Myasthenia Gravis Support Group
Myasthenia gravis (MG) is a neuromuscular disease leading to fluctuating muscle weakness and fatiguability. The hallmark of myasthenia gravis is muscle weakness that increases during periods of activity and improves after periods of rest. Although myasthenia gravis may affect any voluntary muscle, muscles that control eye and eyelid movement, facial expression, and...

Great that your MG is under control! Yes, it is very difficult to know exactly what the level of medication is best, and even which medication is best.
Generally we try prednisone and mestinon to the level we get rid of MG symptoms (or at least the ones that make life difficult). Most folks with ocular MG do progress to general MG, but not all. And of course, everyone's level of MG is different and varies with time and treatment.
Then we try to figure out the lowest effective dose of the meds. With prednisone it is a slow process as what we do today may not show up for weeks or even months as our blood clears the bad antibodies, the muscle receptors grow back and other than medicine side effects we feel OK.
At your level of 15 mg of prednisone, if you want to go lower, and it is worth trying that, you have additional problems -- there is some prednisone withdrawal problems and your adrenal glands have been suppressed and need to start up as you go lower.
My own path to tapering was at about 20 mg per day I switched to 30 mg per alternate days, my neuro telling me that I would get the same prednisone effect with alternate days but my adrenals would be stimulated to begin producing the natural prednisone like substance (cortisol) that makes life tolerable with out so many aches and pains in joints and muscles.
So I changed from 20 per day to 30 on alternate days and noticed nothing different. After several weeks of that, I dropped to 20 on alternate days and after a few weeks still was fine (no MG came back). My neuro said I could drop to 15 (or maybe 18.5) on alternate days next. But I asked her "how about taking 20 mg every 3rd day as a way of tapering." And she was fine with that, just telling me to make changes and wait several weeks or maybe a month to see what happened. Eventually I went to 4 days, 5 days and then a full week and then quit it altogether (I was still taking 20mg a time).
My MG never returned (5 years now). When I finally had stopped prednisone, I got a lot of aches and pains that went away with pain killers -- my neuro said --adrenal glands are still not fully functioning. After about 6 months off prednisone the aches and pains were mostly gone, MG still gone. I had quit taking mestinon as it didn't help when prednisone had worked to remove MG symptoms.
The goal of our treatment is to find the least amount of medications we need, then take it at that level with some occasional mestinon to help with times when MG symptoms flare up. In my own plan, I had figured to find the minimum level of prednisone (which my neuro thought would be between 10 and 15mg per day or 20 alternate days) and then decide if the side effects were tolerable or not, and if not switch to cellcept or imuran long term.
As I tapered, we realized my MG was not coming back, and so guessed a remission, and thus went off of MG. About 15% of us get remissions of varying length of time. At 5 years as of April 1, I am probably in the very lucky category!
I was not afraid of prednisone as my mother had an autoimmune disease (polymyalgia rheumatica) and took it at about 10mg per day from age 65 - 91. It made her life enjoyable rather than unbearable. Of course at my age (I was also 65 when I got MG) we have less worries about the long term effect of drugs.
Good Luck
Russ