Make two small checks instead of one big guess
When buying glasses online with different prescriptions for each eye, start with the right-eye row and finish it before entering the left-eye row. OD means the right eye and OS the left. Keep the original document visible throughout.
Check the SPH sign, the CYL sign and any AXIS for the same eye. A difference between the eyes is a reason to double-check transcription, not a reason to make the numbers match. Do not edit a prescription using an online example.
If you cannot tell which row is which or the handwriting is unclear, ask the prescriber for a legible copy. The prescription-reading guide explains the field labels.
Zero in one field does not mean no prescription
A zero sphere can sit alongside a cylinder correction. A zero-power lens in one eye can also be part of a pair prescribed to correct the other eye. Keep the complete prescription rather than removing a row or inventing a small power.
Our zero-SPH choice remains available for those situations. Fully zero SPH and CYL in both eyes is a noncorrective plano pair, which Fast Eyeglasses does not currently sell.
For cylinder-only prescriptions, enter the nonzero CYL and its AXIS exactly. The online astigmatism ordering guide walks through that checkout question.
Check whether your PD has one number or two
If your measured PD has two values, enter the right and left measurements in their respective fields. They do not need to be identical. A total PD uses the single-number option instead.
Do not split or round a measured value just to make the form resemble somebody else’s order. If you are unsure which format you were given, ask the measuring professional or contact us before ordering.
Our PD preparation guide explains what to do when the measurement is missing. The prescription’s lens powers and the PD measurement are separate parts of the order.
Review eligibility, price and the order record
We currently make eligible single-vision correction, with no bifocals, progressives or prism lenses. A notably different prescription between the eyes may deserve a fit and lens discussion with your eye-care professional before an online purchase.
Stronger-prescription charges are calculated from each eye’s entered sphere and cylinder values beyond the stated thresholds. A higher charge for one eye does not mean the second eye should be changed. Our strong prescription price guide shows an example.
Check the final order against the prescription a second time. Save the confirmation and read the prescription and remake policy. Incorrect numbers entered by a customer are not a free change-of-mind remake.
Questions about ordering
Must both eyes have the same lens power?
No. Enter the current prescribed values for each eye separately. Do not change them to make the rows match.
Can one eye have a zero-power lens?
Yes, where that is part of an eligible corrective single-vision prescription. We do not currently offer fully noncorrective plano pairs.