Ocular herpes simplex infection: pathogenesis and current therapy

Viral Anterior Uveitis: A Practical and Comprehensive Review of Diagnosis and Treatment

Anterior uveitis is the most common type of uveitis worldwide. The etiologies of anterior uveitis can be divided into infectious and non-infectious (idiopathic, autoimmune, autoinflammatory, trauma, and others). The viral pathogens most commonly associated with infectious anterior uveitis include Herpes Simplex Virus, Varicella-Zoster Virus, Cytomegalovirus, and Rubella Virus. Other emerging causes of viral anterior uveitis are West Nile Virus, Human-Immunodeficiency Virus, Epstein-Barr Virus, Parechovirus, Dengue Virus, Chikungunya Virus, and Human Herpesvirus type 6,7, and 8. Early recognition allows prompt management and mitigates its potential ocular complications. This article provides an updated literature review of the epidemiology, clinical manifestations, diagnostic tools, and treatment options for viral anterior uveitis.

Host Molecules That Promote Pathophysiology of Ocular Herpes

Herpes simplex virus type-1 (HSV-1) is a human virus that causes lifelong infections in a large population worldwide. Recurrence of HSV-1 from latency in trigeminal ganglion (TG) is the trigger of the morbidities seen with this virus. In addition to causing fever blisters and cold sores, occasionally the virus can also cause corneal lesions resulting in blindness in untreated individuals. Several host cell proteins play important roles in HSV-1 infection of the eye. HSV-1 enters into the corneal epithelial cells via its interactions with cell surface receptors. In parallel, the Toll-like receptors sense viral invasion and activate defense mechanisms to fight the infection. New data shows that Optineurin, a host autophagy receptor is also activated to degrade viral particles. In contrast, activation of heparanase, a host enzyme, induces an immune-inflammatory response, which triggers pro-inflammatory and pro-angiogenic environment and ultimately results in many of the clinical features seen with HSV-1 infection of the cornea. Rarely, HSV-1 can also spread to the central nervous system causing serious diseases. In this review, we summarize the latest knowledge on host molecules that promote pathophysiological aspects of ocular herpes.

Adoption of Innovation in Herpes Simplex Virus Keratitis

Herpes simplex keratitis, caused primarily by human herpes simplex virus type 1 (HSV-1), remains the most common infectious cause of unilateral blindness and vision impairment in the industrialized world. Major advances in the care of HSV keratitis have been driven in large part by the landmark Herpetic Eye Disease Study randomized clinical trials, which were among the first in ophthalmology to reflect emerging trial conventions, including multicenter subject enrollment, double-masking, placebo controls, and a priori sample size determinations. The results of these trials now form much of the evidence basis for the management of this disease. However, management patterns in clinical practice often deviate from evidence-based care. These perceived quality gaps have given rise to the evolving field of implementation science, which is concerned with the methods of promoting the application of evidence-based medicine within routine care. To overcome variations in the quality and consistency of care for HSV keratitis, a range of clinical- and technology-based innovations are proposed. The most pressing needs include the following: a rational and tractable disease classification scheme that provides an immediate link between the anatomical localization of disease (corneal epithelial, stromal, or endothelial) and the appropriate treatment, and the actualization of an electronic medical record system capable of providing evidence-based treatment algorithms at relevant points of care. The latter would also input data to population-wide disease registries to identify implementation-rich targets for quality improvement, education, and research. These innovations may allow us to reduce the human and economic burdens of this highly morbid, and often blinding, disease.

Clinical Features and Prognosis of Herpetic Anterior Uveitis

Objective:

To evaluate clinical features, complications, visual outcomes and treatment modalities in patients clinically diagnosed with herpetic anterior uveitis (AU).

Materials and Methods:

We retrospectively reviewed the medical records of 67 patients seen at the Umraniye Training and Research Hospital, Ophthalmology Clinic, Uveitis and Cornea Department from January 2009 to June 2013.

Results:

Thirty-seven patients (55.2%) were female and 30 (44.7%) patients were male. The average follow-up period was 12.9 ± 10.6 months (range: 1-45 months). The most common ocular findings were granulomatous keratic precipitates (KPs) (82.2%), corneal involvement (62.6%), iris atrophy (41.7%) and transient elevated intraocular pressure (IOP) (40.2%). Recurrences were observed in 46.2% of the eyes and the median recurrence rate was 1.0 during the follow-up period. Topical steroids and oral antiviral (acyclovir) therapy were applied to all patients during active episodes. Long-term oral acyclovir was used in 29.8% of the patients. Recurrence rates were significantly lower in patients who used oral acyclovir for more than 6 months, whereas complications rates and final visual acuity did not show any difference between groups. Final visual acuity was better than 20/40 in 61.1% of eyes, and visual impairment was due to corneal scarring or cataract formation.

Conclusion:

Herpetic AU can present with or without corneal involvement. Granulomatous KPs, iris atrophy and elevated IOP are important clinical findings for the diagnosis of cases without corneal involvement. Long-term oral acyclovir treatment (more than 6 months) and is important to decrease recurrence rates and possible complications. Visual prognosis is favorable in cases without corneal scarring.

Nanoparticle-based topical ophthalmic formulation for sustained release of stereoisomeric dipeptide prodrugs of ganciclovir

Poly(d,l-lactic-co-glycolic acid) (PLGA) nanoparticles (NP) of Val-Val dipeptide monoester prodrugs of ganciclovir (GCV) including L-Val-L-Val-GCV (LLGCV), L-Val-D-Val-GCV (LDGCV) and D-Val-L-Val-GCV (DLGCV) were formulated and dispersed in thermosensitive PLGA-PEG-PLGA polymer gel for the treatment of herpes simplex virus type 1 (HSV-1)-induced viral corneal keratitis. Nanoparticles containing prodrugs of GCV were prepared by a double-emulsion solvent evaporation technique using various PLGA polymers with different drug/polymer ratios. Nanoparticles were characterized with respect to particle size, entrapment efficiency, polydispersity, drug loading, surface morphology, zeta potential and crystallinity. Prodrugs-loaded NP were incorporated into in situ gelling system. These formulations were examined for in vitro release and cytotoxicity. The results of optimized entrapment efficiencies of LLGCV-, LDGCV- and DLGCV-loaded NP are of 38.7 ± 2.0%, 41.8 ± 1.9%, and 45.3 ± 2.2%; drug loadings 3.87 ± 0.20%, 2.79 ± 0.13% and 3.02 ± 0.15%; yield 85.2 ± 3.0%, 86.9 ± 4.6% and 76.9 ± 2.1%; particle sizes 116.6 ± 4.5, 143.0 ± 3.8 and 134.1 ± 5.2 nm; and zeta potential -15.0 ± 4.96, -13.8 ± 5.26 and -13.9 ± 5.14 mV, respectively. Cytotoxicity studies suggested that all the formulations are non-toxic. In vitro release of prodrugs from NP showed a biphasic release pattern with an initial burst phase followed by a sustained phase. Such burst effect was completely eliminated when NP were suspended in thermosensitive gels with near zero-order release kinetics. Prodrugs-loaded PLGA NP dispersed in thermosensitive gels can thus serve as a promising drug delivery system for the treatment of anterior eye diseases.

CXCL1 but not IL-6 is required for recurrent herpetic stromal keratitis

Herpetic stromal keratitis (HSK) is characterized by an inflammatory response that includes neutrophils, macrophages, NK cells, and T cells. The factors that are responsible for this inflammation are proinflammatory cytokines and chemokines. Many of these factors have been defined for primary disease, but relatively few have been investigated during recurrent HSK. The present study was designed to determine the role that two of these factors, IL-6 and CXCL1, play during recurrent HSK. Results clearly indicate that unlike primary disease, IL-6 plays no role in recurrent HSK. However, the presence of CXCL1 is required for recurrent HSK as evidenced by the lack of corneal disease in mice treated with anti-CXCL1 Ab. This was confirmed using mice lacking the primary receptor for CXCL1, CXCR2. Corneal disease in this strain was significantly reduced compared with wild-type C57BL/6 controls. Unexpectedly, lack of disease occurs even though CXCL1 knockout mice display increased viral shedding at the cornea. The primary mechanism that CXCL1 plays during disease is its ability to stimulate neutrophils to infiltrate the cornea following reactivation. This paper provides further evidence that primary HSK and recurrent HSK possess overlapping yet distinct disease mechanisms.

Presumed Herpetic Anterior Uveitis: A Study with Retrospective Analysis of 79 Cases

Purpose

To describe the clinical features, visual outcome, medical treatment, and complications of presumed herpetic anterior uveitis.

Methods

We retrospectively analyzed the clinical data related to 79 eyes of 77 patients with presumed herpetic anterior uveitis seen at the Uveitis Unit of the Ulucanlar Eye Training and Research Hospital from 1996 to 2011. Age at onset of disease, sex, follow-up duration, existence of corneal involvement, posterior synechiae, distorted pupil, iris atrophy, characteristic of keratic precipitates, elevated intraocular pressure (IOP), medical treatment, recurrence rate, complications, visual acuities (VA), and surgery for complications were recorded. The complication rates in patients with and without corneal involvement were compared.

Results

There were 38 (49.4%) female and 39 (50.6%) male patients. The mean age at presentation was 48.5 ± 14.8 (20–82) years. The follow-up period was 26.5 (2–127) months. Two patients had bilateral involvement. Ocular findings were a corneal scar or active keratitis in 37 (46.8%) eyes, secondary glaucoma in 14 (17.7%), iris atrophy in 39 (49.4%), distorted pupil in 16 (20.3%), posterior synechiae in 23 (29.1%), and granulomatous anterior uveitis in 30 (40%) eyes. Eight (10.1%) eyes had a posterior subcapsular cataract. Glaucoma surgery was required for uncontrolled IOP with maximum medical treatment in 2 (2.4%) eyes. Long-term oral acyclovir was used in 9 (11.3%) patients. Final VA was ≤ 0.1 in 8 (10.1%) eyes; of these, 6 had either corneal scarring or cataract and 2 preexisting amblyopia.

Conclusions

Presumed herpetic anterior uveitis with or without keratitis has characteristic clinical findings that enable the diagnosis. Long-term prophylactic antiviral therapy should be considered especially in patients <50 years old.

Differential contributions of impaired corneal sensitivity and reduced tear secretion to corneal epithelial disorders

BACKGROUND/AIMS

To determine the possible roles of impaired corneal sensitivity and reduced tear secretion in various types of corneal epithelial disorders.

METHODS

A total of 99 patients (179 eyes) with corneal epithelial disorders classified as persistent epithelial defects (PED), corneal erosion, or superficial punctate keratopathy (SPK) and 115 individuals (230 eyes) without apparent ocular surface disorders (controls) were enrolled in a prospective study. Corneal sensitivity was measured with a Cochet-Bonnet esthesiometer, and tear secretion was measured by the Schirmer test in each subject.

RESULTS

Corneal sensitivity of eyes in the PED and corneal erosion groups was significantly lower than that in the control group. Schirmer test values for eyes in the SPK group were significantly reduced compared with those in the control group.

CONCLUSION

A loss of corneal sensitivity may contribute to the development of PED and corneal erosion, whereas reduced tear secretion may be a contributing factor for SPK. Both results indicate the importance of corneal sensory innervation to the maintenance of corneal integrity.

Ocular sustained release nanoparticles containing stereoisomeric dipeptide prodrugs of acyclovir

PURPOSE

The objective of this study was to develop and characterize polymeric nanoparticles of appropriate stereoisomeric dipeptide prodrugs of acyclovir (L-valine-L-valine-ACV, L-valine-D-valine-ACV, D-valine-L-valine-ACV, and D-valine-D-valine-ACV) for the treatment of ocular herpes keratitis.

METHODS

Stereoisomeric dipeptide prodrugs of acyclovir (ACV) were screened for bioreversion in various ocular tissues, cell proliferation, and uptake across the rabbit primary corneal epithelial cell line. Docking studies were carried out to examine the affinity of prodrugs to the peptide transporter protein. Prodrugs with optimum characteristics were selected for the preparation of nanoparticles using various grades of poly (lactic-co-glycolic acid) (PLGA). Nanoparticles were characterized for the entrapment efficiency, surface morphology, size distribution, and in vitro release. Further, the effect of thermosensitive gels on the release of prodrugs from nanoparticles was also studied.

RESULTS

L-valine-L-valine-ACV and L-valine-D-valine-ACV were considered to be optimum in terms of enzymatic stability, uptake, and cytotoxicity. Docking results indicated that L-valine in the terminal position increases the affinity of the prodrugs to the peptide transporter protein. Entrapment efficiency values of L-valine-L-valine-ACV and L-valine-D-valine-ACV were found to be optimal with PLGA 75:25 and PLGA 65:35 polymers, respectively. In vitro release of prodrugs from nanoparticles exhibited a biphasic release behavior with initial burst phase followed by sustained release. Dispersion of nanoparticles in thermosensitive gels completely eliminated the burst release phase.

CONCLUSION

Novel nanoparticulate systems of dipeptide prodrugs of ACV suspended in thermosensitive gels may provide sustained delivery after topical administration.

Herpes simplex virus keratitis: histopathologic inflammation and corneal allograft rejection

OBJECTIVE

To identify whether histopathologic and immunoassay biomarkers of inflammation are predictive for allograft rejection after penetrating keratoplasty (PKP) for herpes simplex virus (HSV) keratitis.

DESIGN

Retrospective, interventional case series with prospective component of pathologic evaluation of frozen tissue.

PARTICIPANTS

Sixty-two consecutive patients with HSV keratitis who underwent PKP.

METHODS

A chart review and histopathologic examination of the excised host corneal button was performed to identify associations between clinical data and histopathologic presence of inflammation. Enzyme-linked immunosorbent assay for interleukin (IL)-8 and monocyte chemotactic protein-1 (MCP-1) chemokines and immunohistochemical staining for human leukocyte antigen (HLA)-DR and intercellular adhesion molecule-1 (ICAM-1) antigens was also performed in inflamed and noninflamed specimens.

MAIN OUTCOME MEASURES

To determine whether the presence of subclinical inflammation at the time of PKP predicts allograft rejection.

RESULTS

Although 81% of patients had clinically quiescent disease, histopathology revealed that 74% had active corneal inflammation, a finding that was associated with the presence of clinical neovascularization (P = 0.01). Allograft rejections were experienced by 34% of the patients in this cohort. The histopathologic presence of inflammation was a risk factor for allograft rejection (P = 0.02). Corneal specimens demonstrating inflammation had significantly increased IL-8 (P = 0.0005) and MCP-1 (P = 0.003) levels, and greater immunoreactivity for HLA-DR and ICAM-1 when compared with specimens without inflammation. Treatment with IL-10 ex vivo significantly inhibited IL-8 (P = 0.006), and MCP-1 (P = 0.01) chemokines, and qualitatively substantially reduced HLA-DR, but not ICAM-1, expression.

CONCLUSIONS

Histopathologic inflammation is a risk factor for corneal allograft rejection.

Level of herpes simplex virus type 1 latency correlates with severity of corneal scarring and exhaustion of CD8+ T cells in trigeminal ganglia of latently infected mice

A hallmark of infection with herpes simplex virus type 1 (HSV-1) is the establishment of latency in ganglia of the infected individual. During the life of the latently infected individual, the virus can occasionally reactivate, travel back to the eye, and cause recurrent disease. Indeed, a major cause of corneal scarring (CS) is the scarring induced by HSV-1 following reactivation from latency. In this study, we evaluated the relationship between the amount of CS and the level of the HSV-1 latency-associated transcript (LAT) in trigeminal ganglia (TG) of latently infected mice. Our results suggested that the amount of CS was not related to the amount of virus replication following primary ocular HSV-1 infection, since replication in the eyes was similar in mice that did not develop CS, mice that developed CS in just one eye, and mice that developed CS in both eyes. In contrast, mice with no CS had significantly less LAT, and thus presumably less latency, in their TG than mice that had CS in both eyes. Higher CS also correlated with higher levels of mRNAs for PD-1, CD4, CD8, F4/80, interleukin-4, gamma interferon, granzyme A, and granzyme B in both cornea and TG. These results suggest that (i) the immunopathology induced by HSV-1 infection does not correlate with primary virus replication in the eye; (ii) increased CS appears to correlate with increased latency in the TG, although the possible cause-and-effect relationship is not known; and (iii) increased latency in mouse TG correlates with higher levels of PD-1 mRNA, suggesting exhaustion of CD8+ T cells.

Induction of interleukin-6 in human retinal epithelial cells by an attenuated Herpes simplex virus vector requires viral replication and NFkappaB activation

Gene delivery has potential for treating ocular disease and a number of delivery systems have been tested in animal models. However, several viral vectors have been shown to trigger undesirable transient inflammatory responses in the eye. Previously, it was shown that an attenuated Herpes simplex virus vector (hrR3) transduced numerous cell types in the anterior and posterior segments of monkey eyes, but this was accompanied by inflammation. In the retina, retinal pigment epithelial cells were the predominant cell type transduced by hrR3. IL-6 is an important pro-inflammatory cytokine and may play a role in the response to the hrR3 vector. Infection of human ARPE-19 cells with hrR3 resulted in increased IL-6 expression and secretion 3-4h post-infection. In the presence of acyclovir (70 microM) or in cells infected with UV-inactivated hrR3, IL-6 was not up-regulated indicating viral replication was required. Expression of the HSV-1 alpha and beta genes may be necessary but was not sufficient for NF-kappaB activation and IL-6 up-regulation. The translocation of NF-kappaB into the nucleus also occurred between 3 and 4h post-infection, coincident with increased IL-6 expression. Inhibition of NF-kappaB translocation by an Adenovirus vector expressing a dominant negative IkappaB (AdIkappaBam) inhibited IL-6 up-regulation, indicating that NF-kappaB plays a role in increasing IL-6 expression in APRE-19 cells. The hrR3 virus lacks viral ribonucleotide reductase (RR) activity, thus RR is not required for NF-kappaB activation or IL-6 up-regulation in ARPE-19 cells.

Epithelial herpetic simplex keratitis recurrence and graft survival after corneal transplantation in patients with and without atopy

PURPOSE

To compare the incidence of herpes simplex virus (HSV) epithelial recurrence and graft survival after penetrating keratoplasty (PK) in patients with and without self-reported atopy.

DESIGN

Retrospective cohort comparative study.

METHODS

SETTING

Cornea Service, Wills Eye Hospital.

STUDY POPULATION

Patients who presented with previously diagnosed ocular HSV between March 2003 and March 2004 and who underwent primary PK for ocular HSV at the Cornea Service. From the 58 patients invited, 49 patients (50 eyes) were included. Nine patients were ineligible in accordance with the exclusion criteria: no active classic HSV episode before PK, immunosuppression, less than one year of follow-up, previous history of PK before presentation at the Service. Eligible patients filled out a questionnaire regarding their history of atopic disease, considering: presence of allergic rhinitis, asthma, or atopic dermatitis. Ocular history was obtained through chart review. main outcome measures: Incidence of epithelial HSV recurrences and corneal graft survival in both groups.

RESULTS

Each group (atopic and nonatopic) included 25 eyes. The atopic patients had a mean incidence of 0.07 episode/eye year (SD +/- 0.9) compared with 0.12/eye year (standard deviation [SD] +/- 0.21) in the nonatopics (P = .002). At 10 years of follow-up, the survival rate in the atopics was of 92% and in the nonatopics was of 79% (P = .88).

CONCLUSIONS

Nonatopics had significantly more epithelial recurrences after PK compared to atopics; however, both groups presented low incidences of recurrences and high graft survival rates.

Congenital Corneal Anesthesia

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

Efficacy of oral antiviral prophylaxis in preventing ocular herpes simplex virus recurrences in patients with and without self-reported atopy

PURPOSE

To compare the efficacy of oral antiviral prophylactic treatment for herpes simplex virus (HSV) recurrences in patients with and without self-reported atopy.

DESIGN

Retrospective cohort comparative study.

METHODS

setting: Cornea Service, Wills Eye Hospital. study population: Patients who presented with previously diagnosed ocular HSV between March 2003 and March 2004. From 244 patients invited, 54 patients (58 eyes) were included. One hundred and ninety patients were excluded according to exclusion criteria: no active episode during follow-up, immunosuppression, less than one year of follow-up, or previous history of penetrating keratoplasty. The Questionnaire regarding history of atopic disease, considers: presence of allergic rhinitis, asthma or atopic dermatitis, and chart review of ocular history. main outcome measures: Incidence of all types of HSV recurrences with and without antiviral prophylaxis within each group and between groups. HSV episodes were classified into infectious, inflammatory, and mixed for analysis.

RESULTS

Atopic/nonatopic (P value): mean follow-up without prophylaxis 8.1 (+/- 8.2)/7.3 years (+/- 8.6) (P = .71); mean follow-up with prophylaxis 2.9 (+/- 2.3)/2.6 years (+/- 2.2) (P = .51); the effect of prophylaxis significantly reduced the all recurrences in both groups except in the inflammatory recurrences in the atopic group and in the mixed recurrences in both groups. Prophylaxis decreased infectious episodes by 44% in nonatopic and 76% in atopics and decreased inflammatory manifestations by 69% in the nonatopic group and 8% in the atopic group.

CONCLUSION

Antiviral prophylaxis for HSV recurrences was more effective in reducing infections in atopics and less effective in reducing inflammatory episodes in atopics versus nonatopics.

Inhibition of Cyclooxygenase 2 Synthesis SuppressesHerpes simplexVirus Type 1 Reactivation

Recurrent herpes virus infection, in which the virus reactivates from the nervous system and causes painful lesions in peripheral tissues, is a significant clinical problem. Our recent studies showing that the amount of cyclooxygenase 2 (COX-2) in the trigeminal ganglia of heat-stressed untreated mice is higher than the amount in heat-stressed mice treated with the COX-2 inhibitor, celecoxib, have indicated that the prostaglandin synthesis pathway--and in particular COX-2--may be an intermediate in the pathway to herpes viral reactivation. To further study this process, we infected the corneas of mice using topical application to a lightly scratched epithelium and waited 30 days for Herpes simplex virus type 1 (HSV-1) latency to be established in the trigeminal ganglia. Prior to the induction of viral reactivation, the mice were treated orally with celecoxib. Treated and untreated mice were induced to undergo reactivation by immersion in 43 degrees C water for 10 min. The shedding of virus at the ocular surface was determined by culturing ocular swabs with indicator cells. The presence of infectious virus in the trigeminal ganglion was evaluated by incubating ganglion homogenates with indicator cells and observing for cytopathic effect. Celecoxib treatment significantly suppressed viral reactivation when given prophylactically by the gastrointestinal route. The numbers of corneas and ganglia containing infectious virus were significantly lower in the celecoxib-treated animals, compared to the placebo-treated mice. These experiments demonstrate that a selective COX-2 inhibitor can suppress hyperthermic stress-induced herpes viral reactivation in the nervous system. It may be possible to use COX-2 inhibitors to prevent viral reactivation in high-risk patients by drug prophylaxis.

Involvement of CD8+ T-cells in exacerbation of corneal scarring in mice

PURPOSE

To determine the specific immune responses involved in the exacerbation of corneal scarring induced by HSV-1 in gK vaccinated mice.

MATERIALS AND METHODS

BALB/c mice were vaccinated with HSV-1 glycoprotein K (gK) and ocularly challenged with HSV-1. Infiltration into the cornea of T cells and macrophages was monitored by immunocytochemistry, and the effect of depletion of CD4+ T-cells, CD8+ T-cells, or macrophages on corneal scarring was determined.

RESULTS

Following ocular challenge, CD4+ and CD8+ T-cells and macrophages were more abundant in the corneas of gK-vaccinated mice than in the corneas of mock vaccinated mice. Depletion of CD8+ T-cells, but not of CD4+ T-cells or macrophages, reduced the severity of corneal scarring in gK-vaccinated mice.

CONCLUSIONS

We have shown that gK vaccination causes an overall increase in T cells and macrophages in the cornea after ocular HSV-1 challenge. The immunopathology induced by gK vaccination appears to be related to CD8+ T-cell activity, as depletion of these cells, but not other immune cells, reduced corneal scarring.

Apoptosis, necrosis, proliferation, and myofibroblast generation in the stroma following LASIK and PRK

The aim of this study was to semi-quantitatively analyze stromal cell apoptosis, stromal cell proliferation, and myofibroblast generation over time points from 4hr to 3 months in rabbit eyes having photorefractive keratectomy (PRK) or laser in situ keratomeliusis (LASIK). Stromal cell necrosis and inflammatory cell infiltration were also studied. PRK for low myopia (-4.5diopters [D]), PRK for high myopia (-9.0D), and LASIK for high myopia (-9.0D) were performed in rabbit eyes, and corneas were obtained for examination at 4, 24, and 72hr, 1 and 4 weeks, and 3 months after surgery. A total of 144 rabbits were included in the study. Stromal cell apoptosis, proliferation, and myofibroblast generation were evaluated semi-quantitatively by TUNEL assay, immunocytochemical analysis of Ki67, and immunocytochemical analysis of alpha-smooth muscle actin, respectively. Stromal cell necrosis and characteristics of other cell types in the stroma were evaluated by electron microscopy. Keratocyte apoptosis and the subsequent proliferation and generation of myofibroblasts were qualitatively and quantitatively different in PRK for high myopia compared to either PRK for low myopia or LASIK for high myopia. Stromal cell necrosis becomes a significant form of cell death by 24hr after injury and may involve corneal fibroblasts, myofibroblasts, and inflammatory cells. Large numbers of polymorphonuclear cells and monocytes invade the cornea by 24hr after surgery and persist for over 1 week. The qualitative and quantitative differences in the cellular wound healing response after PRK for high and low myopia and LASIK for high myopia are likely determinants of the clinical differences in refractive outcome and some of the complications, such as regression and haze, seen after these procedures.

Visual outcome in herpes simplex virus and varicella zoster virus uveitis: a clinical evaluation and comparison

PURPOSE

To compare clinical characteristics and outcomes in patients with uveitis caused by herpes simplex virus (HSV) and varicella zoster virus (VZV).

DESIGN

Retrospective comparative study.

PARTICIPANTS

Forty patients with HSV uveitis and 24 patients with VZV uveitis.

METHODS

A retrospective study of 40 patients with HSV and 24 patients with VZV uveitis was performed. The patients were followed between May 1987 and September 1999 (median follow-up time, 46 months). The diagnosis of HSV uveitis was made clinically and serologically, and the diagnosis of VZV uveitis was made clinically.

MAIN OUTCOME MEASURES

Clinical presentation of the disease, ocular complications, visual acuity, surgical and medical treatments needed.

RESULTS

Both populations were comparable for gender and age at disease onset. The course of the disease tended to be remitting and recurrent in HSV patients and chronic in VZV patients (P = 0.046). The most frequent ocular complication in both groups was secondary glaucoma (54% HSV, 38% VZV). Twenty-five percent of VZV patients developed posterior pole complications (cystoid macular edema, epiretinal membrane, papillitis, retinal fibrosis, and detachment) compared with 8% of HSV patients (P = 0.069). Treatment modalities selected were generally similar in the two groups, although periocular and systemic steroids were required more frequently in HSV patients (60% versus 25%; P = 0.01). Surgical procedures were required with similar frequency in both populations. The percentage of eyes that were legally blind at end of follow-up was also comparable (HSV, 20%; VZV, 21%). The visual outcome was similar in the studied populations.

CONCLUSIONS

This study represents the only direct comparison of HSV and VZV uveitis patients reported in the literature. HSV patients were more likely to be treated with periocular and systemic steroids, and VZV patients were more likely to develop posterior pole complications (a finding of borderline significance). Other parameters evaluated in this study were not statistically different in the two patient groups.

Herpes simplex virus epidemiology and ocular importance

PURPOSE

To review the changing epidemiology of herpes simplex disease and correlate it with the epidemiology of ocular herpes simplex disease.

METHOD

A review of pertinent reports in the world literature about the epidemiology of herpes simplex and specifically about ocular herpes simplex.

RESULTS

In developed countries, many individuals are reaching adolescence and adulthood without prior herpesvirus infection. Herpes simplex genital infection is increasing at a rapid rate in sexually active adolescents and adults, with about one in six adults now infected in the United States. Similar statistics are confirmatory worldwide in developed countries. Active herpes simplex infection is a risk factor for acquisition of human immunodeficiency virus. The Herpetic Eye Disease Study, as well as prior studies from Moorfields Eye Hospital and the Mayo Clinic in Rochester, Minnesota, provides us with the epidemiology of ocular herpes simplex. Recent studies suggest an older age of onset and perhaps overall more severe ocular disease as compared with the older literature.

CONCLUSIONS

Herpes simplex is a significant health concern at present with genital infections increasing in epidemic proportions. This is also reflected in a rise in the incidence of neonatal herpes. Herpes simplex virus type 1 (HSV-1) infection is being acquired for the first time in an older age group. A significant and increasing proportion of genital herpes is caused by HSV-1. Serologic studies are no longer as useful in distinguishing orofacial herpes from genital herpes. More acute retinal necrosis syndrome cases are associated with HSV-2. Speculation about the future of ocular herpes is made based on this changing epidemiology.

Recurrent herpes simplex virus-induced erythema multiforme: different HLA-DQB1 alleles associate with severe mucous membrane versus skin attacks

In some individuals a local herpetic lesion precipitates a generalized inflammation of the skin, designated as erythema multiforme (EM). We determined the frequencies of the immune response genes of the HLA system by molecular HLA class II typing in 46 patients with EM and in many of their family members. Allele frequencies were correlated with disease form and disease-inducing factors. We found that specific complications of HSV infection occur preferentially in patients with certain HLA-DQB1 alleles. In 21 of the 46 patients EM was induced by recurrent HSV infection. Thirteen of these patients showing only minor or no involvement of mucous membranes had the HLA allele DQB1*0302 (phenotype frequency 61.9% versus 18.8% in controls, p corr = 0.0008) and all three patients with major involvement of mucous membranes had the rare HLA allele DQB1*0402 (phenotype frequency in controls 6,4%, p corr = 0.017).

Slow viral replication of HSV-1 is responsible for early recurrence of herpetic keratitis after corneal grafting

BACKGROUND

The presence of herpetic DNA has been shown in diseased and healthy corneal tissue. A clinical correlation with the activity of the disease has not yet been demonstrated. This study was done to evaluate the use of DNA amplification for HSV-1 from different sites for the clinical prognosis after corneal grafting.

PATIENTS AND METHODS

Eighteen patients with herpetic keratitis, 8 patients with other forms of keratitis, and 15 patients with corneal disease unrelated to herpes undergoing penetrating keratoplasty were investigated. From these, aqueous humor was obtained at the time of surgery. The excised cornea was divided into three parts for paraffin embedding, 24 h tissue culture and preparation of minced tissue. All samples were processed for HSV-1 glycoprotein D PCR followed by Southern blot and DNA hybridization.

RESULTS

In the herpes group, target DNA was detected in 4/18 aqueous humor samples, 7/16 minced tissue preparations, 6/18 explant culture fluid samples and 4/15 paraffin sections. In the control groups of other keratitis and non-herpetic eye disease, respectively, target DNA was found in 0/5 and 2/12 aqueous humor samples, 1/6 and 0/12 minced tissue preparations, 0/8 and 0/15 explant culture fluid samples and in 1/6 and 1/14 paraffin sections. Five of six patients in whom herpes DNA was detected in the short-term tissue culture experienced an episode of herpes reactivation, within 4 months after transplantation, whereas only one of the remaining patients in all three groups did so (p = 0.0005).

CONCLUSION

A slow viral replication may be responsible for early recurrence of herpetic keratitis after corneal grafting. Detection of herpetic DNA in short-term tissue cultures from explant tissues may help to define the patients at risk.

Evaluation of topical 0.03% flurbiprofen drops in the treatment of herpetic stromal keratitis

PURPOSE

The management protocol for herpetic stromal keratitis (HSK) is still controversial. We have attempted to compare the relative efficacy of topical dexamethasone 0.01% and flurbiprofen 0.03% in combination with topical acyclovir 3% in HSK.

METHODS

In this institutional, prospective, randomized, controlled, double-blind study, 45 clinically diagnosed cases of HSK were randomly distributed into three coded treatment groups--topical placebo, dexamethasone 0.01%, and flurbiprofen 0.03% each in tapering frequency and in combination with acyclovir 3% ointment five times per day for four weeks. Therapeutic response was assessed every third day for four weeks. Decoding of the treatment groups was done at the conclusion of the study and data analysed.

RESULTS

Four-week success rate was 93.3% (14 of 15) in the dexamethasone-acyclovir treatment group, 66.7% (10 of 15) in the flurbiprofen-acyclovir treatment group and 20% (3 of 15) in the placebo-acyclovir treatment group.

CONCLUSION

While dexamethasone in combination with acyclovir gives the best results in HSK with minimal side-effects, the role of topical flurbiprofen seems promising.

Recurrence rate of herpetic uveitis in patients on long-term oral acyclovir

We examined the recurrence rate of herpetic uveitis (HU) in 13 patients (group A) treated prophylactically with long-term systemic acyclovir (600-800 mg/day) and compared it with that of 7 patients with no prophylactic therapy (group B). HU was diagnosed on the basis of a history of dendritic or disciform keratitis accompanied by iridocyclitis and iris atrophy. The study population consisted of 12 men and 8 women with a mean age at onset of uveitis of 52.9 years (range 19-78 years). All patients were followed for at least 8 months. The mean follow-up time of patients on long-term oral acyclovir was 26.0 months. In this group, only one patient experienced a single recurrent episode of uveitis while on 600-800 mg/day of acyclovir therapy; two additional patients had recurrence of HU within 16.2 months after the acyclovir dose was tapered below 600 mg/day. In striking contrast, 16 recurrences occurred in the 7 patients of group B (p < 0.05). Of these, the initial recurrence occurred within an average of 4.3 months following cessation of therapy. There was a significant difference (p < 0.05) in the mean recurrence-free interval between patients in group A (24.6 months) and those in group B (3.4 months). Herpetic uveitis is a serious ocular disease in which recurrence of inflammation results in severe ocular complications. The long-term use of oral acyclovir may be of benefit in the prevention of recurrences, and hence may reduce the blinding complications of this disease. Efforts at completing a randomized, placebo-controlled trial on this matter by the Herpes Epithelial Disease Study Group were unsuccessful due to insufficient patient recruitment.

Herpes simplex keratitis in children

Ophthalmic findings are reported in 31 eyes of 28 children with herpes simplex keratitis. Twenty two had dendritic ulcers, and nine had geographic ulcers or disciform stromal keratitis. After resolution of keratitis, 80% (19/22) of children with dendritic ulcers achieved corrected visual acuity of 6/9 or better, 50% (11/22) had induced astigmatism, 45% (9/22) had one to five recurrences. In the group with geographic or disciform lesions, 89% (8/9) had reduced corrected vision, 78% (7/9) had induced astigmatism which was predominantly against the rule, and 87% (7/9) had one to six recurrences.

HSV antigens and HSV DNA in avascular and vascularized lesions of human herpes simplex keratitis

Fifty-one corneal buttons obtained by penetrating keratoplasty from patients with a preoperative clinical diagnosis of nonulcerative herpetic keratitis and/or disciform stromal scarring (44) as well as ulcerative necrotizing stromal keratitis (7) were processed for herpes simplex virus (HSV) antigens using an immunoperoxidase technique and for HSV DNA by the polymerase chain reaction (PCR). HSV antigens were detected significantly more often (p less than 0.025) in specimens with avascular nonulcerative keratitis than in those with vascularization. In contrast to HSV antigens, HSV DNA was identified at equal proportions in avascular and vascularized lesions. Both HSV antigens and HSV DNA were detected in all specimens from patients with ulcerative necrotizing stromal keratitis. The implications of these findings with regard to possible mechanisms underlying herpetic keratitis in man are discussed.

Collagen shield delivery of trifluorothymidine

Corneal and aqueous levels of topically applied trifluorothymidine (F3T) were compared with and without the collagen shield in normal and damaged rabbit eyes. Shields were presoaked in 1% F3T for 15 minutes prior to application. Rabbits received either a presoaked shield, 1% F3T drops every two hours, or both. Corneal and aqueous levels of F3T were measured at 30 minutes, two, four, and eight hours. If 5 mm epithelial defects were created, the collagen shield and topical F3T drops produced significantly higher levels of F3T than drops alone at all periods tested (P less than .05). A presoaked shield alone produced greater levels of F3T than drops alone at 30 minutes and two hours (P less than .05). Collagen shields did not enhance F3T levels in eyes with intact epithelium. Implications for treatment of herpetic keratouveitis are discussed.

Detection of herpes viral genomes in normal and diseased corneal epithelium

Herpetic ocular disease is one of the major causes of corneal blindness. Clinical diagnosis of corneal disease is based principally on corneal appearance. However, abnormal morphology of the corneal epithelium (CE) is not an indicator for the presence of a herpes virus. Further, it has not been established if herpes viruses are present in normal corneal epithelial tissue. In these studies, the polymerase chain reaction was used to evaluate normal and diseased corneal epithelium for the presence of herpes simplex virus type 1 (HSV-1), Epstein-Barr virus (EBV) and cytomegalovirus (CMV) genomic sequences. Thirty-two normal corneal epithelium specimens obtained from cadavers shortly after death were analyzed for HSV-1, EBV and CMV genomic sequences. Three of the 32 normal CE specimens were positive for amplified EBV DNA, 1 was positive for HSV-1 DNA, and none was positive for CMV DNA. We also tested eight herpetic dendritic lesions of which 3 were HSV-1 culture and PCR positive. The remaining five dendritic lesions were HSV-1 culture and PCR negative. Since these lesions were not evaluated for other herpesviruses, the etiology of these dendritic lesions is unknown. Six corneal epithelium samples from HIV-infected donors were negative for EBV, CMV and HSV-1 amplified sequences. Positive EBV, CMV and HSV-1 serology on all normal donors and on donors with clinically apparent disease did not correlate with positive PCR results. The results of these studies suggest that EBV and HSV-1 DNA can be amplified from a small percentage of apparently normal corneal epithelium.

Herpes simplex stromal and endothelial keratitis. Granulomatous cell reactions at the level of Descemet's membrane, the stroma, and Bowman's layer

Fifty-three (25%) of 215 keratectomy specimens of patients with herpes simplex stromal keratitis displayed granulomatous reactions at the level of Descemet's membrane (50/53), midstroma (13/53), and Bowman's layer (5/53). Using an immunoperoxidase technique, herpes simplex virus (HSV) antigens were detected in keratocytes, endothelial cells, and foci of epithelioid histiocytes and multinucleated giant cells around Descemet's membrane. Both granulomatous reactions and HSV antigens were identified significantly more often in specimens with ulcerative necrotizing stromal keratitis than in those from patients with stromal scarring or nonulcerative nonnecrotizing keratitis (P less than 0.00001 and P less than 0.005, respectively). Herpes simplex virus antigens also were present in endothelial cells adjacent to foci of granulomatous reactions around Descemet's membrane in association with disciform stromal scarring. To our knowledge, this is the first demonstration of HSV antigens in human corneal endothelial cells and in the granulomatous reactions at the level of Descemet's membrane.