Spectral Domain Optical Coherence Tomography

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JOURNAL OF OPHTHALMIC AND VISION RESEARCH 2012; Vol. 7, No. 4 ... with loss of vision in his right eye from 6 months earlier. .... Colour atlas/text.
Photo Essay

Spectral Domain Optical Coherence Tomography Features of Subretinal Cysticercus Cyst Vishal Raval, DNB, MD; Vikas Khetan, DO, DNB, MD Sankara Nethralaya Medical Research Foundation, Chennai, India

A 31-year-old man of Asian descent presented with loss of vision in his right eye from 6 months earlier. Best corrected visual acuity (BCVA) was limited to light perception in the right eye and was 6/6, N6 in the left one. Slit lamp examination revealed normal anterior segments bilaterally. Intraocular pressure was 8 and 14 mmHg in the right and left eyes, respectively. Fundus examination in the right eye showed a large subretinal cysticercus cyst, accompanied by total retinal detachment (RD), severe extensive subretinal fibrosis and membranes (Fig. 1A). B-scan ultrasound (Alcon Ultrascan, Alcon Laboratories, Fort Worth, Texas, USA) images illustrated total RD with a hyperechoic area within the cystic cavity suggestive of cysticercus scolex (Fig. 1B). Spectral domain optical coherence tomography (OCT) (Topcon 3D OCT2000, Topcon Medical Systems, Oakland, New Jersey, USA) demonstrated a highly reflective cyst wall and a more hyper-reflective domeshaped structure within the wall suggestive of the scolex (Fig. 1C). The posterior extent of the cyst could not be visualized due to its large size. T1weighted contrast-enhanced magnetic resonance imaging (MRI) of the brain demonstrated a ringshaped enhancing lesion in the left cerebellar hemisphere with perilesional brain edema suggestive of neurocysticercosis (Fig. 1D). The patient was referred to a neurophysician and received a three month course of oral albendazole and steroids. Eventually, he was recommended for follow-up care. DISCUSSION Ocular cysticercosis is caused by the growth of the larval form of Taenia solium within ocular tissues.1,2 The cysts may be located in

descending order of frequency in the subretinal space (35%), vitreous (22%), conjunctiva (22%), anterior segment (5%) and orbit (1%).3 Intraocular cysticercosis usually presents with reduced vision and ocular inflammation. It is believed that the larva reaches the subretinal space through the posterior ciliary arteries. 3-6 As the cyst develops, it may cause exudative retinal detachment.6 As long as the cyst remains viable, it evokes little or no inflammatory response. Once the cyst starts degenerating, an antigen, which may be a metabolic by-product or toxin, leaks from the cyst and induces an inflammatory reaction, manifesting as vitritis, uveitis and sometimes endophthalmitis.3-6 Most often, the characteristic intraocular cyst can be visualized by indirect ophthalmoscopy or detected by B-scan ultrasound in the presence of hazy media.3 B-scan ultrasonography will show a curvilinear echo corresponding to the cyst wall together with an eccentric hyperechoic dot suggestive of the scolex. A-scan analysis reveals two high amplitude echoes representing the anterior and posterior walls of the cyst. Mahendradas et al7 highlighted the features of intraocular cysticercus cyst employing spectral domain OCT; they clearly delineated the hyper-reflective wall of the subretinal cyst with a more hyper-reflective portion within its wall suggestive of the scolex/larva. CNS involvement can be observed in approximately 90% of patients with ocular cysticercosis and MRI is superior to computed tomography (CT) in detecting lesions of neurocysticercosis (NCC).8 In addition, MRI better illustrates cystic lesions in the base of the brain, cerebrospinal fluid (CSF) spaces as

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Photo Essay; Raval and Khetan

Figure 1. (A) Color fundus photograph of the right eye; note total retinal detachment with subretinal fibrosis and membranes, and a large subretinal cysticercus cyst with scolex. (B) B-scan ultrasound image of the same eye demonstrates total retinal detachment with a hyperechoic lesion within the cystic cavity persisting in low gain suggestive of cysticercus scolex. (C) Spectral domain optical coherence tomography image through the cystic cavity showed a hyper-reflective layer suggestive of cyst wall and a highly reflective dome-shaped structure within the cyst suggestive of scolex. (D) T1-weighted contrast-enhanced magnetic resonance image of the brain revealed a ring shaped enhancing lesion in the left cerebellar hemisphere (arrow).

in ventricular NCC and cisternal NCC, and also with intramedullary lesions.9 The scolex may be more readily apparent on MRI than on CT. On MRI, contents of live cysts (vesicular stage) are isointense relative to CSF on T1- and T2weighted images.10 Treatment of ocular cysticercosis is mandatory since it has been reported that 80% of untreated cases result in severe ocular damage. 3 Antihelminthic drugs such as

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praziquantel or albendazole are effective in central nervous system and skin cysticercosis. However, antihelminthics are ineffective in ocular cysticercosis. Corticosteroids may be used in conjunction with these drugs to reduce the inflammatory response. Surgical removal of the cyst can also be performed through transretinal or trans-scleral routes.11 Systemic corticosteroid coverage is required before and after surgical removal of the cysticercus.3

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Photo Essay; Raval and Khetan

Conflicts of Interest

6. Bartholowmew RS. Subretinal cysticercosis. Am J Ophthalmol 1975;79:670-673.

None.

7. Mahendradas P, Avadhani K, Yadav NK, Vinekar A, Shetty R, Shetty BK. High-definition spectral-domain optical coherence tomography of intravitreal and subretinal cysticercus cysts in intraocular cysticercosis. Retina 2011;31:2132-2133.

REFERENCES 1. Chatterjee KD. Parasitology, protozoology and helminthology. 13th ed. Chatterjee Medical Publishers: Calcutta; 2011. 2. Kean BH, Sun T, Ellsworth RM. Colour atlas/text of ophthalmic parasitology. Igaku-Shoin Medical Publishers Inc.: New York; 1991. 3. Kruger-Leite E, Jalkh AE, Quiroz H, Schepens CL. Intraocular cysticercosis. Am J Ophthalmol 1985;99:252-257. 4. Atul K, Kumar TH, Mallika G, Sandip M. Sociodemographic trends in ocular cysticercosis. Acta Ophthalmol Scand 1995;73:438-441. 5. Topilow HW, Yimoyines DJ, Freeman HM, Young GA, Addison R. Bilateral multifocal intraocular cysticercosis. Ophthalmology 1981;88:1166-1172.

8. Garc×a HH, Evans CA, Nash TE, Takayanagui OM, White AC Jr, Botero D, et al. Current consensus guidelines for treatment of neurocysticercosis. Clin Microbiol Rev 2002;15:747-756. 9. Noujaim SE, Rossi MD, Rao SK, Cacciarelli AA, Mendonca RA, Wang AM, et al. CT and MR imaging of neurocysticercosis. AJR Am J Roentgenol 1999;173:1485-1490. 10. Gaur V, Gupta RK, Dev R, Kathuria MK, Husain M. MR imaging of intramedullary spinal cysticercosis: A report of two cases. Clin Radiol 2000;55:311-314. 11. Gupta A, Gupta R, Pandav SS, Dogra MR, Joshi K. Successful surgical removal of encapsulated subretinal cysticercus. Retina 1998;18:563-566.

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