The "stung" cornea - Retained insect sting on the corneal endothelium.

A 43-year-old male presented with the chief complaints of pain, redness, watering, and discharge in right eye (RE) following fall of an insect in the right eye 10 days back. Visual acuity in the RE was 20/25. On examination of RE, eyelids were edematous, conjunctival congestion was present, cornea had infiltrate 1*1.5 mm in size with surrounding stromal edema with a “V”-shaped foreign body on the endothelium [Fig. 1a-c]. There was minimal anterior chamber reaction. Fundus of RE was within normal limits. On anterior segment OCT, two hyperreflective lesions were noted on the endothelium [Fig. 1d]. A provisional diagnosis of retained insect sting resulting in toxic keratitis in the right eye was made. The patient was started on topical moxifloxacin hydrochloride 0.5% 2 hourly and topical prednisolone acetate 1% 4 times a day. After 1 week, patient was symptomatically better with decrease in congestion and size of infiltrate; but the sting persisted on the endothelium. The steroid was tapered weekly and 1 month after presentation, the area was scarred with no signs of inflammation but persisting sting on the endothelium. The patient is on regular follow up with no topical medication at present.

Figure 1

(a) Slit lamp photo of RE - diffuse illumination showing insect sting (yellow arrow) and stromal infiltrate (white arrow). (b) Slit lamp photo of RE - indirect illumination showing insect sting (yellow arrow) along with stromal infiltrate (white arrow). (c) Slit lamp photo of RE - optical section showing foreign body on the endothelium (white arrow). (d) AS-OCT image of RE showing two hyper reflective lesions on the endothelium (yellow arrows)

Discussion

Retained insect sting inside the eye is a relatively rare presentation. It may cause a number of ocular sequelae varying from corneal epithelial defect, corneal infiltrate to anterior uveitis, secondary glaucoma or rarely even posterior segment involvement leading to optic neuritis or optic atrophy.[12] The effects may be due to the mechanical effect of the stinger or due to the venom of the insect inciting an inflammatory response.[3] Prognosis will depend on time of presentation and severity of presentation. The sting, if superficial, should be removed but if it is embedded deeply and is not causing inflammation, it may be left as such.[4]

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Conflicts of interest

There are no conflicts of interest.