Purpose-Toxoplasmosis gondii (T. gondii) is a common world-wide parasite that presents in the eye with focal retinochoriditis and vitritis. Although it is rare, ocular toxoplamosis has been linked to primary intraocular (retinal) lymphoma, which is mostly a diffuse large B-cell lymphoma.Methods-An elderly female patient was treated for recurrent ocular toxoplasmosis, and because of progressive vitritis, a diagnostic vitrectomy was performed. Shortly afterwards she developed multiple brain lesions. Pathological examinations of the vitreous specimen and cerebral tissues were conducted including tests for T. gondii, EBV, and CMV DNA.Results-The patient initially responded to anti-toxoplasmosis treatment, but continued to have persistent vitritis. She was diagnosed with primary intraocular lymphoma and a repeated MRI revealed cerebral lesions. Brain biopsy confirmed lymphoma. T. gondii DNA was found in malignant vitreous cells, but was absent in the non-malignant vitreous cells and brain lymphoma cells. CMV and EBV genes were not found in any of the lymphoma cells. Conclusion-T. gondii may have played a role in lymphoproliferation and PIOL development.Keywords B-cell lymphoma; intraocular lymphoma; primary intraocular (retinal) lymphoma; primary CNS lymphoma; toxoplasmosis; Toxoplasmosis gondii Summary StatementA patient was initially diagnosed and treated for ocular toxoplasmosis, but subsequently developed PIOL and eventual CNS lymphoma. Toxoplasmosis DNA was found within the PIOL cells, but absent in the vitreal non-malignant cells and brain lymphoma cells. We speculate chronic stimulation of the immunological response to toxoplasmosis could be oncogenic.

We evaluated the toxicity of injecting human fibreblast Interferon intravitreally in rabbit eyes. A single intravitreal injection of 166,660 units/0.1 ml was nontoxic to ocular structures, as demonstrated by electroretinographic and histologie examination.