Commentary: Corneal bee sting injury

Ocular bee sting injuries are a relatively rare environmental hazard more commonly observed in people engaged in outdoor activities, professional beekeepers, and rural inhabitants. The ophthalmic manifestations result from a direct mechanical effect of the bee stinger; toxic effects of the bee venom and the immunologic response incited in the host in response to the venom. Corneal bee sting injuries are most commonly observed, with conjunctival, periocular tissue, and palpebral bee stings reported less frequently.[1]

Clinical presentation varies from mild conjunctivitis to severe vision-threatening sequelae including infective keratitis, bullous keratopathy, severe kerato-uveitis, intractable glaucoma, optic neuritis, and endophthalmitis. Various factors affect the severity of presentation, including the depth of penetration of the stinger, toxicity of the bee-venom, and host-inflammatory response.[1]

The diagnosis of corneal bee sting injury may be established based on the typical history of insect bite/bee sting in the eye and directly observing the bee stinger firmly embedded in the cornea on slit-lamp bio-microscopy. Eye lid eversion should be performed when the stinger is not seen at the expected corneal site, as late migration of the stinger from the eyelid to the cornea has been reported weeks after the initial injury.[2] Anterior segment optical coherence tomography and confocal microscopy are useful adjuncts to determine the severity of the inflammatory response and the location as well as extent of bee stinger within the corneal stroma.[1]

Conservative management of corneal bee sting injuries includes topical steroids, topical broad-spectrum antibiotics, cycloplegics, antihistaminic, and antiglaucoma medications if needed. Systemic steroids administered either orally or intravenously have been advocated for effective control of inflammation.[3]

The surgical management involves the removal of the embedded bee stinger and is a matter of debate. Majority of ophthalmic manifestations are related to the toxic and immunologic effects of the bee-venom, and successful management hinges on an effective control of inflammation by systemic steroids rather than the removal of the stinger. The deeply embedded stinger with barbed lancets may induce additional mechanical trauma to the cornea and anterior segment during its removal, and there is a high likelihood of retained fragments even after removal. The chitinous exoskeleton of the stinger is inert and may be left in situ without inciting further inflammation or may be spontaneously absorbed over time.[3] A recent review of literature reported that most cases of bee sting injuries underwent surgical removal of the stingers. Approximately, 40% of cases with stinger removal showed a clinical exacerbation post extraction; of these, 59% had not received systemic steroids.[1]

Alternatively, surgeons recommending immediate extraction hypothesize that the removal of the inciting agent coupled with intensive medical therapy helps in faster resolution of inflammation. Persistent chronic inflammation mimicking viral keratouveitis has been reported in cases managed conservatively while leaving the stinger in situ.[4]

A surgical removal of corneal bee sting is generally advocated in cases with involvement of the visual axis, persistent severe inflammation with corneal oedema and infiltration, worsening on conservative management or associated full thickness perforation with aqueous leakage.[5] The toothed lancets firmly adhere the stinger deep into the corneal tissue and simply pulling it out during a slit-lamp examination may result in incomplete removal with worsening of inflammation. Various surgical techniques have been described to facilitate complete removal of the corneal bee stinger. It is advisable to perform a controlled removal of the stinger under an operating microscope. Jain et al. described the removal of a deeply embedded stinger by creating a flap over it.[4] An intracameral route of removal may be preferred in cases with deeply embedded stinger with one end protruding in the anterior chamber. The use of endoscopic illuminator can be beneficial when increased oedema and surrounding infiltrates hinder intraoperative visualization while extracting the stinger.[6] In this issue, Tyagi et al. successfully removed the bee stinger via the intracameral route facilitated by endoscopic visualization.[7] Tissue adhesives like fibrin glue may be required to seal the defect in cases with full-thickness corneal penetration after removing the stinger.[8]

It is essential to rule out any secondary microbial contamination in these cases, which may further deteriorate with the use of intensive steroid therapy. The extracted stinger should be sent for microbiological culture and antibiotic sensitivity testing.[3]

The patients should be counseled about the possible long-term sequelae that may manifest years after the initial insult. Corneal scarring and persistent bullous keratopathy are commonly observed necessitating a penetrating or endothelial keratoplasty. In addition, cataract, glaucoma, and optic atrophy may develop on follow-up and need to be adequately managed.

To conclude, the management of patients with corneal bee stings should primarily focus on controlling the acute inflammation. Surgical removal of the stinger under an operating microscope may be attempted if feasible, and endoscopy is a useful adjunct to enable complete removal. It is essential to monitor for the occurrence of long-term sequelae that may lead to suboptimal visual outcomes.