Was My Budgie Having A Stroke?

My 8 y.o. Budgie was having several ‘strokes’ for the past couple of months, rarely. Everytime when he was having it, he was screaming, falling off from the perch, and could’t move one of his leg. I didnt know it was something serious until i saw that he became blind. Did the blindness occur because of the ‘stroke’ or was it even a stroke or a seizure, I don’t know at this point. What should I do, is there any way i can return his sight back perhaps? Any help is appreciated.