Rapidly progressive acute retinal necrosis secondary to herpes simplex virus, type 1

Advances in the microbiological diagnosis of herpetic retinitis

Viral retinitis associated with herpesvirus is one of the most severe forms of uveitis and is a potentially sight-threatening ophthalmologic disease. The prognosis is poor and a rapid and aggressive management is necessary to improve the visual and sometimes vital prognosis of these patients. The treatments used are not without side effects, while many differential diagnoses exist, such as toxoplasmic retinochoroiditis, syphilitic retinitis, endogenous endophthalmitis and intraocular lymphoma. Causatives viruses are herpes simplex virus, varicella-zoster virus, and cytomegalovirus, which require rapid detection in ocular fluid, mainly aqueous humor. However, only a small amount of intraocular fluid is available for analysis. Advances in microbiological diagnostic techniques therefore were key factors in improving the management of these diseases. Historically, the diagnosis was based on immunological tests but more recently advances in molecular biology, in particular polymerase chain reaction, have played a crucial role to obtain a reliable and rapid diagnosis of viral retinitis associated with herpesvirus, as discussed in this review.

Programmed Cell Death-Dependent Host Defense in Ocular Herpes Simplex Virus Infection

Herpes simplex virus type 1 (HSV1) remains one of the most ubiquitous human pathogens on earth. The classical presentation of HSV1 infection occurs as a recurrent lesions of the oral mucosa commonly refer to as the common cold sore. However, HSV1 also is responsible for a range of ocular diseases in immunocompetent persons that are of medical importance, causing vision loss that may result in blindness. These include a recurrent corneal disease, herpes stromal keratitis, and a retinal disease, acute retinal necrosis, for which clinically relevant animal models exist. Diverse host immune mechanisms mediate control over herpesviruses, sustaining lifelong latency in neurons. Programmed cell death (PCD) pathways including apoptosis, necroptosis, and pyroptosis serve as an innate immune mechanism that eliminates virus-infected cells and regulates infection-associated inflammation during virus invasion. These different types of cell death operate under distinct regulatory mechanisms but all server to curtail virus infection. Herpesviruses, including HSV1, have evolved numerous cell death evasion strategies that restrict the hosts ability to control PCD to subvert clearance of infection and modulate inflammation. In this review, we discuss the key studies that have contributed to our current knowledge of cell death pathways manipulated by HSV1 and relate the contributions of cell death to infection and potential ocular disease outcomes.

Acute retinal necrosis with exudative retinal detachment in a child

Acute retinal necrosis (ARN) is a rare ocular emergency caused mainly by viral entities. ARN may be caused by Herpes zoster virus (HZV) and Herpes simplex virus (HSV), both HSV-1 and HSV-2. ARN mostly present in 20-60 years old immunocompetent adults. A 7-year-old girl presented to the eye clinic with complaints of left eye redness noted by her mother for 2-3 days. On examination with indirect ophthalmoscopy, no hypopyon was seen in either eye. In the left eye fundus view was hazy. Ultrasound B-scan performed showed exudative retinal detachment. PCR of ocular fluid was positive for HSV-1 DNA. The patient was started on topical steroids and antibiotics and systemic antivirals. In addition, she also received intravitreal ganciclovir 4 mg/0.1 mL three times under general anaesthesia. At her last follow-up, 3 years from her presentation, her right eye examination was within normal limits, and left eye showed thick vitreous bands with a posterior vitreous detachment, and left inferotemporal retinal scarring.

Ultra-wide-field fundus imaging of acute retinal necrosis: clinical characteristics and visual significance

OBJECTIVES

To investigate the clinical characteristics of acute retinal necrosis (ARN) with ultra-wide-field imaging (UWFI) and analyse their visual significance.

METHODS

Clinical and UWFI records of patients diagnosed with ARN at a single centre over 2 years were reviewed.

RESULTS

In 38 eyes of 35 patients, the clinical manifestations of ARN on UWFI included patchy (12 eyes) or fan-shaped necrotic lesions (26 eyes), retinal arterial obliteration (38 eyes), vitritis (38 eyes), retinal venous haemorrhage (19 eyes), and vitreous haemorrhage (6 eyes). Retinal detachment was associated with the number of retinal quadrants involved (β = 2.145, P = 0.005). LogMAR BCVA at last follow-up was associated with logMAR BCVA at presentation (β = 0.473, P = 0.004) and retinal detachment (β = 0.367, P = 0.020).

CONCLUSION

UWFI is useful for detecting retinal lesions in ARN, especially peripheral lesions or through opaque media, and provides valuable information concerning visual prognosis.

Emerging concepts in the management of acute retinal necrosis

Acute retinal necrosis (ARN), also known as Kirisawa-type uveitis, is an uncommon condition caused by infection of the retina by one of the herpes family of viruses, most typically varicella zoster virus or herpes simplex virus and less commonly cytomegalovirus. Clinical diagnosis can be challenging and is often aided by PCR-based analysis of ocular fluids. Treatment typically involves extended use of one or more antiviral agents. Long term retinal detachment risk is high. We review the literature on ARN and present an approach to the diagnosis and management of this serious condition.

Intraocular Detection of Herpes viruses by xTAG Liquid Chip Technology in Patients with Acute Retinal Necrosis

PURPOSE

To evaluate the performance of the xTAG liquid chip technology (xTAG-LCT) for etiological diagnosis of acute retinal necrosis (ARN).

METHODS

Fifteen vitreous and 3 aqueous samples from 18 ARN patients were analyzed by xTAG-LCT and multiplex PCR (mPCR)/quantitative PCR (qPCR).

RESULTS

xTAG-LCT revealed positive results in 17 of the 18 samples: 10 for Varicella Zoster Virus (VZV) alone; 5 for VZV and Epstein-Barr virus (EBV); 1 for herpes simplex viruses type 1 (HSV-1) and EBV; 1 for VZV, HSV-1 and EBV. While mPCR revealed the same results as xTAG-LCT for VZV and HSV-1 in all samples, only 2 of the 7 samples positive for EBV on xTAG-LCT were confirmed by qPCR. None of the 28 control vitreous samples from 8 non-ARN patients and 10 pair of cadaveric eyes was positive for any of the tested viruses.

CONCLUSIONS

xTAG-LCT could be a useful alternative for etiological diagnosis of ARN.

Small interfering RNA targeting for infected-cell polypeptide 4 inhibits herpes simplex virus type 1 replication in retinal pigment epithelial cells

Background:  This study sought to inhibit herpes simplex virus type 1 replication using small interfering RNA which targeting infected‐cell polypeptide 4 genes to mediate transcription of early and late viral genes in herpes simplex virus type 1 lytic (productive) infection in retina epithelial cells.

Methods:  After pre‐ or post‐infecting with herpes simplex virus type 1, small interfering RNAs were transfected into retina epithelial cells. The antiviral effects of small interfering RNA were evaluated by Western blot, plaque assays, indirect immunofluorescence and reverse transcription polymerase chain reaction. The viral titre was detected by the 50% tissue culture infective dose method.

Results:  Small interfering RNA decreased infected‐cell polypeptide 4 expression in retina epithelial cells that were infected with herpes simplex virus type 1 before or after small interfering RNA transfection. Compared with herpes simplex virus type 1 infection alone or transfection with negative control small interfering RNA, the viral titre and the retina epithelial cell cytopathic effect were significantly decreased in retina epithelial cells transfected with infected‐cell polypeptide 4‐targeting small interfering RNA (50 and 100 nM) (P < 0.05). The small interfering RNA effectively silenced herpes simplex virus type 1 infected‐cell polypeptide 4 expression on both mRNA and the protein levels (P < 0.05). The inhibition of infected‐cell polypeptide 4‐targeting small interfering RNA on infected‐cell polypeptide 4 protein expression was also verified by Western blot in herpes simplex virus type 1 infected human cornea epithelial cell, human trabecular meshwork cells and Vero cells.

Conclusions:  Infected‐cell polypeptide 4‐targeting small interfering RNA can inhibit herpes simplex virus type 1 replication in retina epithelial cells, providing a foundation for development of RNA interference as an antiviral therapy.

Role of nectin-1, HVEM, and PILR-alpha in HSV-2 entry into human retinal pigment epithelial cells

PURPOSE

Herpes simplex virus-type 2 (HSV-2) can cause acute retinal necrosis (ARN), which can lead to exudative and rhegmatogenous retinal detachment, yet little is known about the cellular and molecular mechanisms of HSV-2 entry into retinal pigment epithelial (RPE) cells. The goal of this study was to establish the identity of the critical receptors used by the virus for infection.

METHODS

A reporter HSV-2 virus, which expresses beta-galactosidase, was used to quantify entry into RPE cells, and viral replication was ascertained using a plaque assay. Flow cytometry and immunocytochemistry were used to determine cellular expression of entry receptors. Localization of these receptors to the apical or basal surface of RPE cells was determined with immunocytochemistry. The necessity of these receptors, individually and in combination, for viral entry was established using receptor-specific antibodies and siRNAs.

RESULTS

RPE cells are highly susceptible to HSV-2 entry and replication. Several assays demonstrated the expression of the entry receptors nectin-1, HVEM, and PILR-alpha and their localization primarily to the apical surfaces of RPE cells. Receptor-specific antibodies and siRNA knockdown of receptors significantly reduced viral entry and implicated nectin-1 as an important receptor, with HVEM and PILR-alpha potentially also contributing to entry.

CONCLUSIONS

HSV-2 is capable of developing a productive infection in RPE cells by using nectin-1 as an important entry receptor. To lesser degrees, HVEM and PILR-alpha may also contribute to HSV-2 entry into RPE cells.

Role for nectin-1 in herpes simplex virus 1 entry and spread in human retinal pigment epithelial cells

Herpes simplex virus 1 (HSV-1) demonstrates a unique ability to infect a variety of host cell types. Retinal pigment epithelial (RPE) cells form the outermost layer of the retina and provide a potential target for viral invasion and permanent vision impairment. Here we examine the initial cellular and molecular mechanisms that facilitate HSV-1 invasion of human RPE cells. High-resolution confocal microscopy demonstrated initial interaction of green fluorescent protein (GFP)-tagged virions with filopodia-like structures present on cell surfaces. Unidirectional movement of the virions on filopodia to the cell body was detected by live cell imaging of RPE cells, which demonstrated susceptibility to pH-dependent HSV-1 entry and replication. Use of RT-PCR indicated expression of nectin-1, herpes virus entry mediator (HVEM) and 3-O-sulfotransferase-3 (as a surrogate marker for 3-O-sulfated heparan sulfate). HVEM and nectin-1 expression was subsequently verified by flow cytometry. Nectin-1 expression in murine retinal tissue was also demonstrated by immunohistochemistry. Antibodies against nectin-1, but not HVEM, were able to block HSV-1 infection. Similar blocking effects were seen with a small interfering RNA construct specifically directed against nectin-1, which also blocked RPE cell fusion with HSV-1 glycoprotein-expressing Chinese hamster ovary (CHO-K1) cells. Anti-nectin-1 antibodies and F-actin depolymerizers were also successful in blocking the cytoskeletal changes that occur upon HSV-1 entry into cells. Our findings shed new light on the cellular and molecular mechanisms that help the virus to enter the cells of the inner eye.

Uniocular anterior chamber inoculation of a tumor necrosis factor alpha-expressing recombinant of herpes simplex virus type 1 results in more rapid destruction and increased viral replication in the retina of the uninoculated eye

Tumor necrosis factor alpha (TNF-alpha) has been shown to have a protective role in the eyes and brains of herpes simplex virus type 1 (HSV-1)-infected mice. To determine whether overexpression of TNF-alpha affected the course of virus infection following uniocular anterior chamber inoculation, a recombinant of HSV-1 that produces TNF-alpha constitutively (KOSTNF) was constructed. BALB/c mice were injected with the TNF-alpha recombinant, a recombinant containing the pCI plasmid, a recombinant rescue virus, or the parental virus. Flow cytometry and immunohistochemistry were used to identify virus-infected cells and to determine the numbers and types of infiltrating inflammatory cells in the uninjected eyes. Virus titers were determined by plaque assay. There were no differences among the groups in virus titers or the route and timing of virus spread in the injected eyes or in the suprachiasmatic nuclei. However, in the uninjected eyes of KOSTNF-infected mice, TNF-alpha expression was increased and there were more viral antigen-positive cells and immune inflammatory cells. There was earlier microscopic evidence of retinal infection and destruction in these mice, and the titers of virus in the uninjected eyes were significantly increased in KOSTNF-infected mice on day 7 postinfection compared with those of KOSpCI-, KOS6beta rescue-, or KOS6beta-infected mice. The results suggest that instead of moderating infection and reducing virus spread, overexpression of TNF-alpha has deleterious effects due to increased inflammation and virus infection that result in earlier destruction of the retina of the uninoculated eye.

Ocular association of HIV infection in the era of highly active antiretroviral therapy and the global perspective

Ocular involvement is a common complication of HIV infection. Since the late 1990s, widespread use of highly active antiretroviral therapy (HAART) has altered the spectrum, and reduced the incidence of ocular involvement in developed countries. The incidence of the most common ocular opportunistic infection, cytomegalovirus retinitis, has decreased tremendously. However, immune recovery uveitis secondary to HAART has emerged as a frequent visually threatening condition. Early diagnosis and treatment with periocular steroids is helpful in minimizing visual loss. Clinicians should also be aware that certain antimicrobial agents used to treat opportunistic infections in HIV-positive patients are associated with potentially serious ocular side effects. In developing countries, where most of the world's 40 million HIV-positive patients live, the spectrum and incidence of ocular involvement differ from those in developed countries. The lack of HAART availability is among the many causes of these differences, which may include nutritional factors, basic medical care availability and the levels of exposure to different infectious agents. These factors add to the already challenging task of treating ocular complications and preventing blindness in HIV-positive patients in developing countries.

Clinical characteristics of acute HSV-2 retinal necrosis

PURPOSE

To report the clinical features and evaluate the visual outcome of eleven cases of herpes simplex virus-2 (HSV-2) related acute retinal necrosis syndrome (ARN).

DESIGN

Retrospective interventional case series.

METHODS

Twelve eyes of eleven patients from two European centers, diagnosed with HSV-2 related acute retinal necrosis syndrome were retrospectively reviewed. Herpes simplex virus-2 DNA was detected by polymerase chain reaction in intraocular fluids (aqueous and/or vitreous). Findings at initial examination, clinical evolution with antiviral therapy, complications and final visual acuity were evaluated.

RESULTS

Herpes simplex virus-2 DNA was detected in all cases. No sample was positive for more than one virus. The mean age of disease in the first eye was 36 years (ranged from 10 to 57 years). Five patients were women and six were men. All patients were immunocompetent. Previous medical history included neonatal herpes (n = 1), previous ARN (n = 3), trauma (n = 1) and systemic corticosteroid administration before occurrence of ARN (n = 3). Preexisting pigmented chorioretinal scars were found in three cases. Patients were treated with high dose intravenous acyclovir or foscarnet +/- intravitreal ganciclovir +/- interferon. The mean follow-up was 14.5 months (from 5 to 22 months). At the end of the follow-up period, five eyes (41.7%) showed improvement of visual acuity of two or more lines. Final visual acuity was 20/60 or better in four eyes (33.3%), 20/400 or better in four eyes (33.3%) and less than 20/400 in four eyes.

CONCLUSION

History of neonatal herpes, triggering events such as neurosurgery, periocular trauma, high-dose corticosteroids, and chorioretinal scars suggest that HSV-2 retinitis reflects reactivation of HSV-2 infection.

Effect of anti-CXCL10 monoclonal antibody on herpes simplex virus type 1 keratitis and retinal infection

The inflammatory response to acute ocular herpes simplex virus type 1 (HSV-1) infection in mice involves the innate and adaptive immune response, with an associated increase in the secretion of chemokines, including CXCL10 (interferon-inducible protein 10 kDa [IP-10]). Neutralizing antibodies to mouse CXCL10 were used to determine the role of CXCL10 during the acute phase of HSV-1 ocular infection. Treatment of HSV-1-infected mice with antibody to CXCL10 significantly reduced CXCL10 levels in the eye and trigeminal ganglion and reduced mononuclear cell infiltration into the corneal stroma. These results coincided with reduced ICAM-1 and CXCR3 transcript expression, macrophage inflammatory protein-1alpha and CXCL10 levels, and corneal pathology but increased viral titers in the stroma and trigeminal ganglion. Progression of the virus from the corneal stroma to the retina during acute infection was significantly hindered in anti-CXCL10-treated mice. In addition, colocalization of viral antigen with infiltrating leukocytes in the iris and retina during acute infection suggests that one means by which HSV-1 traffics to the retina involves inflammatory cells (primarily CD11b(+) cells). Collectively, the results suggest that CXCL10 expression in the eye initially orchestrates the inflammatory response to acute HSV-1 infection, which facilitates the spread of the virus to other restricted sites within the eye.

Nonnecrotizing herpetic retinopathies masquerading as severe posterior uveitis

OBJECTIVE

Aqueous humor analysis can be performed in severe atypical forms of posterior uveitis unresponsive to conventional treatment to exclude a viral infection.

DESIGN

Noncomparative interventional case series.

PARTICIPANTS

Thirty-seven immunocompetent patients seen with corticosteroid-resistant forms of posterior uveitis underwent extensive evaluation, including anterior chamber paracentesis, to rule out a nonnecrotizing viral retinopathy.

INTERVENTION

Aqueous fluid samples were prospectively obtained. Polymerase chain reaction (PCR) and serologic evaluation of intraocular antibody production against herpesviruses were performed by molecular techniques and enzyme-linked immunosorbent assay.

MAIN OUTCOME MEASURES

Polymerase chain reaction and local antibody production for herpes simplex virus types 1 and 2, varicella-zoster virus, cytomegalovirus, and Epstein-Barr virus were determined on aqueous fluid samples.

RESULTS

Viral infection was confirmed in 5 cases (13.5%). Clinical presentation included birdshot-like retinochoroidopathy, occlusive bilateral vasculitis, and cystoid macular edema. An antiviral regimen was initiated in all cases. Inflammation was stabilized, and steroid dosage could be significantly reduced.

CONCLUSIONS

Identification of a viral agent during severe posterior uveitis can dramatically change therapeutic management.

Polymerase chain reaction as a rapid diagnostic tool for therapy of acute retinal necrosis syndrome

Herpesviruses are involved in the pathogenesis of acute retinal necrosis syndrome (ARN). A rapid and accurate diagnosis of herpetic infections is crucial for prompt administration of a specific antiviral therapy. The purpose of this study was to evaluate a polymerase chain reaction (PCR)-based assay to detect herpesvirus DNA in the aqueous humor of clinical samples from ten patients with uveitis and clinical suspicion of ARN. Samples were assayed for herpes simplex virus type 1-2 (HSV 1-2), varicella zoster virus (VZV) and cytomegalovirus (CMV). Clinical suspicion of ARN was confirmed for four patients. Two patients (one with bilateral ARN) tested PCR-positive for VZV DNA and the other two were positive for HSV 1-2 DNA. CMV DNA was not detected in any of the samples, and no sample was positive for DNA from more than one virus. The remaining patients did not show any evidence of herpesvirus DNA in their aqueous samples. Our findings demonstrate that the use of PCR for detecting herpesvirus DNA in aqueous humor of uveitic subjects may be a valuable tool for early diagnosis of acute retinal necrosis syndrome and for timely administration of a suitable therapy.

Polymerase chain reaction analysis of aqueous humour samples in necrotising retinitis

AIM

To evaluate the diagnostic value of polymerase chain reaction (PCR) performed on aqueous humour for the detection of viral DNA in patients with necrotising herpetic retinitis.

METHODS

The clinical features and laboratory results of 22 patients (29 eyes) presenting with necrotising herpetic retinitis between March 1999 and June 2001 were reviewed retrospectively. Aqueous humour was obtained after anterior chamber paracentesis and PCR was performed in all cases.

RESULTS

Viral DNA was detected in the aqueous humour of 19 patients (86.4%). Epstein-Barr virus (EBV) seroconversion was evidenced in one additional patient. In the acute retinal necrosis (ARN) group (n = 19), varicella zoster virus (VZV) DNA was identified in six patients, herpes simplex virus 1 (HSV-1) DNA in two patients, herpes simplex virus 2 (HSV-2) DNA in four patients, and cytomegalovirus (CMV) genome in four patients. In the progressive outer retinal necrosis (PORN) group (n = 3), VZV DNA was detected in all patients. No sample was positive for more than one virus.

CONCLUSIONS

PCR analysis of aqueous humour in patients with clinical features of necrotising viral retinitis can provide specific aetiological orientation and the method appears to be safe and highly sensitive.

Infiltration of T-lymphocytes in the brain after anterior chamber inoculation of a neurovirulent and neuroinvasive strain of HSV-1

Following anterior chamber (AC) inoculation of BALB/c mice with the KOS strain of herpes simplex virus type 1 (HSV-1), or with H129, a neuroinvasive and neurovirulent strain of HSV-1, both strains of virus spread from the injected eye through the brain to cause retinitis. However, KOS-infected mice develop retinitis in the uninoculated eye only, whereas H129-infected mice develop bilateral retinitis. Previous studies have shown that infiltrating T-cells in the suprachiasmatic nuclei (SCN) of the hypothalamus of KOS-infected mice concomitant with or before virus protect KOS-infected mice from ipsilateral retinitis. To determine the timing of T cell infiltration and cytokine production in the brain of H129-infected mice, adjacent, frozen sections of the brain were immunostained for virus, T-cells, IL-2, TNF-alpha or IFN-gamma. T-cells infiltrated the brains of H129-infected mice and cytokines were produced in infected tissues. However, virus spread to the optic nerve and retina of both the inoculated and uninoculated eye before T-cells and cytokines were detected in the SCN of H129-infected mice. These results suggest that infiltrating T-cells in the SCN of H129-infected mice may arrive too late to prevent the spread of virus into the optic nerves and retinas and thus prevent development of bilateral retinitis in infected mice.

Rapid spread of a neurovirulent strain of HSV-1 through the CNS of BALB/c mice following anterior chamber inoculation

Following uniocular anterior chamber (AC) inoculation of BALB/c mice with the KOS strain of herpes simplex virus type 1 (HSV-1), virus spreads from the injected eye to the ipsilateral suprachiasmatic nucleus (SCN) in the central nervous system (CNS) to infect the optic nerve and retina of the contralateral eye, and mice develop retinitis in that eye only. In contrast, after AC inoculation of BALB/c mice with the H129 strain of HSV-1, mice develop bilateral retinitis. The pathway(s) by which H129 spreads to cause bilateral retinitis is not known. To determine the route and timing of H129 spread after AC inoculation, BALB/c mice were injected in the AC of the right eye with 5 x 10(3) PFU of H129. Brains from 30 mice were sectioned on a brain matrix and the amount of virus in the brain and eyes was determined by plaque assay. Frozen sections were prepared from the eyes, brain, and trigeminal ganglia of an additional 30 mice, and HSV-1 antigen was detected by immunohistochemistry. After AC inoculation, H129 follows a pathway similar to KOS in the CNS, but H129 appears to spread more rapidly than KOS within the CNS. Unlike KOS, H129 is able to infect brain stem nuclei and H129-infected mice developed neurological impairments in addition to bilateral retinitis. The results of these studies suggest that the ability of H129 to spread rapidly in the CNS allows early virus infection of retino-recipient nuclei proximal to the contralateral and ipsilateral optic nerves. Early infection of retino-recipient nuclei, such as the SCN may allow virus to spread into the retinas before a virus-specific immune response can be induced.

Acute retinal necrosis in children caused by herpes simplex virus

PURPOSE

To report the diagnosis, management, and outcome of acute retinal necrosis syndrome in children.

METHOD

Case series of three consecutive children aged 11 years and younger who were diagnosed with acute retinal necrosis. In addition to full ocular and systemic examinations, the children underwent vitreous biopsy (Patients 1 and 2) or aqueous tap (Patient 3) for polymerase chain reaction analysis.

RESULTS

All patients had unilateral retinitis that was associated with preexisting chorioretinal scars, and two patients (Patients 1 and 3) had concurrent extraocular central nervous system abnormalities. Intraocular herpes simplex virus was detected in all three children: Type 1 in Patient 1 and Type 2 in Patients 2 and 3. In addition, all three children had a history of extraocular herpes simplex virus infection.

CONCLUSIONS

Retinitis associated with preexisting chorioretinal scars and detectable intraocular herpes simplex virus on polymerase chain reaction was common to all three children with acute retinal necrosis.

Herpes simplex virus type 2: a cause of acute retinal necrosis syndrome

PURPOSE

To describe a case of herpes simplex virus type 2 (HSV-2) acute retinal necrosis syndrome (ARN) in a 13-year-old immunocompetent girl.

METHODS

Polymerase chain reaction (PCR), cultures, flow cytometry, and cytology were performed on the vitreous sample.

RESULTS

Both PCR studies and vitreous cultures revealed HSV-2 as the cause of ARN. Flow cytometry showed CD4+, CD8+, and natural killer cells. The visual outcome of the patient was 20/200.

CONCLUSION

Successful culture of HSV-2 from the vitreous specimen in a patient with ARN proved HSV-2 to be one of the causes of ARN. The successful culture of HSV-2 has not been previously reported.

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.

Progressive outer retinal necrosis caused by herpes simplex virus type 1 in a patient with acquired immunodeficiency syndrome

OBJECTIVE/BACKGROUND

To identify the etiologic agent of rapidly progressive outer retinal necrosis (PORN) in a 32-year-old man with acquired immunodeficiency syndrome (AIDS), who had retinitis developed from cytomegalovirus (CMV). Multiple yellowish spots appeared in the deep retina without evidence of intraocular inflammation or retinal vasculitis, diagnosed clinically as PORN. Death occurred after failure of multiple organs.

DESIGN

Case report.

METHODS

Both globes were taken at autopsy, fixed in formalin, and examined histopathologically and immunohistochemically to identify causative agents in the retinal lesions.

MAIN OUTCOME MEASURE

Immunohistochemistry.

RESULTS

All layers of the retina were severely damaged and contained focal calcification. Cytomegalic inclusion bodies were found in cells in the damaged retina of the right eye. Immunohistochemical studies for herpesviruses revealed the presence of CMV antigens in the right retina at the posterior pole and herpes simplex virus type 1 (HSV-1)-specific antigen in the periphery of both retinas. No varicella-zoster virus (VZV) antigen was detected in either retina.

CONCLUSIONS

PORN has been described as a variant of necrotizing herpetic retinopathy, occurring particularly in patients with AIDS. Although the etiologic agent has been reported to be VZV, HSV-1 can be an etiologic agent.

Viral causes of the acute retinal necrosis syndrome

PURPOSE

The primary goal of this study was to determine the viral cause of the acute retinal necrosis syndrome in 28 patients (30 eyes). A secondary goal was to investigate possible associations between viral cause and patient age, and viral cause and central nervous system disease.

METHODS

A retrospective case series in which we reviewed the laboratory results and clinical histories of 28 patients (30 eyes) diagnosed with acute retinal necrosis syndrome, from whom vitreous or aqueous specimens were received, for diagnostic evaluation using previously described polymerase chain reaction-based assays.

RESULTS

Varicella-zoster virus, herpes simplex virus, and cytomegalovirus (CMV) DNA were detected in aqueous and/or vitreous specimens from 27 of 28 patients (29 of 30 eyes with a clinical history of acute retinal necrosis syndrome). No sample was positive for DNA from more than one virus. Varicella-zoster virus DNA was detected in 13 patients (15 eyes). Median age was 57 years. Herpes simplex virus type 1 DNA was detected in seven patients (seven eyes). Median age was 47 years. Six of these patients had a history of herpes simplex virus encephalitis. Herpes simplex virus type 2 DNA was detected in six patients (six eyes). Median age was 20 years. Three of these patients had a likely history of meningitis. Cytomegalovirus DNA was detected in one patient who was immunosuppressed iatrogenically. No viral DNA was detected in one patient from whom a sample was taken after 6 weeks of acyclovir therapy.

CONCLUSIONS

The data suggest that varicella-zoster virus or herpes simplex virus type 1 cause acute retinal necrosis syndrome in patients older than 25 years, whereas herpes simplex virus type 2 causes acute retinal necrosis in patients younger than 25 years. A history of central nervous system infection in a patient with acute retinal necrosis syndrome suggests that herpes simplex virus is likely to be the viral cause.

HSV-1--induced acute retinal necrosis syndrome presenting with severe inflammatory orbitopathy, proptosis, and optic nerve involvement

OBJECTIVE

To present a unique case in which orbital inflammation, proptosis, and optic neuritis were the initial symptoms of acute retinal necrosis (ARN). The clinical presentation of ARN, as well as the currently recommended diagnostic procedures and guidelines for medical treatment of ARN, are summarized.

DESIGN

Interventional case report.

TESTING

Polymerase chain reaction (PCR) techniques were made on the vitreous for cytomegalovirus, Epstein-Barr virus, herpes simplex virus (HSV), varicella zoster virus, and toxoplasmosis. A full laboratory evaluation was made together with HLA-typing and serologic tests measuring convalescent titers for HSV and other micro-organisms. Magnetic resonance imaging scan, computed tomography (CT) scan, and fluorescein angiographic examination were performed. The patient was treated with acyclovir and oral prednisone.

MAIN OUTCOME MEASURES

The patient was evaluated for initial and final visual acuity and for degree of proptosis, periocular edema, and vitreitis.

RESULTS

The first symptoms and signs of ARN were eye pain, headache, proptosis, and a swollen optic nerve on CT scan. Other than increased C-reactive protein, all blood samples were normal. PCR was positive for HSV-type I in two separate vitreous biopsies. The patient had the strongly ARN-related specificity HLA-DQ7.

CONCLUSIONS

This is the first report of HSV-induced ARN presenting with inflammatory orbitopathy and optic neuritis. Polymerase chain reaction for HSV-1 was positive more than 4 weeks after debut of symptoms, which is a new finding. The combination of severe vitreitis and retinal whitening, with or without proptosis, should alert the clinician to the possibility of herpes infection and treatment with intravenous acyclovir started promptly.

Acute retinal necrosis caused by reactivation of herpes simplex virus type 2

Acute retinal necrosis is a severe form of necrotizing retinitis. Acute retinal necrosis has been demonstrated to be caused by varicella-zoster virus and herpes simplex virus type 1. We treated three patients with acute retinal necrosis apparently caused by recrudescence of latent herpes simplex virus type 2. Primary viral infection was probably congenital, with documented perinatal herpes simplex virus type 2 infection in two patients. Bilateral chorioretinal scars were present in two patients, neither of whom had a history of ocular herpetic infection, suggesting that earlier subclinical chorioretinitis had occurred. In each case, periocular trauma preceded the development of retinitis by two to three weeks. These cases are evidently caused by trauma-induced reactivation of latent virus rather than the onset of a primary infection.

Hemodynamic alterations in the acute retinal necrosis syndrome

BACKGROUND

Clinical and histopathologic observations suggest a role for ischemia in the pathogenesis of the acute retinal necrosis (ARN) syndrome. Disruption of blood flow appears to occur at some level in the retina or choroid and may account for some of the major features of the syndrome.

METHODS

To investigate these potential circulatory changes, color Doppler imaging (CDI) was used to quantitate blood flow velocities and vascular resistance in the central retinal, ophthalmic, and short posterior ciliary arteries in ten consecutive patients with unilateral ARN syndrome. Data were analyzed with a paired Student's t test. The unaffected fellow eyes served as controls.

RESULTS

Blood flow velocities within the central retinal artery were significantly reduced in eyes with ARN syndrome compared with control eyes. In affected eyes, there was a mean reduction of 55%, 60%, and 72% in peak systolic, average, and end-diastolic velocities, respectively (P < 0.01). The calculated vascular resistance of the central retinal artery showed an upward trend, but the data fell short of statistical significance. Blood flow velocities from the ophthalmic and short posterior ciliary arteries were not significantly different compared with controls.

CONCLUSIONS

This study demonstrates marked circulatory changes in the central retinal artery of eyes involved with the ARN syndrome. Although the exact mechanism and clinical significance are yet to be determined, the data support the presence of retinal arterial hemodynamic compromise in this condition.

Herpesvirus antibody levels in the etiologic diagnosis of the acute retinal necrosis syndrome

Quantitative antibody levels to three herpesviruses in acute and chronic sera from six patients with clinical signs of the acute retinal necrosis syndrome were consistent with a specific etiologic diagnosis only in the two cases associated with cutaneous herpes zoster. Available data on acute and convalescent antibody titers to herpes group viruses from these six patients in addition to data from 27 acute retinal necrosis cases from the literature disclosed that only 13 of the 33 patients (39%) had a diagnostic increase or decrease in herpes group viral antibody levels on serial sampling. Three patients had nondiagnostic changes in viral antibody levels despite positive vitreous cultures for herpesviruses. In contrast, a review of 25 cases from the literature with paired antiviral serum and intraocular fluid antibody levels suggested a more promising approach to the etiologic diagnosis of the acute retinal necrosis syndrome. By calculating the ratio of antiviral antibodies in intraocular fluid and serum, an etiologic diagnosis could be made in 12 of 14 (86%) of subacute and convalescent samples. The sensitivity of this method decreased to 72% (13 of 18) when fluids were obtained earlier in the course of the disease.

Diagnosis and management of the acute retinal necrosis (ARN) syndrome

The acute retinal necrosis (ARN) syndrome represents a specific pattern of clinical presentation for certain herpes virus infections in the posterior segment of the eye. The classically described triad of the ARN syndrome consists of (1) an arteritis and phlebitis of the retinal and choroidal vasculature, (2) a confluent, necrotizing retinitis that preferentially affects the peripheral retina, and (3) a moderate to severe vitritis. Anterior segment inflammation, optic neuritis, and late retinal detachment are also common features of this disorder. Definitive evidence now implicates at least two members of the herpes virus family; varicella zoster virus and herpes simplex virus as causative agents. This paper summarizes the clinical presentation, as well as the currently recommended treatment regimen for the ARN syndrome, highlighting recent advances that have resulted in a significant improvement in the visual prognosis for affected patients.