Would a treatment of plasmapheresis be useful now, after the treatment 18 months ago double vision went away, with strong dose of prednisone at the same time

The short version: plasmapheresis is a rescue treatment for acute myasthenic crises, not a maintenance therapy for a stable patient who recovered 18 months ago.

Plasmapheresis filters antibodies out of the blood. It works fast, usually within days, but the effect fades in weeks as your body makes new antibodies. It is reserved for sudden worsening, breathing trouble, or before surgery. Your double vision resolved with prednisone and has stayed away for 18 months. That is a stable, mild disease state. There is no evidence that plasmapheresis now would prevent a future relapse, and it carries real risks: bleeding from the catheter, infection, blood pressure swings, and allergic reactions to the replacement fluid.

The evidence base for plasmapheresis in myasthenia gravis is thin and mostly observational. No trial has tested whether a single course of plasmapheresis in a stable patient reduces future relapses. The studies that exist compare it to IVIg during acute crises, not as maintenance. The retrieval here returned no records at all, so I cannot cite a specific trial. What is well established outside this retrieval is that plasmapheresis is a short-term bridge, not a long-term strategy.

The real question is whether your disease is still active. If you have been stable for 18 months on no treatment or a low prednisone dose, the risk of a relapse is lower than the risk of the procedure. If you are still on a high prednisone dose and the double vision was a warning sign, the better move is adjusting your immunosuppressant, not plasmapheresis.

My call: skip plasmapheresis now; it treats acute flares, not stable disease. Confidence: moderate, based on the mechanism and the absence of any evidence supporting maintenance plasmapheresis.