Where does fusion occur in the visual process?

Fusion, in the context of the visual process, refers to the integration of visual information received from both eyes to create a single, coherent perception of the visual field. This process primarily occurs in the brain, specifically in the visual cortex, where signals from the optic nerves, which carry information from the retina, are combined.

As images from each eye have slight differences due to their spatial separation (binocular disparity), the brain synthesizes these images, allowing for depth perception and a unified view of the environment. This integration is crucial for tasks such as depth perception, which relies on the brain's ability to interpret the differences in images from both eyes.

The retina captures light and initial image processing begins there, while the lens focuses the light onto the retina. The ciliary body is involved in adjusting the shape of the lens for focusing. However, the actual fusion of images and the perception of a single visual field take place in the brain. Thus, the brain is the correct answer for where fusion occurs in the visual process.