OCULAR ENVENOMATION BY SPITTING COBRAS (VENOM OPTHALMIA)

Spitting cobras have modified fangs that allow them to spray venom into the eyes of a predator or perceived threat.153–155 The snakes aim at the glint of sunlight reflecting off of the target’s eyes and the venom spray widens like buckshot. The venom is harmless unless it enters the eyes (causing instantaneous burning, lacrimation, blurred vision, etc.) or the bloodstream by injection (such as a bite), through open wounds on the skin or inside of the mouth, or by ingestion (such as drinking a glass of venom with an ulcer). If a significant amount of venom enters the bloodstream through an open wound and produces typical symptoms of a snakebite, it is treated with antivenom like any other envenomation. For ocular exposure alone without signs of systemic envenomation, antivenom is not indicated and the management is like any ocular chemical exposure with copious irrigation. Spitting cobras can also deliver a venomous bite, so it is important to rule out an actual snakebite in patients who have encountered one of these snakes.

SIGNS AND SYMPTOMS

Immediate signs and symptoms of venom ophthalmia include intense local pain, swelling and/or spasms of the eyelid, lacrimation, and leukorrhea.156 The primary concern is corneal epithelial injury which can lead to blindness by secondary infection or scarring if not treated correctly.7,25,54,156–158 Treatment of venom ophthalmia is relatively simple and similar to managing a patient who has been splashed in the eyes with a harmful chemical solution.

FIRST AID

Confirm that the patient did not experience a snakebite in addition to the ophthalmia. Immediately irrigate the eye with copious quantities of water, normal saline, or a bland fluid such as milk if nothing else is available. Remove clothing and decontaminate the patient from head to toe with soap and water to prevent second re-exposure to dried venom.54

CLINICAL MANAGEMENT

Apply topical anesthetic eye drops (tetracaine) to facilitate thorough irrigation and examination of the affected eyes. Irrigate the eyes thoroughly using water or normal saline for ≥ 15 minutes.156

Fluorescein stain and examination using a slit lamp or ophthalmoscope for corneal injury. If present, treat with antimicrobial eye drops (such as ofloxacin or moxifloxacin) or ointments and mydriatics. Reassess daily with slit lamp or ophthalmoscope examination. If absent, consider benefits vs risks of antimicrobial eye drops.

ADDITIONAL TREATMENTS TO CONSIDER

Topical eye drops containing either epinephrine (1:1000) or phenylephrine (10%) are reported to immediately relieve the burning sensation produced by the venom.54,156

CONTRAINDICATED TREATMENTS

Antivenom (topical or systemic) IS NOT indicated for patients with ocular exposure to snake venom.54,156,159 Topical steroids are contraindicated for these patients.