The detection of herpesviral DNA in aqueous fluid samples from patients with Fuchs' heterochromic cyclitis

Members of the herpesvirus family have been found in association with a variety of intraocular inflammatory conditions. The aetiology and pathogenic mechanisms underlying the specific uveitis entity Fuchs' heterochromic cyclitis (FHC) have yet to be determined. This study investigates the presence of specific herpesviral DNA in samples of aqueous fluid from patients with FHC. Aqueous humour was obtained from 40 patients undergoing cataract surgery, 20 patients with a clinical diagnosis of FHC and 20 patients with senile cataract who acted as controls. Each sample was tested for the presence of Epstein-Barr virus (EBV), cytomegalovirus (CMV), herpes simplex virus (HSV) and varicella-zoster virus (VZV) DNA after initial amplification with virus specific primers using the polymerase chain reaction (PCR). Herpesviral DNA could not be detected in any of the aqueous samples from the FHC patients. Although a viral aetiology is unlikely, this study cannot exclude the possibility that a virus may be the initiating factor in the development of FHC or that virus may be sequestered in different ocular tissues. Control patients also showed no significant carriage of herpesvirus in their aqueous humour implying that detection of any herpesviral DNA in aqueous samples may be clinically relevant.     

Diagnostic assays in cytomegalovirus retinitis: detection of herpesvirus by simultaneous application of the polymerase chain reaction and local antibody analysis on ocular fluid.

AIM: To determine the value of the polymerase chain reaction (PCR) technique and the analysis of intraocularly produced antibodies by calculating a Goldmann-Witmer quotient (GWq) as diagnostic assays in the confirmation of a clinically diagnosed cytomegalovirus (CMV) retinitis in a group of unselected AIDS patients. METHODS: Eleven samples of undiluted ocular fluid, obtained from nine AIDS patients with a clinically diagnosed CMV retinitis were analysed for the presence of genomic DNA from CMV, HSV-1, VZV, and EBV by PCR. Nine of these samples were analysed for the presence of locally produced IgG antibodies against these herpesviruses by calculating a GWq. Ten samples obtained from patients with various entities of clinical non-herpetic uveitis and 17 samples of aqueous humour obtained at cataract surgery were used as controls. RESULTS: In 10 out of 11 samples from AIDS patients (91%) the presence of CMV DNA was demonstrated. In four out of nine (44%) patients this was accompanied by CMV DNA in the blood indicating a CMV viraemia. In one sample, VZV DNA was detected and in another sample both CMV and VZV DNA were detected. No HSV-1 or EBV DNA could be demonstrated in these 11 samples. In contrast, simultaneous analysis of locally produced IgG antibodies against herpesviruses could not confirm the initial diagnosis of CMV retinitis. Ocular fluid samples obtained from 10 control uveitis patients were negative for DNA from CMV, VZV, and EBV by PCR. In one of 10 uveitis control samples HSV-1 DNA was detected; antibody analysis did not confirm this. In the uveitis control group, a significant GWq was calculated in one sample for HSV-1 and in another sample for VZV. The cataract control samples were all herpesvirus DNA negative by PCR. CONCLUSIONS: To establish the diagnosis of CMV retinitis in AIDS patients, ophthalmoscopic examination is a sensitive method. In confirming a diagnosis in indistinctive cases, application of a PCR assay detecting CMV DNA is a more sensitive method than analysis of locally produced antibodies by calculating a GWq. In clinical non-herpetic uveitis, secondary release of HSV-1 and VZV should be considered requiring additional therapeutic anticipation.     

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.     

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.     

Multiplex polymerase chain reaction for the detection of herpes simplex virus, varicella-zoster virus and cytomegalovirus in ocular specimens

PURPOSE: A majority of ocular viral diseases are caused by herpes group of viruses. Such infections, especially atypical herpetic keratitis, iridocyclitis and intra-ocular inflammations, can often present with overlapping clinical manifestations misleading the diagnosis. Molecular techniques are most useful in such instances for an accurate and rapid diagnosis since conventional methods are time consuming and less sensitive. A multiplex PCR was developed and used for the detection of herpes simplex virus (HSV), varicella zoster virus (VZV), and cytomegalovirus (CMV) in ocular samples. METHODS: One hundred and forty six ocular samples (corneal scrapings - 52, aqueous fluid - 36, vitreous fluid - 31, tissues - 26, skin vesicle scraping - 1) were included in the study. The sensitivity of the assay was determined using serial dilutions of standard strains of HSV, VZV, and CMV vis-à-vis plaque forming assay. RESULTS: The sensitivity of the assay was 4, 4 and 12 PFU/ml or 20, 20 and 60 genome copy numbers of HSV, VZV and CMV respectively. Using DNA from various sources (fungal, bacterial, human leukocytes, tissues) along with standard positive controls, the assay was found to be highly specific. HSV DNA was detected in majority of the clinical samples (33.6%), most frequent being corneal samples. Comparatively, VZV and CMV infections were detected in small number of samples (VZV-3, CMV-2). CONCLUSIONS: We found the assay very useful in our set-up whenever a differential diagnosis of herpetic infections was suggested by the ophthalmologist. The multiplex PCR we have described here can be of greater value in clinics with larger number of patients suspected of having HSV, VZV or CMV infections.     

The diagnostic significance of enzyme linked immuno-sorbent assay for herpes simplex,varicella zoster and cytomegalovirus retinitis

PURPOSE: To evaluate the diagnostic usefulness of enzyme linked immuno-sorbent assay (ELISA) in single serum samples to associate herpes simplex virus (HSV), varicella zoster virus (VZV) or cytomegalovirus (CMV) with viral retinitis as against polymerase chain reaction (PCR) on intraocular specimens. It was also designed to study the seroprevalence in normal healthy individuals, and the genomic prevalence of HSV, VZV and CMV in patients without an active viral inflammatory process. METHODS: PCR for the detection of HSV, VZV and CMV genomes was done on 33 and 90 intraocular fluids from viral retinal patients and non-viral controls respectively. ELISA was done on 30 and 100 serum samples from viral retinitis patients and normal healthy controls respectively. RESULTS: PCR did not detect HSV, VZV and CMV genomes except one, in which VZV-DNA was detected. ELISA showed prevalence rates of 28%, 83% and 90% for antibodies against HSV, VZV and CMV respectively in the normal population. In the 30 viral retinitis patients, PCR detected HSV-DNA in 2 (6.7%), VZV-DNA in 7 (23.3%) and CMV-DNA in 6 (20.0%) patients, while ELISA detected antibodies against HSV, VZV and CMV in 13 (43.3%), 24 (80.0%) and 23 (76.7%) patients respectively. ELISA was of value in indirect diagnosis only in 6 (20.0%) as compared to 15 (50.0%) of 30 patients by PCR, this difference was statistically significant (McNemar test, P value = 0.005). CONCLUSION: Serology by ELISA is no longer a useful diagnostic tool to associate HSV, VZV and CMV viruses with viral retinitis.     

Typing of Herpes Simplex Virus in Patients with Uveitis

Aim: To examine the type of herpes simplex virus (HSV) in cases with uveitis.Materials and Methods: Intraocular fluid specimens obtained from 3 cases with herpetic iridocyclitis and 6 cases with acute retinal necrosis (ARN) were examined by polymerase chain reaction (PCR). HSV typing was performed by the restriction patterns of the PCR products. Serum samples obtained from these cases and 33 cases with uveitis were examined by neutralization test (NT) for the availability of the typing of HSV.Results: The restriction patterns of the PCR products amplified from 3 specimens of iridocyclitis revealed HSV type 1 DNA. HSV type 2 DNA was identified in 5 of 6 cases of ARN and HSV type 1 DNA was found in only one case. The results of serum NT titers correlated with the typing of the amplicons.Conclusions: In the cases studied, HSV type 1 was the dominant etiological agent in herpetic iridocyclitis, while HSV type 2 plated a similar role in HSV-associated ARN. The examination of the serum NT may be helpful for the identification of the etiological types of HSV in patients with uveitis.     

Searching for viral antibodies and genome in intraocular fluids of patients with Fuchs uveitis and non-infectious uveitis

Background

To characterise the polyspecific intraocular antibody synthesis in aqueous humor of patients with Fuchs uveitis and other types of non-infectious uveitis.

Methods

Aqueous and serum samples collected from 24 patients with Fuchs uveitis, 21 patients with non-infectious uveitis, and 27 healthy subjects undergoing elective cataract surgery (control group) were analysed. In addition, vitreous samples, collected from seven uveitis patients (five Fuchs and two panuveitis) during retinal surgery, were examined. Specific immunoglobulin G antibodies against cytomegalovirus (CMV), rubella virus, herpes simplex virus (HSV), and varicella zoster virus (VZV) were investigated, and Goldmann–Witmer coefficients (GWCs) were calculated. Real-time PCR was performed to detect viral genome for HSV, VZV, and CMV, while nested PCR was conducted to detect rubella RNA.

Results

None of the control samples tested positive for any of the viral antibodies investigated. Intraocular antibody production was found in eight samples of patients affected by Fuchs uveitis (6/8 positive for rubella virus and 2/8 positive for herpes virus). Among patients with non-infectious uveitis, three tested positive for intraocular antibody production (one RV, one HSV and one for VZV). PCR was positive for RV in two patients with Fuchs uveitis, in three patients with non-infectious uveitis (one for RV and two for HSV), and in three control subjects (one for CMV and one for HSV).

Conclusions

Our series confirmed the presence of specific viral antibodies, especially against rubella virus, in the subgroup of patients affected by Fuchs uveitis, suggesting that this virus may be responsible for this chronic inflammatory condition. Rubella virus is probably the main causative agent of Fuchs uveitis, but other viruses may also be involved in the pathogenesis of this disease.     

Typing of herpes simplex virus in patients with uveitis

AIM: To examine the type of herpes simplex virus (HSV) in cases with uveitis. MATERIALS AND METHODS: Intraocular fluid specimens obtained from 3 cases with herpetic iridocyclitis and 6 cases with acute retinal necrosis (ARN) were examined by polymerase chain reaction (PCR). HSV typing was performed by the restriction patterns of the PCR products. Serum samples obtained from these cases and 33 cases with uveitis were examined by neutralization test (NT) for the availability of the typing of HSV. RESULTS: The restriction patterns of the PCR products amplified from 3 specimens of iridocyclitis revealed HSV type 1 DNA. HSV type 2 DNA was identified in 5 of 6 cases of ARN and HSV type 1 DNA was found in only one case. The results of serum NT titers correlated with the typing of the amplicons. CONCLUSIONS: In the cases studied, HSV type 1 was the dominant etiological agent in herpetic iridocyclitis, while HSV type 2 played a similar role in HSV-associated ARN. The examination of the serum NT may be helpful for the identification of the etiological types of HSV in patients with uveitis.     

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.     

Detection of herpesvirus genome by multiplex polymerase chain reaction (PCR) and real-time PCR in ocular fluids of patients with acute retinal necrosis

PURPOSE: The human herpesvirus (HHV) family consists of types 1 to 8 (HHV1-8). The purpose of this study was to investigate the detection of HHV DNA, especially HSV1 (herpes simplex virus 1, HHV1), HSV2 (herpes simplex virus 2, HHV2), and VZV (varicella-zoster virus, HHV3) in ocular fluids of patients with acute retinal necrosis(ARN). METHODS: The intraocular genome for HHV1-8 was determined in 19 ocular fluid samples (12 vitreous fluid and 7 aqueous humor samples) taken from ARN patients (n=14). The samples were tested for the presence of virus DNA by two systems of polymerase chain reaction (PCR): the multiplex PCR screening test and real-time quantitative PCR. RESULTS: Multiplex PCR demonstrated VZV (n=16, 84%), HSV1 (n = 1.5%) or HSV2 (n = 2.11%)genomic DNA in all the samples. In real-time PCR, a high copy number of virus DNA was detected. The virus DNA-positive samples contained Epstein-Barr virus (EBV, HHV4) DNA in 9 of 19 samples (47%). No HHV6-8 DNA was detected in the ocular samples, and no virus DNA was detected in the serum samples. CONCLUSIONS: The genome for HHV1-3 was detected in the patients with ARN. All cases contained a high copy number for the virus DNA that indicates viral replication. PCR systems are useful for determing whether virus infections are associated with uveitis.     

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.     

Acute retinal necrosis--a case report

We present a case of acute retinal necrosis (ARN) which is a rare but devastating and rapidly progressive viral retinitis. It is caused mainly by Herpes simplex virus (HSV) or Varicella zoster virus (VZV) (2), but also Cytomegalovirus (CMV) and Epstein-Barr virus infections may be aethiological factors of ARN. A 17-year-old male patient was referred with history of painful sudden worsening of visual acuity in the left eye and the presence of floaters in the visual field of the right eye. Based on the ophthalmological examination the diagnosis of bilateral ARN was established. Aqueous humor aspirates were analyzed using polymerase chain reaction (PCR) for Herpes simplex virus (HSV), Varicella zoster virus (VZV), Cytomegalovirus (CMV) and Epstein-Baar virus (EBV). PCR confirmed the presence of Varicella zoster virus in aqueous humor samples. Prompt systemic antiviral therapy combined with steroids was initiated. Since a rapid and accurate diagnosis is crucial for prompt administration of antiviral therapy, PCR-based analysis of intraocular fluids orovides a valuable tool in the establishina an etiologic factor in patients with retinitis caused by herpesvirus.     

Acute Retinal Necrosis

Acute retinal necrosis (ARN) is an uncommon intraocular inflammatory syndrome characterized by severe and diffuse uveitis, retinal vasculitis, and retinal necrosis. It is typically described to occur in immunocompetent patients, but can also be found in immunocompromised subjects. Varicella-zoster virus (VZV), herpes simplex virus (HSV 1 and 2), cytomegalovirus (CMV), and Epstein-Barr virus (EBV) have been implicated in the etiology of ARN. The characteristic features of the disease include iridocyclitis, vitritis, retinal vasculitis, and retinal necrosis. Bilateral involvement occurs in two-thirds of the patients, frequently in the first six weeks, but sometimes months to years later. Retinal detachment occurs in 75% of the cases. The diagnosis of ARN is usually based in clinical features. The use of polymerase chain reaction (PCR) in aqueous humor samples is useful to identify the etiology of the disease. The treatment of ARN includes intravenous acyclovir, corticosteroids and aspirin. To prevent fellow eye involvement, intravenous acyclovir is followed by oral acyclovir for 14 weeks. Alternatives to acyclovir include ganciclovir, foscarnet, famcyclovir, brivudine, and valgancyclovir.     

Acute retinal necrosis

Acute retinal necrosis (ARN) is an uncommon intraocular inflammatory syndrome characterized by severe and diffuse uveitis, retinal vasculitis, and retinal necrosis. It is typically described to occur in immunocompetent patients, but can also be found in immunocompromised subjects. Varicella-zoster virus (VZV), herpes simplex virus (HSV 1 and 2), cytomegalovirus (CMV), and Epstein-Barr virus (EBV) have been implicated in the etiology of ARN. The characteristic features of the disease include iridocyclitis, vitritis, retinal vasculitis, and retinal necrosis. Bilateral involvement occurs in two-thirds of the patients, frequently in the first six weeks, but sometimes months to years later. Retinal detachment occurs in 75% of the cases. The diagnosis of ARN is usually based in clinical features. The use of polymerase chain reaction (PCR) in aqueous humor samples is useful to identify the etiology of the disease. The treatment of ARN includes intravenous acyclovir, corticosteroids and aspirin. To prevent fellow eye involvement, intravenous acyclovir is followed by oral acyclovir for 14 weeks. Alternatives to acyclovir include ganciclovir, foscarnet, famcyclovir, brivudine, and valgancyclovir.     

Overview and diagnosis of acute retinal necrosis syndrome

Acute retinal necrosis (ARN) syndrome, also known as Kirisawa's uveitis, is one of the most serious ocular diseases, and is characterized by a combination of peripheral, confluent, necrotizing retinitis, retinal arteritis, and intraocular inflammation. ARN syndrome is caused by the herpesvirus family, including herpes simplex virus (HSV) and varicella-zoster virus (VZV). The diagnosis of ARN syndrome is fundamentally based on clinical appearance and the demonstration of viral infection. Recently, polymerase chain reaction techniques permit detection of very small amounts of viral DNA in intraocular specimens. This knowledge can help in both the diagnosis and design of therapeutic strategy for ARN syndrome. Here we review the clinical presentation and the current advances in the diagnosis of ARN syndrome.     

Overview and Diagnosis of Acute Retinal Necrosis Syndrome

Acute retinal necrosis (ARN) syndrome, also known as Kirisawa's uveitis, is one of the most serious ocular diseases, and is characterized by a combination of peripheral, confluent, necrotizing retinitis, retinal arteritis, and intraocular inflammation. ARN syndrome is caused by the herpesvirus family, including herpes simplex virus (HSV) and varicella-zoster virus (VZV). The diagnosis of ARN syndrome is fundamentally based on clinical appearance and the demonstration of viral infection. Recently, polymerase chain reaction techniques permit detection of very small amounts of viral DNA in intraocular specimens. This knowledge can help in both the diagnosis and design of therapeutic strategy for ARN syndrome. Here we review the clinical presentation and the current advances in the diagnosis of ARN syndrome.     

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.     

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.     

Laboratory investigations on viral and Chlamydia trachomatis infections of the eye: Sankara Nethralaya experiences

PURPOSE: To review our experiences on the laboratory investigations of viral and chlamydial conjunctivitis, congenital cataract and acute retinal inflammations seen from 1990 to 1998 at Sankara Nethralaya, Chennai, India. METHODS: Conjunctival swabs/scrapings from 1061 patients with conjunctivitis were investigated. Nested polymerase chain reaction (nPCR) and restriction fragment length polymorphism (RFLP) techniques were applied on 74 conjunctival swabs during the 1996 outbreak of acute viral conjunctivitis. The occurrence of Rubella virus in 86 lens aspirates of congenital cataract was investigated. Tests were performed for the association of Herpes simplex virus (HSV), Varicella zoster virus (VZV) and Cytomegalovirus (CMV) with acute retinal inflammation in 32 patients. RESULTS: The causative agents of conjunctivitis were Adenovirus in 13.8%, HSV in 2.2% and C. trachomatis in 20.9% of the patients. Epidemics were due to Adenovirus type 4 in 1991, type 3 in 1992-93 and type 7a in 1996. PCR was 37.9% more sensitive in detecting Adenovirus than virological methods. RFLP identified the conjunctivitis epidemic strain of 1996 as Adenovirus 7a. Rubella virus was isolated from 8.1% of lens aspirates from congenital cataract. Nineteen of the 32 patients with acute retinitis had confirmed virus infections (VZV: 8; HSV: 5; and CMV: 6) and the rapid detection of the virus agent helped institute specific chemotherapy resulting in useful vision in some patients. CONCLUSION: Laboratory investigations for diagnosis of viral and C. trachomatis ocular infections were useful in establishing the aetiology and determining the incidence of causative agents of specific ocular diseases.