How successful is Botox in the treatment of Strabismus?

Hi, I originally had an intermittent exotropia that never caused me double vision. The doctors measured it around 25 diopter at near and 17 at far. I've had several surgeries and now have an esotropia of 4-6 diopters that is intermittent straight ahead and permanent when I look to the sides. The esotropia causes double vision. How successful is botox for strabismus? Is 1 injection all that's needed if it is successful? Are there any good websites that explain it? I read that it can cause ptosis.