Prescription capture

If you come from Shopify rather than from optics, start with the glossary. Setting this step up is far easier once you know what you are asking the customer for.

Glossary: what each value means

A spectacle prescription is a list of numbers, one set per eye. Here is what they mean:

Abbreviation	Name	What it does
OD	Right eye	From the Latin oculus dexter. It is the right eye in every country
OS / OI	Left eye	OS in English (oculus sinister); Spanish prescriptions write OI
SPH	Sphere	The main correction. Negative for short-sightedness (poor distance vision), positive for long-sightedness (poor near vision)
CYL	Cylinder	Corrects astigmatism: the cornea isn’t perfectly round, so the image comes out distorted. Usually negative, and can be 0
AX	Axis	The angle that cylinder sits at, from 0 to 180 degrees. Only meaningful when there is a cylinder
ADD	Addition	Extra power for close-up vision. Appears on progressive and bifocal lenses, from the mid-forties onwards. Always positive
PD	Pupillary distance	The millimetres between the centre of one pupil and the other. Used to centre the lenses in front of the eyes. Adults are typically between 54 and 74 mm

Dioptres are measured in steps of 0.25. That is why the dropdowns jump like this: -1.00, -1.25, -1.50…

Why it matters that the customer copies it correctly

These numbers get manufactured exactly as entered. A customer who flips a sign, or swaps the right eye for the left, receives glasses they cannot see through. That is why it is worth adding a summary step so they confirm before paying.

The two step types

• Graduation (Rx) — a full prescription, with every value above. For genuine prescription eyewear.
• Reading Rx (grid) — just a magnification (+1.00, +1.50…). For pre-made reading glasses, the ready-to-wear kind that carry no prescription.

Graduation (Rx) step

Captures the values for each eye: OD (right) and OS (left).

Field ranges

Every field has a configurable Min, Max and Step. Set them to what your lab can actually make: if you don’t work below -8, set that as the minimum and customers can’t order it.

• Show ADD field — turn it on only if you sell progressives or bifocals. On ordinary glasses it is noise.

Pupillary distance

• Show PD — adds pupillary distance capture.
• Single or per-eye PD — one number (the usual case), or one per eye. The customer switches with a toggle.
• Validation messages — what they are told if they leave it blank.

Simple by default

The per-eye PD toggle starts off: the customer types a single number unless they turn it on. Most prescriptions carry one value, so the common case stays frictionless.

Changing the labels

Every text in the step can be rewritten without touching code. Before you do, read Languages & wording — the boxes come pre-filled in English and there is a catch.

Graduation summary step

Shows the customer the prescription they just entered, laid out per eye, before adding to cart.

Add it whenever you capture full prescriptions. It is the last chance for the customer to spot their own mistake, and it saves you returns.

Reading Rx (grid) step

For pre-made reading glasses, where the customer only picks a magnification.

• Minimum, maximum, step and columns of the grid.
• Value prefix — usually +, so it reads +1.50.
• Live preview of how many values it generates.

How the prescription reaches the order

When the customer adds to cart, the prescription travels inside the Shopify order, alongside the product. You see it on the order detail in your usual admin, and it carries through to whatever you send your lab.

It is written compactly, one line per eye, in the notation any optician reads:

Frame type: Prescription glasses
Lens type: Standard thin lenses
OD: -2.50, -1.25, 90°, +1.50
OS: -3.00, -0.75, 180°, +2.00
PD: 63

The order within each line is always sphere, cylinder, axis, addition.

The prescription can’t be removed from the order

There is a checkbox to keep steps out of the cart, but it does not appear on the steps that carry the prescription, nor on photo upload. An order for prescription eyewear with no prescription on it cannot be filled, so the app won’t let you reach that state even by accident.

What you do decide is whether the customer sees those values. See Design & cart.

If the customer uploads a photo of their prescription instead of typing it, the order shows the file name. See Uploading the prescription.