Which of the following pathways do NOT use the LGN?

• A. Light reflex pathway
• B. Visual pathway
• C. Near reflex pathway
• D. All pathways use LGN

Answer: (A)

The main idea is that the LGN is the thalamic relay for the retino-geniculo-cortical visual pathway. Not all pupil responses rely on this route.

For the pupillary light reflex, the signal travels from the retina to the midbrain’s pretectal area, then bilaterally to the Edinger–Westphal nucleus and onward to the ciliary ganglion and sphincter pupillae. This path bypasses the LGN and the cortical visual areas, so it does not use the LGN.

In contrast, the visual pathway clearly passes through the LGN on the way from retina to primary visual cortex, and the near reflex depends on cortical processing of blur and distance to coordinate accommodation and convergence, with the pupillary response linked through brainstem circuits. That means the light reflex pathway does not use the LGN, while the others do.