Toxoplasmosis is the most common cause of infectious posterior uveitis in adults and children. The ocular manifestations, which are common, are extensively discussed in BCSC Section 9, Uveitis and Ocular Inflammation.
CNS toxoplasmosis is often associated with immune deficiency. Toxoplasmic optic neuritis is rare, characterized by subacute visual loss and ONH swelling, at times accompanied by a macular star (neuroretinitis). CNS toxoplasmosis produces multifocal lesions, with a predilection for the basal ganglia and the frontal, parietal, and occipital lobes. Patients experience headaches, focal neurologic deficits, seizures, mental status changes, and fever. Neuro-ophthalmic findings include homonymous hemianopia and quadrantanopia, ocular motor CN palsies, and gaze palsies. Long-term antitoxoplasmosis treatment is necessary to prevent recurrences.
MRI typically shows multiple lesions that are isointense with the brain on T1-weighted images and isointense or hyperintense on T2-weighted images. Gadolinium administration reveals enhancement.
Excerpted from BCSC 2020-2021 series: Section 5 - Neuro-Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.