The sting of members of the order Hymenoptera (e.g. bees, wasps, and biting ants) has long been known to cause local and regional reactions, systemic anaphylactic response, and less commonly delayed-type hypersensitivity. Only female hymenopteran insects have stingers, a modified ovipositor. In the act of stinging, these insects introduce two bodily components into the eye, the stinger and the specific venom. The venom of hymenopteran insects contains biologic amines (histamine), polypeptide toxins (melittin), and enzymes (hyaluronidase).
A 34-year-old male presented with history of fall of insect in the left eye (LE) of 2 days duration. LE examination showed an uncorrected visual acuity (UCVA) of 20/200 with diffuse corneal stromal edema and Descemet's membrane folds along with a stinger protruding from the 7° clock limbus [Fig. 1]. Anterior chamber (AC) reaction was present. The stinger was immediately removed at the slit lamp and topical antibiotic − steroid eye drops and systemic steroids were started and tapered gradually over 6 weeks. The necrotic area scarred with a localized peripheral anterior synechia by the 4th week. The corneal edema completely cleared with UCVA improving to 20/20 [Fig. 2].
A 32-year-old female presented with insect injury in right eye (RE) of 10 days duration. RE examination showed a UCVA of 20/400 with diffuse corneal stromal edema and a necrotic area at 5° clock limbus with a suspicious brown particle in its center [Fig. 3]. After starting topical and systemic steroids, the necrotic area was explored. About four brown stingers were removed from the deeper layers of the cornea and one from the AC. The necrotic tissue was excised and a patch graft was done. During the third postoperative week, the corneal edema and AC reactions cleared and the UCVA improved to 20/30 [Fig. 4].
A 32-year-old male, presented within hours after injury with insect in the RE. UCVA in the RE was 20/100. A dirty white necrotic area with three brown sharp needle-like foreign bodies lying in various levels of stroma was noted [Fig. 5]. The surrounding stroma was edematous. The three foreign bodies hard chitinous in nature were removed. He was treated with topical and systemic steroids in tapering doses. Since the patient showed an increase in intraocular pressure (IOP), low dose steroids were started and tapered by 6 weeks along with antiglaucoma medications. The necrotic area scarred but the stromal edema persisted till the last follow-up at 1 year. The UCVA in the RE was 20/60.
A 70-year-old female presented with severe edema involving the face and arms after stings by honey bee of 1 day duration. Ocular examination of the LE showed stingers protruding from 11O’ clock limbus into the AC with surrounding necrosis along with diffuse granular infiltration and corneal edema. The AC appeared to be filled with a brownish fluid. Visual acuity was perception of light in LE. The ultrasonic B scan was normal. The two stingers along with the brownish, curdy fluid in the AC were removed. Postoperatively, the patient was given tapering doses of topical and systemic steroids. Postoperatively, the corneal infiltration gradually cleared but edema persisted. Complicated cataract developed [Fig. 6]. IOP increased up to 48 mm of Hg by the 3rd week but the patient lost to follow-up.
A 3-year-old girl, presented with a history of bee sting injury in the RE of 4 days duration. Ocular examination of the RE showed diffuse corneal edema along with 2-3 bits of bee stingers embedded in the corneal stroma with surrounding area of necrosis at 8-11O’ clock position. Bee stinger removal was done immediately. Postoperatively, tapering doses of topical and systemic steroids were given. The edema gradually reduced during the postoperative period. At 3 months review, the corneal edema completely cleared with a localized scar at 8 − 11O’ clock. Anterior subcapsular cataract developed with vision dropping to 20/400 in the RE [Fig. 7].
Specular analysis and intraocular pressure measurements in all the 5 cases are consolidated in Table 1.
In all the five cases, the insect was identified as bee based on the patient's history. Bees use the stinger only as a defensive weapon to inject venom into the tissues of the victim and leave the stinger in the process. If the venom gland is still adherent acutely, attached muscle fibers will continue to contract, resulting in additional venom discharge and more toxicity (case 1 = 2 days; case 2 = 10 days). Even though the time interval between exposure and removal of the stingers is crucial, we also believe that a favorable outcome depends on the type of species of bee responsible for the trauma (case 3 = few hours) [Table 2].
In relation to the several species of bees, it was observed that differences exist between the compositions of venom components, with variations in the levels of enzymes present, suggesting that this can result in different degrees of immunogenic potential and/or toxicity. Bee venoms share both neurotoxic and hemolytic properties. The main toxin in bee venom is melittin, a basic compound with strong surface activity. The chemotaxis of polymorphnuclear leukocytes result in a white corneal infiltrate with surrounding intense stromal edema. This infiltrate mimics a microbial keratitis and in cases associated with severe uveitis it may be misdiagnosed as viral keratouveitis. Unless a high degree of suspicion is maintained, these cases will be treated with antifungals or antibiotics or antivirals and thus deprived of the need to remove the stinger and administer high doses of steroids. The severe eye pain after bee sting is caused by the sudden release of highly concentrated biogenic amines, such as histamine, in the venom. Posterior segment complications like retrobulbar neuritis, papilledema, and optic atrophy have also been reported.
Although rare, insect stings can result in severe impairment of vision in humans. The retained insect parts are usually very tiny with surrounding inflammatory reactions and necrosis so that they can be easily missed and may mimic microbial keratitis even under slit-lamp biomicroscopy. Since the treatment modalities are entirely different and the earlier the diagnosis, the better the chance of visual prognosis, a high level of clinical suspicion and immediate removal of the stingers along with administration of high doses of topical and systemic steroids will reduce the chances of permanent corneal damage and intraocular complications.
1. Graft DF, Schuberth KC. Hymenoptera allergy in children Pediatr Clin North Am. 1983;30:873–86
2. Gilboa M, Gdal-On M, Zonis S. Bee and wasp stings of the eye. Retained intralenticular wasp sting: A case report Br J Ophthalmol. 1977;61:662–4
3. Smolin G, Wong I. Bee sting of the cornea: Case report Ann Ophthalmol. 1982;14:342–3
4. Arcieri ES, França ET, de Oliveria HB, De Abreu Ferreira L, Ferreira MA, Rocha FJ. Ocular lesions arising after stings by hymenopteran insects Cornea. 2002;21:328–30
5. Al-Towerki AE. Corneal honeybee sting Cornea. 2003;22:672–4
6. Mackler BF, Kreil G. Honey bee venom melittin: Correlation of nonspecific inflammatory activities with amino acid sequences Inflammation. 1977;2:55–65
7. Jain V, Shome D, Natarajan S. Corneal bee sting misdiagnosed as viral keratitis Cornea. 2007;26:1277–8
8. Razmjooh H, Abtah MA, Roomizadeh P, Mohammadi Z, Abtahi SH. Management of corneal bee sting Clin Ophthalmol. 2011;5:1697–700
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Conflict of Interest: None declared.