The TNO test is designed primarily for screening children of age 2-1/2 to 5 years for defects of binocular vision. It consists of 7 plates (to be viewed with red/green glasses) that carry figures that can be seen only when both eyes cooperate to give stereoscopic vision. 4 plates enable the examiner to quickly establish whether stereoscopic vision is present at all. The three quantitative plates may then be used for the exact determination of stereoscopic sensitivity. The strength of the TNO test is that there are no monocular clues. Red/green glasses included.