A variety of isolation structures for semiconductor substrates include a trench formed in the substrate that is filled with a dielectric material or filled with a conductive material and lined with a dielectric layer along the walls of the trench. With the current invention damage to the eye, in particular the cornea, in particular damage to the eye, in particular the cornea, of a person wearing a contact lens, or as a consequence of wearing a contact lens is prevented or reduced. The insert also includes a series of locking lugs that mate with the locking lugs on the bolt. The barrel member is movable between a retracted position wherein the distal end is disposed within the interior of the writing instrument portion, and an extended position wherein the distal portion is disposed exteriorly of the writing instrument portion.