It's not the eyesight going, it's the hand-eye coordination going almost completely. Every pro player in his prime had certain 'quirks' which his youthful coordination helped him overcome Hendry used to drop his elbow into his back on the backswing and then bring it back up on the delivery but he was able to manage that quirk until around 35+ years or so.
Whenever a pro had a technique which was close to perfect with no quirks he was able to carry on up to about 50 years or so, Steve Davis is a perfect example of this and so was Joe Davis. Neither had any quirks which had to be coordinated.
Take it from a player who has been there (although not as a pro) that without a doubt the hand-eye coordination does go south past 40 years or so. Yes, the eyesight generally gets worse but that can be easily fixed.
I also think the motiviation plays a big factor too.
Whenever a pro had a technique which was close to perfect with no quirks he was able to carry on up to about 50 years or so, Steve Davis is a perfect example of this and so was Joe Davis. Neither had any quirks which had to be coordinated.
Take it from a player who has been there (although not as a pro) that without a doubt the hand-eye coordination does go south past 40 years or so. Yes, the eyesight generally gets worse but that can be easily fixed.
I also think the motiviation plays a big factor too.
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