The Titmus Fly-Test: Evaluation of subjectiv depth perception simply by finger pointing. A clinical study on 73 patients and volunteers

Background: Subjects with different binocular defects were tested for their stereoscopic achievement. The determination of the subjects limiting dispa rity (in seconds of are) was not used to characterize their stereoscopic ac uity, but the subjective depth perception as a simple clinical method. Methods: 52 subjects with different binocular defects and 21 normosensoric volunteers were examined for their stereoscopic achievement. In our stereos copic measurement we ask the subjects to indicate the subjective plane of t he fly's wings manually by their own finger, or by a hand-held plastic card , or with the aid of a mechanic instrument. The results of the different me thods were compared with each other. Results: There were no differences between the results within the group of normosensoric subjects. The patients with reduced abilities exhibit signifi cantly different results in depth perception when measured manually or by m achinery. The subjective depth localization correlates well with the binocu lar defect and is independent of the used stereoscopic method. Conclusions: The basic finger test of the subjective level of the Fly's win gs gives a quite reasonable approximation of focal stereoscopic depth perce ption. in terms of practical investigation the finger test shows in convinc ing manner whether the individual sterescopic ability is based on normal, s ubnormal or anomalous binocular interaction.