Final answer:
Refraction is the bending of light as it passes between two different media, crucial for vision and optical devices. The refractory media in the eye are the cornea and the lens, which together focus light onto the retina.
Step-by-step explanation:
Refraction is a phenomenon where light rays change direction when they pass through the interface of two media with different densities.
This bending of light occurs either towards or away from the line perpendicular to the boundary surface, dictated by principles such as Snell's law. In the context of the human eye, refraction is critical for focusing light onto the retina. The primary refractory media within the eye includes the cornea and the crystalline lens, both of which adjust the path of incoming light to form clear images on the retina.
Understanding refraction is essential for predicting the behavior of light, such as when viewing an object through a medium - for instance, a fish in water appears at a different depth than its actual position due to refraction. Likewise, optical instruments like microscopes and telescopes rely on refraction to magnify images. Thus, whether in natural systems like the eye or engineered devices, refraction's role in image formation is indispensable.