Treating CS gas injuries to the eye

Exposure at close range is particularly dangerous

EDITOR,--Jean-Paul Yih's editorial on injuries to the eye caused by O-chlorobenzylidene malono-nitrile (CS) gas, or tear gas, draws attention to the short term effects of the gas on the eye and suggests that such injuries may well be a future problem as individual police officers in Britain will soon be carrying pocket aerosols of CS gas.1 Yih implies that the ocular toxicity of CS gas is rapidly reversible; however, the ocular irritation from 1-chloroacetophenone (another tear gas agent) typically lasts only 15 minutes but may persist for up to three days.2 The problems are particularly pronounced when the charge of tear gas is fired at close range: powder infiltration of the conjunctiva, cornea, and sclera will occur. The forces are so great that conjunctival tearing may occur. Corneal stromal oedema and later deep vascularisation may ensue, and a multitude of complications have been reported, including symblepharon, pseudopterygium, infective keratitis, trophic ketatopathy, posterior synechia, secondary glaucoma, cataracts, hyphaema, vitreous haemorrhage, and traumatic optic neuropathy.2 Thus exposure to tear gas is not a benign phenomenon, and serious ocular morbidity can result. One would expect this to occur frequently when tear gas is being administered at close range from an aerosol likely to be directed at the subject's face.

A major problem in handling a casualty with a chemical injury is to prevent the attendant staff from being contaminated with residual chemical agent. Thus the casualty's contaminated clothing should be removed and is best decontaminated by being hung on a washing line on a windy day. As this is probably impossible in most hospitals, the clothing should be temporarily stored in a sealed polythene bag to prevent degassing. If clothing is to be washed, cold water should be used because hot water will cause any residual CS gas to vaporise and give rise to symptoms in staff. Eyes contaminated with CS gas should be treated by blowing dry air over them; this should ideally be done in an open space with no attendants down wind or they too will be exposed to the effects of the gas. The casualty's facial skin and hair are best decontaminated by washing in cool water.