Acute Persistent Visual Loss: Optic Neuritis
What causes it?
Autoimmune inflammation directed against optic nerve myelin. This may be idiopathic or part of multiple sclerosis.
Vision loss develops over hours to days, often accompanied by periocular pain exacerbated by eye movement. The optic fundus is usually normal because inflammation lies far behind the eyeball!
Since the eyeball looks normal, look for proof of optic nerve dysfunction by finding an afferent pupil defect.
What to do?
The patient should be offered treatment with intravenous methylprednisolone 1 gm/day for three days, followed by prednisone 1 mg/kg for 11 days.
A large collaborative trial proved that this regimen slightly speeds visual recovery and reduces the occurrence of new neurologic events within the next two years.
Brain MRI can be performed to exclude alternative causes of optic neuropathy.
To learn more, go to Principal Ophthalmic Conditions: optic neuritis.