I had similar problems a week after being diagnosed with Type 2 and taking Metformin.
My eyesight went back to the point where I couldn't drive, as I couldn't see properly with or without my glasses. Got tested and my right eye had gone from 2.5 shortsighted to 0.75 longsighted!!!
As it had only been a week I was advised to get a cheap pair as my eyes may change again.
Sure enough, the following week I had 2 days where I couldn't wear my glasses as everything was blurred. Still very shortsighted with my left eye, but overall better with no glasses.
Then back to wearing the glasses again.
It would seem that if I eat something high in sugar, like a Muller Light Youghurt, then my eyesight goes funny.
Lesson learned - stay off the sugar
Dal