Abstract
Purpose: :
To review polymerase chain reaction (PCR) testing of aqueous or vitreous humor specimens collected from patients with intraocular inflammation between 11/1/01 and 10/31/06 in a single institution and to determine clinical characteristics associated with diagnostic yield.
Methods: :
IRB-approved interventional case series. Microbiology logs were reviewed to identify cases that had PCR testing performed because of intraocular inflammation, and medical records were reviewed for patient information and clinical course.
Results: :
Sampling was performed on 143 patients. Etiologic organisms were detected in 78% of cases originally diagnosed with acute retinal necrosis syndrome,76% of cases originally diagnosed with cytomegalovirus retinitis, 89% of patients initially diagnosed with progressive outer necrosis syndrome, and 57% of patients initially diagnosed with toxoplasmosis. Anterior chamber sampling was performed 111 times; vitreous sampling 30 times; and vitreous wash 2 times. An average of 4.1 tests were performed on each sample. A total of 581 diagnostic tests were performed. HSV1 testing was performed 130 times with 5/130 positive results (4%); HSV II, 130 times with 12/130 positive results (9%); VZV, 118 times with 28/118 positive results (24%); CMV, 113 times with 25/113 positive results (22%); EBV, 24 times with 2/24 positive results (8%); and toxoplasmosis, 66 times with 12/66 positive results (18%). The most frequently performed tests were for HSV I (130) and HSV II (130). The most frequently positive test was VZV (28/118, or 24%). The clinical sensitivity of panel PCR testing was 76.5%, and clinical specificity was 97.1%. The positive predictive value of panel testing was 98.7%, and the negative predictive value was 59.6%. Clinical characteristics associated with diagnostic yield included the presence of vascular lesions (p < 0.001), optic nerve lesions (p = 0.019), immunocompromised state (p = 0.023), or sampling within the first week after presentation (p = 0.037). Lesion location was a significant predictor of a positive PCR test (p = 0.002), and patients with both posterior and peripheral lesions were more likely to produce a positive PCR result.
Conclusions: :
PCR testing of aqueous humor is a relatively non-invasive, safe, easily performed first-line diagnostic procedure that is useful in adjunct with a careful history and clinical examination. Immunocompromised patients with diffuse posterior inflammation are the most likely to produce positive test results; however, PCR testing is a useful technique in a variety of cases with atypical presentations.
Keywords: retinitis • uveitis-clinical/animal model • inflammation