Electron microscopy and mass spectroscopy used to identify the morphology and metallic nature of a lower lid margin foreign body

A man in his 60s presented to a Tertiary Referral Teaching Hospital with sudden, spontaneous onset of left eye pain. Slit lamp examination with fluorescein demonstrated multiple vertical linear staining corneal abrasions. The patient was initially suspected of having an upper lid tarsoconjunctival foreign body (FB). Eventually, the expected FB was located not on the tarsoconjunctiva, but on the lower lid margin. It was suspected of being an insect stinger as there was no corroborating history of ocular trauma by metal, such as due to grinding or drilling. The FB was removed via slit lamp examination, and was submitted to electron microscopy and mass spectroscopy.