How to Buy Glasses Online: The Complete Guide

Buying Glasses Online Shouldn’t Be Complicated. We Made It Simple.

Let’s be honest: buying your first pair of glasses online can feel daunting. What do all those numbers on your prescription mean? How do you know if a frame will fit? How do you choose the right lenses?

This uncertainty is the #1 reason people hesitate to buy eyewear online. We believe that has to change.

At JOIUSS™, we have obsessed over every detail of the online experience to remove the fear and replace it with confidence and joy. This is your complete, step-by-step guide to navigating the process with ease, from understanding your prescription to unboxing a pair of glasses that feels like it was made just for you.

Step 1: Understand Your Prescription

Your prescription is the blueprint for your lenses. While it may look like a secret code, it’s actually quite simple. Here’s a quick breakdown of the key terms:

Feature What it means Example
SPH (Sphere) The main strength of your lens, measured in diopters. A minus sign (-) means you are nearsighted (difficulty seeing far away), and a plus sign (+) means you are farsighted (difficulty seeing close up). -2.50
CYL (Cylinder) This indicates the presence of astigmatism — when the eye is shaped more like a rugby ball than a football, causing blurriness at certain angles. The CYL value can be written as either a minus (−) or a plus (+) number; this is purely a matter of the optometrist's notation preference and does not change the lens that is made for you. If you have prescriptions from different practices that show different signs, do not be alarmed — they are clinically equivalent. −1.25 or +1.25
Axis If you have a CYL value, you will have an Axis value. This is a number between 1 and 180 that indicates the orientation of the astigmatism. 90
ADD (Addition) This is the additional magnifying power in the lower part of a multifocal lens, used to correct presbyopia (age-related difficulty with reading). It's what makes bifocal or progressive lenses work. +2.00
Prism A prism prescription is used to correct double vision or eye alignment problems (known as strabismus or binocular vision dysfunction). Unlike a standard lens, which bends light to correct focus, a prismatic lens physically shifts the image seen by one eye so that both eyes can work together comfortably. Prisms are measured in prism dioptres (Δ) and are accompanied by a base direction (Base In, Base Out, Base Up, or Base Down) that tells the lab which way to orient the prism. Not all prescriptions include a prism — it is only prescribed when clinically necessary. 2Δ Base In

The JOIUSS™ Difference:

You don’t need to be an expert. Simply enter the numbers from your prescription into our clear, easy-to-use online form. Our system validates the information, and if anything looks unusual, our optical team will reach out to you personally to double-check.

Step 2: Measure Your Pupillary Distance (PD)

Your Pupillary Distance (PD) is the distance in millimeters between the centers of your pupils. This measurement is crucial because it ensures that the optical center of your lenses aligns perfectly with your eyes, giving you the clearest, most comfortable vision.

How to Measure Your PD at Home:

While your optician can provide the most accurate measurement, you can easily measure it at home with a ruler and a mirror, or with the help of a friend.

1. Look Straight: Stand about 8 inches (20cm) away from a mirror.

2. Align the Ruler: Hold a ruler against your brow.

3. Close Your Right Eye: Align the 0mm mark of the ruler with the center of your left pupil.

4. Close Your Left Eye: Without moving the ruler, open your right eye and close your left. The millimeter mark that aligns with the center of your right pupil is your PD.

Most adult PDs fall between 54mm and 74mm.

Step 3: Find Your Perfect Fit & Style

This is where the fun begins. Finding a frame that complements your features is about understanding balance and proportion.

Use Our Face Shape Guide: Our dedicated Cat Eye Glasses for Your Face Shape guide provides detailed recommendations for Round, Square, Oval, and Heart-shaped faces, explaining the optical principles behind why certain frames work.

• Check Your Current Pair: Look on the inside arm of your current glasses. You’ll often see a series of numbers like 52-18-140. These represent the lens width, bridge width, and temple arm length. You can use these as a benchmark when browsing our frames.

• Virtual Try-On: Use our live Virtual Try-On tool on every product page to see how the frames look on your face in real-time. Input your PD into the tool for a more accurate fitting experience.

Step 4: Choose Your Lenses (The Easy Way)

This is the step where other websites overwhelm you with confusing choices about lens materials and thickness. We decided to fix that.

The Old, Complicated Way:

Other retailers force you to choose between lens indexes like 1.56, 1.61, 1.67, or 1.74. They expect you to know at what prescription strength you should upgrade to a thinner, lighter, high-index lens. This creates anxiety and leads to customers either overpaying for unnecessary upgrades or choosing a lens that is too thick and heavy for their prescription.

The New, Intelligent JOIUSS™ Way:

You don’t choose a lens index. You just give us your prescription.

Our proprietary Intelligent Lens Selector automatically determines the optimal lens material for you. Our system, designed by our founding optometrist, analyzes your specific SPH, CYL, and ADD values and selects the thinnest, lightest, and most aesthetically pleasing lens for your individual needs — at no extra cost.

Lens Selection Overview

Feature Our System Automatically Selects... The Benefit to You
Low (e.g., +/-2.50) Standard Index Lens Crystal-clear optics for everyday use.
Medium (e.g., +/-4.50) Thin & Light High-Index 1.61 A noticeably thinner and lighter lens, improving comfort and appearance.
High (e.g., +/-6.50) Ultra-Thin High-Index 1.67/1.74 The thinnest possible lens, eliminating the “coke bottle” effect and ensuring maximum comfort.

The JOIUSS™ Difference: Our online tool calculates your bespoke lens based on the exact powers you input into the selector, ensuring you get it right the first time. No guesswork needed.

You simply choose the type of lens you want, and we handle the rest.

Reading, Single Vision, or Progressive?

• Want to add Blue Light filtering? (Choose from Clear, Yellow, or Red tints)

• Want them to be sunglasses? (Choose your tint colour and gradient)

That’s it. No anxiety, no confusion, clear charges for thinner lenses.

Just the perfect lens, every time.

Step 5: The JOIUSS™ Promise (Your Peace of Mind)

We built our brand on trust and quality. Buying glasses from us is entirely risk-free.

• Fast, Tracked Shipping: All orders are shipped quickly and securely.

• 30-Day No-Quibble Returns: If you don’t love your new glasses for any reason, you can return them within 30 days for a full refund or exchange. No questions asked.

• One-Year Guarantee: Every frame is covered by a one-year warranty against manufacturing defects.

• Expert Support: Our friendly, UK-based customer support team is here to help you at every step of the way.

Ready to begin?

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Single Vision Lens

Frequently Asked Questions

What if I enter my prescription incorrectly?

This is a very common worry, and we have a two-step process to prevent it. First, our online form is designed to catch common errors. Second, if our system flags anything that looks unusual or inconsistent, a member of our optical team will personally email you to clarify before your glasses are made. You are not on your own. We also require a hard copy of your prescription for our experts to check before we make each and every pair of glasses.

How can I be sure the frames will actually suit me?

We have three tools to help you choose with confidence. Start with our Face Shape Guide to understand the principles of balance and proportion. Then, use the measurements from your current glasses as a guide. Finally, use our live Virtual Try-On tool on every product page to see the frames on your face in real-time. It’s the closest you can get to being in a physical store.

Do I really need to pay extra for thinner lenses if I have a strong prescription?

No. At JOIUSS™, you will never be asked to pay extra for thinner lenses. Unlike other retailers who force you to make a confusing choice and then up-charge you for high-index materials, our Intelligent Lens Selector does the work for you. It automatically analyzes your prescription and selects the thinnest, lightest, and most aesthetically pleasing lens for your individual needs. The price updates automatically in the lens customiser — so you always know exactly what you are paying before you commit, with no surprises at checkout.

Is it safe to buy progressive or bifocal lenses online?

Absolutely, provided it’s done with care and expertise. We use the highest quality digital progressive lenses and our experienced optical team verifies every order. The key is providing an accurate prescription and Pupillary Distance (PD). As long as those details are correct, we can create a perfectly customised pair of multifocal lenses for you.

What happens if I just don’t like the glasses when they arrive?

It’s simple: you send them back. Our 30-day no-quibble returns policy means that if you are not 100% happy with your new glasses for any reason — whether it’s the fit, the style, or you’ve simply changed your mind — you can return them for a full refund or exchange. Prescription lenses are non refundable.