Question

25 y/o female with L eye pain which increases with moving the eye. Diminished acuity in L eye, pupils constrict well with light on R eye, but only constrict weakly with light on L eye. Dx?

Answer 1

If light in the right eye only causes the left pupil to constrict, the direct reflex is lost and the consensual reflex is intact, indicating damage to the right oculomotor nerve.

Step-by-step explanation:

If light in the right eye only causes the left pupil to constrict, the direct reflex is lost and the consensual reflex is intact, which means that the right oculomotor nerve (or Edinger-Westphal nucleus) is damaged. Damage to the right oculomotor connections will be evident when light is shined in the left eye. In that case, the direct reflex is intact but the consensual reflex is lost, meaning that the left pupil will constrict while the right does not.