This patient with a left sixth nerve palsy moves his eyes well to the right, but upon left gaze, cannot abduct the left eye.
About sixth nerve palsy
Patients with a sixth nerve palsy have horizontal diplopia, double vision in which the two images are side-by-side. They have disconjugate gaze due to weakness of abduction of the affected eye.
Localization
The sixth cranial nerve originates in the pons and innervates the lateral rectus muscle which abducts the eye. It courses along the bony clivus and is particularly susceptible to the effects of increased intracranial pressure.