I recently read that humans tend to age in bursts, one being around 44-46 and another in their early 60s. This makes sense, as aging doesn't seem to be the gradual decline some people tend to think. This can be a blessing, as during those crisis periods, after the initial shock, a wise person can adapt their lifestyle according to their new, more fragile self.
I had good eyesight, but at age 44, I experienced a sudden decline. After a quick search, I found out that 44 is commonly the age when many people start to experience presbyopia.
One thing is certain, the early 40s are the latest a person should give up perma bulking before encountering age related health problems.