Overview and Diagnosis of Acute Retinal Necrosis Syndrome

Acute Retinal Necrosis Associated with Pseudorabies Virus Infection: A Case Report and Literature Review

PURPOSE

To analyze a case of acute retinal necrosis (ARN) associated with pseudorabies virus (PRV) infection and discusses the clinical characteristics of PRV-induced ARN (PRV-ARN).

METHODS

Case report and literature review of ocular features in PRV-ARN.

RESULTS

A 52-year-old female diagnosed with encephalitis presented with bilateral vision loss, mild anterior uveitis, vitreous opacity, occlusive retinal vasculitis, and retinal detachment in her left eye. The result of metagenomic next-generation sequencing (mNGS) indicated that both cerebrospinal fluids and vitreous fluid tested positive for PRV.

CONCLUSION

PRV, a zoonosis, can infect both humans and mammals. Patients affected with PRV may experience severe encephalitis and oculopathy, and the infection has been associated with high mortality and disability. ARN is the most common ocular disease, which develops rapidly following encephalitis and is characterized by five figures: bilateral onset, rapid progression, severe visual impairment, poor response to systemic antiviral drugs, and an unfavorable prognosis.

Diagnostic and therapeutic challenges in acute retinal necrosis; an update

Acute retinal necrosis (ARN) is a rare but severe ophthalmic pathology defined by panuveitis, retinal necrosis, and high rates of retinal detachment. ARN may lead to poor visual outcomes even if promptly diagnosed and treated. ARN may present with a wide spectrum of clinical findings compatible with panuveitis including anterior uveitis, scleritis, vitritis, necrotizing retinitis, occlusive vasculitis, and optic disc edema. The American Uveitis Society introduced clinical criteria in 1994 for the diagnosis of ARN, while more recent criteria have been proposed by the Standardization of Uveitis Nomenclature (SUN) Working Group and the Japanese ARN Study Group. Multimodal imaging is a valuable tool in evaluating patients with ARN, particularly in unusual cases, while utilizing retinal imaging and applying AI algorithms in these areas of clinical research could be highly beneficial. Over the last few years, significant progress has been made in achieving timely diagnosis and treatment. The precise identification of the viral cause in suspected ARN cases has been greatly enhanced by the advancements in PCR techniques and flow cytometry used for intraocular fluids. systemic (intravenous or oral) antivirals with adjunctive intravitreal antiviral therapy are recommended as first-line therapy to reduce disease severity, the risk of vision loss, and retinal detachment incidence. Although aciclovir was the first existing antiviral agent, at present many clinicians prefer high-dose valaciclovir orally or intravenous aciclovir combined with intravitreal foscarnet. Despite significant progress in diagnosing and treating ARN, further research is needed to improve visual outcomes in this challenging clinical condition.

Bilateral Pattern Electroretinogram Abnormalities in Patients with Herpes Zoster Keratitis and Conjunctivitis

INTRODUCTION

Herpes zoster ophthalmicus (HZO) results from the reactivation of varicella zoster virus (VZV) in the ophthalmic branch of the trigeminal nerve. The inflammation caused by VZV involves multiple tissues in the eyes. Our goal is to evaluate pattern electroretinogram (PERG) changes and their relationship with corneal sub-basal nerve changes in patients with HZO.

METHODS

Twenty-two patients with herpes zoster keratitis or conjunctivitis and 20 healthy volunteers were recruited for this cross-sectional study. A PERG test was performed on both eyes of HZO patients and one eye of the healthy controls. In vivo confocal microscopy (IVCM) was also performed on both eyes of the HZO patients to detect corneal nerve damage.

RESULTS

Our results showed changes in the PERG parameters in both eyes of HZO patients compared to the healthy controls. Affected eyes showed delayed N95 peak time and decreased P50 and N95 amplitude compared to the unaffected eyes (p < 0.05, respectively). Both affected and unaffected eyes in HZO patients showed delayed P50 peak time and decreased N95 amplitude (p < 0.05, respectively) compared to controls. In HZO patients, no significant differences in each PERG parameter were found between eyes with and without corneal lesions or between eyes with and without increased Langham's cells in the corneal epithelial sub-basal layer. The IVCM images showed decreased total nerve length and number at the sub-basal layer of the epithelial cornea in affected eyes compared to unaffected eyes (p < 0.05). No significant correlation was found between total nerve length and PERG changes.

CONCLUSIONS

Our results showed that VZV-affected eyes without central cornea involvement displayed reduced N95 amplitude and prolonged P50 peak time in bilateral eyes compared to the healthy controls. Larger studies are needed to further explore the effect of HZO on the electrophysiological response of the eye and the posterior segment.

A Single-Center Case Series of Acute Retinal Necrosis at Teikyo University: Clinical Characteristics and Treatment Outcomes

Aim To evaluate the clinical characteristics, treatment course, and prognosis of patients with acute retinal necrosis (ARN), which can rapidly progress and cause severe vision loss. Design Single-center retrospective case series. Subjects and methods Six patients and seven eyes diagnosed with ARN at Teikyo University Hospital were included in this study. The clinical presentation and treatment prognosis were investigated based on data obtained from medical records. Results The mean age of the patients at the initial diagnosis was 63.6 years. Although the mean Logarithm of the Minimum Angle of Resolution (LogMAR) visual acuity tended to decrease from 0.77 at the first visit to 1.29 at the last visit, the difference was not statistically significant. Intraocular manifestations observed during the study period included ocular hypertension (14.3%), anterior uveitis (100.0%), retinal hemorrhage (71.4%), vitreous opacity (100.0%), retinal exudative vasculitis (85.7%), optic nerve atrophy (85.7%), retinal vascular occlusion (85.7%), choroidal atrophy (85.7%), macular edema (100.0%), subretinal fluid in the macula (71.4%), and retinal detachment (85.7%). Treatment modalities included oral and intravitreal antivirals (85.7%), antiplatelet medications (85.7%), steroid eye drops (85.7%), subcapsular (57.1%) and vitreous (42.9%) steroid injections, oral steroids (71.4%), and surgical intervention (85.7%). Vitrectomy led to retinal recovery in all five eyes that underwent the procedure. Conclusions The visual prognosis of patients with ARN is poor, particularly in those with preexisting visual impairment. Early detection coupled with antiviral therapy and prompt surgical intervention have been identified as potential factors that influence visual outcomes. Given the severity of ARN, collecting data from multiple centers could aid in devising future diagnostic and therapeutic strategies.

Clinical and Virological Characteristics and Prognostic Factors in Viral Necrotizing Retinitis

Purpose: Describe the clinical and virological characteristics of viral necrotizing retinitis (VNR) and assess its prognostic factors. Methods: Retrospective study (Pitié Salpêtrière Hospital, Paris) of consecutive VNR patients diagnosed and monitored by qPCR on aqueous humor between 2015 and 2019. All patients received induction therapy with intravenous +/− intravitreal injections (IVI) of antivirals. Results: Forty-one eyes of 37 patients with a mean age of 56 years were included. Involved viruses were VZV (44%), CMV (37%) and HSV2 (19%). Acute retinal necrosis represented 51%, progressive outer retinal necrosis 12% and CMV retinitis 37% of eyes. Forty-six percent of patients were immunocompromised. Median BCVA was 0.7 LogMAR at baseline and 0.8 LogMAR after an average of 14.1 months. VNR bilateralized in 27% of cases after 32 months. Retinal detachment (RD) occurred in 27% of cases after a mean duration of 98 days. Factors associated with a “poor BCVA” at 1 month were: advanced age, low baseline BCVA, high vitritis grade and viral load (VL) at baseline and the “slow responder” status (i.e., VL decrease <50% after 2 weeks of treatment). Factors associated with RD were: advanced age, immunocompetence, low baseline BCVA, high vitritis grade at baseline and use of ≤5 IVIs. Conclusions: Clinical factors including advanced age, immunocompetence, low BCVA and high vitritis grade at baseline were associated with a poor prognosis. New virological factors were predictive of a poor outcome: high baseline VL and the “slow responder” status. Sequential intraocular fluid sampling might help prognosticate the outcomes of VNR.

Automated detection of retinal exudates and drusen in ultra-widefield fundus images based on deep learning

BACKGROUND

Retinal exudates and/or drusen (RED) can be signs of many fundus diseases that can lead to irreversible vision loss. Early detection and treatment of these diseases are critical for improving vision prognosis. However, manual RED screening on a large scale is time-consuming and labour-intensive. Here, we aim to develop and assess a deep learning system for automated detection of RED using ultra-widefield fundus (UWF) images.

METHODS

A total of 26,409 UWF images from 14,994 subjects were used to develop and evaluate the deep learning system. The Zhongshan Ophthalmic Center (ZOC) dataset was selected to compare the performance of the system to that of retina specialists in RED detection. The saliency map visualization technique was used to understand which areas in the UWF image had the most influence on our deep learning system when detecting RED.

RESULTS

The system for RED detection achieved areas under the receiver operating characteristic curve of 0.994 (95% confidence interval [CI]: 0.991-0.996), 0.972 (95% CI: 0.957-0.984), and 0.988 (95% CI: 0.983-0.992) in three independent datasets. The performance of the system in the ZOC dataset was comparable to that of an experienced retina specialist. Regions of RED were highlighted by saliency maps in UWF images.

CONCLUSIONS

Our deep learning system is reliable in the automated detection of RED in UWF images. As a screening tool, our system may promote the early diagnosis and management of RED-related fundus diseases.

Implantation of Foldable Capsular Vitreous Body for the Treatment of Acute Retinal Necrosis Syndrome: A Case Report

The authors present the case of a 35-year-old male who was diagnosed with acute retinal necrosis syndrome that evolved into retinal detachment (RD), even after immediate treatment with systemic antiviral medications, as well as intravitreal injection and laser photocoagulation. Pars plana vitrectomy plus silicone oil tamponade was performed, but silicone oil emulsified 22 months later. Due to the widespread necrosis lesions and defects of the peripheral retina, RD was highly likely to reoccur after silicone oil removal; thus, foldable capsular vitreous body was implanted to support the retina. No recurrent RD was observed afterward. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:653-657.].

The necessity and optimal time for performing pars plana vitrectomy in acute retinal necrosis patients

BACKGROUND

To compare the efficacy of pars plana vitrectomy (PPV) at different time points to treat acute retinal necrosis (ARN) and to investigate the necessity of PPV for ARN.

METHODS

A retrospective review of the treatment options and outcomes of the ARN patients was performed. Thirty ARN patients (34 eyes) were included in this study. The eyes were divided into 3 groups depending on the treatment administered. In the medically treated group, there was no retinal detachment (RD) at the first visit. The routine group patients were treated with systemic antiviral medications, as well as with intravitreal antiviral injections. In the early PPV treatment group, there was no RD at the first visit. The early PPV treatment group patients were treated with systemic antiviral medications and PPV plus silicone oil tamponade and intravitreal injection. In the PPV group, there was RD at the first visit. The PPV group patients were treated with systemic antiviral medications and PPV plus silicone oil tamponade and intravitreal injection.

RESULTS

In the medically treated group, the mean baseline best corrected visual acuity (BCVA) (logMAR) was 1.38 ± 0.35. The BCVA was 1.21 ± 0.36 at the last visit for the medically treated group. In this group, one eye (12.5%) developed RD after 1 month of treatment. In the early PPV treatment group, the mean BCVA (logMAR) was 1.68 ± 0.26. The BCVA was 1.83 ± 0.21 at the last visit for the early PPV group. In this group, five eyes (29.4%) had recurrent RD before silicone oil removal. In the PPV group, the mean BCVA (logMAR) was 2.0 ± 0.35. The BCVA was 1.72 ± 0.34 at the last visit for the PPV group. In this group, one eye (11.1%) had recurrent RD before silicone oil removal. There were no significant differences among the three groups in the baseline BCVA and the BCVA at the last visit (p>0.05). There were no significant differences between the early PPV group and the PPV group in the recurrent RD rates (p = 0.38).

CONCLUSIONS

Prophylactic PPV showed no difference in recurrent RD rates or better BCVA. Therefore, prophylactic vitrectomy cannot prevent RD nor improve the prognosis of ARN based on our research.

Varicella Zoster Virus-Associated Necrotizing Retinitis After Chickenpox in a 10-Year-Old Female: A Case Report

A necrotizing retinitis in children is a rare but vision-threatening ocular complication of chickenpox. We report a 10-year-old girl who developed chickenpox 1 month before presenting with panuveitis and necrotizing retinitis. After prompt antiviral treatment, her inflammatory signs were resolved. Early detection and treatment of varicella zoster-associated necrotizing retinitis after chickenpox can achieve good visual outcome.

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.

Chronic Retinal Necrosis Severely Complicated by Neovascular Glaucoma: A Case Report

BACKGROUND

Chronic retinal necrosis (CRN) is a rare chronic granular necrotizing retinitis that was first described in 2013. CRN is characterized by intraocular inflammation accompanied by occlusive vasculitis, granular retinitis, and slowly progressing necrosis around the retina in a host with partial immune dysfunction. Cytomegalovirus (CMV) is reported to be a causative agent. There are several ocular complications such as retinal detachment and neovascular glaucoma; however, there has been no description of a clinical manifestation of neovascular glaucoma in CRN. We herein present a case of severe neovascular glaucoma in association with CRN.

CASE PRESENTATION

An 80-year-old man was referred to our hospital with poor control of inflammation and intraocular pressure (IOP). The IOP in his left eye was 29 mm Hg. Anterior chamber cells (2+) and keratic precipitates were observed. In the peripheral retina, vitreous opacities and granular necrotizing retinitis were noticed. Fluorescein angiography revealed extensive retinal nonperfusion area from the macula lesion to the periphery. PCR analysis of aqueous humor showed the presence of CMV. A diagnosis of CRN was made soon afterwards. Antiviral drug and systemic corticosteroid were administered. The treatment temporally resolved the symptom; however, panretinal photocoagulation and intravitreal injection of bevacizumab were performed to treat iris neovascularization. During the follow-up, trabeculectomy was performed because of poor IOP control. At the final visit, severe uncontrolled neovascular glaucoma caused hyphema, and his left eye lost light perception.

CONCLUSION

The prognosis of CRN is poor because of severe neovascular glaucoma and careful observation and active treatments are necessary.

Acute Retinal Necrosis: Presenting Characteristics and Clinical Outcomes in a Cohort of Polymerase Chain Reaction-Positive Patients

PURPOSE

To identify determinants of adverse outcomes in acute retinal necrosis (ARN), presenting characteristics and incidence rates of vision loss and ocular complications in a cohort of polymerase chain reaction (PCR)-positive eyes were analyzed.

DESIGN

Retrospective observational cohort study.

METHODS

Forty-one eyes of 36 patients with clinically diagnosed ARN, PCR-positive for herpes simplex virus or varicella zoster virus and evaluated between January 2002 and June 2013, were included. Main outcome measures included incidence rates of vision loss and retinal detachment (RD).

RESULTS

Presenting visual acuity was generally poor (20/50 to >20/200 in 27%; 20/200 or worse in 56%). The incidence rate of ≤20/200 was 0.66/eye-year (EY), (95% confidence interval [CI], 0.32/EY to 1.22/EY); the rate of light perception or no light perception vision was 0.07/EY (95% CI, 0.02/EY to 0.16/EY). During follow-up, 59% of eyes developed at least 1 RD (rate = 0.40/EY, 95% CI, 0.19/EY to 0.58/EY). Eyes with retinitis involving ≥25% of the retina at presentation detached at nearly 12 times the rate, as compared to those with <25% retinal involvement (0.70/EY vs 0.06/EY; P = .001). Development of an RD was the greatest determinant of adverse visual outcomes, with 4% of eyes, that had experienced at least 1 RD, achieving a best-corrected visual acuity of ≥20/40 compared to 53% of eyes that never detached (P = .0003).

CONCLUSIONS

Poor outcomes in ARN were common in this cohort. RD confers the greatest risk of incident vision loss, and once 25% or more of the retina is involved the risk of RD and visual loss increases significantly.

Development and validation of new diagnostic criteria for acute retinal necrosis

PURPOSE

The purposes of this study are to develop and validate new diagnostic criteria for acute retinal necrosis (ARN) based on the ocular findings, clinical course, and virologic testing of intraocular fluids.

SUBJECTS AND METHODS

The Japanese ARN Study Group, comprising 8 uveitis specialists and 1 statistician, was formed to develop new diagnostic criteria for ARN. The criteria used a combination of clinical features consistent with ARN including 6 early-stage ocular findings ([1a] anterior chamber cells or mutton-fat keratic precipitates; [1b] yellow-white lesion(s) in the peripheral retina [granular or patchy in the early stage, then gradually merging]; [1c] retinal arteritis; [1d] hyperemia of the optic disc; [1e] inflammatory vitreous opacities; and [1f] elevated intraocular pressure), 5 clinical courses ([2a] rapid expansion of the retinal lesion(s) circumferentially, [2b] development of retinal breaks or retinal detachment, [2c] retinal vascular occlusion, [2d] optic atrophy, and [2e] response to antiviral agents), and the results of virologic testing of intraocular fluids by means of either polymerase chain reaction or the Goldmann-Witmer coefficient for herpes simplex virus or varicella zoster virus. Various combinations of findings were analyzed to maximize the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). The criteria were then used to retrospectively analyze patients who had been diagnosed as having ARN or control uveitis. Patients were followed at 1 of 7 tertiary uveitis clinics between 2009 and 2011.

RESULTS

Analysis of the data allowed delineation of 2 levels of diagnosis: "virus-confirmed ARN" (defined as the presence of both early-stage ocular findings 1a and 1b, the presence of any 1 of the 5 clinical courses, and a positive virologic test result) and "virus-unconfirmed ARN" (defined as the presence of 4 of 6 early-stage ocular findings including 1a and 1b, presence of any 2 of the 5 clinical courses, and a negative virologic test result, or when virologic testing had not been performed). The new diagnostic criteria were applied to 45 patients with ARN and 409 patients with control uveitis, resulting in a sensitivity of 0.89, a specificity of 1.00, a PPV of 1.00, and an NPV of 0.99.

CONCLUSIONS

New diagnostic criteria for ARN were developed and found to achieve high statistical values.

Validity and agreement of uveitis experts in interpretation of ocular photographs for diagnosis of Behçet uveitis

Abstract Purpose: To evaluate agreement and estimate sensitivity and specificity of uveitis specialists' interpretation of ocular photographs in diagnosing Behçet uveitis.

METHODS

Fourteen Turkish uveitis specialists, masked to demographic and clinical features of patients, independently labeled ocular photographs (29 Behçet/30 other diagnoses) as "Behçet uveitis" or "non-Behçet." Level of agreement was evaluated using kappa statistics. Photographs were categorized based on ocular signs captured and performance of observers.

RESULTS

Exact agreement with the correct diagnosis was 56-81%. Seven reviewers correctly labeled more than 70% of photographs. Interobserver agreement among those 7 reviewers revealed moderate (κ = 0.41-0.60) or substantial (κ = 0.61-0.80) agreement in 76% of pairs. Smooth layered hypopyon, superficial retinal infiltrate with retinal hemorrhages, and branch retinal vein occlusion with vitreous haze were correctly recognized as Behçet uveitis by majority of reviewers.

CONCLUSIONS

There are ocular signs of Behçet disease that can be considered diagnostic even in the absence of any other clinical information.

Differential diagnosis of behçet uveitis

The diagnosis of Behçet disease is clinical and based on the presence of characteristic ocular and systemic inflammatory manifestations. Patients may present with anterior, posterior, or panuveitis in one or both eyes. The differential diagnosis includes a variety of infectious and noninfectious causes of acute nongranulomatous anterior uveitis, intermediate uveitis, occlusive retinal vasculitis, focal or multifocal retinitis, and necrotizing retinitis. A course characterized by sudden onset with improvement followed by recurrence of inflammatory signs is most typical for Behçet uveitis.

Efficacy and necessity of prophylactic vitrectomy for acute retinal necrosis syndrome

AIM

To compare the efficacy of prophylactic vitrectomy for acute retinal necrosis syndrome(ARN) with routine treatment in Chinese patients, thereby investigate the necessity of prophylactic vitrectomy for ARN.

METHODS

Thirty patients (37 eyes) were retrospectively included in this study. The eyes were divided into 2 groups by treatment, including routine treatment, which consisted of antiviral medication and vitrectomy after retinal detachment (RD) (n=21), and prophylactic vitrectomy, which consisted of antiviral medication and vitrectomy for the prevention of RD performed during the active inflammatory phase (n=16). The extent of necrosis was determined by fundus photographs at the time of presentation (for eyes with mild vitreous opacity) or the drawings in the operation records. Necrosis of the 37 eyes was divided into 3 grades, including peripheral, middle-peripheral and extensive. The follow-up period ranged from 8 to 57 months. Differences in visual acuity and necrosis between groups were identified using independent samples t-test.

RESULTS

Necrosis was more extensive in the routine treatment group than in the prophylactic vitrectomy group (P<0.05). In the routine treatment group, conservative treatment improved necrosis and prevented RD in 6 eyes (29%). Seven eyes (33%) obtained anatomical success, but retinal redetachment occurred in 8 eyes (57%). There were also 5 eyes (24%) developed ocular hypotony or atrophy. Ten eyes (48%) achieved equal or increased visual acuity. In the prophylactic vitrectomy group, RD occurred in 2 eyes (13%). Twelve eyes (75%) were completely anatomically successful, and 10 eyes underwent silicone oil removal. Only one eye (6%) became ocular hypotony. Fourteen eyes (88%) achieved equal or increased visual acuity. The prophylactic vitrectomy group achieved better vision trends than the routine treatment group (P<0.05). Eyes with peripheral necrosis had better visual outcomes than those with mid-peripheral (P<0.05) or extensive (P<0.05) necrosis. However, there was no significant difference between eyes with mid-peripheral and extensive necrosis (P=0.3008)

CONCLUSION

Prophylactic vitrectomy can prevent RD and improve the prognosis of ARN, making it an option for cases with rapidly progressing necrosis despite antiviral treatment and cases with moderate to extensive necrosis and severe vitreous opacity.

Acute retinal necrosis after Boston type I keratoprosthesis

A case report of a 68-year-old male who developed acute retinal necrosis (ARN) after Boston type I keratoprosthesis is presented. The procedure was performed for multiple graft failure secondary to herpetic keratitis. Clinical data including visual acuity, color fundus photography, fluorescein angiography, laboratory tests findings, and management are presented. After exclusion of other causes by laboratory workup, the patient was diagnosed with ARN most likely secondary to herpetic infection. Intravenous acyclovir and oral prednisolone were administered to the patient resulting in marked improvement in visual acuity and regression in the size of the retinitis. The patient eventually developed a soft eye and choroidal detachment with light perception vision. In patients with a history of herpetic keratitis or keratouveitis, it is highly advisable to maintain prophylactic systemic antiviral treatment before and after any ocular procedure such as the Boston keratoprosthesis.

[Acute retinal necrosis]

Acute retinal necrosis syndrome (ARN) is a rare retinitis caused by the herpes virus family, including herpes simplex virus and varicella zoster virus. ARN most commonly occurs in otherwise healthy patients of either sex at any age. It is characterized by an initial onset of episcleritis or scleritis, periorbital pain, and a frequently granulomatous anterior uveitis. The key criterion is a necrotizing retinitis starting in the periphery and spreading towards the posterior pole, associated with vitreous opacification. Optic neuropathy may also occur. A total of 75% of untreated eyes develop retinal detachment within the first two months after onset of the disease. Two out of three ARN cases show involvement of the fellow eye. Early intravenous antiviral therapy is mandatory to stop ARN progression. Peripheral retinal breaks can be treated by laser photocoagulation, thereby reducing the risk of retinal detachment. Vitreoretinal surgery is often required, and silicon oil is the tamponade of choice in ARN, resulting in good reattachment rates (90%). Visual prognosis, however, is guarded.

MRI deterioration in herpes simplex encephalitis despite clinical recovery

OBJECTIVES

Herpes simplex virus type 1 is a sporadic cause of viral encephalitis. Relapse of encephalitis occurs in up to 10% of patients, manifested by recurrent symptoms, clinical and MRI findings, and the presence of herpes simplex virus type 1 DNA in the cerebrospinal fluid (CSF).

METHODS

We describe the clinical features, MRI findings and outcome in 2 patients with herpes simplex encephalitis during the acute phase and 6 months after the onset of encephalitis.

RESULTS

Both patients had a good response to treatment and an excellent recovery. Despite clinical recovery, in a 6-month follow-up MRI lesions consistent with recurrence were disclosed, without any clinical findings or CSF abnormalities.

CONCLUSIONS

The mechanism underlying this MRI deterioration is unclear and an immune-mediated mechanism may be involved. Thus, MRI deterioration after herpes simplex encephalitis should be interpreted with caution and it does not always represent a relapse, especially when the imaging studies do not correlate with the clinical and CSF findings.

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.