Venom ophthalmia caused by venoms of spitting elapid and other snakes: Report of ten cases with review of epidemiology, clinical features, pathophysiology and management.
Chu ER., Weinstein SA., White J., Warrell DA.
Venom ophthalmia caused by venoms of spitting elapid and other snakes: report of ten cases with review of epidemiology, clinical features, pathophysiology and management. Chu, ER, Weinstein, SA, White, J and Warrell, DA. Toxicon XX:xxx-xxx. We present ten cases of ocular injury following instillation into the eye of snake venoms or toxins by spitting elapids and other snakes. The natural history of spitting elapids and the toxinology of their venoms are reviewed together with the medical effects and management of venom ophthalmia in humans and domestic animals including both direct and allergic effects of venoms. Although the clinical features and management of envenoming following bites by spitting elapids (genera Naja and Hemachatus) are well documented, these snakes are also capable of "spraying" venom towards the eyes of predators, a defensive strategy that causes painful and potentially blinding ocular envenoming (venom ophthalmia). Little attention has been given to the detailed clinical description, clinical evolution and efficacy of treatment of venom ophthalmia and no clear management guidelines have been formulated. Knowledge of the pathophysiology of ocular envenoming is based largely on animal studies and a limited body of clinical information. A few cases of ocular exposure to venoms from crotaline viperids have also been described. Venom ophthalmia often presents with pain, hyperemia, blepharitis, blepharospasm and corneal erosions. Delay or lack of treatment may result in corneal opacity, hypopyon and/or blindness. When venom is "spat" into the eye, cranial nerve VII may be affected by local spread of venom but systemic envenoming has not been documented in human patients. Management of venom ophthalmia consists of: 1) urgent decontamination by copious irrigation 2) analgesia by vasoconstrictors with weak mydriatic activity (e.g. epinephrine) and limited topical administration of local anesthetics (e.g. tetracaine) 3) exclusion of corneal abrasions by fluorescein staining with a slit lamp examination and application of prophylactic topical antibiotics 4) prevention of posterior synechiae, ciliary spasm and discomfort with topical cycloplegics and 5) antihistamines in case of allergic kerato-conjunctivitis. Topical or intravenous antivenom and topical corticosteroids are contraindicated. Clinical outcome of venom ophthalmia is largely dependent on prompt treatment and appropriate follow-up.