[classicman]

The tri-focals are very difficult to get used to. Some people never do, while others adjust over time. They seem to be trying to do too much for me, I mean if you have your head turned or tilted in one direction and look through the "wrong" part of the lens then your vision will be blurred or otherwise obscured. They only work when you are looking directly at a specific object. If there are multiple images in your line of sight and they are at differing distances, it becomes increasingly difficult to process the info and focus.
They are not for me - that's for sure.

edit: I am not an optometrist nor optician, I just play on on teh Cellar.