Should you choose this?
Choose online only when your measurements and prescription needs are clear. Choose store support when fitting height, varifocals, prism or strong prescription risk is high.
Prescription-reading verdict
Do not guess prescription fields. Match SPH, CYL, AXIS, ADD and any prism exactly from a current prescription, and ask the retailer or optician if anything is unclear.
Who needs to decode a glasses prescription
This guide is for buyers who have a prescription but are unsure how it maps to an online retailer form. It is not a substitute for clinical advice.
Prescription details to check before checkout
Online forms vary, but the same core details matter: right and left eye values, plus or minus signs, cylinder, axis, reading add and whether PD is required separately.
- Prescription date and expiry.
- Right eye and left eye values.
- Plus and minus signs.
- CYL and AXIS pairing.
- ADD value for reading or varifocals.
- Prism or special notes.
Prescription entry mistakes to avoid
The common mistake is missing a minus sign, entering contact lens prescriptions, ignoring prism, or guessing PD when the retailer needs an exact value.
Best route by prescription complexity
Single vision distance
Usually the simplest online form, but signs and axis still matter.
Reading glasses
Check whether the retailer needs near prescription or distance plus ADD.
Varifocals
ADD and fitting measurements become more important.
Prism or complex notes
Ask before ordering online.
How to use the prescription on retailer forms
Enter the prescription slowly and compare each field before moving to the next. Right eye and left eye values can be easy to swap, and plus or minus signs are not optional details.
If the retailer form does not show a field that appears on your prescription, stop and ask support. This is especially important for prism, near add values, occupational prescriptions or notes from the optician.
Do not use an old prescription just because it is convenient. A current prescription and recent eye test make online ordering safer and reduce the risk of paying for glasses that are not comfortable.
| Low-risk order | Current prescription, familiar frame size, simple lenses and clear returns. |
|---|---|
| Higher-risk order | First varifocals, strong prescription, unfamiliar frame, reglazing or unclear service terms. |
| Best next step | Compare the total order cost and ask the retailer before checkout if any measurement or term is unclear. |
Prescription fields that deserve extra care
Most online forms look simple, but several fields are easy to misread. The risk is not only an order error; it is paying for lenses that technically match the typed form but do not match your actual prescription.
| Plus and minus signs | A missing sign can change the lens power completely. Enter the sign exactly as written. |
|---|---|
| CYL and AXIS | These usually work together for astigmatism. Do not move one without the other. |
| ADD | Often used for reading or varifocals. Check whether the retailer wants the ADD separately or built into a near prescription. |
| Prism | Ask before ordering online if prism appears. Not every retailer or frame route is suitable. |
Prescription entry checklist
Treat prescription entry like data entry for a medical device.
- Use a current glasses prescription.
- Do not use a contact lens prescription unless told it is suitable.
- Enter every sign and decimal carefully.
- Check whether PD is missing.
- Pause if prism or notes are present.
Glasses prescription FAQs
What does SPH mean?
Sphere is the main lens power for short or long sight.
What are CYL and AXIS?
They relate to astigmatism and must be entered together accurately.
What is ADD?
ADD is additional near power, often used for reading or varifocals.
Affiliate disclosure: Some retailer links may earn commission at no extra cost to you. We still compare retailer suitability, caveats and alternatives before linking out.
Build a safer prescription checklist
Use the retailer comparison after reading this guide so the final choice reflects lens needs, fit risk, delivery timing and returns.
Before entering your prescription online
Use this page as the first decision point. First, decide whether the order is low risk or fitting sensitive. Then open the relevant retailer review and compare the same basket across at least two retailers. The useful comparison is the full order after prescription lenses, coatings, thinning, delivery, discount terms and returns are included.
For a lower-risk order, such as a familiar single-vision spare pair, the buyer can focus on price, delivery and basic return clarity. For a higher-risk order, such as varifocals, a strong prescription, reglazing valuable frames or prescription sunglasses for driving, the buyer should give more weight to measurement support, lens advice, production expectations and aftercare.
UK Glasses Guide is designed to make those trade-offs visible. Retailer pages explain where each shop may fit, while the guide pages explain the optical and service questions that are easy to miss during checkout. If a retailer page and a guide point in different directions, choose the safer route for your prescription and use case.
| Price check | Compare the total order cost with the same lens package and delivery route. |
|---|---|
| Fit check | Confirm PD, frame measurements, bridge fit and any fitting-height requirement. |
| Service check | Read production time, return terms, remake process and support route before paying. |
| Safety check | Use an optician when the prescription, eye health or fitting need is complex. |
Checked on 26 April 2026. Retailer information, comparison notes and source links are reviewed for buyer relevance, but prices, codes, delivery times and policies can change without notice.
Sources checked
This page is written as buyer information, not optical advice. Check current retailer terms and speak to a qualified optician if your prescription, eye health or fitting needs are complex.