"Worm in the eye": the rationale for treatment of DUSN in south India

Abstract

Aim: To discuss the rationale for different techniques of treatment for DUSN (diffuse unilateral subacute neuroretinitis) and their effectiveness in two patients from south India. Methods: Two rare cases of live worms in DUSN from India are reported, where filarial Brugia malayi is endemic. Both cases presented with progressive unilateral loss of vision with no history of animal contact. They were 40 year old, apparently healthy men. In case 1, the worm (1500-2000 mm) was easy to identify with wriggling movements among crisscrossing diffuse subretinal tracks. The worm was destroyed by a single shot of laser to its advancing end, which was followed by oral steroid to control the inflammation caused by the dead worm. In case 2, the worm was small and difficult to identify. Initially diffuse neuroretinitis was diagnosed and treated with intravenous methylprednisolone and oral corticosteroid. A week later, a small live worm (400-600 mm) was found and subsequently destroyed by laser photocoagulation followed by a combination of anthelminthics. Results: The patients' vision had improved to 6/60-6/36 from counting fingers after a few weeks. Conclusion: The role of a combination of laser treatment, systemic steroid, and anthelminthics is discussed.

Diffuse unilateral subacute neuroretinitis in the United Kingdom

“…Cases of DUSN have been reported in several countries including Brazil, Venezuela, USA, Canada, Caribbean, Spain, Germany, Senegal and India [1,3,[6][7][8][9][10]. To our knowledge, our two cases are the first from the UK that have been reported in the literature to be successfully treated with albendazole.…”

Retinal nerve fiber layer atrophy as relevant feature for diffuse unilateral subacute neuroretinitis (DUSN): case series

“…The differential diagnosis may be difficult to establish, especially when the worm is not found, which is very often because of its microscopic size and high mobility. The visual prognosis, though, is much better when the etiologic agent is early detected and treated (4)(5)(6) . OCT may be helpful when DUSN is suspected, by providing detailed information of the retinal nerve fiber layer and areas of edema and has not been associated with side effects, although it is rarely possible to find the actual worm.…”

Answers

“…The use of antihelminthic therapy, alone or in combination with photocoagulation, is more controversial, though successful systemic treatment has been reported in cases where the worm could not be localised 8 9. To date, only one case has been reported with bilateral DUSN,10 so most ophthalmologists feel comfortable using only photocoagulation with or without anti-inflammatory coverage and further observation.…”