Dendritic (herpetic) keratitis. I. Incidence--seasonal variations--recurrence rate--visual impairment--therapy

Antiviral and Anti-Inflammatory Therapeutic Interventions for Treating Herpes Stromal Keratitis: A Systematic Review

PURPOSE

Herpes stromal keratitis (HSK) is an immune-mediated corneal inflammation that occurs after a herpes simplex virus infection. This paper aims to systematically identify and compare interventions for treating HSK and their patient outcomes.

METHODS

This systematic review followed the PRISMA methodology. Online databases were searched to obtain all relevant papers. Two independent reviewers screened through 168 records. Seven papers were included and used for data extraction. A qualitative analysis was conducted.

RESULTS

HSK patients receiving prednisolone phosphate and acyclovir showed a higher treatment success rate and significantly longer time to failure compared to patients receiving only acyclovir (P < .001). No difference in resolution time was found between oral and topical acyclovir. Between groups receiving dexamethasone and flurbiprofen, resolution occurred in 93% and 67% of patients, and BCVA (LogMAR) improved from 1.0 to 0.30 and 0.48, respectively. BCVA improved in both cyclosporine-A (P < .001) and its control (prednisolone) groups (P = .002). A tacrolimus treatment group showed greater improvement in BCVA compared to its control (prednisolone) group (P < .001).

CONCLUSION

Corticosteroids and antivirals managed HSK most effectively only when used concurrently. Oral acyclovir showed similar effectiveness to its ointment counterpart, a preferable alternative for easier administration. Corticosteroid use could induce greater therapeutic benefits when tapered in concentration and frequency and administrated for at least 10 weeks. Anti-inflammatory drugs including flurbiprofen, cyclosporine-A, and tacrolimus could be safe and effective for treating HSK. Future long-term follow-up and RCTs could provide insights on the therapeutic benefits of these potential alternatives.

Endothelial Involvement in Monocular Mpox Keratitis: In Vivo Confocal Microscopy Approach

PURPOSE

The aim of this study was to describe the clinical features and endothelial involvement in a case of Mpox virus keratitis by in vivo confocal microscopy (IVCM).

METHODS

This is a case report.

RESULTS

A 35-year-old man presented with redness, photophobia, pain, tearing, and a low visual acuity of 0.09 (decimal) in the left eye with a 6-week history of Mpox and corneal trauma. Previous testing of blood, interdigital skin lesions, and conjunctival and eyelid margin swabs confirmed the presence of Mpox by polymerase chain reaction. Biomicroscopy displayed superficial stromal infiltrates with a continuous but irregular epithelium. IVCM revealed the presence of pseudoguttata, loss of defined cell boundaries, infiltration of inflammatory cells in the endothelial layer, endothelial ridges, and precipitated pigmented granules, consistent with endotheliitis. After this episode, the patient had 4 reactivations, also treated with topical corticoids and oral tecovirimat 600 mg twice a day for 2 weeks. On the fourth reactivation, this treatment was extended to 4 weeks. On the last visit, the patient presented a visual acuity of 0.5 with disciform keratitis and reduced endotheliitis signs. The endothelial cell density remained normal during the follow-up (2763 ± 376 cell/mm2 at baseline and 2795 ± 238 cell/mm2 at the last visit). Polymegathism and pleomorphism showed altered values during the follow-up.

CONCLUSIONS

Patients with an altered corneal epithelial barrier could suffer Mpox endotheliitis, like other DNA viruses, before disciform keratitis appears. IVCM is a useful tool for the early detection of endotheliitis and for describing its evolution, improving patient care.

The epidemiology of infectious keratitis

Infectious keratitis is a rare but potentially severe sight-threatening disease, associated with considerable societal burden, cost and morbidity. This review summarises the most recent evidence for the incidence, risk factors and impact of disease, all of which vary widely according to region, access to health care, socioeconomic and environmental factors, predisposing conditions and causative organisms. The frequency and societal impact of infectious keratitis are significantly higher in low-income countries. In non-viral infectious keratitis, bacterial causes predominate in most regions. Fungi, particularly linked with agricultural trauma, are more frequently associated with infectious keratitis in low-income regions, particularly in India and certain African countries. The disease impact is compounded by poverty and limited access to services and treatment. Early diagnosis, access to appropriate treatment, prophylaxis in ocular trauma, availability of eye protection, awareness of risk factors may be associated with reduced disease severity and vision loss. Evidence for the incidence and burden of disease is lacking in certain regions and well-designed epidemiological studies to identify independent risk factors for the disease and those associated with more severe outcomes may better identify causation and guide resource allocation and preventative strategies.

INCIDENCE OF HERPES SIMPLEX VIRUS KERATITIS AND OTHER OCULAR DISEASE: GLOBAL REVIEW AND ESTIMATES

Purpose: We aimed to review available data on the incidence of herpes simplex virus (HSV) keratitis and other HSV ocular disease and to estimate the global burden of HSV ocular disease. Methods: We searched Medline and Embase databases to October 2020 for studies reporting on the incidence of HSV ocular disease. Study quality was evaluated using a four-point checklist. Pooled estimates were applied to 2016 population data to estimate global HSV ocular disease burden. Numbers with uniocular vision impairment (any visual acuity <6/12) were estimated by applying published risks to case numbers. Results: Fourteen studies had incidence data; seven met our quality criteria. In 2016, an estimated 1.7 (95% confidence interval, 95% CI 1.0–3.0) million people had HSV keratitis, based on a pooled incidence of 24.0 (95% CI 14.0–41.0; N = 2; I² = 97.7%) per 100,000 person-years. The majority had epithelial keratitis (pooled incidence 16.1 per 100,000; 95% CI 11.6–22.3; N = 3; I² = 92.6%). Available studies were few and limited to the USA and Europe. Data were even more limited for HSV uveitis and retinitis, although these conditions may collectively contribute a further >0.1 million cases. Based on global incidence, some 230,000 people may have newly acquired uniocular vision impairment associated with HSV keratitis in 2016. Conclusion: Over 1.8 million people may have herpetic eye disease annually. Preventing HSV infection could therefore have an important impact on eye health. Herpetic eye disease burden is likely to have been underestimated, as many settings outside of the USA and Europe have higher HSV-1 prevalence and poorer access to treatment.

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 Pattern And Visual Impairment Associated With Herpes Simplex Keratitis

Purpose

Herpes simplex keratitis (HSK) has varied presenting patterns, and is one of the leading causes of corneal scarring and subsequent visual disability. This study was carried out to determine the incidence and patterns of HSK presenting at a tertiary eye center in eastern Nepal and to assess the associated visual impairment.

Methods

This was a descriptive, cross-sectional study at a tertiary eye-care center that included 302 cases of clinically diagnosed HSK over a period of 1 year. Detailed ocular examination was done in all patients. Clinical manifestations and visual acuity at presentation and on subsequent visits in cases that followed up were recorded. Findings were noted in structured format and later assessed.

Results

Of 302 cases of HSK, 53 presented with epithelial keratitis, 156 with stromal keratitis without ulceration, 22 with stromal keratitis with ulceration, 66 with endothelitis, and five with neurotrophic ulcers. Presenting visual acuity in 108 patients (35.7%) was <3/60. Of 175 patients who followed up, 36 patients continued to have vision <3/60.

Conclusion

This study shows that HSK has diverse presentation and can cause significant vision impairment. Stromal keratitis without ulceration was the most common presentation in our study. In developing nations, due to higher incidence of fungal and bacterial keratitis, HSK is not studied much. Few epidemiological data are available on the subject, and since the disease is notorious for recurrence, long-term study is paramount to estimate the burden of visual morbidity caused by the disease.

Bilateral Herpes Simplex Virus-related Peripheral Ulcerative Keratitis Leading to Corneal Perforation in a Patient with Primary Herpes Simplex Virus Infection

Purpose:

To present a case of bilateral peripheral ulcerative keratitis (PUK) caused by primary herpes simplex virus-1 (HSV-1) infection resulting in corneal perforation.

Case Report:

A 24-year-old man presented at the eye casualty of our clinic, with a 20-day history of severe pain, redness, photophobia, and tearing in both of his eyes. Slit-lamp examination revealed bilateral superior corneal perforation. A laboratory work-up that included immunological testing for infectious and autoimmune factors showed primary HSV infection. Positive PCR analysis of corneal scrapings for HSV confirmed initial end-organ ocular infection. Because the patient showed progressive HSV-1-related PUK resulting in bilateral superior corneal perforation with iris prolapse, he was prescribed both systemic and topical acyclovir and prednisone. He then underwent bilateral surgical intervention, namely eccentric penetrating keratoplasty in one eye and a two step procedure in the other, whereby two corneal patch grafts and an amniotic membrane transplant were initially used, followed 1 month later by a large diameter penetrating keratoplasty.

Conclusion:

In cases of PUK, differential diagnosis should include infectious and autoimmune diseases. Primary HSV should also be considered as a potential cause of this form of keratitis, which, if left untreated, can lead to devastating outcomes. To our knowledge, this is the first published case of bilateral PUK caused by primary HSV-1 infection.

Severe Herpetic Keratitis. II. The Costs Associated with Penetrating Keratoplasty

We report a study on 100 patients with severe herpetic keratitis.

Overall, one in three of the study group required a penetrating keratoplasty (PK). These patients required a mean of 18 days as an inpatient and 15 outpatient visits in the year the PK was performed; these figures fell to 1 inpatient day and 8 outpatient visits in the second year after surgery. The financial cost of such therapy is discussed.

The epidemiology of herpes simplex virus eye disease in Northern California

PURPOSE

To calculate the incidence and prevalence of herpes simplex virus (HSV) eye disease in a large, well-defined population in Northern California, USA, and to determine the recurrence rate following an initial episode of disease in this cohort.

METHODS

A retrospective, observational, cohort study using population-based data and medical record review. The patient database of a large, regional health maintenance organization (Northern California Kaiser Permanente) was searched, and the study population consisted of 1,042,351 people over a 1-year study period from 1 July 1998 through 30 June 1999. Only ocular HSV cases with definitive clinical or laboratory confirmed diagnoses were included. Active and inactive cases were included, however only active cases were used in incidence and prevalence calculations. Bilateral disease was counted as one case. Newly diagnosed cases were followed for recurrence from initial presentation through 31 December 2002.

RESULTS

After chart review of 322 possible cases, 71 new cases and 59 previously diagnosed active cases of ocular HSV were confirmed. This resulted in an incidence rate of 6.8 new cases/100,000 person-years (95% confidence interval, CI, 5.3-8.6). Incidence increased with age, and rates were highest in people over 75 years of age (p < 0.001). The recurrence rate in new cases was 18% for the 3-year follow-up time, and was equal to 5% per year (95% CI 3-9%).

CONCLUSION

The incidence and prevalence of ocular herpes simplex in this study was lower than previously reported. Incidence increased with age, and there were significantly higher rates in the older population.

Association between unprotected ultraviolet radiation exposure and recurrence of ocular herpes simplex virus

Studies have suggested that exposure to ultraviolet (UV) light may increase risk of herpes simplex virus (HSV) recurrence. Between 1993 and 1997, the Herpetic Eye Disease Study (HEDS) randomized 703 participants with ocular HSV to receipt of acyclovir or placebo for prevention of ocular HSV recurrence. Of these, 308 HEDS participants (48% female and 85% white; median age, 49 years) were included in a nested study of exposures thought to cause recurrence and were followed for up to 15 months. We matched weekly UV index values from the National Oceanic and Atmospheric Administration to each participant's study center and used marginal structural Cox models to account for time-varying psychological stress and contact lens use and selection bias from dropout. There were 44 recurrences of ocular HSV, yielding an incidence of 4.3 events per 1,000 person-weeks. Weighted hazard ratios comparing persons with ≥8 hours of time outdoors to those with less exposure were 0.84 (95% confidence interval (CI): 0.27, 2.63) and 3.10 (95% CI: 1.14, 8.48) for weeks with a UV index of <4 and ≥4, respectively (ratio of hazard ratios = 3.68, 95% CI: 0.43, 31.4). Though results were imprecise, when the UV index was higher (i.e., ≥4), spending 8 or more hours per week outdoors was associated with increased risk of ocular HSV recurrence.

Herpes simplex epithelial and stromal keratitis: an epidemiologic update

Herpes simplex virus (HSV) is associated with a variety of ocular diseases, including epithelial and stromal keratitis. HSV can cause stromal opacification and is believed to be the leading cause of infectious blindness in the developed world. An improved understanding of the global burden of HSV keratitis, including the incidence of severe vision loss, could have a significant effect on prevention and treatment and place it in perspective among causes of corneal ulceration. We found that the global incidence of HSV keratitis is roughly 1.5 million, including 40,000 new cases of severe monocular visual impairment or blindness each year. We also discuss relevant epidemiologic issues regarding HSV epithelial and stromal disease.

Ocular herpes simplex virus: how are latency, reactivation, recurrent disease and therapy interrelated?

Most humans are infected with herpes simplex virus (HSV) type 1 in early childhood and remain latently infected throughout life. While most individuals have mild or no symptoms, some will develop destructive HSV keratitis. Ocular infection with HSV-1 and its associated sequelae account for the majority of corneal blindness in industrialized nations. Neuronal latency in the peripheral ganglia is established when transcription of the viral genome is repressed (silenced) except for the latency-associated transcripts and microRNAs. The functions of latency-associated transcripts have been investigated since 1987. Roles have been suggested relating to reactivation, establishment of latency, neuronal protection, antiapoptosis, apoptosis, virulence and asymptomatic shedding. Here, we review HSV-1 latent infections, reactivation, recurrent disease and antiviral therapies for the ocular HSV diseases.

Trends in the indications for penetrating keratoplasty in Shandong, 2005-2010

AIM

To identify the current indications and the trend shifts for penetrating keratoplasty (PKP) in Shandong.

METHODS

The medical charts of all patients who underwent PKP at Shandong Eye Institute from June 1, 2005 to May 31, 2010 were analysed retrospectively.

RESULTS

A total of 875 patients (875 eyes) received PKP in this 5-year period, accounting for 61.6% of all corneal transplantation surgeries. The leading indications for PKP were infectious keratitis (37.1%), HSK (19.1%), keratoconus (11.2%), bullous keratopathy (8.5%), regrafting (6.7%) and corneal scarring (4.8%). The percentage of PKP for keratoconus declined year by year, whereas the percentage of bullous keratopathy had a mild annual increase. Fungal infections accounted for 65.2% of the infectious keratitis cases, remaining the leading cause of corneal infection. In addition, 54.1% of bullous keratopathy cases were associated with cataract surgery. The leading initial diagnoses associated with regrafting were infectious keratitis (38.9%), HSK (18.6%) and corneal burn (16.9%). The major causes of regrafting included graft endothelial dysfunction (39.0%), graft ulcer (28.8%) and primary disease recurrence (15.3%).

CONCLUSION

Infectious keratitis remained the leading indication for PKP in Shandong, and fungal infections were still the major cause of corneal infections. There was an increasing trend in the percentage of PKP cases indicated for bullous keratopathy but a decline in the same for keratoconus. Even with a decline in the overall proportion among all corneal transplantation surgeries, PKP is still the major corneal transplant choice in Shandong.

Ocular HSV-1 latency, reactivation and recurrent disease

Ocular infection with HSV-1 continues to be a serious clinical problem despite the availability of effective antivirals. Primary infection with HSV-1 can involve ocular and adenaxial sites and can manifest as blepharitis, conjunctivitis, or corneal epithelial keratitis. After initial ocular infection, HSV-1 can establish latent infection in the trigeminal ganglia for the lifetime of the host. During latency, the viral genome is retained in the neuron without producing viral proteins. However, abundant transcription occurs at the region encoding the latency-associated transcript, which may play significant roles in the maintenance of latency as well as neuronal reactivation. Many host and viral factors are involved in HSV-1 reactivation from latency. HSV-1 DNA is shed into tears and saliva of most adults, but in most cases this does not result in lesions. Recurrent disease occurs as HSV-1 is carried by anterograde transport to the original site of infection, or any other site innervated by the latently infected ganglia, and can reinfect the ocular tissues. Recurrent corneal disease can lead to corneal scarring, thinning, stromal opacity and neovascularization and, eventually, blindness. In spite of intensive antiviral and anti-inflammatory therapy, a significant percentage of patients do not respond to chemotherapy for herpetic necrotizing stromal keratitis. Therefore, the development of therapies that would reduce asymptomatic viral shedding and lower the risks of recurrent disease and transmission of the virus is key to decreasing the morbidity of ocular herpetic disease. This review will highlight basic HSV-1 virology, and will compare the animal models of latency, reactivation, and recurrent ocular disease to the current clinical data.

Therapeutic interventions for herpes simplex virus epithelial keratitis

BACKGROUND

Many clinical trials have been performed on the acute treatment of dendritic epithelial keratitis. Surveys of ocular antiviral pharmacology and of herpes simplex virus (HSV) eye disease have evaluated different interventions, but a systematic review of all comparative clinical studies has not previously been undertaken.

OBJECTIVES

The objective of this review was to compare the effects of various therapeutic interventions for dendritic or geographic HSV epithelial keratitis.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials - CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) in The Cochrane Library (Issue 3, 2007), MEDLINE (1966 to September 2007), EMBASE (1980 to September 2007), LILACS (up to September 2007), SIGLE (1980 to September 2007), ZETOC (21 September 2007), BIOSIS (up to 2005), JICT-EPlus (up to 2005), Index Medicus (1960 to 1965), Excerpta Medica Ophthalmology (1960 to 1973), reference lists of primary reports and review articles, and conference proceedings pertaining to ocular virology.

SELECTION CRITERIA

This review included comparative clinical trials that assessed one-week or two-week healing rates of topical ophthalmic or oral antiviral agents and or physical or chemical debridement in people with active epithelial keratitis.

DATA COLLECTION AND ANALYSIS

The review author extracted data and assessed trial quality. Interventions were compared by the proportions of participants healed at seven days and at fourteen days after trial enrolment.

MAIN RESULTS

This review included data from 99 trials that randomised a total of 5363 participants. The topical application of vidarabine, trifluridine, acyclovir or ganciclovir resulted in a high proportion of participants healing within one week of treatment. Among these antiviral agents, no treatment emerged as significantly better for the therapy of dendritic epithelial keratitis. Insufficient placebo-controlled studies were available to assess debridement and other physical or physicochemical methods of treatment. Interferon monotherapy had a slight beneficial effect on dendritic epithelial keratitis but was not better than other antiviral agents. Interferon was very effective when combined with another antiviral agent such as trifluridine.

AUTHORS' CONCLUSIONS

Currently available antiviral agents are effective and nearly equivalent. The combination of a nucleoside antiviral with either debridement or with interferon seems to speed healing. Future trials of the acute treatment of HSV epithelial keratitis must aim to achieve adequate statistical power for assessing the primary outcome of epithelial healing and should consider the effect of lesion size and other characteristics on treatment response.

Therapeutic interventions for herpes simplex virus epithelial keratitis

BACKGROUND

Many clinical trials have been performed on the acute treatment of dendritic epithelial keratitis. Surveys of ocular antiviral pharmacology and of herpes simplex virus (HSV) eye disease have evaluated different interventions, but a systematic review of all comparative clinical studies has not previously been undertaken.

OBJECTIVES

The objective of this review was to compare the effects of various therapeutic interventions for dendritic or geographic HSV epithelial keratitis.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials - CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) in The Cochrane Library (Issue 3, 2006), MEDLINE (1966 to July 2006, week 3), EMBASE (1980 to 2006, week 30), LILACS (up to August 2006), SIGLE (1980 to March 2005), ZETOC (1 August 2006), BIOSIS (up to 2005), JICT-EPlus (up to 2005), Index Medicus (1960 to 1965), Excerpta Medica Ophthalmology (1960 to 1973), reference lists of primary reports and review articles, and conference proceedings pertaining to ocular virology.

SELECTION CRITERIA

This review included comparative clinical trials that assessed one-week or two-week healing rates of topical ophthalmic or oral antiviral agents and or physical or chemical debridement in people with active epithelial keratitis.

DATA COLLECTION AND ANALYSIS

The review author extracted data and assessed trial quality. Interventions were compared by the proportions of participants healed at seven days and at fourteen days after trial enrolment.

MAIN RESULTS

This review included data from 98 trials that randomised a total of 5211 participants. Compared to idoxuridine, the topical application of vidarabine, trifluridine, or acyclovir resulted in a significantly greater proportion of participants healing within one week of treatment. Among these latter three antiviral agents, no treatment emerged as significantly better for the therapy of dendritic epithelial keratitis. Insufficient placebo-controlled studies were available to assess debridement and other physical or physicochemical methods of treatment. Interferon monotherapy had a slight beneficial effect on dendritic epithelial keratitis but was not better than other antiviral agents. Interferon was very effective when combined with another antiviral agent such as trifluridine.

AUTHORS' CONCLUSIONS

Currently available antiviral agents are effective and nearly equivalent. The combination of a nucleoside antiviral with either debridement or with interferon seems to speed healing. Future trials of the acute treatment of HSV epithelial keratitis must aim to achieve adequate statistical power for assessing the primary outcome of epithelial healing and should consider the effect of lesion size and other characteristics on treatment response.

Predictors of recurrent herpes simplex virus keratitis. Herpetic Eye Disease Study Group

PURPOSE

Determinants of the natural history of recurrent herpes simplex virus (HSV) keratitis have not been consistently established. We assessed how previous HSV eye disease affects the risk of recurrent HSV keratitis and evaluated whether demographic and other variables play any predictive role.

METHODS

Three hundred forty-six patients in the placebo group of the Herpetic Eye Disease Study's Acyclovir Prevention Trial who had experienced an episode of HSV eye disease in the previous year were followed up for 18 months. Recurrences were categorized according to the type of involvement. Relative rates of recurrence were compared for categories of demographic variables, types and number of previous ocular HSV episodes, previous nonocular HSV infection, and month of the year.

RESULTS

Fifty-eight (18%) of the 346 patients developed epithelial keratitis and 59 (18%) developed stromal keratitis during the 18 months of follow-up. Previous epithelial keratitis did not significantly affect the risk of epithelial keratitis (p = 0.84). In contrast, previous stromal keratitis increased the risk of stromal keratitis 10-fold (p < 0.001), and the risk was strongly related to the number of previous episodes (p < 0.001). Age, gender, ethnicity, and nonocular herpes were not significantly associated with recurrences, and no seasonal effects were observed.

CONCLUSION

Among patients who experienced active ocular HSV disease in the previous year, a history of epithelial keratitis was not a risk factor for recurrent epithelial keratitis. In contrast, previous, especially multiple, episodes of stromal keratitis markedly increased the probability of subsequent stromal keratitis.

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.

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.

Prospects for control of herpes simplex virus disease through immunization

Herpes simplex viruses (HSVs) can cause a variety of infections, including genital herpes. Despite effective antiviral therapy, HSV infections remain a significant worldwide public health problem. Vaccines offer the best hope for controlling spread and limiting HSV disease. This article discusses the pathogenesis and immunobiology of mucocutaneous HSV infections, summarizes the spectrum of diseases caused by HSV, and provides a review of the field of HSV vaccine research. This article also discusses what might be realistically expected of a vaccine intended for control of genital herpes and explores the question of whether a vaccine that is effective in controlling genital HSV disease might also be effective in controlling nongenital HSV disease. The efficacy of such vaccines for the full spectrum of HSV disease will eventually determine the timing and targeting of immunization, ranging from selective immunization in preadolescence to universal childhood immunization as part of the routine childhood regimen.

The spectrum of herpes simplex virus disease of the anterior segment in the 1990s

We have sampled our clinic population in order to ascertain the proportion with herpetic eye disease of the anterior segment. The age, gender predominance, and incidence of bilateral disease amongst such patients has not changed over the past 20 years. The predominant disease type was stromal keratitis, with significant morbidity and visual handicap. Herpetic eye disease of the anterior segment utilizes only 1% of out-patient clinic resources overall, but 17% of specialist external disease clinic time. There was a statistically significant correlation between total length of follow-up and reduced visual acuity. It would seem that the prevalence of herpetic eye disease of the anterior segment appears to have halved since comparable reports were published. In addition, the prognosis of the disease, in terms of the prevalence of visual impairment, has worsened.

Evidence for herpes simplex viral latency in the human cornea

Patients undergoing penetrating keratoplasty for prior herpes simplex keratitis (group A) and corneal disease unrelated to herpes simplex (group B) were investigated to assess whether the cornea is a site for herpes simplex viral latency. All patients were seropositive for herpes simplex viral antibody. Virus was isolated from the tear film postoperatively in one patient and on cocultivation from the cornea of another patient. Herpes simplex viral DNA, however, was detected in the corneas of all patients from group A and half of those from group B by means of the polymerase chain reaction and primers to three well separated regions of the viral genome. Three donor corneas had no evidence of herpes simplex viral DNA. Using RNA polymerase chain reaction, we found evidence of a latency associated transcript and also that of a glycoprotein C coding transcript in two corneas, indicating viral replication. Nine corneas had evidence of a latency associated transcript but no glycoprotein C transcript, which suggests that herpes simplex virus may be maintained in a latent state in the corneas of patients with prior herpes simplex keratitis and in some patients with corneal disease unrelated to the herpes simplex virus.

Herpes simplex keratitis in renal transplant patients

Five out of 430 patients (1.16%) undergoing kidney transplantation developed an atypical clinical picture of herpetic dendritic keratitis within four weeks after surgery. It was manifested by multiple dendrites, located mainly in the corneal periphery or the limbus, developing in relatively uninflamed eyes. The response to acyclovir therapy was prolonged and took at least three weeks. Additionally, subepithelial infiltrates with ultimate scarring developed in all patients. Disciform keratopathy was not found. This clinical course is ascribed to the patients' immunosuppressed state.

Severe herpetic keratitis. I: Prevalence of visual impairment in a clinic population

We report a prevalence study of the best visual acuity in the affected eye of 100 selected patients with herpetic keratitis seen during a two-year period. Sixty-two patients retained an acuity of 6/9 or better without requiring penetrating keratoplasty (PK). The prevalence of reduced visual acuity severe enough to warrant PK was 33%. Patients requiring PK for whom full clinical records were available suffered a mean of 6.8 episodes of keratitis. In this group of patients the vision of 18 fell from 6/6 to 6/60 over a mean period of 8.5 years. Once visual acuity was permanently reduced to 6/12, 78% of patients proceeded to lose vision to 6/60. Unilateral visual impairment occurs in at least a third of patients with severe herpetic keratitis. Once vision falls permanently to 6/12, the long-term prognosis for vision appears to be poor.

Isolation of herpes simplex virus from the cornea in chronic stromal keratitis

Images

Bilateral herpetic keratitis

Thirty patients with bilateral herpetic keratitis were evaluated, 40% of whom were atopic. Stromal keratitis occurred in 40% of the eyes and recurrent ulceration in 68%. Four patients (5 eyes) developed secondary microbial keratitis. Visual acuity decreased to 6/60 or less because of corneal opacification in 17% of the eyes.

Keratitis dendritica. An epidemiological investigation

One hundred and seven outbreaks of dendritic keratitis have been registered by the ophthalmologists over a 2-year-period in a region with a population of approximately 446 000 persons. The incidence was found to be 12/100 000/year. The average age of our sample was 46.5 years with the same age distribution for males and females, and with a non-significant predominance of males. No seasonal variation of dendritic keratitis was observed. 50% of the patients had previously suffered from dendritic keratitis. In 25% of the patients the onset of the disease had been preceded by an infectious disease, while 6% were on local steroid therapy for non-dendritic eye diseases prior to the dendritic outbreak.

The management of ocular herpesvirus infections

The many treatment methods in current use for every known complaint only seem to aggravate the difficulty of treating ocular herpes simplex virus (HSV) infections, which are generally self-limited in the immunocompetent host. The cornea is already a somewhat immune-deficient tissue since its lack of blood vessels separates it partially from the host, and treatment with glucocorticoids, which are immunosuppressive, increases the risk of damaging complications such as scarring, prolonged morbidity, bacterial or fungal superinfection, and the occasional corenal perforation. Accepted methods of treatment of specific lesions, are discussed, as are some methods that are not yet accepted, but which seem promising. Herpes zoster may result in scarring and significant loss of vision even without the use of glucocorticoids, the disease often manifesting itself in the already compromised host. The major complication is postherpetic neuralgia. None of the available treatment methods has been fully satisfactory, and every effort should be made to prevent eye lesions in patients with early infection of the ophthalmic branch of the trigeminal nerve. Stimulation of cellular immunity by various means appears to offer some new promise for control of the disease. Management of varicella, cytomegalovirus, and infectious mononucleosis are also discussed.

The essentials of data sources in eye epidemiology

The extensive literature on eye epidemiology was selectively reviewed to provide a concise and comprehensive summary on the current status of available data sources. The topics being covered were epidemiologic data evaluation, data handling, card registration, computer analysis, geographic factors, socio-economic conditions, personal attributes, genetic backgrounds, twin analysis and laboratory procedures for host defense factors including humoral and cellular immunity. Also, the scope of this article encompassed such major practical issues as glaucoma, cataract and other blinding diseases as well as traffic and occupational hazards. Epidemiologic information thus obtainable through data searching may prove tobe instrumental in the identification of any potential preventive measures in ophthalmology and public health.