Case Presentation: A 48-year-old man without significant past medical history presented with 1 week of left eye central vision loss and left frontal headache. He denied eye pain or photophobia. Examination revealed left relative afferent pupillary defect and visual acuity at count fingers at 4 feet. Fundoscopic examination showed grade 5 disc/retinal edema with flame hemorrhages, temporal Paton’s lines, and early macular star, characteristic of retinitis. Examination of the right eye was unremarkable. MRI brain showed no evidence of optic neuritis or active demyelination. Serologic testing for a panel of infectious causes of retinitis resulted negative, including Bartonella, Brucella, HIV, syphilis, Toxoplasma, and Toxocara. QuantiFERON-TB Gold was positive. Chest radiograph showed multiple calcified granulomas. The patient’s risk factors for Mycobacterium tuberculosis (TB) infection included immigration to the US from Guatemala 15 years prior and strong family history (his father died of TB at age 35). Given his presentation concerning for ocular TB, the patient started rifampin, isoniazid, pyrazinamide, and ethambutol (RIPE). After 5 months of RIPE therapy, his left eye visual acuity improved to 20/160 with marked improvement in disc edema.

Discussion: Ocular TB is an uncommon extrapulmonary manifestation of TB. Its true incidence is uncertain as diagnosis is often presumptive and based on clinical history in the context of appropriate epidemiologic exposures (1). Ocular tissue sampling for microbiologic examination is not routinely performed because of the risks of such procedures and the low yield of specimens (2). Ocular TB typically affects the uveal tract (including the iris, choroid, and ciliary body) due to its vascularity as TB spreads hematogenously. TB retinitis, which involves the retina alone is uncommon. Retinitis classically presents as painless vision loss and can be associated with infectious agents as well as systemic inflammatory conditions including rheumatic diseases and hypersensitivity reactions. The most common infectious causes of retinitis include Toxoplasma gondii and Cytomegalovirus. Though a rare cause of retinitis, TB should remain on the differential for patients with significant risk factors. Clinical presentations of reported cases of TB retinitis include patients with eye involvement without systemic disease (3), with active pulmonary TB (4), or with disseminated extrapulmonary TB (5). The treatment of retinitis varies based on the underlying etiology. For idiopathic cases, high dose corticosteroids are often administered. After excluding other possible causes, patients with newly diagnosed retinitis who have positive QuantiFERON and known history of TB exposure should be treated for ocular TB with RIPE (2). In this case, the patient came from an endemic region, had a strong family history of TB, a positive QuantiFERON, and chest radiographic findings of prior granulomatous disease.

Conclusions: Although it is challenging to definitively diagnose ocular TB, the benefits for treating our patient for ocular TB outweighed the risks of adverse effects of therapy. His vision improved without steroid administration and with TB treatment, which supports TB retinitis rather than an idiopathic etiology. Given that tuberculosis remains a global health burden and ocular TB has a risk of high morbidity, teaching clinicians to recognize and promptly treat atypical presentations of TB is of high importance.

IMAGE 1: Our patient’s left fundus exam prior to RIPE initation, showing optic disc edema with subretinal exudates in a partial macular star pattern.