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.

The axis switches on with the cylinder

All three values for each eye — sphere, cylinder and axis — start empty. Not at 0.00: zero is a real clinical value, it means “no astigmatism”, and it can’t be confused with “I haven’t filled this in yet”.

The axis field also starts switched off, greyed out and untouchable. It only switches on once the customer enters a cylinder other than zero, because an axis with no cylinder means nothing — it is the angle of something that doesn’t exist. If the customer goes back and clears the cylinder, the axis empties and switches off again.

And the other way round: if there is a cylinder, the axis is required. The app won’t move past the step until it is filled in.

The cylinder can come in positive too

Spanish prescriptions usually carry the cylinder as a negative number, but much of Europe writes it positive, and both notations are equally valid. The axis switches on for any cylinder other than zero, whatever its sign.

There is nothing to configure here: it works this way in every form, always.

Pupillary distance

• Show PD — adds pupillary distance capture.
• How the customer enters it — free text (they type the number; the historical behaviour) or a dropdown with the allowed values. The dropdown avoids typos and values your lab cannot make; free text is faster for someone who knows their PD. It starts at “—”: nobody has a default PD.
• Ranges in mm — the single value (40 to 85 by default, in 0.5 steps) and the per-eye value (20 to 45). They are both what the dropdown offers and what the free text accepts: a customer who types 6 instead of 63 gets a warning, not an impossible order.
• 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.

The customer gets help on every field

Your customer is not an optician. They are holding their prescription and do not know what a cylinder is, whether the axis carries a sign, or which of the numbers is the pupillary distance. That is why every field in the step has a small “?” to the right of its label — SPH, CYL, AX, ADD and the PD title — which opens a short, plain-words explanation on hover, tap or keyboard: what the value is, which sign it takes and where to find it on the prescription.

It comes switched on in every form, with texts already written in your store’s language. There is nothing you need to do.

What you can do:

• Switch it off — in the step settings, untick Show a help icon next to each prescription field. All five “?” disappear at once.
• Rewrite the texts — under Labels & translations in the same step, heading Help texts. Each box shows up empty with the default text in grey, in your store’s language — the same text your customer reads. Type over it to say it your way — for instance, with the notation your lab uses — and if you empty the box, it goes back to the default (how it works, in Languages & wording). The ADD and PD texts only appear when those fields are enabled.
• Translate them — like every other label, from each language’s tab. See Languages & wording.

The “?” icons use the same colour, size and background settings as the ones on the form’s options. Change them under Design & cart, section Tooltips and help.

And a sample prescription

At the top right of the step there is a link, “How to read your prescription”, which opens a sample prescription built with your own labels: two eyes with SPH, CYL and AX (and ADD if you have it enabled), and the PD underneath. The customer taps a column and the app highlights it and explains that value with the same help text as the matching “?”. It is what helps most someone holding a paper prescription: they see where each number sits in an example that looks like theirs.

It comes switched on. Turn it off in the step settings (Show a “How to read your prescription” link…), and rewrite the link text, the caption above the sample and the hint under it in Labels & translations, under Sample prescription guide. The explanations are the same as the “?” ones: change one and it changes in both places.

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 before adding to cart: a table with your labels as headers (SPH, CYL, AX and ADD if present), one row per eye and the PD underneath — the same layout as the sample prescription in the previous step, so they never have to guess which number is which.

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.

If the customer uploaded a photo of their prescription instead of typing it, the summary shows them the image, not just the file name. That is the difference between confirming prescription.png and confirming the numbers that are about to be manufactured: a wrong file — a gym receipt, a screenshot of something else — is obvious at a glance. If they uploaded a PDF, which can’t be drawn, a document icon appears with the name and the size.

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 one line per eye, each value preceded by its field’s label — yours, in the customer’s language — so anyone can read it without knowing the order of the numbers:

Frame type: Prescription glasses
Lens type: Standard thin lenses
OD: SPH -2.50 · CYL -1.25 · AX 90° · ADD +1.50
OS: SPH -3.00 · CYL 0.00 · AX — · ADD +2.00
PD: 63

An eye without a cylinder has no axis: it prints AX —, just like the addition when only one eye has it — never a made-up 0° an optician would read as a real axis. It is the same line the customer sees in the cart, at checkout and in the confirmation email.

If you have an integration with your practice software, the same prescription also travels in the hidden property you agreed with it, in the format that software expects (there an empty axis does go as 0, because that is what its contract asks for). See Integration.

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.