Glass eye: 1. An artificial replacement for an eyeball. In other words, an artificial eye, a globe of glass or plastic colored so it looks like an eyeball.
2. By extension, a real eye that looks glassy and as lifeless as a poorly crafted glass eye,
The first glass eye was made in 1832 by the glassblower Ludwig Muller-Uri in Lauscha, Germany. Although artificial eyes can be manufactured from plastic today, no other material is said to be equal to a glass eye created from a special blend of Cryolite glass. See also: Ocular prosthesis.