Final answer:
Tests for assessing fusion include the Cover Test and variations like the Cover-Uncover Test, while stereopsis can be measured using tests such as the Randot Stereo Test or the Titmus Fly Test, which involve specialized glasses and 3D patterns.
Step-by-step explanation:
To assess fusion and stereopsis, specific tests are used within the field of ophthalmology and optometry. Fusion, the ability of the eyes to turn inward or outward to maintain single vision, is often tested using various techniques such as the Cover Test. In this test, one eye is covered to observe the movement of the uncovered eye; if it moves to regain focus, this indicates that fusion is keeping the eyes aligned. The Cover-Uncover Test and the Alternate Cover Test are variations used to diagnose phorias or tropias, which are misalignments of the eyes.
Stereopsis, the perception of depth and 3-dimensional structure obtained based on visual information deriving from two eyes, is commonly tested with the Stereopsis Test, which involves using specialized glasses (polarized or red-green) and viewing a book or a screen with patterns that will appear three-dimensional when proper binocular vision is present. The Randot Stereo Test or the Titmus Fly Test are examples of this kind of assessment. These tests measure how well the two eyes work together to perceive depth and can identify issues like amblyopia (lazy eye) or strabismus (crossed eyes).