I got a special type of lens for the left eye that physically corrects the distortion, so it's as if my left eye is suddenly normal again. But my brain doesn't trust it yet. So it's actually not focusing unless I actively will it to. But with both eyes open, I'm not succeeding at willing the left eye to focus. It's as if my brain is saying, what? and goes on using the signal from the right eye. If I cover my right eye and look intently with the left, everything focuses super-sharp and I can see the leaves on the trees perfectly.
As an experiment, I've fashioned a sleeping mask into an eyepatch and am wearing it over my right eye (Arrr!) -- and my brain's all like, "Aaaagh! I can't see! WTF?! get it off me! It's dark in here!" and I'm all like, "look over here, silly! you can see fine! look!". It's been at least 15 minutes now and we still can't agree on this.
Or, it could just be an incorrect prescription. It's happened before.