Prescription Scuba Masks
1. Rx-Able Masks
This may come as a surprise to many, but not all scuba masks are capable of having prescription lenses installed. With the ever growing number of masks available today, it's important to know what to look for in a mask if you're considering having prescription lenses installed in it.
Most of the big name brand masks (Cressi, Tusa, Atomic, Aquatic, ScubaPro, etc.) can easily accommodate a set of prescription lenses, but you don't have to purchase a name brand mask for this purpose. You can find many scuba masks both in a local dive shop, or online, and they can usually be fitted with prescription lenses. Usually, they come in two common varieties: they may have two separate lenses, or even one large single lens that covers the entire front of the mask. The main feature to look for when shopping for a quality scuba mask is to ensure the lenses in the faceplate are made out of tempered glass (not plastic or polycarbonate). If you want to see an example of how a mask is marked to show the lenses are made of tempered glass, click here.
2. Accuracy of the Prescription
Not all companies that make prescription scuba lenses, make them to the exact prescription written by the eye doctor. This is commonly referred to as, "Spherical Equivalent". This means that the prescription will add half of the cylinder power to the sphere power, and eliminate the axis.
For example, if the right prescription is: -1.00 -2.00 080 then the spherical equivalent will be -2.00 and this would be the lens power used. This can work good for emergency situations, but customers usually prefer and it's generally recommended to use your actual full prescription. This not only gives you the best vision possibly, but helps reduce the chances of contributing to eyestrain and eye fatigue.