G. S. Baarsma

Serologic and Polymerase Chain Reaction Analysis of Intraocular Fluids in the Diagnosis of Infectious Uveitis

PURPOSE Infectious uveitis entities are usually rapidly progressive blinding diseases that can be prevented by prompt administration of specific antimicrobial therapy. With the aim of improving early diagnosis in patients with infectious uveitis, intraocular fluid samples from patients with sight-threatening posterior uveitis were investigated to determine the causative agent. METHODS Thirty-eight patients with acquired immunodeficiency syndrome (AIDS) and retinitis, eight immunosuppressed patients with retinitis, 16 immunocompetent patients with acute retinal necrosis, and 22 immunocompetent patients with toxoplasmic retinochoroiditis were analyzed by polymerase chain reaction for the presence of herpesviruses and Toxoplasma gondii DNA and for local antibody production against these microorganisms. RESULTS In patients with AIDS and retinitis, polymerase chain reaction was positive for cytomegalovirus DNA in 21 (91%) of the 23 ocular fluid samples obtained during active cytomegalovirus retinitis, whereas local antibody production analysis was negative in all cases. In acute retinal necrosis, varicella-zoster virus or herpes simplex virus could be established as the inciting agent in 81% of the cases, using the combination of both techniques. Polymerase chain reaction was positive in all samples obtained within two weeks after the onset of disease. Toxoplasma gondii DNA was detected in 4 of 13 samples (31%) from immuno-competent patients with active toxoplasmic retinochoroiditis; in each case, local antibody production was also detected. In contrast, no local antibody production was observed in two of three samples from transplant recipients that were positive for T. gondii DNA. All the control samples tested were negative for the above-mentioned tests. CONCLUSIONS In patients with AIDS, polymerase chain reaction analysis is preferable above local antibody production in detecting the inciting agent of retinitis. In other cases, the combination of both techniques can make a valuable contribution to the diagnosis.

Therapy for ocular toxoplasmosis.

We performed a prospective multicentre study to evaluate the efficacy of therapeutic strategies currently used for ocular toxoplasmosis in a large number of patients (n = 106). Treatment was given for at least four weeks and consisted of three triple drug combinations: group 1, pyrimethamine, sulphadiazine and corticosteroids (n = 29); group 2. clindamycin, sulphadiazine and corticosteroids (n = 37); and group 3. cotrimoxazole (trimethoprim and sulphamethoxazole) and corticosteroids (n = 8). Patients with peripheral retinal lesions remained without systemic therapy (group 4, n = 32). Patients from group 1 received leucovorin 5 mg twice a week. No difference in the duration of inflammatory activity was observed between the treated and untreated patients or between the separate groups of patients. The most important factor predicting the duration of inflammatory activity was the size of the retinal focus itself, independently of the therapy given (P less than 0.05). We showed a reduction in size of the retinal inflammatory focus in 52% of the pyrimethamine patients as compared to 25% of untreated cases. However the most frequent side effects were also associated with pyrimethamine medication and included hematologic complications as thrombocytopenia and leucopenia despite leucovorin medication.

AQUEOUS-HUMOR ANALYSIS AS A DIAGNOSTIC-TOOL IN TOXOPLASMA UVEITIS

Analysis of local toxoplasma antibody production to confirm a suspected clinical diagnosis of toxoplasma chorioretinitis is a valuable diagnostic tool. Determination of toxoplasma antibodies in the blood of the patient is of limited use. When blood toxoplasma tests are negative this indicates that toxoplasma as a causative organism in the pathogenesis of uveitis is unlikely.A positive blood test is a sensitive test (100% patients positive) but not a specific test since so many healthy individuals already have undergone subclinical infection and have acquired humoral immunity against the parasite.We analysed 93 paired aqueous and serum samples for toxoplasma antibodies and total IgG and determined the Goldmann-Wittmer coefficient. In patients retrospectively diagnosed as having toxoplasma chorioretinitis 16 out of 22 had a positive coefficient, indicating local parasite antibody production. In one patient with AIDS we also found a positive toxoplasma coefficient. Three out of 15 patients with posterior uveitis of unknown origin also had a positive coefficient. None of the cataract patients tested (n=32) had a positive coefficient. Major drawbacks of aqueous humor analysis are that a false negative antibody coefficient can occur when a massive blood aqueous barrier breakdown has occurred.

The Predictive Value of Serum Angiotensin Converting Enzyme and Lysozyme Levels in the Diagnosis of Ocular Sarcoidosis

We determined the serum angiotensin converting enzyme and lysozyme levels in 221 patients with uveitis and in 67 control subjects. Angiotensin converting enzyme and lysozyme levels were found to be age dependent. Of the 221 patients, 12 had sarcoidosis. In patients with uveitis who had an angiotensin converting enzyme level above 50 units/l (mean + 2 S.D.), the sensitivity of the test was 84%, the specificity was 95%, and the predictive value was 47%. In these same patients the sensitivity was 60% for a lysozyme level above 8 mg/l (mean + 2 S.D.), the specificity was 76%, and the predictive value was 12%.

Cyclosporin in the treatment of severe chronic idiopathic uveitis

In a randomised double-masked study of 27 patients with a severe chronic idiopathic uveitis we evaluated the efficacy, safety, and tolerability of cyclosporin. All received prednisone in a low dose (0.3 mg/kg/day). In 14 patients this was combined with cyclosporin in a single daily dose of 10 mg/kg/day, while 13 patients received a placebo. The dosages were tapered off in accordance with a protocol, and we compared the number of months of successful therapy before the uveitis relapsed. The efficacy results, as expressed in a Kaplan-Meier curve, were in favour of cyclosporin. Owing to the small sample size, however, this difference did not reach statistical significance. The immunosuppressive effect of cyclosporin was not permanent, and in all but one patient the intraocular inflammation relapsed on reduction of dosage. Rather small cumulative doses of cyclosporin proved to be nephrotoxic, but subjective tolerability for cyclosporin was good.

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.

Therapy of ocular toxoplasmosis

We performed a prospective multicentre study to evaluate the efficacy of therapeutic strategies currently used for ocular toxoplasmosis in a large number of patients (n=106). Treatment was given for at least four weeks and consisted of three triple drug combinations: group 1, pyrimethamine, sulphadiazine and corticosteroids (n=29); group 2. clindamycin, sulphadiazine and corticosteroids (n=37); and group 3. cotrimoxazole (trimethoprim and sulphamethoxazole) and corticosteroids (n=8). Patients with peripheral retinal lesions remained without systemic therapy (group 4, n=32). Patients from group 1 received leucovorin 5 mg twice a week.No difference in the duration of inflammatory activity was observed between the treated and untreated patients or between the separate groups of patients. The most important factor predicting the duration of inflammatory activity was the size of the retinal focus itself, independently of the therapy given (P<0.05).We showed a reduction in size of the retinal inflammatory focus in 52% of the pyrimethamine patients as compared to 25% of untreated cases. However the most frequent side effects were also associated with pyrimethamine medication and included hematologic complications as thrombocytopenia and leucopenia despite leucovorin medication.

Birdshot Chorioretinopathy and Lyme Borreliosis

Two patients in whom ocular Lyme disease was suspected and who had antibodies to Borrelia burgdorferi developed birdshot chorioretinopathy and carried the HLA-A29 antigen. In a series of 11 patients with birdshot chorioretinopathy who carried the HLA-A29 antigen, three patients had antibodies against B. burgdorferi as determined by either immunofluorescence assay, enzyme-linked immunosorbent assay, Western blot analysis, or a combination of these tests. Further studies will be necessary to evaluate whether this is a false-positive reaction or whether B. burgdorferi has a causative role in the pathogenesis of birdshot chorioretinopathy.

Association of birdshot retinochoroidopathy and HLA-A29 antigen.

We tested the association of birdshot retinochoroidopathy and the HLA-A29 antigen. We could confirm a high association, as found by Nussenblatt et al. in 1982.

Aqueous chamber taps in toxoplasmic chorioretinitis

The clinical value of the determination of toxoplasma antibodies in anterior chamber taps was evaluated in 12 posterior uveitis patients suspected of a toxoplasmic retinochoroiditis, in four patients with Fuchss heterochromia and in 31 cataract patients.The posterior uveitis patients all had marked inflammation of the vitreous obstructing the examination of the fundus of the time of aqueous humour aspiration. The clinical diagnosis toxoplasmic uveitis (n = 9) was made after the inflammation of the vitreous had subsided and fundus examination became possible again. Paired serum and aqueous samples were tested for total immunoglobulin levels and toxoplasma antibodies.Eight of the nine clinical toxoplasmic uveitis patients had detectable toxoplasma antibodies in their aqueous, whereas none of the other seven uveitis patients were positive. All of these eight toxoplasmic uveitis patients had a coefficient above 1.5. Of the 31 control patients only one had a positive antibody titer at a dilution of 1/2 with a corresponding coefficient of 1.1. This study shows that aqueous humour examination for toxoplasma antibodies is a valuable diagnostic tool in a selected group of posterior uveitis patients.