Boy, 9, burns hole in his eye after playing with a laser pointer

The child's dad bought him a green laser pointer at a market as a toy. Photo / New England Journal of Medicine.

A nine-year-old boy is now partially blind after playing with a green laser pointer that burned a hole in his eye.

The child came in for a check-up with his doctor in Volos, Greece, more than a year after his injury, and complained of some issues seeing.

A scan soon revealed a large hole in the part of his left retina called the macula, which is crucial for mapping out things like faces and words, the Daily Mail reports.

Normally macular holes are treatable, though the surgery inevitably causes cataracts, which permanently clouds vision.

However, even that wasn't an option in this case; the nerves surrounding the hole were completely obliterated, making surgery futile.

Writing in a paper for the New England Medical Journal, the doctors who dealt with the case warned parents should be wary of the life-changing dangers of a strong beam from a laser.

According to the paper, published today, the boy's dad bought the laser from a street market, to give to his son to play with.

Lasers are dangerous as a toy for many reasons.

Laser light is different from normal light. First, its light contains only one wavelength - one specific color. The particular wavelength of light is determined by the amount of energy released when the excited electron drops to a lower orbit.

Beyond that, laser light is directional. While a laser generates a very tight beam, a flashlight produces light that is diffuse.

But one of the biggest issues in this case, according to his doctor Sofia Androudi, was the color.

Green lasers or blue lasers can be more damaging than red or orange ones, because of the frequency at which they omit light - around 550 nanometers - which is extremely powerful.

These days, red ones omit light at around 670 nanometers.

As a result, the boy's vision in his left eye was obliterated. It was measured at 20/100 (meaning he needs to be within 20 feet to see what most see from 100 feet).

'[E]ven if the surgery would be successful, the boy would not be able to see,' Dr Androudi said.

Currently, a year and a half later, his vision is stable at 20/100 in his left eye.

'When you have something as powerful like a laser, it's so powerful that it is converted to heat like a burn,' Dr. Thomas C. Lee, director of the Vision Center at Children's Hospital Los Angeles, who was not involved in the case, told CNN.

'That can leave scar tissue behind and can cause bleeding. The patient can actually get a blind spot right in the middle of the eye. ... It's like a magnifying glass burning a piece of paper. It's the same thing.'