No one solution
There isn't a single solution that works for everyone.
If you are young, then your eyes can still adjust for distance, within a range. Young people who can't adjust between reading and distance vision can get a single-prescription pair of glasses or contacts, and then see both near and far. The only problem with the glasses in this case is they may be too low or tilted too much. We've seen some ways to solve this problem in this thread.
Older folks' eyes lose the ability to "accommodate", to refocus over near and far distance. And the reduced ability to focus that remains is slower. What used to be unnoticed, apparently instantaneous, can now take a second or two. Bifocal lenses are the general solution to this problem, but may not be the best for pool.
Another type of consideration is if you get down over the ball, chin touching the cue or nearly so, when you shoot. Then indeed bifocals are not of much help, since the head stays still and the eye doesn't move up or down much at all to try to see near and far.
Also, full correction for neither reading nor distance vision is needed for pool. Where you need sharp vision for pool is from about 3 feet (your eyes to the cue tip and cue ball, for all shots) to about 12 feet (your eyes on a shot from a short rail to the far corner pocket on a 9' table).
My vision center was having a twofer sale (buy one, get one) so when I talked to the optometrist he made the exam for a distance pair, I then asked him to make me a prescription for pool, for overall best focus between 3-12 feet. He found that interesting, and said he'd have to take a few minutes to work it out based on my distance prescription. Then he came out into the frame shopping area with those frames the optomotrist slips lenses in and out of to find your prescription. He said to try this, and I put two printed A-frame things lying around on one of their tables for cue ball and far pocket/object ball, pretended it was a pool table and bent over for a rail shot. It was a bit soft on one end, and sharp at the other, and I told him so. Back to the back he went, and came back saying "how about now". These were well-balanced for 3-12 feet, so I went with that. I had the lenses put into a set of Rayban Clubmaster sunglasses frames, and I'm very happy with them.
The other way to really boost almost everyone's visual acuity is to provide proper lighting over the table. Most rooms have horrible lighting over the tables: too dimly lit, and unevenly lit. Sharpness of vision is greatest when the eye's pupil is about 2mm wide, on average. And on average, a pupil that has to open to 4mm in a poorly-lit room is more than twice as bad as far as sharpness goes. This is not something that can be fixed with standard glasses or contacts. Also, when the pupil is smaller, the range of distance where everything is in focus at once is larger - a clear win-win.
Rooms that replaced their free vendor (beer logo) 4 foot table fixtures containing two 36" fluorescent tubes with a 7 or 8 foot fixture with 2 long (72" or 96") or 4 short (36" or 48") tubes would be improving every customer's game, and a sign the owner is taking care of his customers.
