The diagnosis of<unk>  is often difficult since the optic nerves initially appear normal. The injury occurs<unk>  to that portion of the nerve visible during ophthalmoscopic examination. There may be an abnormal relative pupillary response (APD) if the injury is confined to one optic nerve, but often it is bilateral and the symmetry of pupillary responses is maintained. Furthermore, MRI scanning may not be helpful. It is not uncommon for the erroneous diagnoses of malingering or cortical blindness to be made. If possible, an urgent neuro-ophthalmology consult is most likely to lead to the correct diagnosis. There is no confirmatory test for<unk> .<unk>  is a diagnosis of exclusion. To prevent impending blindness, it is urgent to rule out giant cell arteritis when a patient over 50 presents with sudden vision loss. Differential diagnosis In the postoperative setting, without gross eye injury, visual loss requires an assessment of the whole visual system for ischemic damage. The optic nerve is not the only tissue of the visual pathway susceptible to decreased blood flow. Decreased oxygenation of the retina or brain could also impair vision. Anterior ischemic optic neuropathy<unk>  is less common than Anterior Ischemic Optic Neuropathy (AION). Blood supply and surrounding anatomy make the anterior and<unk>  portions of the optic nerve susceptible to different ischemic pressures. The<unk>  optic nerve receives blood primarily from the pial branches of the ophthalmic artery. The optic canal, a boney tunnel leading to the brain, surrounds the most<unk>  part of this optic nerve segment. The anterior optic nerve receives blood primarily from the<unk>  ciliary arteries. The anterior optic nerve, a.k.a. the optic nerve head, is surrounded by the scleral canal, and is vulnerable to crowding of nerve fibers. The portion of the optic nerve head that is visible by looking into the eye with an ophthalmoscope is called the optic disc.<unk>  versus AION At the onset of symptoms, ophthalmoscope examination can differentiate AION from<unk> . If optic nerve head involvement is observed, it is AION.<unk>  does not produce optic atrophy that is observable via ophthalmoscope until four to eight weeks after onset. In addition, AION often shows a characteristic altitudinal defect on a Humphrey Visual Field test. GCA The American College of Rheumatology has defined a combination of physical symptoms and inflammatory changes to diagnose giant cell arteritis.
Posterior ischemic optic neuropathy
Anterior ischemic optic neuropathy
Ischemic optic neuropathy
Arteritic anterior ischemic optic neuropathy
Optic neuritis
Autoimmune optic neuropathy
Retinal vasculitis
Toxic and nutritional optic neuropathy