Serology in ocular toxoplasmosis.

The diagnostic value of toxoplasma serology in ocular disease was evaluated in the following groups of patients: (I) uveitis cases of various causes (n = 291); (II) consecutive posterior and panuveitis patients (n = 60); (III) patients with definite congenital and ocular toxoplasmosis (n = 8); (IV) cases of clinical ocular toxoplasmosis (n = 25); and control patients with uveitis of non-toxoplasma origin (n = 12). No relation was observed between the level of the dye test titres and the diagnosis of ocular toxoplasmosis (groups I and II). During the active stages of the disease no typical change of the titres occurred in several longitudinally studied patients with toxoplasmosis. In group III one case was discovered to be negative by the dye test despite active ocular disease; however, IgG antibodies against toxoplasma were detected by the ELISA technique. In group IV, which was investigated by the ELISA technique, 100% of the toxoplasmosis patients were positive for IgG versus 58% of the control patients. Circulating immune complexes containing IgG and toxoplasma antigen were detected in seven of 25 toxoplasmosis patients (28%) and in two of 12 control patients (16%). Our study shows that the definite diagnosis of ocular toxoplasmosis or its exclusion by serological means only is not yet feasible. The possible superiority of the ELISA test to the dye test warrants further investigation.     

Diagnostic and therapeutic dilemmas in ocular toxoplasmosis

Ocular toxoplasmosis, a leading cause of visual handicaps in young people, represents a late manifestation of congenital infection in the majority of cases. Ocular involvement in acquired toxoplasmosis has been repeatedly reported and shows that toxoplasmic retinitis may develop in the wake of acquired infection. The diagnosis of ocular toxoplasmosis is mainly clinical since serologic tests are positive for a considerable percentage of the general population and are not indicative for ocular involvement. The demonstration of local synthesis of toxoplasma antibodies in the eye by intraocular fluid analysis is a valuable diagnostic tool. The application of the polymerase chain reaction, in which the parasite's DNA is detected, may be expected to change the diagnostic repertoire drastically in the future. The need for appropriate therapy for patients with ocular toxoplasmosis is a matter of continued debate: the majority of the medications used for treatment have potentially serious side effects and the efficacy of treatments has not been clarified in previous studies. Recently, a prospective multicenter study to evaluate the efficacy of current therapeutic strategies for ocular toxoplasmosis was performed in The Netherlands and included 106 patients with active ocular toxoplasmosis. The principal conclusion of this study is that only drug therapy with pyrimethamine had any perceptible influence on any aspect of ocular toxoplasmosis, but this effect may not be worth the risk of side effects except in fovea threatening lesions.     

The Usefulness of Aqueous Fluid Analysis for Epstein–Barr Virus in Patients with Uveitis

ABSTRACT

Purpose: To determine characteristics of patients with laboratory findings indicative of intraocular Epstein–Barr-virus (EBV) infection and to establish the usefulness of the laboratory analysis in patients with uveitis.

Methods: Retrospective study of patients who underwent diagnostic aqueous fluid analysis. Diverse demographic data of patients were registered.

Results: EBV-PCR tested positive in 3/201 (1%) and EBV-GWC in 22/245 (9%). The prevalence of immunosuppression was similar in EBV positive (by PCR/GWC) and EBV negative patients (7/25; 28% vs. 50/272;18%, P = 0.29). Out of all 22 EBV-GWC positive patients, GWC was between 3 and 10 in 91%. In total, 14 patients had laboratory results indicating only EBV infection. Patients without an alternative explanation for uveitis (6/14; 43%) had a chronic recurrent course and good visual prognosis.

Conclusion: Low EBV-GWC values combined with multiple positive GWC and/or PCR for other infectious agents. Intraocular assessment for EBV in the initial examination of uveitis patients has limited value.     

The Pros and Cons of Intravitreal Triamcinolone Injections for Uveitis and Inflammatory Cystoid Macular Edema

Intravitreal triamcinolone acetonide (IVTA) injections are gaining in popularity and are regularly administered nowadays for various ocular diseases. This paper presents a literature review on the use, efficacy, and complications of IVTA application in non-infectious uveitis and inflammatory cystoid macular edema (CME). In addition, we describe the experiences of our own institute. IVTA applications brought about a quick improvement in vision in the majority of cases. Drawbacks included the temporary duration of the effect with the need for repeated injections which re-exposed patients to the risk of complications. The risk of bacterial endophthalmitis was 0.5% and was further influenced by the specific IVTA preparation. Based on the literature review, we chose ready-for-use IVTA injections prepared by our pharmacy department, in which 90% of the toxic additives were removed and the dispensed dose of triamcinolone acetonide was validated to diminish the risk of endophthalmitis. Elevated intraocular pressure (IOP) was seen in 30–43% of the eyes and cataract developed in 29% of the eyes of patients, who were usually of advanced age. In conclusion, the rapid effect of IVTA might be of value in severe presentations of non-infectious uveitis and CME and might shorten the time interval needed for the improvement.     

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.     

Recurrent ocular disease in postnatally acquired toxoplasmosis

PURPOSE: Although recurrences are typical of congenital toxoplasmosis, the long-term ocular manifestations in postnatally acquired toxoplasmosis have never been systematically studied. We report on the ocular manifestations complicating the chronic phase of postnatally acquired toxoplasmosis. METHODS: Review of the clinical data of 14 patients who presented with active ocular toxoplasmosis not associated with scars and who had serologic characteristics of recently acquired systemic toxoplasmosis. RESULTS: Mean follow-up was 4.6 years. Recurrent ocular disease developed in eight (57%) of 14 cases. The number of patients with recurrences increased with the follow-up time: four (29%) of 14 during the first year of follow-up; eight (57%) of 14 during the second year; and eight of nine during the third follow-up year. No risk factors for the development of recurrences were identified. Satellite lesions developed in five of eight patients with recurrences, whereas lesions not adjacent to old scars, located in areas of previously unaffected retina, developed in three patients. CONCLUSIONS: In postnatally acquired toxoplasmosis, frequent recurrences of ocular disease can be seen during the chronic phase of infection.