Diffuse Unilateral Subacute Neuroretinitis: A Case Report

ABSTRACT Diffuse unilateral subacute neuroretinitis (DUSN) represents an ocular infectious disease capable of precipitating severe visual impairment and, in some cases, blindness. It predominantly affects healthy young individuals, manifesting in various stages, which may include vitritis, multifocal Gray-white lesions in the outer retina, derangement of the retinal pigment epithelium, and narrowing of the retinal vessels, among other symptoms. The etiologic agent of DUSN encompasses parasites of varying sizes and species, such as Ancylostoma caninum, Toxocara canis, and others. Consequently, it is postulated that diverse infectious worms may be implicated in both the autoimmune and toxic forms of nematode retinopathy. Given the variability of serologic testing, a definitive diagnosis is established when clinical characteristics of DUSN are observed in conjunction with the presence of an intraocular worm. Additional diagnostic tools, including fluorescein and indocyanine green angiography, electrophysiological tests, visual field studies, and more recently, optical coherence tomography angiography, can aid in the differential diagnosis when the nematode cannot be directly visualized. In cases where the worm is identified, it is classified as confirmed DUSN, whereas eyes exhibiting typical clinical features but lacking worm identification are categorized as presumed DUSN. The standard treatment for confirmed DUSN involves direct photocoagulation of the worm, although its visualization is observed in only 30% to 40% of cases. Treatment of presumed DUSN with high-dose oral Albendazole has demonstrated promising outcomes. However, the rarity of the disease or its underdiagnosis may contribute to the lack of comparative studies evaluating the efficacy of current treatment modalities in both presumed and confirmed DUSN. Given the potential for DUSN to be, in part, an autoimmune form of nematode retinopathy, the use of corticosteroids in conjunction with Albendazole or laser therapy may prove beneficial. Therefore, further comparative studies are imperative to determine the most effective treatment approach for this potentially blinding condition. Keywords: Albendazole, Diffuse unilateral subacute neuroretinitis (DUSN)