Many people would rather not think about what’s happening to their flesh during laser surgery. And until recently, scientists assumed it wasn’t much different from what happens to water, since living things are mainly water.

But a new study of pulsed ultraviolet lasers finds that living tissue actually helps the lasers cut more effectively. These lasers are used in many eye and brain surgeries. they generate plasma with each pulse. When the pulse ends, the plasma collapses and explodes, splitting molecules in the tissue.

Using fruitfly embryos, scientists from Vanderbilt University found that this plasma forms more easily in living tissue than in water.  So lasers for some surgeries can be less powerful and less damaging than thought. The researchers also found that living tissue stretches during the plasma explosions.  This stretching makes the laser incisions smaller and more precise.  These results appear in physical review letters.

So while you may be mainly water, it’s the parts of you that aren’t that mean the most under the laser.

--Chelsea Wald