A system for draining fluid from the posterior chamber of the eye into the optic nerve or subarachnoid space, said system comprising a shunt device in combination with an introducer that is usable for implantation of the shunt device within the eye of a subject, the shunt device comprising: a straight tube member having a proximal end, a distal end, a smooth cylindrical side wall and a lumen extending therethrough and a conical tip member on the distal end of the tube member, the conical tip member having a tapered side wall and a proximal end, a plurality of barbs located on the proximal end of the conical tip member, the distal end of the tube member being connected to the conical tip member at a location inboard of the barbs such that the barbs protrude outwardly adjacent to the side wall of the tube member; a plurality of openings formed in the tapered side wall of the substantially conical tip member to allow fluid to drain out of the lumen of the tube; a laterally extending flange member on the proximal end of the tube member; and a shielding member which deters foreign matter or cells from clogging the tube; and a one way valve that allows fluid to flow in the distal direction through the lumen of the tube member; wherein the width of the shunt device is between 1 micron and 2000 microns at its widest point; and the introducer comprising: a tubular cannula into which the shunt device is initially loadable and an elongate member that is then useable to push the shunt device out of the distal end of the tubular cannula, the introducer being sized for insertion into the eye and useable for implanting the shunt device in an implantation position wherein a) the proximal end is within the posterior chamber of the eye, b) the flange engages the lamina cribosa and the plurality of openings are positioned either i) within the optic nerve so that fluid which first drains through the lumen of the tube member will enter into the optic nerve and diffuse into the subarachnoid space or ii) within the subarachnoid space adjacent to the optic nerve so that fluid which drains through the lumen of the tube member will enter directly into the subarachnoid space. a straight tube member having a proximal end, a distal end, a smooth cylindrical side wall and a lumen extending therethrough and a conical tip member on the distal end of the tube member, the conical tip member having a tapered side wall and a proximal end, a plurality of barbs located on the proximal end of the conical tip member, the distal end of the tube member being connected to the conical tip member at a location inboard of the barbs such that the barbs protrude outwardly adjacent to the side wall of the tube member; a plurality of openings formed in the tapered side wall of the substantially conical tip member to allow fluid to drain out of the lumen of the tube; a laterally extending flange member on the proximal end of the tube member; and a shielding member which deters foreign matter or cells from clogging the tube; and a one way valve that allows fluid to flow in the distal direction through the lumen of the tube member; wherein the width of the shunt device is between 1 micron and 2000 microns at its widest point; and the introducer comprising: a tubular cannula into which the shunt device is initially loadable and an elongate member that is then useable to push the shunt device out of the distal end of the tubular cannula, the introducer being sized for insertion into the eye and useable for implanting the shunt device in an implantation position wherein a) the proximal end is within the posterior chamber of the eye, b) the flange engages the lamina cribosa and the plurality of openings are positioned either i) within the optic nerve so that fluid which first drains through the lumen of the tube member will enter into the optic nerve and diffuse into the subarachnoid space or ii) within the subarachnoid space adjacent to the optic nerve so that fluid which drains through the lumen of the tube member will enter directly into the subarachnoid space. a tubular cannula into which the shunt device is initially loadable and an elongate member that is then useable to push the shunt device out of the distal end of the tubular cannula, the introducer being sized for insertion into the eye and useable for implanting the shunt device in an implantation position wherein a) the proximal end is within the posterior chamber of the eye, b) the flange engages the lamina cribosa and the plurality of openings are positioned either i) within the optic nerve so that fluid which first drains through the lumen of the tube member will enter into the optic nerve and diffuse into the subarachnoid space or ii) within the subarachnoid space adjacent to the optic nerve so that fluid which drains through the lumen of the tube member will enter directly into the subarachnoid space.