Tears Naturale^® II soothes and moisturizes your dry、 sensitive eyes just like your own tears. Tears Naturale^®II contains POLYQUAD^® preservative、 recommended by doctors as being one of the most gentle on the eye. Store brand eye drops and even some national brands are still using a preservative called BAC (benzalkonium chloride)、 which has been shown to be harsher to the surface of the eye with frequent use.