A complete oculomotor nerve palsy will result in a characteristic down and out position in the affected eye. The eye will be displaced outward and displaced downward; outward because the lateral rectus (innervated by the sixth cranial nerve) maintains muscle tone in comparison to the paralyzed medial rectus . The eye will be displaced downward, because the superior oblique (innervated by the fourth cranial or trochlear nerve), is unantagonized by the paralyzed superior rectus , inferior rectus and inferior oblique . The affected individual will also have a ptosis , or drooping of the eyelid , and mydriasis (pupil dilation).
Since almost 50% of optic neuritis is likely a result of a post-viral immune reaction, minimizing your risk of acquiring a viral respiratory infection decreases your risk of optic neuritis. It is impossible to totally avoid exposure to respiratory viruses, but research has shown that frequent hand-washing and attempting to not touch one's face without first washing one's hands decreases the incidence of the common cold . Teaching children to cover their mouths and noses when sneezing and instructing them on personal hygiene can also decrease the chances of upper respiratory virus spreading within families.
As mentioned earlier, optic disc edema is always present in the acute phase of NAION (the reason will be discussed in the section under Pathophysiology) and comes in two varieties, diffuse or segmental. Segmental (typically altitudinal) is more common but it does not consistently correspond to the accompanying area of visual field loss 15. The edema is typically hyperemic and rarely pallid. Pallid edema is common in AAION and should alert the clinician to the possibility of giant cell arteritis. Peripapillary splinter hemorrhages are seen in nearly three-quarters of patients 12 and its presence can sometimes help to differentiate NAION from optic neuritis since they will be present in 5-15% of patients with optic neuritis 16, 17. Retinal exudates are uncommon but both hard and soft exudates were reported in up to 7% of patients in the IONDT 12 and the retinal arterioles can be focally narrowed in the peripapillary region in two-thirds of patients 18.