They are experts and you can see them through the MDA clinic in Rochester. I can't think of anyone closer to you. You can check some of the other PPA doctors on the left side of the menu.
Strabismus has been associated with myotonic muscular dystrophy, but it's not quite as clear how common it is with myotonia congenita. My granddaughter with MC has it, but so do many normal kids.
Quinine sulfate is the oldest treatment for myotonia and is hardly ever prescribed any more. Since you're in the US, you should be able to get a prescription for Mexitil, which is the most effective and seems to have less side effects than some of the other medications like Tegretol, Dilantin, and Diamox. You will need a cardiac workup before starting Mexitil and you have to start with the lowest dose and work up gradually.
Please let me know about your experience if you are able to get in to the Rochester clinic -
I just noticed that Dr. Lewis is in Willow Grove, PA. Here's his information (I don't know anyone personally who has been a patient):
Dr. Stephen Fraser Lewis, M.D.
After attending Davidson College and graduating with a BS in Biology, Dr. Lewis spent 6 years doing basic Neuroscience Research (at Weill Medical School of Cornell University and Wake Forest University Medical School). He then attended medical school at Wake Forest University, interned at Abington Memorial Hospital (Abington, PA) and was Resident in Neurology at Thomas Jefferson University Hospital (Philadelphia, PA). After completing residency he entered private practice in general adult Neurology (he is board-certified by the American Board of Psychiatry and Neurology). Dr. Lewis is currently self-employed in solo practice with offices in Willow Grove, PA; and is on staff at Abington Memorial Hospital.
Dr. Lewis has always been interested in "the unusual" neurological diseases and became specifically interested in the Periodic Paralyses when he made the diagnosis in a friend-patient who had been "passed around" the Philadelphia medical community. She and Dr. Lewis worked together to discern a treatment regimen that "works for her". He believes that disease management is best when directed in a controlled setting with frank open discussion in a partnership between patient and physician. Clinical management of few (if any) Neurological conditions can be "cook-booked" - each person is different and needs to be treated uniquely.