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/FAQ
Prescription(RX)
How do I read my prescription?
Figuring out what all of those numbers an letters on your prescription mean can be a little tricky, but we've got that covered. Come check out our tutorial on how to read your prescription.https://www.sllac.com/help/how-to-read-prescription
What is "PD" and how do I get mine?
PD, or pupilalry distance, is the distance in millimeters between the center of one pupil to the other measured in millimeters. Your PD is usually included in your prescription. If not, you can measure your PD yourself. https://www.sllac.com/help/how-to-measure-your-pd
How to order single vision lenses for reading if I have a prescription with ADD.

If you have a glasses prescription with an NV-ADD, it is best to order Prescription Reading Glasses. If you do not have a glasses prescription and typically buy reading glasses from the drugstore, you may consider Over the Counter Reading Glasses.

Prescription Reading Glasses

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!

Over the Counter Reading Glasses

If you are used to buying reading glasses over the counter from the drugstore, you can easily buy them from Sllac as well – with even more benefits.

Start by picking your favorite frame. Once you know your recommended reading power (such as +2.00), select “Single Vision” as the Prescription Type, and enter the same power for each eye in the Sphere (SPH) category. Do not enter a value in the CYL, Axis, or Prism boxes. You’ll need to lower your distance Single PD by 3 millimeters.

How can I measure my PD?
You can do it yourself or have someone else measure it using a mirror and a ruler. Place a ruler, millimeter side up, directly under the center of your right or left pupil. While looking straight ahead, measure the distance from the center of your left pupil to the center of your right pupil. Repeat for accuracy. Note that the average PD is between 57 and 65mm. https://www.sllac.com/help/how-to-measure-your-pd
Can I use contact lens prescription for ordering glasses?
Contact prescriptions and eyeglasses prescriptions differ and using them interchangeably will result in problems with your glasses. Make sure you have the correct prescription before entering it.