Herpes simplex virus and persistent epithelial defects after penetrating keratoplasty

Distribution of Microbial Keratitis After Penetrating Keratoplasty According to Early and Late Postoperative Periods

Objectives:

The aim of this study was to investigate the distribution of microbial agents in the early and late postoperative periods in patients with microbial keratitis (MK) after penetrating keratoplasty (PK).

Materials and Methods:

The records of 36 patients who were clinically diagnosed as having MK after PK were retrospectively reviewed. Culture results were obtained from microbiology records and the organisms that were produced were noted. A case was deemed as viral keratitis based on the clinical appearance, negative cultures, and response to antiviral treatment. Keratitis development times were evaluated in 2 categories: early (within the first year) and late (after year 1) postoperative period. Mann-Whitney U and Kruskal-Wallis tests were used to compare numerical variables that did not show normal distribution and chi-square test was used to compare categorical variables.

Results:

The majority of MK cases were of bacterial origin (55.5%, n=20), followed by viral (41.7%, n=15) and fungal (2.8%, n=1). Of the 15 cases of early postoperative MK, 10 were bacterial, 4 were viral, and 1 was fungal; however, among cases of late postoperative MK, 10 were bacterial and 11 were viral. The majority (65%) of early and late bacterial infections were caused by gram-positive strains (most commonly staphylococci). Gram-positive bacteria caused keratitis significantly earlier than gram-negative bacteria (p=0.037). Viral and gram-negative bacterial MK was more frequent in the late postoperative period, but the difference was not statistically significant.

Conclusion:

In our study, bacterial keratitis was more common in post-keratoplasty MK than viral and fungal keratitis. Gram-positive bacteria were the most common causative agents. The increased incidence of gram-negative bacterial agents and viral keratitis in the late postoperative period can be explained by long-term topical steroid use.

Epithelial defects after penetrating keratoplasty in infectious keratitis: An analysis of characteristics and risk factors

To investigate the clinical characteristics, treatment, risk factors of occurrence and graft transparency of corneal epithelial defects after penetrating keratoplasty in patients with infectious keratitis. 594 patients (594 eyes) with infectious keratitis treated by penetrating keratoplasty at Shandong Eye Institute were reviewed retrospectively between January 2008 and January 2018. We investigated the demographic data, diameter and sources of graft, onset time, location, scope, time of healing and treatment of epithelial defects, as well as other postoperative complications and graft clarity. 114 of the 594 grafts (19.2%) that developed epithelial defects were included in the epithelial defects group, while the other 480 patients were classified in the non-defect group. The mean age of patients with epithelial defects was statistically greater than that of patients without epithelial defects (P = 0.006). The epithelial defects group accounted for a larger proportion of male patients (P<0.001). The proportion of patients with a graft diameter >9mm in the epithelial defect group (29.8%) was more than that in the non-defects group (16.3%) (P = 0.001). The incidence of epithelial defects significantly differed among the pathogenic causes of infectious keratitis (P = 0.002). The incidence of graft infection (21.1%, 9.2%, respectively, P<0.001) and graft dysfunction (7.9%, 2.5%, respectively, P = 0.012) in the epithelial defect group was higher than in the non-defects group. Multivariate logistic regression revealed that male sex (P = 0.001), age ≥ 60 years (P = 0.024), graft diameter >9mm (P = 0.001), bacterial (P = 0.039) and herpes simplex keratitis (P = 0.008), rheumatism (P = 0.031) and cancer treated with chemo- or radiotherapy (P = 0.032) were independent risk factors for epithelial defects. Graft clarity after epithelial defects were significantly differed between fungal and viral infections (P<0.001). We found that being an elderly male patient, a graft diameter >9 mm, bacterial and viral keratitis and systemic diseases (including rheumatism and cancer treated with chemo- or radiotherapy) were independent risk factors for postoperative epithelial defects.

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.

Infectious keratitis following keratoplasty

Infectious keratitis following corneal transplantation is one of the leading causes of failure of a corneal graft. The incidence of graft infection is variable, with developing countries having a higher incidence. The majority of the graft infections occur within 1 year of the corneal transplantation. Suture-related problems and persistent epithelial defect are the most common risk factors predisposing to graft infection. Pneumococcus species and Staphylococcus aureus have been found to be the commonest microorganisms in the developed world, whereas Staphylococcus epidermidis is the most often detected microorganism in corneal graft infection in the developing world. The early identification of predisposing risk factors in patients and their appropriate management at the earliest may prevent the occurrence of graft infection and might improve graft survival. Visual prognosis in eyes with post-keratoplasty graft infection is poor even after optimal therapy and there is a high rate of graft decompensation.

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.

New onset of herpes simplex virus epithelial keratitis after penetrating keratoplasty

PURPOSE

To report a series of patients with no previous history of herpes simplex virus (HSV) infection who had new onset of herpetic keratitis after penetrating keratoplasty (PK).

DESIGN

Noncontrolled, retrospective case series.

METHODS

We included in the study the patients who had new onset of herpetic keratitis after penetrating keratoplasty for corneal diseases unrelated to HSV infection who were seen at the Cornea Service at Wills Eye Hospital (Philadelphia, Pennsylvania) from January 1996 to December 2002. The diagnosis of HSV epithelial keratitis was based on clinical characteristics of either a classic herpetic dendrite, a geographic ulcer, or a nonhealing epithelial defect that responded only to antiviral therapy.

RESULTS

Fourteen patients were included in the study. Eight of these (57%) had presented with a geographic ulcer whereas six patients (43%) had a classic dendrite. The most common primary corneal disease that led to PK was pseudophakic bullous keratopathy (36%), followed by keratoconus (29%), Fuchs dystrophy (21%), and corneal scar unrelated to HSV (14%).

CONCLUSIONS

The ophthalmologist should be aware of the possibility of herpetic keratitis in eyes after PK, even in patients with no previous history of HSV infection.

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.

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

AIM

To report the clinical consequences of contamination of human donor corneas by herpes simplex virus (HSV) in organ culture.

METHODS

Two patients without previous history of ocular HSV infection underwent penetrating keratoplasty (PK), one for keratoconus and the other for Fuchs' endothelial dystrophy. One patient suffered primary graft failure while the other developed a persistent epithelial defect, ultimately resulting in graft failure. Viral culture of swabs taken from both corneas during the early postoperative period was undertaken. The failed donor corneas were examined histopathologically by immunohistochemistry (IHC) for HSV-1 antigens, transmission electron microscopy (TEM), and by polymerase chain reaction (PCR) for HSV DNA. Both failed corneas were replaced within 6 weeks of the initial surgery. The records of the fellow donor corneas were also examined for evidence of infection.

RESULTS

HSV was cultured from both corneas during the early postoperative period. Histology of both donor corneas demonstrated a thickened corneal stroma with widespread necrosis of keratocytes and loss of endothelial cells. IHC showed keratocytes positive with antibodies to HSV-1 antigens. TEM demonstrated HSV-like viral particles within degenerating keratocytes. PCR performed on the failed corneal grafts was positive for HSV-1 DNA, whereas PCR performed on the excised host corneal buttons was negative in both patients. Records of the fellow donor corneas showed that one cornea was successfully transplanted into another recipient after 18 days in organ culture, whilst the other was discarded because of extensive endothelial cell necrosis noted after 15 days in organ culture.

CONCLUSION

HSV within a donor cornea may cause endothelial destruction in organ culture and both primary graft failure and ulcerative keratitis after transplantation. Endothelial necrosis of a donor cornea in culture also raises the possibility of HSV infection within the fellow cornea.

Advances in diagnosis and management of herpetic uveitis

Herpetic eye disease is common and is frequently associated with intraocular inflammation or uveitis. Despite recent advances in measuring anti-herpes virus antibodies and viral DNA in ocular fluids, diagnosis remains largely clinical. The two more common syndromes include anterior uveitis, often associated with keratitis, and the acute retinal necrosis (ARN) syndrome. Treatment is complex and requires careful monitoring to provide the appropriate balance of antiviral medication and corticosteroids. Long-term prophylaxis with oral antiviral agents may be required in selected patients to help prevent the vision-compromising complications associated with recurrences.

Newly acquired herpes simplex virus keratitis after penetrating keratoplasty

BACKGROUND

After penetrating keratoplasty for reasons unrelated to herpes simplex virus (HSV) keratitis, any nonspecific epithelial defect may still be caused by HSV. The purpose of this study is to determine the incidence of newly acquired herpetic keratitis and to assess contributing factors.

METHODS

The authors retrospectively studied the results of 2398 penetrating keratoplasties performed between 1980 and 1995. Three typical case histories are discussed.

RESULTS

Of 2112 patients in whom the primary diagnosis was not related to HSV keratitis, 18 presented with epithelial herpetic keratitis in their corneal graft. The incidence of newly acquired herpetic keratitis after penetrating keratoplasty was 1.2 per 1000 person-years. In most cases, the infection occurred in the first 2 years after the transplantation. Most often, well-known reactivating stimuli could have caused the HSV infection.

CONCLUSIONS

Herpes simplex virus keratitis may develop after penetrating keratoplasty even without a clinical history of HSV in the host. Thus, HSV should be considered in the differential diagnosis of a postpenetrating keratoplasty epithelial defect. The high incidence of this infection in the first 2 years after such surgery suggests a causal relation between corneal transplantation and the HSV infection.

Detection of herpes simplex virus DNA in donor cornea culture medium by polymerase chain reaction

AIMS/BACKGROUND

Herpes simplex virus (HSV) may establish latent infection in the cornea and therefore be transmissible by corneal transplantation. Monitoring of donor cornea culture medium was evaluated for HSV infection.

METHODS

HSV was sought using virus isolation in cell culture, and its DNA was amplified to detectable levels using the polymerase chain reaction (PCR).

RESULTS

Virus isolation in cell culture was negative on neat, cell pellet, and cell free supernatant prepared from the spent culture media of 80 corneas. Three cell pellets (3.8%) were positive for HSV DNA. The PCR positive culture negative results might have reflected latent rather than active HSV infection of the cornea. Post transplant follow up of the three recipients of corneas with HSV PCR positive organ culture media revealed no evidence of HSV induced eye disease or primary graft failure.

CONCLUSION

Screening of corneal culture medium for HSV by virus culture or for HSV DNA by PCR could not be recommended.

Reactivation of latent herpes simplex virus by excimer laser photokeratectomy

We tested whether excimer laser photorefractive and phototherapeutic keratectomy may reactivate latent herpes simplex and cause recurrent keratitis in mice. Two of ten latently infected mice that were treated with ten excimer laser pulses to the corneal epithelium shed herpes simplex virus type 1, as did four of ten mice that were treated with 50 excimer laser pulses. Ocular shedding of herpes simplex virus was detected in four of ten mice that were treated with ethylenediamine-tetraacetic acid (EDTA) scraping of the corneal epithelium without laser keratectomy, and in six of ten mice on which combined EDTA-facilitated epithelial removal was performed followed by the application of ten excimer laser pulses. In both EDTA-treated groups, viral shedding was prolonged and 18 of 20 mice developed marked corneal opacification or neovascularization, or both. Corneal photoablation with the excimer laser may induce reactivation of latent herpes simplex virus, even in mice with clear and smooth-appearing corneas, and should be considered in the differential diagnosis of humans with persistent corneal epithelial defects after refractive or therapeutic excimer procedures.