Safety of lasers with RA and myasthenia gravis depends on the medications you are on, the problem you are trying to address, and the specific laser.
For example, if you are on aspirin, that would interfere with vascular lasers. That being said, lasers will not cause muscle weakness ( a concern with MG) or cause any autoimmune issues with your RA.
Find a laser center with a board certified physician present at all times, and have a consult to get the best information for your specific concerns.
Hope that helps.
Madeline Krauss, M.D.