Your levels have dropped from 25 to 8 in just a few weeks, I would consider that to be amazing progress, although your concerns about your eyesight are completely understandable.
I have no idea what your diet is like at the moment but if I were in your shoes and my eyesight was at risk , I would cut out as many carbs as possible. I would even consider going totally carnivorous, if you don't put the carbs in the glucose can't get into your blood. I would also try intermittent fasting to try and clear as much stored glucose from my body as possible.
But if everything were to fail to get my levels to where they need to be then I would welcome insulin with open arms. It's not the demon everyone seems to think and you don't necessarily have to be on it forever, just long enough to get to a point where your eyesight can be fixed.