Stereoscopic comparator. Wtih primary use for optic discs

• A new device makes it much easier and more satisfactory to compare different sets of stereophotographs of an optic disc than is possible with ordinary stereo viewers that accept only one stereopair at a time. Two ordinary stereophotographic transparencies of the optic disc are inserted and viewed simultaneously through a single pair of eyepieces. By means of a pair of mirrors in the device, the two stereophotographs are made to appear close to one another so that with very small eye movements one can look from one to the other and make a very satisfactory comparison. It is desirable that the sensitivity for detection of glaucomatous change in the optic disc by this simple means be compared with the results of more complex and costly methods of analysis of the optic cup.