--Last fall I had the opportunity to dive with the Hydro Optix Mega 4.5 DD mask. See www.HydroOptix.com The advertisement states that this mask gives you 5X more field of view. This is a large volume mask that put your eyes at the center of a double dome. It really does give you a great view.
If you are near sighted like I am this mask is made for you. The only problem I had is at my age with my older eyes I couldn`t focus on my gauges. I am needing bifocals now and my eyes don`t have the focal range that they had when I was younger. If you are a younger diver that is near sighted you might want to give this mask a try. Your eye`s lens should be flexible enough to focus on the entire range from near to far objects.
The masks diopter is -4.5 if you are far sighted or have 20/20 vision the company says that you can wear contact to make yourself near sighted to use the mask. The company hopes the wider field of view will attract the non near sighted to use the mask with contacts. The company also has surface-interval eyewear to correct your vision back to 20/20 between dives.
I have been wearing contacts most of my life and wearing them while diving has always been problematic. I am sticking with my prescription bifocal mask.
This is a very well made mask but you must be careful not to scratch the lens because it is molded from polycarbonate.
Check it out for your self. In NH Diver`s Den in Manchester sells this mask for $200.00.
Stay wet and dive safe, Dick