How to read your prescription

HOW TO READ YOUR EYE GLASSES PRESCRIPTION TO DETERMINE WHAT TYPE OF DIVE MASK LENSES YOU NEED

READ THE SPHERE - OFTEN ABBREVIATED AS SPH

SEE EXAMPLE BELOW -  IN YELLOW

IF SPHERE SHOWS A NEGATIVE DIOPTER  - YOU ARE NEAR SIGHTED.   Select your mask and pick lenses

IF SPHERE SHOWS A POSITIVE DIOPTER - YOU ARE FAR SIGHTED.   Select your mask and pick lenses

IF THERE IS A COLUMN FOR AN ADD NUMBER ( IN BLUE IN ABOVE EXAMPLE ) THEN YOU HAVE BI FOCALS  - OR YOU NEED READERS TO SEE UP CLOSE. - THIS IS ALWAYS A PLUS ( + ) NUMBER.    

If you are a SCUBA diver who can see distance, but cannot see things up close like your camera, air gauges, or dive computer, then you can select your mask and pick lenses

OD - MEANS YOUR RIGHT EYE

OS - MEANS YOUR LEFT EYE

ALL OTHER INFORMATION ( CYL OR AXIS OR BASE ) SHOWS THAT YOU MAY HAVE ASTIGMATISM WHICH CAN ONLY BE CORRECTED WITH CUSTOM LENS OPTIONS