Case Presentation: An 87 year old male with a history of bilateral cataract surgery 18 months prior and recent immigration to the United States as a farmer from Honduras presented for bilateral vision loss and eye pain worsening over the last 3 months. Evaluation by Ophthalmology revealed left panuveitis, right anterior uveitis, and right retinal detachment. Infectious workup included marked eosinophilia (absolute count 2400 K/uL), positive Strongyloides serology, positive Toxoplasma serology (IgG positive and IgM negative), negative Toxocara serology, and diagnosis of latent tuberculosis infection. An autoimmune workup was negative. An aqueous tap of the right eye was completed, but insufficient sample prevented processing for Toxoplasma PCR. The patient was started on trimethoprim-sulfamethoxazole for toxoplasmosis but discontinued secondary to acute kidney injury and low index of suspicion for active infection. Strongyloides was felt to be the leading cause of uveitis. The patient received ivermectin for 2 days with resolution of eosinophilia and repeated dosing at 2 weeks. He was discharged from the hospital with significant improvement in visual acuity a month later in the cornea clinic.

Discussion: Uveitis is an uncommon but serious ocular complication that can lead to permanent vision loss. The most common causes of infectious uveitis include herpes simplex virus, varicella zoster virus, toxoplasmosis, and cytomegalovirus (1). Toxoplasmosis is a common cause of posterior uveitis outside of the United States. Toxoplasma serology can be misleading in these patients as IgM is often negative in patients with retinal disease (1). An additional emerging cause of infectious uveitis is diffuse unilateral subacute neuroretinitis (DUSN) which is caused by parasites such as Strongyloides stercoralis and Toxocara canis (2). Definitive diagnosis of DUSN requires visualization of the nematode on ophthalmologic exam, however this can be difficult so diagnosis may be made with high clinical suspicion and positive serology (2). We present an immunocompetent patient with uveitis and serology positive for both Strongyloides and Toxoplasma.Loss of vision is a devastating consequence for patients with uveitis regardless of etiology. It is important to maintain a high level of suspicion for infectious sources when addressing these patients, especially since treatment may have a more favorable prognosis in earlier stages of the disease (3). In this case, we present a patient that demonstrates this principle. DUSN has presented with visible worms on fundoscopy in 30-40% of confirmed cases and may be treated directly with photocoagulation (3). If no worm is visible, chemotherapy with anthelmintic drugs has been used with efficacy and safety (3). Definitive identification of ocular parasitic infections including Strongyloides and Toxoplasma through direct visualization, serology and aqueous sampling is often challenging and leaves the clinician with no clear answer. This patient avoided potential permanent vision loss after receiving treatment with antiparasitic medication in the setting of presumed parasitic uveitis.

Conclusions: Obtaining early serology to evaluate for infectious causes of uveitis is crucial to guiding therapy and curbing progression of vision loss.