Estimation of the stereoscopic threshold utilizing perceived depth.

Recent reports in the literature indicate that a random-dot style of stereoscopic test is the most accurate method of assessing stereoscopic threshold [Cooper, J., Feldman, J. and Medlin, D. (1979) J. Am. optom. Ass. 50, 821-825]. While this is undoubtedly true for those who can respond to the test, it is less so for very young, infirm or other patients who do not or cannot have the requisite attention span. This experiment finds that the amount of perceived depth seen on a test like the Titmus fly correlates very accurately with the measured stereoscopic threshold and can therefore be used as a measure of the threshold without having to employ the entire testing procedure of the random dot tests. The regression equation derived from the data is presented, as well as a table that allows a practitioner to estimate the stereoscopic threshold from the amount of perceived depth on a common stereo test: the Titmus fly.