What is the highest degree of fusion?

• A. Fusion
• B. Depth perception
• C. Stereopsis
• D. Binocularity

Answer: (C)

Stereopsis is the highest degree of fusion because it represents the brain’s ability to fuse two slightly different images from each eye into a single perception that includes depth. This binocular depth perception, driven by retinal disparity, shows how well the visual system integrates information from both eyes to create a three‑dimensional experience. It requires precise motor fusion (eye alignment) and sensory fusion, making it the most advanced form of combining the two eye views.

Fusion alone means seeing a single image, without depth. Depth perception is a broader term for judging distance and can rely on monocular cues, not just binocular fusion. Binocularity simply describes using both eyes, but it doesn’t specify the depth quality that stereopsis provides.