Might develop in middle age!? That's outrageous. By then at the rate of change now, I'm confident there'll be surgery to get perfect/instant fusion.
They seem all too willing to end people's dreams with such minor issues. Lose an eye just after getting your licence, and you can carry on for the next 50 years.
I suppose the problem is getting the brain to accept intervention when older since it seems important to get eyes right before the age of 7. While this may be important, it's clearly not an absolute.
I was looking into the eyes of a 70 year old this week who had perfect 'lock on' in both eyes. When young she'd had an eye lying on her cheek while doing whatever it is they do. So, at least 60 year old technology.