LAUSR

© BMJ Publishing Group Limited 2022. No commercial reuse. See rights and permissions. Published by BMJ. DESCRIPTION A man in mid50s noticed mild irritation in right eye for 10 days following ocular trauma with an unknown insect 1 month ago. His visual acuity was 20/20 in both eyes. Slit lamp examination of left eye revealed an elevated lesion with ovalshape, brown colour, welldefined margins and corrugated surface in inferior cornea. It was relatively translucent, and rigid shelllike, with a convex outer surface that had a waxy coating resembling the exoskeleton of insects (figure 1). It was associated with surrounding stromal infiltration and vascularisation. On fluorescence staining, dye gathered around the edges of the lesion with no epithelial defect. There was no associated conjunctival discharge, forniceal foreign body (FB) or anterior chamber reaction. A diagnosis of insect wing case (IWC) corneal FB (CFB) was made. Anterior segment optical coherence tomography (ASOCT, Cirrus, Carl Zeiss, Meditec, Germany) revealed a crescentshaped concavoconvex surfaced hyperreflective FB with sharp welldefined margins in the anterior cornea with shadowing of underlying structures. Central shadowing was noted beyond 451 μm of stromal thickness and marginal shadowing was noted underneath one edge of CFB (figure 2). It was removed with McPherson forceps on slitlamp under topical anaesthesia and topical moxifloxacin (0.5%) was administered 6hourly for 5 days following which the site healed with minimal scarring. CFB revealed no microbiological growth. IWCs are rarely described CFBs, last reported by Fogla et al in the month of November and December due to seasonal variation in the insect population. The authors suggested that the firm adhesion of this convexoconcave FB on convex ocular surface could be due to vacuum created by the pressure of eyelid on the FB. As IWCs may cause corneal infiltration, neovascularisation and infective keratitis, they should be removed immediately and subjected to microbiological evaluation. ASOCT, a valuable noninvasive tool that provides high resolution details of anterior segment structures, is known to aid in diagnosis of CFB and in guiding an appropriate method of its removal. 3 Metallic CFBs may be deposited either superficially or deeply into the corneal stroma (due to their high velocity), are hyperreflective on ASOCT and cause mirroring and shadowing effect on underlying structures, while organic FBs remain lodged superficially (due to their low velocity) and few organic CFBs such as hairy chestnut spines may not be detectable on ASOCT. To the best of our knowledge, this is the first time, ASOCT is being used for imaging IWC. We noted localised shadowing of corneal details underlying the IWC. We also noted marginal shadowing under one edge of CFB. These findings are very similar to the those reported by Wang et al in their case 3, where a translucent brown shell CFB was identified clinically, and on ASOCT, a crescentshaped low reflective signal with bilateral marginal zone shadowing 21 μm below the epithelium surface was noted. Although the beginning of shadowing usually indicates the