Rapid detection of changes in the optic disc: Stereochronoscopy

Abstract

In the evaluation of stereochronoscopic pairs of fundus pictures (Sc) venous pulse is an interfering factor. Visual observation and photography show that when a magnification of 15x is used, as in our case, venous pulse is seen only at the emerging part of the big veins and in their immediate neighborhood, whereas veins of 100 microns diameter or less show no pulsation. Over relatively short time intervals (some minutes) the temporal course of venous pulse in terms of vessel width is a more or less periodic phenomenon; for longer periods (months) a study is underway. In the majority of cases the filling state of pulsating veins seems to reach a minimum shortly after the R peak of the ECG. An investigation as to whether the interference of venous pulse can be reduced by coupling the camera flash to the R peak has been begun. However, for the time being, it appears that the best method is to pass over the pulsating vessel parts, and to observe Sc effects only in the small vessels, when Sc evaluation is applied. Statistics show that venous pulse is significantly more frequent in suspected and early glaucoma subjects (T greater than 21 mm appl.) than in healthy subjects. We feel that with the methods proposed all conditions pertaining to an extensive follow-up of ocular hypertension and early glaucoma cases are now established.