both of which were positive for HSV-1 DNA by polymerase chain reaction.

STUDY DESIGN

A retrospective case series study.

RESULTS

Both patients who underwent endothelial keratoplasty (EK) developed persistent corneal edema with or without keratic precipitates, and mild anterior chamber inflammation on postoperative day 3 and 17 respectively. Despite adequate antiviral treatment, they developed graft detachment subsequently and experienced graft replacement. Transmission electron microscopy showed denuded Descemet's membrane without any endothelial cells on both removed grafts and viral particles were identified within the residual posterior stroma of the thicker graft. As for those who underwent deep anterior lamellar keratoplasty, one patient presented with graft rejection for the sake of self-discontinuation of all anti-rejection agents. The other's graft remained clear at the final follow-up.

CONCLUSIONS

HSV existed in the posterior stromal and endothelial layer of the donor corneas. Reactivation of HSV and severe endothelial loss may occur on corneal endothelial grafts in the early postoperative period while anterior lamellar grafts could be quiescent. Considering the possibility of graft failure caused by viral reactivation, it's of great significance to screen for viral DNA in donor corneas prior to the surgery, especially for EK.

The presence and impact of herpes virus DNA in recipient cornea and aqueous humor on graft survival following penetrating keratoplasty

BACKGROUND/PURPOSE

Reactivation of herpes viruses poses threat to corneal graft survival. This study evaluated the presence of herpes simplex virus type 1 (HSV-1), HSV type 2 (HSV-2), and cytomegalovirus (CMV) DNA in recipient corneas and the aqueous humor of patients undergoing penetrating keratoplasty (PKP), and the impact on graft survival.

METHODS

This retrospective study reviewed 90 eyes of 71 patients underwent PKP between 2008 and 2016. Cornea and aqueous humor samples were sent for polymerase chain reaction (PCR) testing for viral DNA. The main outcomes were PCR results and graft survival.

RESULTS

Recipient corneas tested positive for HSV-1 in 47 eyes (52.2%), for HSV-2 in 24 eyes (26.7%), and for CMV in seven eyes (7.8%). Aqueous humor tested positive for HSV-1 in 44 eyes (48.9%), for HSV-2 in 25 eyes (27.8%), and for CMV in eight eyes (8.9%). The presence of aqueous HSV-1 DNA was associated with higher risk of graft failure (p = 0.005), whereas corneal HSV-1 DNA was not. The presence of HSV-2 DNA had no significant impact on graft survival. Aqueous CMV DNA was associated with higher risk of graft failure in univariate model, but not in multivariate model.

CONCLUSION

There were high positive rates of HSV-1, HSV-2, and CMV DNA in recipient corneas and aqueous humor at the time of PKP, even among patients not suspected of latent viral infection. The presence of aqueous HSV-1 DNA was associated with higher risk of graft failure.

A serious adverse surgical event: Management of suspected HSV-1 keratitis in a donor cornea

PURPOSE

To describe the management of a serious adverse event in a patient undergoing penetrating keratoplasty (PK).

CASE REPORT

A 68-year-old man underwent PK for an aphakic bullous keratopathy following previous complicated cataract surgery. He had no past history of herpetic disease. Storage of the corneoscleral disc in the transport bottle precluded microscopic examination. After placement of the trephined donor cornea on the open eye of the recipient, a large dendritiform geographic ulcer was noted on the donor cornea. A replacement cornea was used after changing potentially contaminated instruments. Intravenous antiviral treatment was commenced intraoperatively to reduce the risk of infection to the central nervous system. Postoperatively, oral and topical antiviral treatment was commenced and 6 months following surgery the patient developed a geographic corneal ulcer at the graft host interface.

CONCLUSION

Containers to transport corneoscleral discs should enable microscopic examination by the surgeon prior to use. High dose systemic antivirals may reduce the risk of herpetic disease involving the posterior segment of the eye and neuroretina in the aphakic eye and spread to the central nervous system.

Occurrence of viral DNA in paired samples of corneal rim and cornea preservation fluid

Corneal transplants have one of the highest success rates among all transplantological procedures. Corneas intended for transplantation are stored in a preservation fluid, which is then tested for bacterial and fungal infections. Among all analyses of infectious complications following corneal transplants, infections caused by bacteria or fungi are the most prominent. Surprisingly, however, apart from a few publications, there is a lack of data regarding the occurrence of viruses in donor corneas and the risk of transmitting these to their recipients. The intention of this research was therefore to determine the frequency with which human herpesvirus 1 (HHV-1), human herpesvirus 2 (HHV-2), and human adenovirus (HAdV) occur in transplanted corneal tissue, as well as in samples of preservation fluid. The study comprised 57 paired samples, with each pair consisting of a fragment of the corneal tissue remaining after its trepanation for transplantation surgery and a sample of corneal preservation fluid. Sample pairs were all tested for the presence of the DNA of three viruses (HHV-1, HHV-2, and HAdV) using real time PCR technique. Viral DNA was found in three of the tested corneas-HHV-1 DNA in one paired sample (1.8%) and adenovirus DNA in two single samples (3.5%). We postulate that virological testing of corneas for transplantation should be considered, particularly in the case of donors with increased risk factors for herpesvirus and adenovirus reactivation. J. Med. Virol. 89:732-736, 2017. © 2016 Wiley Periodicals, Inc.

Ganciclovir ophthalmic gel 0.15% for the treatment of acute herpetic keratitis: background, effectiveness, tolerability, safety, and future applications

Eye disease due to herpes simplex virus (HSV) is a leading cause of ocular morbidity and the number one infectious cause of unilateral corneal blindness in the developed parts of the globe. Recurrent keratitis can result in progressive corneal scarring, thinning, and vascularization. Antiviral agents employed against HSV have primarily been nucleoside analogs. Early generation drugs included idoxuridine, iododesoxycytidine, vidarabine, and trifluridine. While effective, they tended to have low bioavailability and measurable local cellular toxicity due to their nonselective mode of action. Acyclovir 0.3% ointment is a more selective agent, and had become a first-line topical drug for acute HSV keratitis in Europe and other places outside of the US. Ganciclovir 0.15% gel is the most recently approved topical treatment for herpes keratitis. Compared to acyclovir 0.3% ointment, ganciclovir 0.15% gel has been shown to be better tolerated and no less effective in several Phase II and III trials. Additionally, topical ganciclovir does not cause adverse systemic side effects and is therapeutic at lower concentrations. Based on safety, efficacy, and tolerability, ganciclovir 0.15% gel should now be considered a front-line topical drug in the treatment of dendritic herpes simplex epithelial keratitis. Topics of future investigation regarding other potential uses for ganciclovir gel may include the prophylaxis of recurrent HSV epithelial keratitis, treatment of other forms of ocular disease caused by herpesviruses and adenovirus, and ganciclovir gel as an adjunct to antitumor therapy.

Detection of herpes simplex virus type 1 in failed descemet stripping automated endothelial keratoplasty grafts

PURPOSE

To determine the prevalence of herpes simplex virus type 1 (HSV-1) DNA in failed Descemet membrane stripping automated endothelial keratoplasty (DSAEK) grafts.

METHODS

A retrospective interventional case series of patients with DSAEK graft failure treated at the New York Eye and Ear Infirmary between January 2009 and July 2012 was performed. Repeat DSAEK, penetrating keratoplasty, or keratoprosthesis procedure was subsequently performed on eyes with failed grafts. All failed grafts were examined immunohistochemically and with qualitative real-time polymerase chain reaction for HSV-1 DNA. In HSV-1-positive cases, corneoscleral donor rims from the original DSAEK procedures were also examined immunohistochemically and with polymerase chain reaction.

RESULTS

Fifty-one failed DSAEK grafts from 50 eyes of 49 patients were identified. Indications for DSAEK were pseudophakic bullous keratopathy (28/51, 55%), Fuchs corneal endothelial dystrophy (12/51, 23%), failed penetrating keratoplasty (7/51, 14%), corneal decompensation from glaucoma (2/51, 4%), herpetic endotheliitis (1/51, 2%), and failed DSAEK (1/51, 2%). Forty-three grafts (83%) were primary DSAEK graft failure. HSV-1 DNA was isolated from 2 of 51 failed DSAEK grafts (4.0%). The corresponding corneoscleral donor rims did not demonstrate the presence of HSV-1.

CONCLUSIONS

Based on our results, HSV-1 infection plays a minor role in DSAEK graft failure. The data suggest that recipient reactivation, rather than donor transmission, plays a role in HSV infection.

Eye banking and corneal transplantation communicable adverse incidents: current status and project NOTIFY

PURPOSE

Evidence of the transmission of disease via donor ocular tissue has been demonstrated for adenocarcinoma, rabies, hepatitis B virus, cytomegalovirus, herpes simplex virus, Creutzfeldt-Jakob disease, and a variety of bacterial and fungal infections.

METHODS

Although there is no evidence to date of disease transmission for HIV infection, syphilis, hepatitis C, hepatitis A, tuberculosis, HTLV-1 and -2 infection, active leprosy, active typhoid, smallpox, and active malaria, these entities remain contraindications for transplantation for all eye banks nationally and internationally. The potential sources of contamination include infected donors, during the process of removing tissue from cadaveric donors, the processing environment, and contaminated supplies and reagents used during processing. The transmissions of Herpes simplex virus and HSV via corneal graft have been shown to be responsible for primary graft failure. HSV-1 may also be an important cause of PFG.

RESULTS

The long latency period of some diseases, the emergence of new infectious disease, and the reemergence of others emphasize the need for long-term record maintenance and effective tracing capabilities.

CONCLUSIONS

The standardization of definitions for adverse events and reactions will be necessary to support the prevention and transmission of disease. International classification of a unique identification system for donors will be increasingly important for vigilance and traceability in cross-national exportation of human cells, tissues, and cellular- and tissue-based products. Opportunities for continuous improvement exist as does the need for constant vigilance and surveillance.

Repeat corneal graft failure due to graft-to-host herpetic infection

Background

Herein, we present the case of a young female patient with keratoconus, who was subjected twice to repeat keratoplasty, and each time, she experienced a corneal graft failure.

Findings

Under the suspicion of herpetic eye disease, we administered topical and systemic anti-herpetic treatment after the second repeat keratoplasty. The postoperative course was uneventful, and the corneal graft is clear, until recently. Immunohistochemistry and DNA-polymerase chain reaction were negative for herpes simplex virus-1 (HSV-1) in the host cornea, but they detected HSV-1 in both transplanted corneal grafts, thereby supporting our clinical hypothesis that graft-to-host HSV-1 infection elicited this chain reaction of complications in our patient.

Conclusion

This clinical report illustrates in a unique way the dramatic impact an unsuspected herpetic infection in the corneal graft in cases of keratoplasty may have and underscores the necessity of suspecting and adequately treating these distinct cases.

Ocular surface deficits contributing to persistent epithelial defect after penetrating keratoplasty

PURPOSE

To determine the ocular surface deficits contributing to persistent epithelial defect (PED) after penetrating keratoplasty (PKP).

METHODS

Four ocular surface deficits that contribute to PED and their corrective measures were reviewed in 11 eyes of 11 patients with PED after PKP.

RESULTS

Among these 11 eyes, PED developed early in 8 eyes and late in 3 eyes after PKP. They all had more than 2 ocular surface deficits, with infrequent blinking (11 eyes) and lagophthalmos (9 eyes) being more common. Proper corrective measures resulted in rapid epithelialization in 1 week (1 eye), 2 weeks (9 eyes), and 3 weeks (1 eye) via insertion of a bandage contact lens to maintain tear film for treating infrequent blinking (4 eyes), tarsorrhaphy to correct nocturnal lagophthalmos (2 eyes), and fornix reconstruction to eliminate pathogenic symblepharon (4 eyes). During the follow-up of 22.1 ± 7.6 months after healing of PED, 8 eyes retained a stable and clear graft, whereas 3 eyes with more ocular surface deficits had recurrent PED and graft failure develop. Two of the latter were corrected by a repeat PKP combined with oral mucosal graft to correct the remaining cicatricial eyelids.

CONCLUSIONS

Besides the neurotrophic state and aqueous tear deficiency dry eye common in this cohort, infrequent blinking, lagophthalmos, and pathogenic symblepharon also contribute to PED after PKP. Proper corrective measures and vigilant follow-up are crucial for maintaining PKP graft survival in these severe cicatricial ocular surface diseases.

Ocular herpes simplex virus type 1: is the cornea a reservoir for viral latency or a fast pit stop?

PURPOSE

To present a review supporting and refuting evidence from mouse, rabbit, nonhuman primate, and human studies of herpes simplex virus type 1 (HSV-1) concerning corneal latency.

METHODS

More than 50 research articles on HSV-1 published in peer-reviewed journals were examined.

RESULTS

Infectious HSV-1 has been found in mouse denervated tissues and in tissues with negative cultures from the corresponding ganglion. However, the different mouse strains have shown varied responses to different strains of HSV, making it difficult to relate such findings to humans. Rabbit studies provide excellent evidence for HSV-1 corneal latency including data on HSV-1 migration from the cornea into the corneoscleral rim and on the distribution of HSV-1 DNA in the cornea. However, the available methods for the detection of infectious HSV-1 may not be sensitive enough to detect low-level infection. Infectious HSV-1 has been successfully isolated from the tears of nonhuman primates in the absence of detectable corneal lesions. The recurrence of corneal ulcers in nonhuman primates before the appearance of infectious HSV-1 in tears suggests that the origin of the HSV-1 is the cornea, rather than the trigeminal ganglion. Human studies presented evidence of both ganglion and corneal latency.

CONCLUSIONS

Understanding HSV-1 disease progression and the possibility of corneal latency could lead to more effective treatments for herpetic keratitis. However, it is unlikely that operational latency in the cornea will be definitively proven unless a new method with higher sensitivity for the detection of infectious virus is developed.

Corneal latency and transmission of herpes simplex virus-1

The transmission of herpes simplex virus (HSV)-1 by corneal transplantation has rarely been reported. It is believed that these cases have resulted either from reactivated virus traveling from the trigeminal ganglion to the cornea or from latent HSV-1 in the donor cornea itself. Studies of long-term viral presence in corneal tissue have sought to determine whether there is evidence of true non-neuronal latency, although there are problems in its definition. Recent studies provide new insights into neuronal latency, while similar HSV-1 gene regulation in the cornea may implicate corneal latency in pathophysiology and as a potential risk for transplant recipients. This issue has led to concerns over eye banking, which currently screens for other infectious agents but not HSV-1. Here we review the literature regarding corneal latency and the transmission of HSV-1.

Topical treatment with nerve growth factor in an animal model of herpetic keratitis

BACKGROUND

In vitro and in vivo studies demonstrated the antiviral efficacy of nerve growth factor (NGF) and its cyto-protective effect in herpes simplex virus (HSV)-infected cells. The aims of this study were to evaluate the role of endogenous NGF in HSV corneal infection, and the effects of topical NGF treatment on herpetic keratitis.

METHODS

Herpetic keratitis was induced in 40 rabbits with the HSV-1 McKrae strain. Animals were divided into four groups, and treated with topical neutralizing anti-NGF antibodies, NGF, acyclovir or balanced salt solution (BSS) respectively. The clinical course of HSV keratitis was evaluated and scored by slit-lamp examination. In addition, biochemical (immunohistochemistry for glycoprotein D) and molecular (nested PCR for glycoprotein D) analyses were carried out to estimate viral replication.

RESULTS

Treatment with anti-NGF antibodies induced a more severe keratitis associated with increased biochemical and molecular markers of active viral replication. Two animals in this group developed lethal HSV encephalitis. Conversely, topical treatment with NGF induced a significant amelioration of clinical and laboratory parameters when compared to the BSS treated group (control). No significant differences were observed between NGF- and acyclovir-treated groups.

CONCLUSIONS

This study demonstrated the crucial role of endogenous NGF in herpetic keratitis. The comparable effects of NGF and acyclovir confirm the antiviral activity of NGF, and indicate a potential use of topical NGF in herpetic keratitis.

Corneal buttons obtained from patients with HSK harbor high copy numbers of the HSV genome

PURPOSE

To detect herpes simplex virus (HSV) genome in the cornea, we sampled the limbal corneas and scleras of the imported eye bank eyes and recipient's corneal buttons and quantitated HSV genome in them by real-time polymerase chain reaction (PCR).

METHODS

Forty-four recipient corneas including 7 corneas with and 37 corneas without a history of herpetic keratitis, 70 eye bank donor limbal corneas, and 35 eye bank donor scleras were obtained. Primers for real-time PCR were synthesized using the HSV-1 and -2 common regions of the viral DNA polymerase. Primers for conventional PCR were designed to detect HSV-1 and -2 and varicella zoster virus (VZV).

RESULTS

Significantly higher copy number of HSV DNA was detected in corneas with a history of herpetic keratitis 85.7% (6/7), with an average of 1.6 x 10(4) copies/mg tissue weight than in corneas without a history of herpetic keratitis 10.8% (4/37), with an average of 8.7 copies/mg tissue weight (P < 0.05, Mann-Whitney U test). HSV DNA was detected in 5.7% (4/70) of the eye bank donor corneas, with an average of 4.9 x 10(2) copies/mg tissue weight, and in 8.6% (3/35) of the donor scleras, with an average of 10.6 copies/mg tissue weight. HSV-2 and VZV-DNA were not detected in these samples.

CONCLUSIONS

Real-time PCR quantitated HSV genome in the cornea even at a quiescent phase of infection. HSV genome was detected in the corneas and scleras without a past history of herpetic keratitis by this method.

Cornea as a tissue reservoir of Trypanosoma cruzi

Trypanosoma cruzi causal agent of Chagas' disease is a paninfective parasite of mammals transmitted through skin fecal contamination by Triatominae vectors. Studies of alternative routes for infection are scarce; therefore, eye infection should be important, because of the eye's high blood irrigation and brain proximity, as port of entry of the parasite. Trypanosoma cruzi parasites and/or their genetic material in ocular and adjacent muscle tissues were studied in batches of six NMRI mice (15 g) and Trichomys apereoides, an ancient caviomorph (250 g) inoculated with T. cruzi metacyclics from Brazilian (2) and Venezuelan (3) isolates genetically typified as T. cruzi I and II. Two animals/batch in the acute or chronic phase were killed and necropsies of cardiac and skeletal muscles, eyeball, and surrounding ocular muscle were processed for hematoxylin-eosine staining. Tissue parasitism was determined. DNA of the digested sections of the eyeball (5-10 mum) was extracted for T. cruzi k-DNA amplification by PCR, with S35 and S36 primers. The PCR products were analyzed. The average of maximum values of parasitemia of all infected animals was of 10(5) trypomastigotes/ml blood. Skeletal muscle and heart were colonized in patent infection for all isolates. Amastigote nests were found in corneal tissue of 2/3 of the used isolates and adjacent ocular muscle and connective tissue were parasitized. Trypanosoma cruzi k-DNA (330-bp band) was observed in ocular tissue of 4/6 of the isolates studied in both animal models. Investigations concerning infection of the eye globe tissues by T. cruzi are extremely scarce. The presence of stages of T. cruzi and/or its genetic products in ocular tissues indicate a broad colonization from a systemic infection. The results show the ocular environment as a possible appropriate microniche for T. cruzi and emphasize the risk of transmitting T. cruzi by ocular fluids and by parasitized cornea through transplants.

Major Endothelial Loss From Corneas in Organ Culture

PURPOSE

The aim of this study was to show that major losses can still occur on corneas judged suitable for grafting at the first count. In addition, we studied the frequency of these losses on 1992 corneas over a period of 4 years to evaluate the risk incurred.

METHODS

We evaluated the incidence of these major losses and the associated risk factors. An Ishigawa diagram was created with the Cornea Bank team and the ophthalmologists involved in organ retrieval. Endothelial losses caused by bacterial or fungicidal contamination were excluded from the study. For the 29 corneas that suffered major losses, we analyzed the donor files for donor age, clinical file, geographical origins of the corneas, the person who did the retrieval, the length of time the cornea was stored, the data resulting from examining the endothelium at the bank by optical microscope, and the method used for sterilizing the material used. Specific analyses in cases of major loss of endothelial content: anatomopathologic examination of the corneas and search for the herpes simplex virus (HSV; type 1 or 2) by polymerase chain reaction (PCR). We carried out a statistical analysis using a chi(2) test on the 1992 corneas studied to see if the presence of diabetes (type 1 or 2) in the donor led to reduction levels different from those of corneas originating from nondiabetic donors.

RESULTS

The incidence was evaluated at between 0.4% and 3% of corneas sampled, and the associated risk factor was between 0.8% and 6% of grafted corneas. The occurrence of major losses was independent of donor age and was independent of the person who did the retrieval. The occurrence of major losses was independent of geographical origin. We tested our media for endotoxin before use and found levels from 0.22 to 3.9 UI/mL. We verified the absence of a chronological relationship between the batches of media used in the bank and the number of major losses observed, showing that the pyrogenicity limit was independent of cytotoxicity limits. Data analysis showed no difference in reduction levels between diabetic and nondiabetic donors (P < 0.05). Results on the detection of HSV-1 by PCR on the storage media were all negative, and these results agree with the anatomopathologic examinations that showed no signs of viral infection.

CONCLUSION

Total endothelial losses amounted to 1.4%/yr. Without the double endothelial counts, we would have had 29 primary graft rejections over that period. During storage, this loss has not been linked to a specific cause, but risk factors such as traumatic death, herpes infections, and badly controlled endotoxin levels should be considered when taking preventative actions. For the moment, a second endothelial count before grafting should be carried out, because all these problem grafts conformed to grafting criteria after the first count. The possibility of carrying out this second count is one of the recognized advantages of storage in organ culture.

Surveillance sérologique pour les Herpesvirus chez les receveurs de cornée

AIMS

Herpesviruses are ubiquitous viruses, providing circulating antibodies in a wide range of patients. Donor-to-host transmission of Herpes simplex virus via corneal graft has been proven, leading to primary graft failure. However, the serological survey of the corneal recipient for Herpesviruses has not yet been investigated.

METHODS

Circulating antibodies to HSV, VZV, CMV, and EBV were tested in 117 corneal recipients prior to surgery as well as 8 days and 3 months following surgery. Twenty-two patients had a history of corneal herpes. All patients were treated with local steroids, and no patient received systemic immunosuppressive therapy.

RESULTS

No seroconversion was encountered, in particular, no CMV--patient was found CMV+ after grafting. The mean concentration of antibodies significantly decreased after grafting in a few patients. A serological profile of EBV reactivation was detected after surgery in four patients at day 8 and three more patients at 3 months.

CONCLUSIONS

This study shows no significant seroconversion after grafting. However, it shows a postoperative decrease in antibody levels as well as a serological profile of EBV reactivation, possibly related to local steroids or graft immune processes.

Herpes keratitis in the absence of anterograde transport of virus from sensory ganglia to the cornea

Herpes stromal keratitis is an immunopathologic disease in the corneal stroma leading to scarring, opacity, and blindness, and it is an important problem in common corneal surgeries. Paradoxically, virus antigens are largely focused in the epithelial layer of the cornea and not in the stromal layer, and viral antigens are eliminated before stromal inflammation develops. It is not clear what drives inflammation, whether viral antigens are necessary, or how viral antigens reach the stroma. It has been proposed that herpes simplex virus (HSV) travels from the corneal epithelium to sensory ganglia then returns to the stroma to cause disease. However, there is also evidence of HSV DNA and infectious virus persistent in corneas, and HSV can be transmitted to transplant recipients. To determine whether HSV resident in the cornea could cause herpes stromal keratitis, we constructed an HSV US9- mutant that had diminished capacity to move in neuronal axons. US9- HSV replicated and spread normally in the mouse corneal epithelium and to the trigeminal ganglia. However, US9- HSV was unable to return from ganglia to the cornea and failed to cause periocular skin disease, which requires zosteriform spread from neurons. Nevertheless, US9- HSV caused keratitis. Therefore, herpes keratitis can occur without anterograde transport from ganglia to the cornea, probably mediated by virus persistent in the cornea.

Specific antibody production in herpes keratitis: intraocular inflammation and corneal neovascularisation as predicting factors

PURPOSE

The purpose of the study is to investigate whether analysis of specific antibody synthesis can aid the diagnosis of herpes keratitis.

METHODS

Aqueous humor was collected from 39 patients with presumed recurrent herpes keratitis, including 23 consulting for keratitis and 16 patients scheduled for penetrating keratoplasty. Local antibody production was ascertained by analysis of paired aqueous humor/serum samples, using a modified micro-ELISA technique.

RESULTS

Local production of antibodies was found in 32 patients (82%): anti-herpes simplex virus (HSV) antibodies in 26 (67%) and anti-varicella zoster virus (VZV) antibodies in 11 (28%). Twenty of 23 patients with active keratitis (87%), and 12 of 16 undergoing keratoplasty (75%), tested positive. Five patients had local production of both anti-HSV and anti-VZV antibodies, whereas seven patients tested negative. Local antibody production was significantly associated with intraocular inflammation (P<0.05), corneal neovascularisation (P<0.05), and positive response to anti-viral treatment (P<0.05). No complications were encountered in sampling aqueous humor.

CONCLUSIONS

Assessment of local anti-HSV and -VZV antibody production is a safe and reliable diagnostic procedure for recurrent herpes keratitis. It might be particularly helpful in patients presenting with intraocular inflammation and neovascularisation since it discriminates between herpes and non-herpes pathologies and may therefore be useful for preventive and therapeutic strategies.

Automated superficial lamellar keratectomy augmented by excimer laser masked PTK in the management of severe superficial corneal opacities

AIM

To assess superficial lamellar keratectomy augmented by excimer laser smoothening with sodium hyaluronate 0.25%, for the management of superficial corneal opacities.

METHODS

Consecutive procedure performed in 14 eyes (13 patients) with an automated microkeratome and excimer laser phototherapeutic keratectomy (PTK) smoothening using sodium hyaluronate 0.25%.

MAIN OUTCOME MEASURES

UCVA, BCVA, pachymetry, degree of haze, ray tracing analysis, and complications. Mean follow up was 12 (SD 1.6) months.

RESULTS

Mean preoperative haze from previous corneal refractive surgeries was 3.5 (SD 0.5) (11/14 cases). In one case, opacity was caused by ocular trauma and in two by infectious keratitis. The mean preoperative UCVA was 0.7 logMAR (0.2 (SD 0.13) decimal value). BCVA was 0.4 logMAR (0.4 (SD 0.17) decimal value). Mean preoperative corneal pachymetry was 508 (SD 62.5) micro m and mean opacity depth measured by corneal confocal microscopy was 115.2 (SD 49.4) micro m. At 6 months, 71.4% of the eyes with previous corneal refractive surgery showed grade I haze or less. Mean postoperative corneal pachymetry at 6 months was 352.36 (SD 49.05) micro m.

CONCLUSIONS

Automated superficial lamellar keratectomy combined with excimer laser PTK smoothening assisted by sodium hyaluronate 0.25% induces a significant improvement of corneal transparency and visual acuity in cases of corneal opacity caused by previous refractive surgery, ocular trauma, and keratitis.

[Clinical and diagnostic developments in corneal herpes]

The indications for keratoplasty in treating herpes keratitis are currently declining because of recent progress in diagnosis and treatment. Clinically, corneal signs may be caused by HSV reactivation or a secondary anti-HSV immune response. Corneal opacification may be acute or the expression of sequela (meta-herpetic keratitis). The virus can be detected on a corneal surface sample by direct examination or cell culture, the only way to detect an infective virus. The detection of local antibody production in the aqueous humor is an inexpensive method, indicating the local immune anti-HSV response. Detection of HSV DNA using PCR is more sensitive, but the presence of HSV DNA within corneal tIssue may be more delicate to interpret. It is now proven that HSV can be transmitted through a corneal graft from donor to recipient, but no diagnostic test currently detects potentially infective corneas in eyebanks.

Culture-proven herpetic keratitis after penetrating keratoplasty in patients with no previous history of herpes disease

OBJECTIVE

To report three cases of herpetic infection in recipients of organ-cultured donor corneas among 586 consecutive corneal transplantation procedures.

METHODS

Three patients with no history of symptomatic herpes infection underwent corneal transplantation for keratoconus (2 patients) and Fuchs dystrophy (1 patient). Two patients developed keratouveitis and primary graft failure. The third patient developed dendritic keratitis in the graft. Culture of corneal scrapings and the patient's bandage contact lens were positive for herpes simplex virus type 1 (HSV-1). Donor and recipient sera were tested for HSV serology by EIA. Recipient corneal buttons were studied by means of transmission electron microscopy and immunohistochemistry. The three HSV-1 strains were genotyped by sequencing part of a variable antigenic domain of glycoprotein B (gB).

RESULTS

None of the donor corneas showed endothelial cell necrosis after organ culture. All keratoplasties performed with the three mate donor corneas had an uncomplicated course. All three donor sera were positive for HSV. Preoperative recipient sera were positive for HSV. Analysis of the recipient corneal buttons showed no evidence of herpetic infection. Sequence analysis revealed three different gB genotypes.

CONCLUSION

Ascertaining that a postoperative herpetic infection in a corneal transplant originates from the donor tissue is still difficult. Although some features of the reported cases suggest donor-to-host transmission of herpes simplex virus, the recipients could have been the source of the virus.

Pathogenesis and management of herpes simplex virus keratitis

Herpes simplex keratitis (HSK) remains a common cause of unilateral corneal disease. Despite intense research over three decades, the mainstay of therapy continues to be topical and, more recently, systemic acyclovir plus topical corticosteroid in some cases. There is increasing recognition that HSK after keratoplasty can occur not only as a result of recurrence in patients with HSK, but also in patients with other primary diagnoses as a result of activation of HSV in the host, or by transmission of virus in the donor tissue.

Herpes simplex virus DNA in corneal transplants: prospective study of 38 recipients

Herpes simplex virus (HSV) infection of the eye can induce epithelial and stromal keratitis and may also lead to postoperative endothelial failure in keratoplasty. Clinical symptoms and/or virus culture of corneal scrapings most frequently provide the basis for diagnosis of ocular HSV infection, and although HSV DNA has been shown to be present in the cornea, its role in success or failure of corneal grafts remains unclear. In this study, a PCR assay was used to detect HSV DNA in corneal buttons of 38 corneal graft recipients and in donor scleral remnants, retaining one-half of each sample for subsequent viral isolation. Recipients were followed up clinically for a period of 6 months after keratoplasty. All recipients but three were found to be HSV seropositive. Eight recipient corneal buttons contained detectable HSV DNA (7 HSV-1, 1 HSV-2, the latter case confirmed by viral culture). Two donor corneas were found positive for HSV-1 DNA, with negative cultures, and endothelial graft failure occurred in one of the matching recipients after 4 months. One recipient with no history of herpes contracted herpetic keratitis 4 months after keratoplasty, even though the corneal button and donor scleral remnants contained no detectable HSV DNA. The study confirms previous observations of HSV DNA in the corneal tissue of HSV seropositive patients apparently unrelated to any clinical manifestation of herpes infection. However, as demonstrated by culture, HSV remains infectious and may therefore induce donor-to-host infection in corneal recipients.

HSV-1 antigens and DNA in the corneal explant buttons of patients with non-herpetic or clinically atypical herpetic stromal keratitis

BACKGROUND

Little is known about the role of HSV-1 in keratitis not primarily attributed to herpetic origin. This study therefore aimed to prospectively evaluate the corneal explant buttons of patients with non-herpetic or clinically atypical herpetic stromal keratitis (experimental group: non-HSK) for the presence of HSV-1 antigens and DNA, and to compare the findings with those from individuals with typical herpetic stromal keratitis (positive control group: HSK) or non-inflammatory degenerative keratopathy (negative control group).

METHODS

Corneal buttons derived from 51 patients with HSK, from 72 with non-HSK and from 30 with degenerative keratopathy were prospectively collected and subjected to immunohistochemical analysis for HSV-1 antigens and to HSV-1 DNA amplification.

RESULTS

In corneal buttons derived from patients with non-HSK, viral antigens were detected immunohistochemically in 8/72 cases and DNA amplified in 16/72. Corresponding values for the HSK group were 16/51 and 11/51. Taking viral antigen and DNA findings together, HSV-1 was detected in 18/72 (25%) patients with non-HSK and in 19/51 (37%) with HSK (p=0.2), but in only 2/30 (6%) individuals with non-inflammatory degenerative keratopathy.

CONCLUSION

Since the detection frequencies for HSV-1 antigens and DNA were comparable in the HSK and non-HSK groups, Herpes may play an underestimated and as yet undefined role in non-herpetic and clinically atypical herpetic stromal keratitis, either as a primary trigger of the disease or as a secondary contributor to it. In this category of individuals, early anti-herpetic therapy should be considered if patients do not respond in the expected manner to treatment for non-herpetic stromal keratitis.

The outcome of corneal grafting in patients with stromal keratitis of herpetic and non-herpetic origin

AIM

To evaluate the outcome of corneal grafting in patients with stromal keratitis of herpetic (HSK) and non-herpetic origin, using predefined diagnostic criteria and standardised postoperative therapeutic strategies.

METHODS

384 adult immunocompetent recipients of a corneal graft for herpetic (n = 186) or non-herpetic (n = 198) keratitis were followed up prospectively for up to 5 years.

RESULTS

The herpetic group displayed significantly more corneal vascularisation (p = 0.013), more epithelial defects (p = 0.049), lower corneal sensitivity (p <0.001), more graft rejection episodes (p = 0.002), and required larger grafts (p<0.001). However, the postoperative course of visual acuity, endothelial cell numerical density, and rate of graft failures were similar in both groups. After 5 years, cumulative probability of graft survival in HSK patients (40.85%) was similar to that observed in individuals with non-herpetic keratitis (50.15%; log rank = 0.874; relative risk: 1.04).

CONCLUSION

Despite a markedly higher preoperative risk profile in herpetic eyes, the functional outcomes of grafts in individuals with keratitis of herpetic or non-herpetic origin were similar. Probably the most important contribution is a consequent close follow up and a therapeutic strategy including systemic prophylaxis of viral recurrence and of graft rejection by well adopted local steroid therapy.

Herpes simplex virus infection in the media of donor corneas during organ culture: frequency and consequences

BACKGROUND AND PURPOSE

According to polymerase chain reaction (PCR) studies 2-38% of organ culture donor corneas may contain herpes simplex virus (HSV) DNA, but there are only 6 reported instances of proven virus replication in a corneoscleral disc. Moreover there are only 6 patients reported in whom primary graft failure and extensive post-operative epithelial defects were probably caused by a herpetic infection of the corneal graft. Recently we observed virus replication in a donor cornea with subsequent complete endothelial necrosis in our cornea bank. The aim of this study was to investigate the possible correlation between herpetic donor cornea infection and endothelial necrosis in organ culture.

METHODS

To evaluate the frequency of HSV as a reason for endothelial necrosis in organ culture we tested the media of 199 donor corneas discarded due to an altered endothelium in the years 1997 to 1999 by PCR for HSV. As a negative control group we screened the media of 117 transplanted corneas using PCR.

RESULTS

In the control group we had only negative PCR results, in contrast to the corneas with severe or complete endothelial necrosis where HSV DNA was detected in 12 media of the corneas of 9 donors. Virus could be cultivated out of 7 media.

CONCLUSIONS

(1) HSV replication is a common cause of severe endothelial necrosis in organ culture corneas. (2) Replication of the virus during organ culture comes close to a virus cultivation using the corneoscleral disc as a cell culture. (3) We consider the danger of transplanting active HSV to be very small if critical assessment of the graft prior to surgery is carried out.

Herpes simplex virus 1 transmission through corneal transplantation

Genetic characterisation of herpes simplex virus type 1 (HSV-1) DNA isolated from a donor cornea before and after corneal transplantation demonstrated the transmission of HSV-1 through transplantation. This study is the first to provide conclusive evidence for the transmission of HSV-1 by penetrating keratoplasty with subsequent reactivation of donor-derived HSV-1 in the transplanted cornea.