I use Prescription Dive Masks in San Diego and they make custom gauge readers for me.

The problem with most gauge readers is the magnification surface area is too small, requiring you look at whatever you need to look at with one eye. For reading a gauge, that is fine, but for underwater photography or videography where you are looking at a monitor or viewfinder, it is less than optimal.

Also, for critter finding, if you can look through both gauge readers simultaneously, it REALLY helps when looking for tiny macro critters.

PDM has a style they refer to as "executive" gauge readers which are much larger. But just talk to them, tell them you read the article here or whatever, and tell them your style of diving and optical needs. They do a lot of work for photogs and know our needs. My bonded in place +2.5 readers go up to the height of the center of my pupils. When swimming sort of horizontal during diving, I am looking above the delineation line, then as soon as something is closer, I look below the line. For the first time in years I can now look at a whip coral looking for commensal shrimp and gobies and use both eyes through the gauge readers and can look at my external HD video monitor with both eyes.

If you get the higher magnification diopter readers, be careful, as some really low volume masks that fit so close to your face had my eyelashes brushing the readers a bit which was annoying.

I switched masks and had new readers done so eliminate that. Funny thing is, while on a dive in the Philippines, spied a masks and snorkel resting on the bottom. I swam over to it, and it was all brand new. But the be4st thing is it was a black silicone version of my clear mask, so since we couldn't find the owner, I had Prescription Dive Masks do their thing and that is now my primary mask with the clear silicone version as my spare.

http://prescriptiondivemasks.com/ima...page_image.jpg