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 Table of Contents    
CLINICAL IMAGE
Year : 2019  |  Volume : 12  |  Issue : 1  |  Page : 59-61  

Diffuse unilateral subacute neuroretinitis


Department of Retina, Aravind Eye Hospital, Puducherry, India

Date of Web Publication30-Jan-2019

Correspondence Address:
Dr. Pratyusha Ganne
Department of Retina, Aravind Eye Hospital, Puducherry - 605 007
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ojo.OJO_89_2017

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   Abstract 


Diffuse unilateral subacute neuroretinitis (DUSN) is a subacute outer retinal inflammation due to the presence of a subretinal worm. The worm is identifiable in only 30% of the cases. The identification of the worm and laser photocoagulation of the worm remains the mainstay of treatment. Here, we describe a case of DUSN with a subretinal worm in the macula which was captured on Optical coherence tomography (OCT) scans and treated with laser photoooagulation.

Keywords: Diffuse unilateral subacute neuroretinitis, laser, optical coherence tomography


How to cite this article:
Ganne P, Dhoble P. Diffuse unilateral subacute neuroretinitis. Oman J Ophthalmol 2019;12:59-61

How to cite this URL:
Ganne P, Dhoble P. Diffuse unilateral subacute neuroretinitis. Oman J Ophthalmol [serial online] 2019 [cited 2019 Jul 20];12:59-61. Available from: http://www.ojoonline.org/text.asp?2019/12/1/59/251042




   Introduction Top


Diffuse unilateral subacute neuroretinitis (DUSN) is a subacute outer retinal inflammation due to the presence of a worm. The movement of this worm in the subretinal space and the associated inflammation eventually result in optic atrophy. The identification of the worm and laser photocoagulation of the worm remain the mainstay of treatment. The worm is identifiable in only 30% of the cases. Here, we describe a case of DUSN where the worm was found in the macula. Optical coherence tomography (OCT) imaging of the worm confirmed its subretinal location. The changes in the retinal layers following laser photocoagulation of the worm were serially documented with OCT scans.


   Case Report Top


A 38-year-old female presented with a subacute visual loss in her right eye. Her medical and ophthalmic histories were unremarkable. Best-corrected visual acuity was 20/40 on the right and 20/20 on the left eyes. Anterior segment examination and intraocular pressure were unremarkable in both eyes. Fundus examination of the right eye showed disc edema, multiple evanescent gray-white outer retinal lesions all over the fundus with a white thread-like mobile structure in the superior macula suggesting a worm-like structure [Figure 1]. There was no vitritis. Examination of the left eye was normal. Complete hemogram, peripheral blood smears, absolute eosinophil count, and stool examination were normal. High-definition optical coherence tomography (HD-OCT) scans through the retina at the site of the worm showed hypo- and hyper-reflective structures in the subretinal space suggesting the subretinal location of the worm with surrounding inflammation [Figure 2]. Laser photocoagulation of the worm was done (400 mW, 0.2 s, 300 spots, 200 μ spot size) [Figure 3]. At 1-month post laser, her vision improved to 6/6. The evanescent lesions faded [Figure 4]. HD-OCT scans showed a hyperreflective scar and resolution of the inflammation [Figure 5].
Figure 1: Fundus examination of the right eye shows disc edema, multiple evanescent gray-white outer retinal lesions (arrowhead), a white thread-like worm in the superior macula (arrow)

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Figure 2: High-definition optical coherence tomography scans through the retina at the site of the worm showing hypo- and hyper-reflective structures in the subretinal space suggesting the subretinal location of the worm with surrounding inflammation

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Figure 3: Fundus photo following laser photocoagulation of the worm

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Figure 4: Fundus photo at one month showing scarring at the site photocoagulation and disappearance of the worm

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Figure 5: High-definition optical coherence tomography scans showing a hyperreflective scar and resolution of the inflammation

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   Discussion Top


Diffuse unilateral subacute neuroretinitis (DUSN) is a subacute outer retinal inflammation due to the presence of a subretinal worm. The disease is endemic in the Caribbean islands, Brazil, Ghana, Germany, China, India, and parts of the United States. Different nematodes have been associated with DUSN including Toxocara canis, Ancylostoma caninum, Strongyloides stercoralis, Ascaris lumbricoides, and Baylisascaris procyonis.[1] The onset is insidious, and the disease is usually unilateral. Early in the course of the disease, the patient presents with central or paracentral scotoma. Examination in the early stage shows a variable degree of vitritis, optic disc edema, multiple evanescent gray-white outer retinal lesions and rarely vasculitis. The worm is identifiable in only 30% of the cases. Late stage is characterized by optic atrophy and diffuse retinal pigment epithelial changes. Fundus fluorescein angiography shows early hypo fluorescence followed by staining of the gray-white lesions. Electroretinography shows inner retinal dysfunction in early stages with the involvement of photoreceptors in the late stages.[2] Optical coherence has been used to demonstrate the subretinal location of the worm and decreased retinal nerve fiber layer thickness.[3] Systemic evaluation, serologic testing, stool examinations, and peripheral blood smears are usually normal in DUSN. The identification of the worm and laser photocoagulation of the worm remains the mainstay of treatment. Oral antihelminthic drugs or oral steroids are of little benefit unless there is significant vitreous inflammation. Souza et al. showed improvement in visual acuity, visual field, and active ocular inflammatory signs after treatment with oral albendazole (400 mg/day) for 30 days.[4] Some authors feel that if the nematode is located in the posterior pole of the retina, surgical removal should be selected over photocoagulation since laser can cause permanent scarring and visual loss.[5],[6]

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Arevalo JF, Arevalo FA, Garcia RA, de Amorim Garcia Filho CA, de Amorim Garcia CA. Diffuse unilateral subacute neuroretinitis. J Pediatr Ophthalmol Strabismus 2013;50:204-12.  Back to cited text no. 1
    
2.
Audo I, Webster AR, Bird AC, Holder GE, Kidd MN. Progressive retinal dysfunction in diffuse unilateral subacute neuroretinitis. Br J Ophthalmol 2006;90:793-4.  Back to cited text no. 2
    
3.
Gomes AH, Garcia CA, Segundo Pde S, Garcia Filho CA, Garcia AC. Optic coherence tomography in a patient with diffuse unilateral subacute neuroretinitis. Arq Bras Oftalmol 2009;72:185-8.  Back to cited text no. 3
    
4.
Souza EC, Casella AM, Nakashima Y, Monteiro ML. Clinical features and outcomes of patients with diffuse unilateral subacute neuroretinitis treated with oral albendazole. Am J Ophthalmol 2005;140:437-45.  Back to cited text no. 4
    
5.
Yamamoto S, Hayashi M, Takeuchi S. Surgically removed submacular nematode. Br J Ophthalmol 1999;83:1088.  Back to cited text no. 5
    
6.
Meyer-Riemann W, Petersen J, Vogel M. An attempt to extract an intraretinal nematode located in the papillomacular bundle. Klin Monbl Augenheilkd 1999;214:116-9.  Back to cited text no. 6
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]



 

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