benzalkonium chloride

Your eyes bother you. So you go down to the drug store and buy a bottle of artificial tears. There are so many brands you really don't know which one is best. Or you trust your eye doctor who may prescribe an eye drop for glaucoma or who recommends an over-the-counter eye drop for your dry, red, itchy, burning eyes. To keep the ingredients from spoiling, manufacturers add preservatives. It is these preservatives, even in doses as small as 1/10th of 1 percent, that are a cause for concern.