We will try to differentiate any effect on the microbial flora caused by the silicone plug or acrylic plug(as a foreign body) versus the punctal closure by thermocautery. (Punctal thermocauterization is an alternative method of punctal closure which is 1) the preferred choice by some ophthalmologists for all their cases, or 2) when the dry eye is severe and irreversible punctal occlusion is desired or 3) if punctal plugs can not be retained due to the large size of the patients punctal). The thermodynamic hydrophobic acrylic plug(SmartPLUG) approved by the FDA for punctal occlusion with the same indications as the traditional silicone plug.