Ask your doctor about Lamictal (the generic name is lamotrigene) or Diamox (acetazolamide). I believe I read that about 10% of people taking flecainide get blurry vision.
You could also try the amino acid Taurine. The dose to reduce myotonia is 1-2 grams per day. This has been shown to be effective in studies done in Italy.
I found mexitil, and i was taking flecainide, so i stopped flecainide immediately and started mexitil, but i feel much more bad, and my sexual inharesemnt is worser, and i am not normal as every morning concerning my sexual issues
please advice, as I can't find a doctor except next month, and i am so worried