Gross stereoscopic acuity: (range 0-15 arc seconds) Our binocular vision allows us to see in three dimensions (3D), or more simply, to see depth. In this test, seated participants wearing 3D glasses are shown images. Inability to see depth or 3D will cause images to appear as points instead of objects. The objects are presented in different stages, with each stage requiring them to discriminate different levels of depth perception. The test is scored in optical units, with a range of 0 to 15 arc-seconds. The maximum score corresponds to the level where the last object was identified.