Final answer:
The symptoms provided are indicative of internuclear ophthalmoplegia, a condition characterized by paralysis of eye adduction and elevation with preserved pupil function, leading to diplopia.
Step-by-step explanation:
The described symptoms of orbital pain with left eye paralysis of adduction and elevation but normal pupil function suggest a diagnosis of internuclear ophthalmoplegia (INO). INO is a disorder of the conjugate lateral gaze due to a lesion in the medial longitudinal fasciculus (MLF) that impairs coordination between the movements of the eyes. In the context given, the medial rectus muscle of one eye is unable to contract in unison with the lateral rectus muscle of the other, resulting in double vision or diplopia. The normal pupil function helps differentiate this from other conditions like Horner's syndrome or third nerve palsies that can also affect eye movements but typically include pupillary involvement.