Although computer usage has not been conclusively shown to cause permanent damage to healthy eyes, there is evidence to suggest that small vision defects, which do not cause symptoms in everyday life, may start to cause problems when carrying out more visually demanding tasks.

BBC: Computer eye tests

They use a multimillion-dollar machine known as the Meisterbock gauge that laser-scans the entire surface of the vehicle for defects as small as a few millimeters.

WSJ: New Chrysler Battling Old Defects

It could be defects due to missing atoms, thermal vibrations of the crystal lattice, or even the boundaries between small, imperfectly formed crystals that make up the material.

ECONOMIST: MONITOR