Detection of herpesvirus DNA in vitreous and aqueous specimens by the polymerase chain reaction

Laboratory Investigations in Infectious Uveitis

Laboratory investigations can play a significant role in the diagnosis and decision-making of infectious uveitis. Though direct demonstration of the infective organism remains the gold standard of diagnosis, it is not always possible with ocular tissues. Recent advancements in molecular techniques have made it possible to overcome these limitations and to identify the genomic DNA of pathogens associated with infectious uveitis. Techniques such as next-generation sequencing can analyze all DNA-based lifeforms, regardless of whether they are bacteria, fungi, viruses, or parasites and have been used in the laboratory diagnosis of intraocular inflammation. On the other hand, serological tests, though they dominate the diagnostic landscape of various infectious etiologies in uveitis in routine clinical practice, have varied specificities and sensitivities in different infectious uveitis. In this review, we focus on various methods of laboratory diagnosis of infectious uveitis and discuss the recent advances in molecular diagnosis and their role in various infectious clinical entities.

An All-in-One Highly Multiplexed Diagnostic Assay for Rapid, Sensitive, and Comprehensive Detection of Intraocular Pathogens

PURPOSE

Intraocular infections are sight-threatening conditions that can lead to vision loss. Rapid identification of the etiologies plays a key role in early initiation of effective therapy to save vision. However, current diagnostic modalities are time consuming and lack sensitivity and inclusiveness. We present here a newly developed comprehensive ocular panel designed to improve diagnostic yields and provide a tool for rapid and sensitive pathogen detection.

DESIGN

Experimental laboratory investigation.

METHODS

A panel containing 46 pathogens and 2 resistance/virulence markers that are commonly detected in intraocular infections was developed. Genomic targets were scrutinized for stretches predicted to be specific for a particular species while being conserved across different strains. A set of primers for sample enrichment, and two 50mer NanoString compatible probes were then designed for each target. Probe-target hybrids were detected and quantified using the NanoString nCounter SPRINT Profiler. Diagnostic feasibility was assessed in a pilot clinical study testing samples from infectious retinitis (n = 15) and endophthalmitis (n = 12) patients, for which the etiologies were confirmed by polymerase chain reaction (PCR) or culture.

RESULTS

Analytical studies demonstrated highly sensitive detection of a broad spectrum of pathogens, including bacteria, viruses, and parasites, with limits of detection being as low as 2.5 femtograms per reaction. We also found excellent target specificity, with minimal cross-reactivity detected. The custom-designed NanoString ocular panel correctly identified the causative agent from all clinical specimens positive for a variety of pathogens.

CONCLUSION

This highly multiplexed panel for pathogen detection offers a sensitive, comprehensive, and uniform assay run directly on ocular fluids that could significantly improve diagnostics of sight-threatening intraocular infections.

Changes and Treatment Prognosis of Aqueous Humor Cytokine Concentrations of Patients with Acquired Immune Deficiency Syndrome Complicated by Cytomegalovirus Retinitis

Purpose: The purposes of this study were to investigate cytokine changes in the aqueous humor after treatment of acquired immune deficiency syndrome (AIDS) complicated with cytomegalovirus retinitis (CMVR) and to determine whether these changes are useful prognostic indicators. Methods: This study included 12 patients (15 eyes) undergoing treatment for AIDS and CMVR. The patients received intravitreal injections and systemic intravenous treatment with ganciclovir and foscarnet sodium. The aqueous humor of each eye was sampled before treatment and before the third and fifth injections. The samples were tested to determine the concentrations of each of 27 cytokines using the Luminex 200™ liquid phase chip. Results: The concentrations of cytokines interleukin (IL)-1rα (P = 0.002), IL-1b (P = 0.001), IL-8 (P = 0.001), basic fibroblast growth factor (bFGF) (P < 0.001), interferon γ-induced protein 10 (IP-10) (P = 0.001), and tumor necrosis factor (TNF)-α (P = 0.004) in the aqueous humor before the third and fifth injections were significantly lower after than before treatment. The reductions in TNF-α (P = 0.028) and IL-1b (P = 0.028) concentrations after treatment were statistically significant compared with the postoperative visual acuity improvement (≥3 lines and <3 lines). The difference in TNF-α (P = 0.018) level before and after treatment (the difference between before treatment and before the fifth intravitreal injection) was also statistically significant compared with the number of injections (≥6 times and <6 times). Conclusion: The cytokines IL-1rα, IL-1b, IL-8, bFGF, IP-10, and TNF-α may offer new avenues for evaluation of therapeutic effect, and TNF-α and IL-1b may be important cytokines for prognostic evaluation (based on visual acuity and the number of injections) in patients suffering from AIDS and CMVR. Clinical Trial Registration: Number: ChiCTR2200056955.

High Blood Cytomegalovirus Load Suggests Cytomegalovirus Retinitis in HIV/AIDS Patients: A Cross-Sectional Study

PURPOSE

To clarify the cut off value of blood CMV load to indicate CMV retinitis and its relationships with ocular features.

METHODS

Patients were divided into non-CMV and CMV retinitis groups. A logistic regression model was applied to estimate the association of each variable with CMV retinitis. Spearman correlation was used to estimate the correlation between the blood and aqueous CMV load.

RESULTS

Blood CMV load higher than 4log₁₀ (OR, 6.897; CI: 2.813-16.910; P < .001) was the major predictor of CMV retinitis. Blood CMV load wasn't different between the initial and early stage (P = .066). No correlation was observed between the blood and aqueous CMV load (P = .083, r = 0.228).

CONCLUSIONS

Blood CMV load higher than 4log₁₀ is an important predictor for CMV retinitis in HIV/AIDS patients, but it couldn't indicate the ocular features. Ophthalmologic screening is still necessary.Abbreviations: CMV: Cytomegalovirus; CMVR: Cytomegalovirus retinitis; HIV: Human Immunodeficiency Virus; AIDS: Acquired Immune Deficiency Syndrome; ART: Antiretroviral therapy; EOD: End-organ diseases; PCR: Polymerase Chain Reaction; OR: Odds Ratio; CI: 95% Confidence Interval; IQR: Interquartile range.

Bilateral CMV Retinitis in a Patient with Relapsed Non-Hodgkin Lymphoma on Oral Metronomic Chemotherapy: Case Report and Review of Literature

Cytomegalovirus (CMV) retinitis is one of the common complications in profoundly immunosuppressed patients such as those with acquired immune deficiency syndrome. It has been rarely reported in patients with lymphoma on aggressive chemotherapy. We encountered a patient with bilateral CMV retinitis who developed this vision-threatening complication while on low-dose palliative metronomic chemotherapy with oral drugs (cyclophosphamide, procarbazine, etoposide, and prednisolone). Though the infection resolved with treatment, there was residual vision loss. This case is presented to sensitize clinicians to the possibility of unusual infections in patients on long-term oral chemotherapies.

Practical Guidance for Clinical Microbiology Laboratories: Diagnosis of Ocular Infections

The variety and complexity of ocular infections have increased significantly in the last decade since the publication of Cumitech 13B, Laboratory Diagnosis of Ocular Infections (L. D. Gray, P. H. Gilligan, and W. C. Fowler, Cumitech 13B, Laboratory Diagnosis of Ocular Infections, 2010). The purpose of this practical guidance document is to review, for individuals working in clinical microbiology laboratories, current tools used in the laboratory diagnosis of ocular infections. This document begins by describing the complex, delicate anatomy of the eye, which often leads to limitations in specimen quantity, requiring a close working bond between laboratorians and ophthalmologists to ensure high-quality diagnostic care. Descriptions are provided of common ocular infections in developed nations and neglected ocular infections seen in developing nations. Subsequently, preanalytic, analytic, and postanalytic aspects of laboratory diagnosis and antimicrobial susceptibility testing are explored in depth.

Clinical utility of aqueous humor polymerase chain reaction and serologic testing for suspected infectious uveitis: a single-center retrospective study in South Korea

Background

This study aimed to assess and compare the clinical value of aqueous humor polymerase chain reaction (PCR) and serologic tests in patients diagnosed with suspected infectious uveitis.

Methods

In this retrospective observational study, data of 358 patients who were diagnosed with suspected infectious uveitis and who underwent aqueous humor PCR testing were analyzed. PCR and serologic test results were compared with the clinical features.

Results

The rates of initial diagnoses for infectious uveitis were higher with PCR (99 patients, 28%) compared to those with serologic tests (38 pateints, 11%). The diagnostic positivity of PCR was 29% for anterior uveitis, 0% for intermediate uveitis, 5% for posterior uveitis, and 30% for panuveitis. In particular, PCR was useful in confirming the diagnosis of cytomegalovirus and varicella-zoster virus infections and Toxoplasma gondii-associated uveitis. For PCR test, the sensitivity was 0.431, specificity was 0.985, and the negative and positive predictive values were 0.506 and 0.980, respectively. For IgM test, the sensitivity was 0.151, specificity was 0.970, and the negative and positive predictive values were 0.403 and 0.895, respectively.

Conclusion

Aqueous humor PCR can be a valuable diagnostic tool for confirming the infectious etiology in patients clinically diagnosed with uveitis. PCR had good predictive and diagnostic value for anterior uveitis and panuveitis compared with that for intermediate and posterior uveitis.

Initial intravitreal injection of high-dose ganciclovir for cytomegalovirus retinitis in HIV-negative patients

BACKGROUND

The purpose of this study is to examine the clinical outcomes achieved by using initial high-dose intravitreal ganciclovir injections to treat cytomegalovirus retinitis in patients without human immunodeficiency virus (HIV) infection.

METHODS

Twenty-four eyes (24 patients) with cytomegalovirus retinitis received multiple intravitreal injections of ganciclovir in weekly intervals. A higher dose (6 mg) of ganciclovir was applied at the first intravitreal injection, and a lower dose was used for maintenance. Anterior aqueous humour was obtained before each injection. The best-corrected visual acuity and cytomegalovirus loads in the anterior aqueous humour were measured.

RESULTS

The mean cytomegalovirus DNA load in aqueous humour decreased significantly from (2.59 ± 2.28) × 10⁵ copies/mL at baseline to (1 ± 1.76) × 10⁴ copies/mL one month later. The aqueous cytomegalovirus DNA load was negative in 17 eyes (70.8%) one month later. No obvious improvement of best-corrected visual acuity was found during the treatment. A positive correlation was proven between initial cytomegalovirus DNA titers in aqueous humour and the total number of intravitreal injections of ganciclovir, as well as between the baseline and final best-corrected visual acuities. No severe complications developed.

CONCLUSIONS

An initial high dose of ganciclovir (6 mg) and continuous intravitreal injections of ganciclovir could significantly decrease the cytomegalovirus load in HIV-negative patients with cytomegalovirus retinitis.

TRIAL REGISTRATION

http://clinicaltrials.gov, NCT03598452, retrospectively registered on 24 July 2018.

Cytomegalovirus retinitis in HIV-negative patients - associated conditions, clinical presentation, diagnostic methods and treatment strategy

In recent years, numerous reports have tied cytomegalovirus retinitis (CMVR) with multiple systemic conditions in the absence of human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS). These range from reports in apparently healthy individuals, through conditions rendering limited immune dysfunction such as advanced age and diabetes mellitus, and finally severe immune dysfunction such as in haematological and rheumatological conditions. Reports are also emerging, suggesting that induced local ocular immunosuppression is a risk factor for CMVR. We herein present a comprehensive collection of the accumulated findings regarding CMVR in non-HIV patients. We summarize the spectrum of underlying morbidity that has been associated with CMVR, its clinical presentation, diagnostic methods and treatment choice in the attempt to suggest the optimal treatment strategy in this complicated and diverse patient population which is still currently lacking a consensus.

Rapid Detection and Identification of Uveitis Pathogens by Qualitative Multiplex Real-Time PCR

Purpose

Infectious uveitis is a serious sight-threatening infection commonly caused by herpesviruses and Toxoplasma gondii. Etiologic diagnosis based on the clinical evaluation is often challenging. We developed and validated a multiplex real-time PCR assay coupled with high-resolution melting (HRM) for rapid detection and identification of herpes simplex viruses 1 and 2 (HSV-1 and HSV-2), varicella-zoster virus (VZV), cytomegalovirus (CMV), and T. gondii.

Methods

The assay was designed to target pathogen genome regions that yield products with distinct melting temperatures. Analytical specificity, sensitivity, and precision of HRM identification were determined. Clinical validation was performed by testing 108 intraocular fluids collected from eyes suffering with infectious uveitis (n = 30) and controls (n = 78).

Results

A nonoverlapping high-precision profile for each pathogen was generated following HRM (coefficient of variation 0%). The assay was highly sensitive, with a limit of detection of 20 genome copies for herpesviruses and 200 genome copies for T. gondii. The intra- and interassay variability of cycle threshold (Ct) measurement was ≤4% and ≤6%, respectively. Thirteen intraocular specimens collected from suspected cases of infectious uveitis were positive (mean Ct values varied from 19.4 to 27.7). Melting profiles of positive cases were consistent with HSV-2 (n = 5), VZV (n = 5), CMV (n = 2), and T. gondii (n = 1). Amplicon identities were confirmed by sequencing. Control intraocular samples from patients without a clinical diagnosis of infectious uveitis were all negative.

Conclusions

This assay allows rapid, sensitive, and reliable detection and identification of the most common known causes of infectious uveitis, making early pathogen information-based intervention possible.

Outcome of polymerase chain reaction (PCR) analysis in 100 suspected cases of infectious uveitis

BACKGROUND

Polymerase chain reaction (PCR) analysis is an important tool in the diagnosis of infectious uveitis. A retrospective, interventional study of PCR analysis of ocular fluid in suspected infectious uveitis cases between January 2014 to July 2016 was done. Nested, real-time and broad range PCR was performed for detection of the genome of Mycobacterium tuberculosis, herpes virus family, Chikungunya virus, Toxoplasma gondii, fungus, eubacterium and propionibacterium acne.

RESULTS

Total of 100 cases included, mean age was 39.2 ± 15.4 years. Uveitis was unilateral in 82% and granulomatous in 40%. Mean visual acuity at the initial visit and final visit was 0.73 logMar and 0.63 logMar respectively. PCR analysis confirmed the clinical diagnosis in 70.1% patients. The sensitivity, specificity, positive predictive value and negative predictive value of PCR analysis was 90.2%, 93.9%, 93.9% and 90.2% respectively. The quantitative value of real-time M. tb. Positive PCR ranged from 32c/ml to 2722 c/ml.

CONCLUSIONS

PCR assay is an accurate technique with high sensitivity and specificity to diagnose the DNA genome in infectious uveitis.

Polymerase Chain Reaction and Goldmann-Witmer Coefficient Testing in the Diagnosis of Infectious Uveitis in HIV-Positive and HIV-Negative Patients in South Africa

PURPOSE

To use polymerase chain reaction (PCR) and Goldmann-Witmer coefficient (GWC) calculation to diagnose infectious uveitis.

METHODS

Prospective cross-sectional study.

RESULTS

Twenty-seven of 106 patients had positive PCR and/or GWC results on aqueous humor (AH) sampling and 15 of 27 (55.6%) were HIV-positive. Patients with non-anterior uveitis (NAU) were more likely to be HIV+ (p = 0.005). More than 1 possible pathogen was identified in 9 of 27 patients of whom 7 were HIV+. The final clinical diagnosis was discordant with AH findings in 9 of 27 cases. A positive EBV PCR result was associated with a discordant diagnosis (p = 0.001). All cases of herpetic anterior uveitis (42.9% HIV+) tested PCR-/GWC+ while all cases of herpetic NAU tested PCR+/GWC- (83.3% HIV+). All rubella virus cases were PCR+/GWC+.

CONCLUSION

PCR is useful to diagnose herpetic NAU in HIV+ patients while GWC is useful to diagnose herpetic anterior uveitis.

Atypical acute retinal necrosis accompanied by Terson's syndrome: a case report

Background

Acute retinal necrosis (ARN) has characterized by panuveitis, vitritis, severe vaso-occlusive vasculitis, and diffuse necrotizing retinitis. There are no case reports on atypical ARN combined with Terson’s syndrome. Herein, we report a case of ARN with atypical clinical features combined with Terson’s syndrome that we successfully treated by intravitreal ganciclovir injection.

Case presentation

A 64-year-old man visited our eye clinic with a complaint of decreased visual acuity in his right eye. At the initial visit, his best corrected visual acuity was 20/125 in the right eye. Slit-lamp examination demonstrated mild hyperemia, keratic precipitates, and anterior chamber inflammatory reaction. Fundus examination revealed multiple diffuse white-yellowish infiltrations in the peripheral retina combined with dot hemorrhages. Ultra-wide-field fluorescence angiography showed obstructive arteritis with peripheral non-perfusion and leakage from the retinal vessels. As a result of the PCR analysis, varicella zoster virus DNA was identified in the aqueous humor. Under the diagnosis with VZV-mediated ARN, we started with intravenous acyclovir and oral prednisolone. After 3 days of the above treatment, the anterior chamber inflammation and vitreous opacity were increased. On fundus examination, multiple whitish infiltrations were increased. In addition, newly developed vitreous and peripapillary hemorrhages were detected. On the T2 brain magnetic resonance imaging (MRI) demonstrated a sub-acute or old hemorrhagic infarction in the right occipital lobe, and contrast-enhancing lesions in the right basal ganglia. The spinal tapping was performed in the department of neurology in our hospital at the time when the patient complained of headache, and intracranial pressure was 31 mmHg. Under the diagnosis of ARN with Terson’s syndrome, we started intravitreal ganciclovir (2 mg/0.5 ml) injections. After 5 intravitreal ganciclovir injections over a period of 8 months, the diffuse whitish infiltrating retinal lesions combined with dot hemorrhage were decreased. The vitreous and peripapillary hemorrhage was significantly reduced. There was no recurrence in the patient’s right eye, in which his visual acuity had improved to 20/60.

Conclusions

In the event of a poor response to traditional treatment such as intravenous acyclovir, intravitreal ganciclovir may have a role as an adjunctive therapy in patients of VZV associated ARN combined with Terson’s syndrome.

Management of Cytomegalovirus Retinitis in HIV and Non-HIV Patients

As CMVR continues to affect HIV-positive and non-HIV immunosuppressed patients, ophthalmologists must continue to tailor diagnostics and therapeutics to individual cases. In HIV-related disease, ocular fluid sampling and intravitreal drug delivery are considerations, but systemic antiviral therapy is paramount in the initial management from both ophthalmic and systemic morbidity standpoints. Non-HIV-related disease should be approached with a multidisciplinary team, including an ophthalmologist/vitreoretinal/uveitis specialist for consideration of intravitreal antiviral therapy with qualitative and quantitative aqueous PCR monitoring, and consideration of PCR genome sequencing for CMV strains that may become resistant to antiviral therapies from long-term antiviral prophylactic exposure. Hematologists or oncologists may help with patients who remain bone marrow-suppressed following transplantation or systemic chemotherapy. Because of related toxicities of the anti-CMV medications and immunosuppressive medications (eg, bone marrow suppression and cytopenias), infectious disease consultation can help in the treatment and monitoring of side effects.

A new era of uveitis: impact of polymerase chain reaction in intraocular inflammatory diseases

Uveitis is a sight-threatening intraocular inflammatory disorder which may occur from both infectious and non-infectious or autoimmune causes. The frequency of infectious uveitis and autoimmune uveitis varies depending on countries and regions. According to a nationwide survey conducted by the Japanese Ocular Inflammation Society, infectious and non-infectious uveitis accounted for 16.4 and 50.1% of new patients, respectively while the remaining 33.5% of new uveitis cases were not classified or were idiopathic uveitis. Infectious uveitis is particularly important because it causes tissue damage to the eye and may result in blindness unless treated. However, it can be treated if the pathogenic microorganisms are identified promptly and accurately. Remarkable advancements in molecular and immunological technologies have been made in the last decade, and the diagnosis of infectious uveitis has been greatly improved by the application of molecular and immunological investigations, particularly polymerase chain reaction (PCR). PCR performed on a small amount of ocular samples provides a prompt, sensitive, and specific molecular diagnosis of pathogenic microorganisms in the eye. This technology has opened a new era in the diagnosis and treatment of uveitis, enabling physicians to establish new clinical entities of uveitis caused by infectious microorganisms, identify pathogens in the eyes of many patients with uveitis, and determine prompt diagnosis and appropriate therapy. Here we review the PCR process, new PCR tests specialized for ocular diseases, microorganisms detected by the PCR tests, diseases in the eye caused by these microorganisms, and the clinical characteristics, diagnosis, and therapy of uveitis.

The value of routine polymerase chain reaction analysis of intraocular fluid specimens in the diagnosis of infectious posterior uveitis

OBJECTIVE

To assess the value of routine polymerase chain reaction (PCR) analysis on intraocular fluid from patients presenting with a first episode of suspected active infectious posterior uveitis in a population with a high prevalence of human immunodeficiency virus infection.

DESIGN

Retrospective, interventional case series. Participants. 159 consecutive patients presenting at a tertiary care hospital over a five-year period.

METHODS

PCR analysis was performed for cytomegalovirus, varicella zoster virus, herpes simplex virus types 1 and 2, Toxoplasma gondii, and Mycobacterium tuberculosis.

RESULTS

PCR analysis confirmed the initial clinical diagnosis in 55 patients (35%) and altered the initial clinical diagnosis in 36 patients (23%). The clinical diagnosis prior to PCR testing was nonspecific (uncertain) in 51 patients (32%), with PCR providing a definitive final diagnosis in 20 of these patients (39%); necrotizing herpetic retinopathy and ocular toxoplasmosis were particularly difficult to diagnose correctly without the use of PCR analysis.

CONCLUSION

The clinical phenotype alone was unreliable in diagnosing the underlying infectious cause in a quarter of patients in this study. Since the outcome of incorrectly treated infective uveitis can be blinding, PCR analysis of ocular fluids is recommended early in the disease even in resource poor settings.

Comparative analysis of polymerase chain reaction assay for herpes simplex virus 1 detection in tear

Purpose

To comparatively analyze the methodological efficacy of the polymerase chain reaction (PCR) assay for herpes simplex virus 1 (HSV) detection in tears.

Methods

This retrospective study reviewed the medical records of 115 patients who were clinically diagnosed with herpes keratitis, and their tear samples were collected for HSV detection. PCR positive rates were analyzed for their dependence on the PCR primers used (conventional PCR primer vs. nested PCR primer), the tear collecting method used (micropipetting vs. collection with schirmer strip), the disease manifestation and the patient's previous medication history.

Results

HSV DNA was detected in 23 out of 115 (20%) tear samples. The PCR positive rate in tear samples did not differ depending on the PCR primer or tear collection method used. Typical epithelial lesions showed a higher positive rate (31.4%) than atypical epithelial lesions (10.9%). The previous history of the antiviral agent seemed to affect the PCR positive rate.

Conclusions

Although the PCR positive rate was not dependent on the tear collection method or primers, HSV detection in tears using PCR was shown to be a supplementary diagnostic test in typical and atypical herpes epithelitis.

Concomitant herpes simplex virus and cytomegalovirus endotheliitis in immunocompetent patient

A case of an immunocompetent 51-year-old healthy man with chronic recurrent disciform corneal oedema and hypertensive anterior uveitis in the right eye for 2 years was unresponsive to topical corticosteroid and systemic acyclovir. Diagnostic anterior chamber tapping was performed and viral DNA PCR was positive for both cytomegalovirus and herpes simplex virus. The patient was treated with both oral valganciclovir for 3 months and long-term oral acyclovir. His condition improved significantly after the treatment; intraocular pressure and anterior chamber inflammation were controlled and the remaining keratic precipitates in the cornea started to clear up.

Repeat corneal graft failure due to graft-to-host herpetic infection

Background

Herein, we present the case of a young female patient with keratoconus, who was subjected twice to repeat keratoplasty, and each time, she experienced a corneal graft failure.

Findings

Under the suspicion of herpetic eye disease, we administered topical and systemic anti-herpetic treatment after the second repeat keratoplasty. The postoperative course was uneventful, and the corneal graft is clear, until recently. Immunohistochemistry and DNA-polymerase chain reaction were negative for herpes simplex virus-1 (HSV-1) in the host cornea, but they detected HSV-1 in both transplanted corneal grafts, thereby supporting our clinical hypothesis that graft-to-host HSV-1 infection elicited this chain reaction of complications in our patient.

Conclusion

This clinical report illustrates in a unique way the dramatic impact an unsuspected herpetic infection in the corneal graft in cases of keratoplasty may have and underscores the necessity of suspecting and adequately treating these distinct cases.

Polymerase chain reaction for diagnosis of herpetic intraocular inflammation

The authors present a polymerase chain reaction method for rapid and direct diagnosis of herpetic intraocular infections using small volume samples of intraocular fluid from 29 patients with various intraocular inflammatory diseases and 24 controls with senile cataract. Of six patients with early acute retinal necrosis from whom aqueous humor was tested, four were found to be positive for the presence of varicella-zoster (VZV) DNA while the other two were positive for the presence of herpes simplex virus (HSV) DNA. One of the patients with HSV DNA had been tested at an extremely early stage, at which time the aqueous humor viral antibody ratio did not predict a specific viral infection. Among four patients with acute retinal necrosis in relatively late stages following treatment with acyclovir from whom vitreous was obtained and tested, only one was found to have the presence of any viral DNA (VZV). On the other hand, the vitreous viral antibody ratio was found to be predictive of VZV infection in all four cases. VZV DNA was also detected in aqueous humor samples from four patients with suspected herpes zoster anterior uveitis, while HSV DNA was found in the aqueous humor of one patient with nonspecific keratouveitis. Neither human cytomegalovirus DNA nor human herpesvirus-6 DNA was detected in any sample included in this study. Finally, Epstein-Barr virus DNA was detected in the aqueous humor of the majority of patients studied and identified in cataract patients as well, suggesting either low specificity of the authors' assay for this virus or ubiquity of this virus in human eyes. In summary, the PCR method proved to be a very useful tool in establishing an etiological diagnosis in patients in the early stages of acute retinal necrosis, and in patients with anterior uveitis due to suspected HSV or VZV infection.

Etiologies of chronic anterior uveitis at a tertiary referral center over 35 years

PURPOSE

To describe the epidemiology of chronic anterior uveitis (CAU) at a tertiary center over 35 years.

METHODS

Data regarding etiology of CAU was collected from medical records of patients evaluated between 1973-2007. Relative frequencies of each diagnosis of CAU were calculated. Linear regression analyses were performed on the common types of CAU.

RESULTS

5970 patients were evaluated between 1973-2007; 31% carried a diagnosis of CAU. Idiopathic disease was diagnosed in 54% of patients (39 to 72% annually), ocular sarcoidosis in 14% of patients (2 to 20% annually), Fuchs heterochromic iridocyclitis (FHI) in 12% of patients (4 to 22% annually), and juvenile idiopathic arthritis (JIA) in 6% of patients (2 to 13% annually). The frequency of diagnosis of idiopathic CAU decreased over time, with no significant change for sarcoidosis, FHI or JIA. An increase in frequency of diagnosis was observed for HLA-B27-related disease and uveitis related to multiple sclerosis and inflammatory bowel disease.

CONCLUSIONS

The relative frequency of idiopathic disease has decreased over the past 35 years at our center. This may be related to an increase in the diagnosis of CAU associated with HLA-B27 positivity, inflammatory bowel disease (including family history) and multiple sclerosis. Despite the advances over the last 35 years, idiopathic disease still comprises at least 39% of our patients with CAU each year.

Development and evaluation of loop-mediated isothermal amplification assay for rapid and inexpensive detection of cytomegalovirus DNA in vitreous specimens from suspected cases of viral retinitis

A loop-mediated isothermal amplification (LAMP) assay for the rapid detection of cytomegalovirus (CMV) was developed and evaluated. The LAMP assay specifically amplified only CMV DNA, and no cross-reactivity with the DNA of herpes simplex virus type 1, varicella-zoster virus, adenovirus, Aspergillus flavus, or Staphylococcus aureus was observed. The sequences of the LAMP assay-positive CMV products were perfectly (100%) matched with the CMV sequence deposited in the GenBank database. The sensitivity of the LAMP assay was found to be 10 copies/microl of CMV DNA. Vitreous samples from 40 patients with suspected retinitis were subjected to LAMP and real-time PCR for the detection of CMV. Of 40 patients with suspected viral retinitis, 10 tested positive for CMV by the real-time PCR and LAMP assays. A 100% concordance was observed between the results of the two methods. The LAMP assay is a rapid, highly specific, and sensitive method for the diagnosis of retinitis caused by CMV.

Polymerase chain reaction analysis of aqueous and vitreous specimens in the diagnosis of posterior segment infectious uveitis

PURPOSE

To assess polymerase chain reaction (PCR) analysis of intraocular fluid as a test for infectious uveitis of the posterior segment in a representative patient population.

DESIGN

Retrospective, interventional case series.

METHODS

One hundred and thirty-three patients with possible infectious chorioretinitis underwent PCR testing of aqueous or vitreous in a university setting. Baseline characteristics predictive of test positivity were identified. Positive and negative predictive values were calculated.

RESULTS

Four hundred and thirty-three PCR tests of 105 aqueous and 38 vitreous specimens (mean, 3.3 tests per patient) identified 77 of the 95 patients with a final clinical diagnosis of infectious uveitis (81%). Herpes simplex virus, varicella zoster virus, and cytomegalovirus PCR analysis were performed in almost all cases, with fewer tests for toxoplasmosis or Epstein-Barr virus. Clinical features associated with positive PCR results were retinal vascular inflammation (P < .001), optic nerve involvement (P = .008), immunocompromised state (P = .039), and extensive retinitis (P = .002). Cases sampled within one week of presentation were more likely to have positive PCR results than those sampled later (P = .071). The predictive value of positive and negative tests was 98.7% and 67.9%, respectively, in this patient group. Alteration in treatment based on PCR and syphilis serologic results led to resolution in 25 of 26 patients after treatment was changed.

CONCLUSIONS

PCR testing is a useful adjunct in the diagnosis of infectious causes of posterior uveitis. Cases with vascular or optic nerve inflammation, extensive retinitis, or immunocompromise are more likely to have positive PCR results and may benefit from PCR testing of aqueous humor.

Clinical features of cytomegalovirus anterior uveitis in immunocompetent patients

PURPOSE

To describe the clinical presentation of cytomegalovirus (CMV) anterior uveitis in human immunodeficiency virus (HIV)-negative patients.

DESIGN

Retrospective, interventional case series.

METHODS

HIV-negative patients with anterior uveitis associated with elevated intraocular pressure (hypertensive anterior uveitis) seen at the Singapore National Eye Centre had their aqueous analyzed for viral deoxyribonucleic acid by polymerase chain reaction, and their records were reviewed for demographic data, ocular findings, laboratory results, and treatment.

RESULTS

Aqueous was obtained from 105 of 106 eligible eyes. Twenty-four eyes demonstrated positive results for CMV (22.8%). Eighteen eyes had Posner-Schlossman syndrome (PSS; 75%) at presentation, five eyesba had Fuchs heterochromic iridocyclitis (FHI; 20.8%), and one eye had a presumed herpetic anterior uveitis. Twelve of the 24 eyes were treated with ganciclovir. Of the 12 who completed treatment, all responded clinically, and their aqueous demonstrated negative results for CMV on repeat testing. However, nine had recurrences within eight months of stopping treatment and required further courses of ganciclovir. The 81 CMV-negative eyes included 30 with PSS, 11 with FHI, 27 with uveitic glaucomas of unknown cause, and 13 with presumed herpetic anterior uveitis.

CONCLUSIONS

CMV anterior uveitis is not uncommon in our immunocompetent patients and it may present as a recurrent acute or chronic inflammation, resembling PSS, herpetic anterior uveitis, or FHI.

Infectious uveitis in immunocompromised patients and the diagnostic value of polymerase chain reaction and Goldmann-Witmer coefficient in aqueous analysis

PURPOSE

To establish the causes of uveitis in immunocompromised patients and to determine the contribution of polymerase chain reaction (PCR) and Goldmann-Witmer coefficient (GWC) analysis of aqueous humor in patients with an infectious etiology.

DESIGN

Retrospective case series of 56 consecutive immunocompromised patients with uveitis.

METHODS

All patients underwent full ophthalmologic examination and laboratory blood analysis for uveitis. Aqueous humor analyses were performed using PCR and GWC for cytomegalovirus (CMV), herpes simplex virus (HSV), varicella zoster virus (VZV), and Toxoplasma gondii.

RESULTS

Of 56 immunocompromised patients, 43 (77%), all posterior and panuveitis, had intraocular infections. Twenty-one (49%) had CMV, three (7%) had VZV, 11 (26%) had T. gondii, six (14%) had Treponema pallidum, and one (2%) each had Aspergillus and Candida. In AIDS patients, CMV was the most common cause. A strong correlation between AIDS and ocular syphilis was also observed (P = .007). In nonAIDS immunocompromised patients, T. gondii was most frequently detected. Twenty-seven patients were examined by both PCR and GWC; five (18.5%) were positive by both assays, 15 (55.5%) were positive by PCR alone and seven (26%) by GWC alone. Viral infections were detected by PCR in 16 of 17 (94%) cases; T. gondii in four of 10 (40%) patients. Using GWC, a viral infection was diagnosed in three of 17 (18%) and T. gondii in nine of 10 (90%) cases.

CONCLUSIONS

In immunocompromised patients, PCR is superior in diagnosing viral infections. Analysis of intraocular antibody production played a decisive role in the diagnosis of ocular toxoplasmosis.

Effects of temperature and time in transit on polymerase chain reaction detection of feline herpesvirus DNA

The purpose of this study was to report methods currently recommended by commercial laboratories for collecting, shipping, and processing of samples for feline herpesvirus type 1 (FHV-1) testing using polymerase chain reaction (PCR) and to determine the effect of temperature and time on the ability of 1 PCR method to detect FHV-1 DNA in experimental and clinical samples. Eleven laboratories offering FHV-1 PCR were surveyed. There was notable variation in sample types and shipping conditions recommended and PCR protocols used by these laboratories. Subsequently, using a single PCR method, FHV-1 DNA was detected in samples exposed to various temperatures within the laboratory. Finally, FHV-1 PCR was performed on paired clinical samples collected from 25 cats and shipped at ambient temperatures via US Postal Service (USPS) or with an ice pack via a courier. Samples sent by USPS were exposed to significantly longer transit time and arrived at significantly higher temperature than did samples sent by courier. Despite this, all sample pairs yielded concordant results when tested for FHV-1 DNA using this PCR method. Although it may not be necessary for samples collected for detection of FHV-1 DNA using this PCR method to be shipped under the most expedient or temperature-controlled conditions, this should be verified for a variety of PCR assays and sample types.

Polymerase chain reaction and Goldmann-Witmer coefficient analysis are complimentary for the diagnosis of infectious uveitis

PURPOSE

To determine the relative contribution of the analysis of intraocular antibody production and the polymerase chain reaction (PCR) in aqueous humor (AH) to the diagnosis of infectious uveitis.

DESIGN

Retrospective case-control study.

METHODS

Paired AH and serum samples from 230 patients suspected of infectious uveitis were examined for intraocular antibody production against herpes simplex virus (HSV), varicella zoster virus (VZV), and Toxoplasma gondii by calculating the Goldmann-Witmer coefficient (GWC). In addition, AH samples were investigated by real-time PCR to determine the presence of microbial DNA.

RESULTS

Positive results were obtained in 54 cases (23%): 13 HSV (24%), 16 VZV (30%), and 25 T gondii (46%). Of these, 23 (43%) were positive for both GWC and PCR, 26 (48%) only for GWC, and 5 (9%) only for PCR. With PCR as the sole diagnostic approach, a correct diagnosis of the infectious etiology would have been missed in 34% of cases for the herpes viruses and in 64% for T gondii. Analysis of the relationship between a positive laboratory diagnosis and the time of sampling after onset of ocular disease demonstrated that intraocular antibody production was found throughout the course of the diseases. Viral DNA was more readily detected early in infection. In contrast, T gondii nucleic acid was not detected until 3 weeks after onset of ocular disease.

CONCLUSIONS

Analysis of intraocular antibody production contributed considerably to the etiological diagnosis of infectious uveitis, most notably of ocular toxoplasmosis early after onset of disease. Therefore, both PCR and GWC determination might be performed for comprehensive diagnosis of intraocular infections.

Diagnostic testing of vitrectomy specimens

PURPOSE

To assess the usefulness of diagnostic tests that are performed on vitrectomy specimens from patients with suspected lymphoma or infection.

DESIGN

Noncomparative, retrospective, interventional case series.

METHODS

Seventy-eight consecutive patients (84 eyes) underwent pars plana vitrectomy for diagnostic purposes. Vitrectomy with cytologic, cytofluorographic, or microbiologic analysis of vitreous samples was performed. The main outcome measures were the efficiency of diagnostic procedure and positive and negative predictive values (PPV and NPV).

RESULTS

There were 28 patients (33 eyes) with suspected intraocular lymphoma and 50 patients (51 eyes) with suspected infection, which was subdivided into chronic endogenous endophthalmitis, atypical chorioretinitis, or chronic postoperative inflammation. Vitreous testing led to a diagnosis in 48 of 78 patients (61.5%); 14 patients with a final diagnosis of lymphoma/leukemia, and 34 patients with a final diagnosis of infection. When preoperative indication was compared with final clinical diagnosis, the efficiency of the diagnostic procedure of cytologic evaluation, flow cytometry, and bacterial/fungal culture was 67%, 79%, and 96%, respectively. For lymphoma, the PPV of cytologic evaluation was 100% and the NPV 60.9%. For infection, the PPV of bacterial/fungal culture was 100% and the NPV 94.9%. CD22+ B lymphocytes >or=20% of total cells on cytofluorographic analysis had a PPV of 88% for lymphoma. A cytofluorographic CD4:CD8 T-lymphocyte ratio >or=4 had a PPV of 70% for immunologically mediated uveitis. Surgical complications were rare and manageable.

CONCLUSION

Diagnostic vitrectomy in selected patients with carefully planned testing is an effective means of supporting diagnoses in intraocular lymphoma, chronic intraocular infections, and atypical chorioretinitis. Flow cytometry quantitates the percentages and ratios of various cell types and is helpful in contrasting intraocular lymphoma with immunologically mediated uveitis.

Failure to Detect Hepatitis B Virus in Vitreous by Polymerase Chain Reaction

PURPOSE

To assay the vitreous of asymptomatic hepatitis B virus (HBV) carriers for the presence of HBV DNA using polymerase chain reaction (PCR).

METHODS

Vitreous and serum specimens were collected from 13 carriers of HBV. The presence of HBV DNA was investigated by using PCR and Digene's Hybrid Capture System. The presence of hepatitis B surface antigen (HBsAg) in vitreous was also investigated by using the enzyme immunoassay (EIA).

RESULTS

The serum was positive for HBV DNA in3 of the 13 asymptomatic carriers using PCR. Vitreous samples of all the patients, including 3 patients who were positive for HBV DNA in serum, were negative for HBV DNA with PCR and were negative for HBsAg with EIA.

CONCLUSION

There is no evidence of HBV in the vitreous of asymptomatic HBV carriers.

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.

Prise en charge diagnostique et thérapeutique des rétinites nécrosantes herpétiques

PURPOSE

To study the viral cause and present the management of necrotizing herpetic retinopathies.

METHODS

Charts of patients presenting with acute retinal necrosis (ARN) or progressive outer retinal necrosis (PORN) diagnosed between March 1997 and June 2001 were retrospectively reviewed. Intraocular specimens were obtained in 33 cases to determine the viral cause using polymerase chain reaction-based assays and/or detection of intraocular antibody production.

RESULTS

The mean age was 43.4 Years. Herpesvirus genome was identified in 29 patients (80.5%). In the ARN group (32 patients, 38 eyes), herpes simplex virus (HSV) DNA was found in 11 patients (34.4%), varicella-zoster virus (VZV) in nine patients (28.1%), and cytomegalovirus (CMV) in four patients (12.5%). One patient (3.1%) presented an Epstein-Barr virus (EBV) infection. ARN was bilateral at initial examination in six patients and secondary bilateralization was observed in four patients. In the PORN group (four patients, eight eyes), the retinitis was bilateral and VZV DNA was detected in all cases. Two patients were treated with intravenous acyclovir, six with foscarnet alone, ten with intravenous foscarnet + acyclovir, 18 with intravenous foscarnet and intravitreous ganciclovir injections. Complications of necrotizing herpetic retinitis were cataract (26%), optic nerve atrophy (23.9%), and retinal detachment (17.4%). Final visual acuity was less or equal to 20/200 in 47.8% of cases.

CONCLUSIONS

It is important to determine the specific viral etiology since progression and prognosis may be different in herpetic necrotizing retinitis caused by HSV, VZV, or CMV. Visual prognosis is improved by intensive antiviral therapy, but remains poor if complications occur.

Phenotypic and genotypic methods for the detection of herpes simplex virus serotypes

Typing of herpes simplex virus (HSV) into its serotypes plays a major role in epidemiology and management of reactivation. To develop and evaluate a polymerase chain reaction (PCR)-based restriction fragment length polymorphism (RFLP) was employed using Hae III and Taq I against neutralization test, allele-specific PCR and DNA sequencing for the detection of HSV serotypes. Neutralization test, allele-specific PCR, DNA sequencing and PCR-based RFLP were applied simultaneously to 2 standard strains (HSV-1 and HSV-2) and 23 clinical isolates. PCR-based RFLP was applied further to 20 culture negative PCR positive clinical specimens. The 179 bp product of the clinical isolates and specimens amplified using the type-common primers of HSV was subjected to DNA sequencing and PCR-based RFLP. Allele-specific PCR was absolutely specific and highly sensitive. All the typing methods differentiated concordantly 23 clinical isolates into 12 HSV-1 and 11 HSV-2. DNA sequencing did not reveal any nucleotide variations within the serotypes among the isolates sequenced. PCR-based RFLP typed a further 20 culture negative clinical specimens into 15 HSV-1 and 5 HSV-2. PCR-based RFLP was a reliable, less laborious and cost-effective molecular biological tool for the determination of HSV serotypes both for the clinical isolates and culture negative specimens.

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.

Intraocular and plasma HIV-1 RNA in HIV-infected patients with CMV retinitis and HIV-infected controls

HIV-1 RNA was quantified in intraocular specimens and plasma from AIDS patients with CMV retinitis undergoing therapeutic vitrectomy and in 8 control subjects undergoing cataract surgery using the Amplicor RT-PCR-based assay. The HIV-1 RNA concentration in the intraocular specimens was significantly lower than in plasma. Patients with CMV retinitis and plasma HIV-1 RNA concentrations > 100,000 copies/ml generally had detectable HIV-1 RNA in their intraocular specimens. These findings point to the risk of percutaneous injury from a sharp instrument used in HIV-infected patients during ophthalmic surgery and possible transmission of HIV during such surgery. Prevention of percutaneous contact will require the use of surgical instruments that reduce the likelihood of injury, as well as the wearing of double gloves during surgery.

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.

Association of herpesviruses in the aqueous humor of patients with serpiginous choroiditis: a polymerase chain reaction-based study

PURPOSE

To determine the presence of herpesvirus DNA in the aqueous humor (AH) of patients with serpiginous choroiditis using polymerase chain reaction (PCR).

METHODS

AH from nine patients previously diagnosed with serpiginous choroiditis were investigated for herpes simplex virus (HSV), varicella zoster virus (VZV), and cytomegalovirus (CMV) by conventional virological methods and PCR. The PCR-positive DNA was gel-purified, extracted, and sequenced using a dye-based Applied Biosystems procedure. The sequences were processed through the National Cancer Institute's BLAST inquiry for species identification.

RESULTS

Culture and cytological examination of AH from all nine patients were negative for HSV, VZV, and CMV. Five were positive for VZV, one was positive for HSV, and three were wholly negative using PCR. Subsequent DNA sequencing of the positive samples authenticated the presence of VZV and HSV DNA in the respective patients.

CONCLUSION

VZV and HSV DNA were detected in a subset of patients with serpiginous choroiditis, suggesting that these viruses may function in the pathogenesis of this disease.

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.

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.

Detection of herpes simplex virus DNA in atypical epithelial keratitis using polymerase chain reaction

AIM

To study herpes simplex virus (HSV) DNA in tears from patients with atypical epithelial keratitis of unknown aetiology.

METHODS

Tear samples were collected from 17 affected eyes of 17 consecutive patients suffering from epithelial keratitis in whom HSV keratitis was suspected but whose diagnosis was difficult on the basis of clinical manifestations alone. Using reduced sensitivity polymerase chain reaction (PCR), tear samples were tested for HSV DNA. Tears from the unaffected eyes of the 17 patients were also examined, along with 38 tear samples from 19 normal volunteers. Southern blot analysis was performed to confirm that amplified DNA bands were specific for HSV. Clinical correlation with photographs of corneal lesions was also investigated.

RESULTS

HSV DNA was detected in tears from the affected eyes of eight of the 17 patients with suspected HSV keratitis. Tears from the affected eyes of the other patients were PCR negative, as were tears from the unaffected eyes of all 17 patients, and from the 38 normal eyes. There was no correlation between PCR results and clinical manifestation of keratitis.

CONCLUSIONS

Based on the sensitivity of the PCR system, eight of 17 suspected HSV keratitis patients were confirmed as suffering from HSV keratitis. HSV keratitis should therefore be considered as a possible diagnosis in atypical epithelial keratitis.