Have you tried Mestinon? It can stabilize your symptoms so you may have better luck with the Prisms. Some MGers eye symptoms are very variable, in which case they have more trouble finding a double vision correction.

My eye symptoms are very constant with the double vision so Prism work great for me. I would agree you should see a neuro and perhaps try Mestinon to see if it improves your symptoms.

Is your MG only ocular or have you had any generalized weakness?

Ice packs on my eyes help when the eye symptoms get really bad.

Good Luck
kathie