It's going to be a bit tough to know exactly what they tested for, because we'd have to know exactly what your doctors were thinking of other possible diagnoses.
serum IgG antibodies (NMO-IgG) - looking for Devic disease
antiribosomal P antibodies
as well as the standard CBC, chemistries, etc.
These could be looking at conditions such as Lupus, Sarcoidosis, and other potential conditions which could cause inflammation of the optic nerve.
Unfortunately, without knowing exactly what they were thinking, this is only a guess