"We think that he was playing with a mirror and that the rays were reflected," said Yosuf El-Shabrawi, chief doctor at the Klagenfurt am Wörthersee clinic in Carinthia, southern Austria.
"His injuries cannot be treated. We can only hope that the worst of the injuries heal themselves and that his condition improves," El-Shabrawi said in a statement on Tuesday.
The boy's father bought the laser pointer on the Internet where it was advertised as a toy for playing with cats.
After a week the boy, named as Lukas, complained of a constant black mark in his field of vision.
The laser pointer in question was labelled as "Class 2" with an output under the European Union legal limit, but it lacked a so-called EN standardisation certificate, El-Shabrawi said.
Laser pointers have soared in popularity in recent years, with powerful ones even directed into the cockpits of planes in 99 recorded cases in 2013 in the United States alone, according to the Federal Bureau of Investigation.