Discussion
Spitting cobras belong to the elapid family of snakes. Of these,
Naja siamensis or the IndoeChinese cobra is found in the South
East Asian region and Naja nigricollis and Hemachatus haemachatus
are found in Africa. Natural habitats of spitting cobras
include hills, lowlands, plains and woodland. They get
attracted towards human settlements due to high population
of rodents. These can spit venom up to a distance of eight to
twelve feet.
Snake venom ophthalmia due to Naja atrahas been reported
from China and Hong Kong.2 “Venom spitting” is a reflex
mechanism aimed at ejecting venom forcefully into the eyes of
its victims.3 Spitting cobra venom contains a mixture of neurotoxins,
cytotoxins, phospholipases and cardiotoxins. Cardiotoxins
with membrane lytic properties are thought to be
responsible for corneal erosions and conjunctival chemosis.4
The ocular effects of the venom depend on duration of contact
of ocular surface with venom. Ocular contact with snake
venom results in pain, diminution of vision, blepharospasm,
conjunctival inflammation and chemosis. Initially there may
be small fluorescein staining corneal epithelial defects. The
epithelial cells lyse to form large epithelial defects or erosions.
Fortunately the venom enzymes do not penetrate the corneal
stroma made up of collagen therefore protecting cornea from
permanent stromal opacification. Systemic effects of snake
venom ophthalmia have not been reported.5
Copious irrigation of the eyes with water at the earliest is
single most important step in management of this condition.