Hi, and welcome!
Well, don't feel completely like the Lone Ranger. I've got about a minus 9.5 or 10.0 (can't remember that high) correction in both eyes, with pretty high astigmatism (seems to be common with high corrections). And now a couple diopters of progressive reading correction in my glasses.
What works fine for me, surprisingly, is off-the-shelf corrective lenses. I managed to find some for my Techni-Sub Look mask here in Europe (identical to the AquaLung Look). They come in 0.5-diopter increments. Couldn't find any other company that makes off-the-shelf lenses in that high a power.
So I'm diving with just spherical correction -- no astigmatism or reading correction.
Several things that I've found:
-- Correction isn't near as critical underwater as it is for me above water. With glasses, an incorrect prescription just drives me crazy.... sphere, astigmatism, or reading. But I've found absolutely no problem underwater. But more... my wife has a mask with minus 5.5 correction in them, that she doesn't use because it doesn't fit. I'd be able to use that in an emergency underwater without too much problem. So that's about four diopters of "forgiveness" underwater... and Garyfotodiver says that six or seven are even doable!!
-- Even with my normal reading correction, I can read my gauges and computer just fine -- again, underwater.
-- These are glass lenses, and they're thick... and heavy. But I've also gotten a neoprene thingy called a Marsoops, in lime yellow... adds just enough bouyancy so that my mask is neutral. If I lose it for some reason, it ought to stay at about my depth until I can find it again. Plus the strap doubles as a protective pouch.
If you can't find off-the-shelf correction in your power, SeaVision will grind you custom spherical lenses for reasonable cost -- on the order of $50 per lens? Spherical would be much cheaper than with other corrections, but everything is possible. Only slight problem is that SeaVision makes their lenses out of polycarbonate plastic. Light, but thick... and they're at least somewhat susceptible to scratching.
Unfortunately, you won't know what kind of correction will work for you until you try out lenses underwater. I was fortunate in that the dive shop I went to let me try out these lenses in a pool... sure enough, I had to go up by a half-diopter, and they swapped them for me.
On the surface, obviously, you'll be blind unless you're wearing your mask. Not a big problem on a boat. But for beach diving, I take along a pair of normal glasses, and stow them in a BC pocket in a neoprene case.
There's absolutely no substitute for trying on a mask in person to make sure it fits. So that's something you pretty much have to get from a local shop. But if you do your homework, you'll know which manufacturers also make off-the-shelf correction for their masks, and therefore which masks to look for. Worst case, you just buy the mask and send it out to SeaVision.
But, hmmm... you're not sure you'll even like the sport.... and even with off-the-shelf lenses, you're talking a mask investment of like $150...
In that case, what I might do if I were you is get a prescription for inexpensive disposable soft contacts, with just a spherical correction. They'll drive you crazy above water, but should work just fine underwater. Who knows... they may work fine for you for diving, forever!
--Marek
