Eye injuries and tasers

To the Editor: Taser (TASER International) injuries have been topical in the news media. This provides an important reminder of the possible traumatic sequelae associated with the use of electronic control devices.

A taser is a battery-powered unit that uses a nitrogen cartridge to propel two darts on a 7 m copper wire.1 Each dart consists of a 4 mm harpoon-like barbed electrode on a 13 mm × 1 mm shaft (Box), deployed at 18 m/s from a distance of 3–6 m. Increasingly, tasers are being used by police in every state of Australia to subdue violent people.

When the deployed darts attach to a target individual's skin or clothing, a current of up to 50 000 volts is released for a period of up to 5 s, depending on the skin's resistance (which varies based on fat content, thickness, cleanliness and body chemistry).2 The mechanical impact of the barbs, combined with the subsequent voltage released, represents a considerable hazard to eyes, genitalia and large blood vessels in the neck.2

Essentially, the eyeball is a liquid-filled globe with a wall thickness < 1 mm, making it particularly susceptible to electrical damage. TASER International states that “serious injury, including permanent vision loss” can result from barb contact with the eye.3 Our literature search found seven case reports and one review of ocular damage relating to taser use.1,2,4-8 In five cases, penetration of the globe was reported;1,4,5,7,8 in three cases, entry through the lids made this difficult to determine without ophthalmic surgical examination.1,2,7 Ocular damage associated with taser use includes mydriasis, iritis, macular cysts, lid lacerations, cataracts, retinal detachment, optic neuritis, vitreous haemorrhage and globe penetration.6 Damage may be thermal or mechanical,6 with visual outcome ranging from final visual acuity of 6/9 to total vision loss and enucleation.1,2,4,5,7,8

As taser use increases, medical staff need to be aware of the implications of both the impact energy and the electrical damage associated with taser deployment. As in the management of a barbed fishhook penetrating the eye or ocular area, a taser barb should not be removed at the scene but should be immobilised (eg, by covering it with a foam or paper cup) until appropriate ophthalmic surgical removal is possible.1

Taser dart, showing dimensions (mm)