A method includes introducing light into a glass article such that at least a portion of the introduced light is emitted from an edge of the glass article. The light emitted from an edge of the glass article is detected. An intensity profile of the emitted light is an intensity of the emitted light as a function of axial position. A first intensity boundary of the intensity profile and a second intensity boundary of the intensity profile are determined. A thickness of a layer of the glass article is determined based on an axial distance between the first intensity boundary and the second intensity boundary.