Another question about underwater vision

[Kim]

Hi -
Well I posted one thread about prescription lenses and have received some good advice - I now have a secondary question!!
I know that masks produce a magnification underwater. Presumably this is the same effect as a + lenses? Would it be correct therefore to assume that if I have something like a +1 correction for normal distance viewing on land this would be about the same as a normal mask underwater? Further - if I have a +3 correction for reading on land - would this reduce to a +2 correction underwater? I am trying to work out if I need a true bifocal lense underwater - or if I only need the extra help in the reading area (for gauges/camera screens/watches etc)

 

[Saturation]

Yes, the water will reduce the need for some magnification, but not enough. Generally, you should correct your eyes with proper prescription lenses, or use standard diopters often sold for popular masks like the TUSA Liberator. Just being 'close' enough to your prescription is more than adequate because of water's effect and limited vis compared to the surface.