Quantitative studies in stereochronoscopy (Sc): application to the disc in glaucoma. I. Phenomenology.

In some details our standard procedure of stereochronoscopic disc picture-taking has been improved. For clinical use (demonstration of a change in the disc surface) a semi-quantitative evaluation with a stereoscope is generally sufficient. For a more accurate and quantitative analysis a flicker comparator is used. A graphical or numerical display of the results allows the follow-up of changes at a given location on the disc over any time interval, e.g. several years in glaucoma simplex, if pictures are taken every 2-4 months. Characteristic curve courses result, of which we describe (1) to and fro movement of the position of a given object on the disc, "papillary unrest" (2) progression of parallax, and (3) "events". The difficulty of judging the efficacy of a therapy is made evident. Here stereochronoscopy should prove to be useful when employed in the form of control charts.