Which statement correctly differentiates OKR from OKN?

• A. OKR stabilizes image during head movements; OKN stabilizes image when the object moves with the head stationary.
• B. OKR stabilizes image during head movements; OKN stabilizes image when the head moves.
• C. OKR stabilizes during head movements; OKN stabilizes image during head movements.
• D. OKR and OKN describe the same mechanism.

Answer: (C)

Both OKR and OKN are responses to movement of the visual field that help keep the image stable on the retina. When the head moves or the environment appears to move, retinal slip would cause the image to blur; the optokinetic system kicks in to minimize that slip. OKR is the eye movement component that follows the moving field to stabilize the image, and OKN is the full pattern that includes that slow tracking plus a rapid reset (the nystagmus). Since both reflexes act to stabilize vision during head movement, they share this functional outcome, which is why this statement is the best choice. The other options misstate when OKN occurs or imply they describe different mechanisms, whereas the key point is that both responses serve to stabilize the image during movement of the scene or the head.