Experts believe laser pen caused retinal injury

17 Jun 2002

Some experts in the US are coming to the view that an 11-year-old girlfrom Arizona is the first person in the world to have suffered retinaldamage from a laser pen. One well-known ophthalmologist is suggesting anew injury mechanism to explain the tiny lesion.

She stared into the beam for ten seconds to prove to classmates that thelight would make her pupil dilate. The result was the lesion right inthe centre of her macula, the area on the retina responsible for detailin vision. Damage to the macula often leads to the permanent loss of theability to read or drive a car.

"I think this is a laser pointer injury. I really think it is. I have noother explanation for it," Martin Mainster, spokesman for the AmericanOphthalmology Association, said at ILSC 99.

The girl's sight fell to the 20/60 level immediately after the accidentbut it has now returned to 20/20. Photographs show that the lesion hasfaded and is still fading after 18 months.

Mainster suggests two possible damage mechanisms. The first is thresholdphoto-coagulation, by which heat damaged the retina.

"The other is phobic retinopathy, from a yet unidentified red-lightsensitive chromophore," he said. "It looks like an injury from solarretinopathy but this is felt to be produced by the blue and ultravioletend of the spectrum."

Some laser experts think that the girl may have stared at the sun aswell as the pen.

The macula is about 350 micrometres across so the girl must have lookeddirectly into the beam to injure the centre of the area. Otherwise theinjury would have been off centre.

"It must have been a deliberate act. You need a voluntary participant inan injury process like this."

Despite hundreds of claims all over the world that laser pens have causepermanent injuries, none has yet been proved. A paper on the Arizonacase is to be published in the American Journal of Ophthalmology.