Optic neuritis can be classified by location and causes.
According to location,
- anterior part of optic nerve induces optic disc swelling
- posterior part inflammation does not result in disc swelling.
Causes of inflammation were divided into two categories.
- Pure inflammation such as multiple sclerosis (MS), neuromyelitis optica (NMO) or autoimmune disorders.
- Infection related inflammation.
In my opinion, although I try to detect any abnormal findings in blood test. almost optic neuritis is idiopathic.
When it comes to proven causes of the optic neuritis
- Anti-Aquaporin 4 (AQP-4) antibody positive finding
- Multiple sclerosis related.
- Syphilis
- Anti nuclear antibody (ANA).
In Korea, optic neuritis related with MS is very rare, however, AQP-4 positive ON is not uncommon. Thus, I always do AQP-4 Ab. test in optic neuritis.
Sometimes, there have been detected ANA in the optic neuritis. Actually I don't know the relationship between optic neuritis and ANA. It may not be cause but coincidence.
In conclusion,
I do AQP-4 test and Syphilis blood test in the optic neuritis. MRI can be performed depend on case, however, we should consider cost-effectiveness of MRI.