Ocular Toxoplasmosis: Morphological and Epidemiological Characterization of a Clinical Case in Southern Chile

Abstract

Toxoplasma gondii is an obligate intracellular protozoan with a wide global distribution, capable of infecting most mammals and birds, including humans. We present the case of a 27-year-old immunocompetent female patient residing in the city of Puerto Montt, Los Lagos Region, Chile. The patient tested positive for anti-Toxoplasma gondii IgG, consistent with a previous infection without evidence of immunosuppression. The patient reported no chronic diseases or recent visual symptoms and maintained visual acuity of 1.0 in both eyes. On ophthalmological examination, a focal cicatricial lesion of necrotizing retinochoroiditis was observed in the superior nasal retina of the right eye, with no macular involvement or signs of active inflammation. Imaging studies using spectral-domain optical coherence tomography allowed for detailed morphological characterization, revealing partial detachment and thickening of the posterior hyaloid, cystoid macular edema secondary to vitreomacular traction, disorganization of the retinal layers, disruption of the outer limiting membrane, and choroidal thinning with increased scleral reflectivity: findings consistent with an inactive lesion. The diagnosis is inactive ocular toxoplasmosis in an immunocompetent individual, likely associated with prior exposure to risk factors such as living with domestic animals and consumption of undercooked meat or untreated water. This case highlights the importance of early diagnosis and ophthalmologic follow-up in endemic regions, where environmental exposure to Toxoplasma gondii is high. It also highlights the utility of spectral-domain optical coherence tomography.