Abstract: A punctum plug for blocking lacrimal fluid flow through a punctum and an associated canaliculus composed of a hydrogel material and a hydrophobic coating which covers the exterior surface of the hydrogel material. The hydrophobic coating averts adsorption of proteinaceous materials onto the hydrogel. The punctum plug has a configuration which includes a generally cylindrical body member, an arcuate head at a first end of the body member, and a placement and retaining member at a second, peripheral end of the body member. An insertion port is located at the first end of the cylindrical body member for receiving a dilator/inserter tool. A hydrating port is fashioned at the peripheral end of the plug and partially extends through the placement and retaining member. The hydrating port is not coated with the hydrophobic material so that fluid in the canaliculus, or canalicular fluid, or preocular tear film may enter the interior portion of the plug and permit the hydrogel to expand to a desired configuration.