Don't worry it is the rapid decrease in your sugar levels that is causing the blur in your vision.
The lens of our eyes is full of fluid and that fluid contains glucose the same as our blood. As your blood glucose has come down so has the concentration of glucose in your eyes. As the glucose concentration in the eye lens fluid changes so does it's refractive index, the amount by which light is bent when it passes through it. Your mind is not used to this "new lens" and this is why your vision has blurred.
After a short period, your brain will compensate for the reduced glucose levels and your eyesight will return to how it was previously
Pavlos