I have to shut my left eye when reading or I get double vision?!

I have to shut my left eye when reading or I get double vision?

I can only read with my right eye open. If my left is open it gets blurry and I have double vision.
Why?

i think you have a condition called monovision. its when your nearsighted in one eye, and far sighted in your other eye. you probably should see your optomiterist to get glasses or contacts to fix your vision.