Diffuse unilateral subacute neuroretinitis: review article

Abstract

Diffuse unilateral subacute neuroretinitis (DUSN) is an ocular infectious disease that can lead to severe visual impairment and blindness. It usually occurs in healthy young individuals and depending on the stage of the disease, it may present as vitritis, multifocal gray-white lesions in the outer retina, and derangement of the retinal pigment epithelium, narrowing of the retinal vessels and optic atrophy. Parasites of different sizes and species have been proposed as the etiologic agent of DUSN, including Ancylostoma caninum, Toxocara canis, and others. Thus, it is hypothesized that different infectious worms may be considered as the likely cause of both an autoimmune and toxic form of nematode retinopathy. Because serologic testing is variable, the definitive diagnosis is made when clinical characteristics of DUSN are found in conjunction with an intraocular worm. Ancillary tests can assist in the differential diagnosis when the nematode cannot be visualized, such as fluorescein and indocyanine green angiography, electrophysiological tests, visual field studies, and more recently, optical coherence tomography angiography. Cases in which the worm can be identified, it is defined as confirmed DUSN, and eyes with the typical clinical features but without identification of the worm should be classified as presumed DUSN. In confirmed DUSN, the classic treatment is directly photocoagulation of the worm; however, it can only be visualized in 30% (to 40%) of cases. Treatment of presumed DUSN cases with high-dose oral albendazole has shown encouraging results. However, perhaps due to the disease's rarity or its underdiagnosis, there are no studies comparing current treatment modalities in both presumed and confirmed DUSN. Due to the possibility of this disease being, in part, autoimmune nematode retinopathy, corticosteroids associated with both albendazole or laser therapy, could be in any way beneficial. Thus, further comparative studies are necessary to elucidate the best treatment for this potentially blinding disease.

Short-term oral albendazole therapy for diffuse unilateral subacute neuroretinitis: A case report

“…Diffuse unilateral subacute neuroretinitis (DUSN) is an infectious ocular disease that may result in visual-acuity deterioration. 1 Although this disease's pathogenesis remains unclear and a specific causative agent has not been identified, parasitic organisms such as Baylisascaris procyonis, Ancylostoma caninum, and Toxocara canis are thought to be involved in its etiology. 1 , 2 DUSN is more prevalent in young individuals, and most patients present with unilateral disease.…”

“… 1 Although this disease's pathogenesis remains unclear and a specific causative agent has not been identified, parasitic organisms such as Baylisascaris procyonis, Ancylostoma caninum, and Toxocara canis are thought to be involved in its etiology. 1 , 2 DUSN is more prevalent in young individuals, and most patients present with unilateral disease. 3 , 4 In the early stages of DUSN, patients may present with a mild loss of visual acuity associated with vitritis, optic disc edema, and gray-white retinal lesions.…”

“… 3 , 4 In the early stages of DUSN, patients may present with a mild loss of visual acuity associated with vitritis, optic disc edema, and gray-white retinal lesions. 1 Because symptoms tend to be more subtle during the early stages, patients may seek medical care later in the course of the disease. Late-stage DUSN is characterized by a severe loss of visual acuity, degenerative retinal pigment epithelium changes, optic atrophy, and retinal arteriole narrowing.…”

“…Late-stage DUSN is characterized by a severe loss of visual acuity, degenerative retinal pigment epithelium changes, optic atrophy, and retinal arteriole narrowing. 1 , 4 …”

“…DUSN is confirmed when a parasite is identified in the retina of a patient presenting with the disease's classic signs and symptoms. 1 , 5 However, in many cases, the parasite cannot be identified, making the diagnosis (in those cases) of DUSN a challenge. 2 , 6 Maintaining a high index of suspicion for this condition is crucial, as early detection and treatment have been associated with better patient outcomes.…”