Control tests of stereoscopic vision

Children with strabismus show a decrease or loss of their stereoscopic vision.

There are many tests for controlling the stereoscopic vision that often involve the use of polarizing glasses and in which the patient is asked to discern stereoscopic images that he is given.

The most famous of these is the Titmus test, which uses stereoscopic images of a fly (that's why among ophthalmologists it is sometimes referred to as "the fly test"), some animals and some circles.

A simple way for a rough check on stereopsis is the two pencils test.

In this method, we give the examinee a pencil or pen and we ask him to hold it vertically and touch with it the tip of the nose of a second pencil, which we are also holding vertically nearby. If the examinee succeeded (we repeat the test a few more times to exclude the possibility that he touched it by chance), this indicates the existence of stereoscopic vision.