Expert warns eclipse watchers to wear NASA recommended glasses

With eclipse fever hitting North America ahead of Monday's celestial event, experts are warning Canadians to make sure they wear NASA-recommended glasses if they intend to watch.
University of Waterloo optometry professor Ralph Chou says staring at the sun for more than a few seconds will cause harm, and since the eye feels no pain, people can cause potentially-permanent damage without realizing it.
NASA says special solar eclipse glasses should be marked with the ``ISO 12312-2'' international safety standard on the label, and should not have any scratches on the lenses.