Diffuse unilateral subacute neuroretinitis in South Korea: a case report
Authors: Jeong Choi Moon 
Published: December 2019

Purposes

The clinical syndrome of diffuse unilateral subacute neuroretinopathy (DUSN) is a progressive ocular infectious disease caused by a variety of nematode species that involve the outer retina and retinal pigment epithelium. However in the absence of clinical visualization of nematode, diagnosis is ambiguous. To the best of our knowledge, DUSN has been rarely reported to date in South Korea. Therefore, we present a case of DUSN in South Korea and review the related literature.

Methods

A 49‐year‐old male patient was referred to Kim’s eye hospital for conjunctival injection and gradual deterioration of vision in the left eye for the past 7 days. He had no specific past medical history. The decimal best‐corrected vi‐sual acuity (BCVA) of the left eye was 0.6‐ and intraocular pressure was 22 mmHg by non‐contact tonometer. There were inflammatory cells in the anterior chamber with conjunctiva injection of the left eye. Fundus examination of the left eye revealed a subfoveal depigmentary scar and multiple, focal, gray‐white subretinal tracks. DUSN was suspected with the results of the fundus examination, optical coherence tomography, and fluorescein angiography. However, from the above examination the posterior segment did not seem to be in active phase despite some inflammation in anterior chamber, so only topical steroid was prescribed. Both visual acuity and inflammation in anterior chamber showed improved, and the steroid was tapered. The patient is being followed up on regular basis.

Results

DUSN is a progressive ocular infectious disease caused by parasites, which may cause slowly progressive vision loss or may even be asymptomatic to the patient. Sometimes patients are not recognize their eye condition in early stage of the disease. Most patients visit ophthalmololgy clinic when they suffer from decreased vision. This phase of the disease may show round yellowish outer retinal lesions with retinal pigment epithelium (RPE) changes and possible mild vitritis or papilloedema. In late stage DUSN, they may suffer from severe visual loss and paracentral or central scotomas. Late stages show multiple chorioretinal atrophic lesions, vessel narrowing, and disc pallor. The choice of treatment in DUSN is laser photocoagulation when the worm is visualized (motile, gray to whitish subretinal track). Photocoagulation will destroy the parasite and will subsequently reduce inflammation. However, when the worm is not found despite repeated examinations, ophthalmologists can consider antihelminthic drugs, such as albendazole. Systemic steroids can be used to control inflammation caused by the parasite and to help prevent deterioration of vision. In our case, the posterior segment did not seem to be in active phase despite some inflammation in anterior chamber, so only topical steroid was prescribed.

Conclusion

Although there is no evidence of active inflammation of the posterior segment, ophthalmologists should suspect DUSN when a patient presents with progressively reduced vision and anterior uveitis with typical subretinal track and further evaluation should be considered such as fundus examination, OCT and FAG.