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How do I read my prescription?
If you need glasses, your eye doctor will provide you with a prescription for corrective lenses. Eyeglass prescriptions may be written in different ways, though most are either printed or handwritten in horizontal rows. The first row is the prescription for the right eye (OD), and the second row is for the left eye (OS). Within each of these rows are three values: Sphere (SPH), Cylinder (CYL), and Axis. The SPH number corrects for nearsighted [indicated with a minus (-)] or farsighted [indicated with a plus (+)] vision. The CYL number and AXIS number correct for astigmatism. You may also have another field labeled as ADD which corrects for the reading power used in a bifocal or progressive lens. To learn more about how to read your prescription, click here. Lastly, eyeglass prescriptions sometimes include the pupillary distance (PD) measurement, which is the distance between your pupils. PD is needed to determine where the optical center of the lens will be for clear, accurate vision. If your prescription does not include your PD, you can measure it yourself with our guide here. An eyeglass prescription will usually expire in 1-2 years, depending on which state you received your eye exam.
Can you fill strong prescriptions?
Sure we can! Single-vision Rx: Up to -20.00 or +12.00 on the Sphere (SPH Up to + or - 6.00 on the Cylinder (CYL). Bifocal Rx: Up to -9.00 or +6.00 on the SPH. Up to + or - 6.00 on the CYL. Up to +3.50 on the NV-ADD. Progressive Rx: Up to -10.00 or +8.00 on the SPH. Up to + or - 6.00 on the CYL. Up to +3.50 on the NV-ADD. Prism (single-vision only): Up to 5.00 in any base direction.
How do I order reading glasses?

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.

Can I use my contact lens prescription to order glasses?
Sorry, a contact lens Rx can only be used for contact lenses.
Can I order bifocals that are computer distance on top and reading on bottom?

yes, you can! Divide the NV-ADD in half. Add one of the halves to your SPHs. Leave the other half in the NV-ADD. This creates computer vision in the top of your lens, and reading vision in the bottom!?

What happens if my prescription changes after I get my glasses
Prescriptions can often change. For customers with extended coverage (20/20), we offer lens changes free of charge in case your prescription does indeed change. Just contact [email protected] to create your return request and shipping label and we will take care of it in a speedy manner.
Do you have safety prescription glasses?
We sure do! They’re located in our Sports Glasses section. Click here to view them. If you need help determining which pair meets your exact needs, call our Customer Service for some guidance.
What if I entered the wrong prescription?
Try to contact us within 24 hrs, since we try to process our orders quickly. As soon as you catch the mistake, call us a call at 1-(831) 888-0086 or email us on our ‘Contact Us’ page. Be sure to have your order number accessible and the correct prescription with you.