Don't know whether we are talking about the same condition, but temporary blurred vision after lowing your blood sugars is common. Don't have a proper reference, but there is a quick mention of this at
https://www.healthline.com/health/diabetes/blurry-vision
You may also get blurred vision when you start insulin treatment. This is due to shifting fluids, but it generally resolves after a few weeks. For many people, as blood sugar levels stabilize, so does their vision.
I've experienced this, both when I initially went on metformin and also when I was switched to insulin.
The way it was described to me was that when your blood sugar was high, some sugar molecules entered your eye fluid, which can causing some blurring. As more entered, some got stuck to the edges of your eye. Here they were out of the way and did not cause the blurred vision (but did cause other problems).
When your blood sugar levels start to come down again, all these molecules detach from the edges and re-enter the eye fluid and so it is the increased numbers that causes the blurred vision to get worse. The number of sugar molecules starts to decrease and so after a number of weeks the vision normally goes back to normal.
I'm
hoping this is what you are thinking of, as it is a lot less serious than "fractured blood vessels
."