This was what I was looking for, the UW correction. It seems that it only applies to farsighted people. So in my case where my presription is mild and nearsighted (sphere = -1.0 and -1.75 and cylinder = -1.0) I would not benefit from the UW correction of -1.0. I actually may get worse since I my new value would be -2 and -2.75.
The other issue I have is if I have contacts in I need to wear reading glasses to read a watch or guages. Having a full mask prescription lens would result in needing to
Thanks for the feedback!
If done correctly, that is by someone who knows what they are doing, you give them the information about your correction as is (glasses, contacts) plus extra info like combing your mask with contacts and they can tell you exactly what you need. Here in Holland all diveshops sent everything to a specialist company (proteye).
I have bifocal -3,75 and +3 but the cylinder -1 is left out since there is no need in a diving mask.
Best advise? Find out if you need prescription glasses simply by diving and looking around and at your instruments. If you do need them find somebody who knows what he is talking about.