These plugs will stop the tear ducts from allowing the tears to just run down and out, preventing them from washing away the moisture basically do need. Poison ivy is scientifically because toxicodendron radicans. http://ivzen.com/__media__/js/netsoltrademark.php?d=WWW.Opticaljournal.com%2Fdry-eye-assessment-using-the-ocular-surface-disease-index-osdi%2F