Common variable immunodeficiency is the most prevalent of the primary immunodeficiency diseases.
It is characterized by impaired antibody responses. Diagnosis is based on exclusion of known causes of humoral immune system defects.
The common immunologic defect in patients with this disease is defective antibody formation. The basic and common immunologic defect in it, is a failure of B-lymphocyte differentiation into plasma cells that produce the various immunoglobulin isotypes.
It is not related to multiple sclerosis.
Very difficult to say about MS, as we have been trained to keep a single diagnosis unless things are very diverse and are unexplainable on the basis of solitary causative. I would think of mild grade infection and look for it.
Vasculitis is again a diagnosis which will have basis of auto immunity or wavered immunity. Inadequate immune response or altered immune responses can be explanation and probably your eyes symptoms may be responsible because of it. Still, I accept that it is a difficult situation, not only by the view point of diagnosis but for management as a whole.