Help me understand my eyeglasses prescription

[gaffa]

I have a prescription for my glasses. I should be getting bifocals, but I can’t afford them. The last time, I managed to get two different types - one with my distance prescription and one for close-up. I lost my close-up glasses, and I don’t know how to order a replacement pair from Zenni Optical. Here’s my prescription:

                     (SPH)         (CYL)        Axis           NV-ADD
OD - Right     -3.50          -1.00         60
                                                                         +2.00
OS - Left       -3.25          -1.00         75
           PD        69

Do I subtract the NV-ADD number from the SPH value? That would make the right eye SPH -1.50 and the left -1.25?

Yes, I know I should buy from my eye professional, but I just don’t have the money. Please help.

[Inner_Stickler]

It is easy to reconfigure an Rx with an NV-ADD. It just involves a little grade-school arithmetic.

You simply take the NV-ADD number on your Rx and add it to the numbers in your Sphere (SPH) category for each eye. Then lower your distance PD by 3 millimeters if it’s the single PD, by 1.5 millimeters for each eye if it’s the dual PD. That gives you an Rx for single-vision reading glasses!

http://www.zennioptical.com/faq/prescriptions?count=5#faqTopic

[gaffa]

Cool, thanks.