Masks - single or doubled lens

[CotoChris]

What difference does it make to have a mask with independent lenses or a single lens? Other than for prescription purposes I've been wondering and can't figure out a reason.

For example:

[Tricky]

When diving with a mask with two lenses, I found my vision was restricted by the material between the two lenses. I only dived with a twin lens mask twice for this reason, depsite having forked out a reasonable amount for it (Poseidon Technica). Of course, my opinion of twin lens masks may be affected by the fact that I started out in a single lens mask so this is what I was used to.

[Twinsetmad]

I've found it doen't make a lot of difference when you have the clear silicon masks. But when you go black, the two lenses give a greater sense of tunnel vision. I've had a black Apeks mask with twin lenses, great fit, but just didn't like it anywhere near as much as my single lense Scubapro, great fit too.

The most important thing about the mask is the fit, nothing else really matters.