Hi CMC and welcome to this forum .....
For a doctor to describe an acoustic neuroma as a growth behind your ear, is very unusual, to say the least.
I did not have blurred vision prior to my diagnosis of a AN, however I did deal with double vision for several weeks following my first surgery, so there may be a connection with eye focus ..... not sure.
If I were you, I would certainly pick out one or more of the major acoustic neuroma treating centers in the country and send a copy of my MRI for another opinion. Most of these facilities will do free evaluations based on your MRI.
If your symptoms are getting worse and to the point they are greatly affecting your life, you need to seek out treatment options from highly experienced physicians (as in many, many acoustic neuroma treatments).
Just my thoughts. Prayers.
Clarice