San Francisco programmer Tris Thomson spends long hours in front of a monitor, designing computer servers -- a job made more difficult after someone fired a laser beam into his right eye.

“The injury has not improved and probably never will,” said Thomson.

It happened during a Mexican Riviera cruise last December. Thomson and other passengers boarded a smaller sailboat for a sunset cruise. He says someone in an apartment building a quarter mile away began strafing the boat with a green laser beam.

“I felt a slight bit of pain in the eyeball. A little searing, like almost you get burnt real quickly or something,” said Thomson.

This eye x-ray shows the retinal burn that's left a black blotch in his vision. Thomson says it's an injury that is permanent and cannot heal itself.

While a typical five milliwatt laser pointer is only about one thousandth as powerful as a 100 watt bulb. Because the laser light is so concentrated, laser experts say its effect on the eye is 10 thousand times more powerful than the bulb.

The Federal Aviation Administration reports increased incidents in which lasers are pointed at aircraft. In some cases, the lasers temporarily blind pilots. It's a felony with fines as high as $11,000 per incident. 

The legal limit for a pocket sized lasers is set at five milliwatts though more powerful ones are easily found. KTVU purchased one 200 milliwatt laser pointer online.

San Leandro opthamologist Dr. Vineet Batra sees patients injured by laser pointers about once a month.

“This is the kind of laser pointer that sometimes is used at parties and can indiscriminately spray people's eyes,” said Dr. Batra.

Recent research indicates green laser beams may be more hazardous than red because the eye is more sensitive to the color green but Dr. Batra says both are dangerous.

“It really depends on the power and the intensity and the spot size and so red or green, they can both cause equal damage,” said Dr. Batra.

Thomson now uses a magnifying glass and a brighter keyboard with bigger letters to do his job.

“There's not treatment at all. There's no operation for it. And there's no therapy. So it's just something I will live with,” said Thomson.