How to Buy Glasses Online in Japan Without Regrets: Prescription, PD, Frame Size and Lens Options
Prices, point rates and sale details in this article were checked by the mottoku editorial team against each service's official site and API (as of the last update). Always check the official sites for current prices, stock and campaign terms.
Buying glasses online comes down to where you get "measured" and "fitted"
Ordering glasses online is nothing unusual these days. There's a huge range of frame designs—sometimes even more than in stores. Yet many people still stumble when buying online, because glasses are both a medical item matched to your eyesight and an accessory you wear on your face. A T-shirt that's a bit off in size is still wearable, but with glasses, a prescription off by just 0.25 changes how you see, and a frame 2–3 mm too wide will slide down your nose all day.
So before "where can I buy cheapest," what matters online is two things: whether you have accurate prescription values on hand (power, PD, astigmatism axis, etc.) and whether you know the frame measurements that fit your face. Get those two right, and the result is the same whether you order in a store or online. If you order just because it's cheap while these are still vague, you'll often end up with glasses that are hard to see through, slip around, and need to be remade.
In this article, we first unpack what's in your prescription (especially PD, which is easy to get wrong when measuring yourself), then sort out technical choices like lens index and progressive lenses from a practical angle. After that we cover reading the numbers on frames, getting the most out of online try-on, knowing when to replace your glasses, and pitfalls specific to online shopping. If blurry vision or eye problems persist, don't assume it's just your glasses—see an eye doctor. Prices and sales change over time, so check each seller's official information before buying.
The minimum prep to avoid online mistakes boils down to just two things.
① Have your latest prescription on paper or as data (including power, astigmatism and PD—don't order with an old prescription).
② Note the size numbers printed on the glasses you wear now (lens width, bridge width and temple length).
With these two, you can avoid most "can't see well" and "keeps slipping" problems, even online.
Reading your prescription — where people trip up on power, astigmatism and PD
When you order glasses online, you enter your prescription values on the order screen. Knowing what the symbols on an eye clinic prescription or an optical shop's prescription card mean helps prevent input errors.
| Label | Meaning | Common mistakes |
|---|---|---|
| S (sphere, SPH) | Power for nearsightedness/farsightedness. Minus = nearsighted, plus = farsighted | Entering the wrong sign. Swapping − and + gives you completely different glasses |
| C (cylinder, CYL) | Astigmatism power | Ordering with "none" even though you have astigmatism |
| AX (axis, AXIS) | Direction of astigmatism (0–180 degrees) | Forgetting AX even though there's a C value. Always required together with C |
| ADD (addition) | Extra power added for close-up vision in progressives, etc. | Entering ADD for single-vision lenses / leaving it out when it's needed |
| PD (pupillary distance) | Distance between the centers of your left and right pupils (mm) | The most important item: often not on prescriptions, and prone to error when self-measured |
Of these, the biggest pitfall online is PD (pupillary distance). It's used to line up each lens's optical center precisely with your pupil; if it's off, the edges of your view can look distorted, and you may get eye strain or feel your eyes pulling inward. The tricky part is that eye clinic prescriptions list your power but often don't list PD. So many online shoppers try to measure it themselves, and that's where errors creep in.
There's a "distance" PD and a "near" PD
Surprisingly few people know this, but PD isn't a single number. When you look far away your lines of sight are nearly parallel, and when you look at something close your eyes turn slightly inward, so near PD is a few mm smaller than distance PD. Regular (single-vision, distance) glasses use distance PD, while reading or close-work glasses use near PD. If a shopping site asks for just one PD, you need to enter the one that matches the use. Mix them up and you get a half-baked result: you can see, but your eyes get oddly tired.
To measure it yourself, hold a ruler against your forehead in front of a mirror, look straight ahead, and read the distance between your pupil centers—but closing one eye at a time or tilting your face slightly can easily throw it off by 1–2 mm. The stronger your prescription, the more a PD error affects your vision, so the stronger your nearsightedness, farsightedness or astigmatism, the more worthwhile it is to get measured in store rather than relying on self-measurement.
Glasses with the wrong prescription can cause not only blurry vision but also eye strain, headaches and stiff shoulders. Swapped signs or a badly off PD in particular directly affect how you feel. Even when ordering online, it's safest to have your exact prescription and PD measured at an eye clinic or optical shop. If your vision suddenly gets worse, or eye pain or blurriness continues, don't self-diagnose—see an eye doctor.
Choose lens refractive index (thickness) based on your prescription
The factor that most affects price and appearance when choosing lenses is the refractive index (屈折率). The higher the number, the thinner the lens can be made—but the higher the price. What matters isn't "thinner is always better" but choosing an index that matches your prescription. If your prescription is weak, choosing the highest index makes little visible difference and just costs more.
| Index (approx.) | Typical prescription range | Result & cost |
|---|---|---|
| Around 1.50 (standard) | Weak (mild nearsightedness/farsightedness) | Often included in the base price. Thickness isn't an issue with a weak prescription |
| Around 1.60 | Moderate | The most popular "just right" range. Good balance of thinness and cost |
| Around 1.67 | Fairly strong | Keeps edge thickness down. Extra charge goes up a bit |
| Around 1.74 (ultra-thin) | Very strong | Thinnest, but with a higher extra charge. For people with high myopia who care about looks |
Where index really matters is edge thickness. Lenses for nearsightedness are thin in the center and thick at the edges, so the stronger the prescription and the bigger the frame, the chunkier the edges look. A higher index keeps edge thickness down for a cleaner look. Put the other way, if you pick a smallish frame with rims, the thickness is less noticeable even without a higher index—frame choice and lens choice go hand in hand.
Here are features you can add to standard lenses. Choosing only what you need is the way to get exactly enough.
- Anti-reflective coating: Reduces reflections on the lens surface. Included with many standard lenses, but the grade affects how little reflection there is.
- UV protection: Protects against UV rays. Often standard.
- Blue light filtering: Often chosen by people with lots of screen time. How much people notice the effect varies, so consider whether you need it. Some types have a slight tint.
- Scratch-resistant (hard coat): For people worried about rough handling. Still, rub hard and it will scratch, so don't rely on it too much.
- Photochromic (changes color): Darkens under outdoor UV, doubling as sunglasses. Higher extra charge, and may not work well inside a car.
If you can't decide whether to go up one index level, the shortcut is to think first about frame size and whether it has rims. With a smallish, full-rim frame, thickness stays hidden even with a near-standard index; with a larger, rimless frame, a higher index keeps the edges from standing out.
Read the 3 numbers printed on your frame and get the size right without trying on
The most common online mistake isn't the prescription but the fit. "Too big and they slide down" or "too small and they pinch" are common complaints after delivery. The surest way to avoid this is to read the size numbers printed on the glasses you wear now. They're usually printed on the inside of a temple (arm) or on the bridge, like this:
| Marking (example) | Meaning | What it affects |
|---|---|---|
| 52 (first number) | Lens width (mm) | Bigger covers more of your face. Shapes how you look from the side |
| □18 (number after □) | Bridge width (the part across your nose) | Directly affects fit on your nose. Too wide and they slide down |
| 140 (last number) | Temple length (full arm length) | Length to your ears. Too short hurts your ears; too long and they lift off |
For example, "52□18-140" means a 52 mm lens width, 18 mm bridge and 140 mm temples. Note these three numbers from a pair you like and use, and pick a frame with similar measurements—that alone greatly reduces sizing mistakes online. Choosing by your actual face width alone doesn't determine bridge width or temple length, so the printed numbers are more reliable.
Besides the three numbers, checking these points makes the result more consistent.
- Nose pad type: If you have a low nose bridge, adjustable nose pads on metal arms are easier to fit. Pads molded into the frame may not suit Asian noses and can slip.
- Full-rim / half-rim / rimless: Rimmed frames are sturdy and suit strong prescriptions. Rimless looks light, but with high myopia the edge thickness can't be hidden and may actually stand out.
- Material: Metal looks slim and light; acetate (a type of plastic) comes in lots of colors and patterns and is durable. Material also changes how it feels on your nose and temples.
- Where you'll use them: For work or sports, pick something that doesn't slip or break easily; for business, a subdued shape. Deciding first whether one pair does it all or you'll split by use makes choosing easier.
How to use online try-on and sample loans
People tend to think "you can't try them on" is online shopping's weak point, but systems to make up for it have developed recently. The main ones are virtual try-on (AR try-on), which overlays frames on your face via your phone or PC camera, and home try-on services, which send you several real frames. Each has strengths and weaknesses, so the trick is to use them for different purposes.
| Try-on method | What you can tell | What you can't |
|---|---|---|
| Virtual try-on (AR) | Whether colors and shapes suit you, the overall vibe | Actual fit, weight, how easily they slip |
| Home try-on (loaned frames) | You can feel comfort, width, slipping and weight | Hassle of sending them back. Limited brands offer it |
| Just trying on in store | Most reliable for fit and previewing how you'll see | Hassle of going to the store. Limited stock |
Here's a rule of thumb. First use AR to narrow down shapes and colors, and once you're down to 2–3 candidates, check the real fit with a home try-on or in store. If you're just torn between colors, AR alone is enough, but when fit is key—like "I want a bigger frame but I'm not sure it'll sit right on my face"—it's safer not to skip handling the real thing. AR is handy, but how frames look changes with camera distance and angle, and it can't reproduce actual weight or how the temples press, so take it with a grain of salt.
A practical "best of both worlds" approach: try frames on in store, note the size and prescription, then buy online. If you note the three numbers printed on a frame you liked in store (like 52□18-140) and the PD they measured for you on the spot, you'll have strong clues when choosing an equivalent model or another color online.
What's covered when the prescription is wrong or the lenses don't feel right
The most frustrating situation with online glasses is when the item isn't "broken" yet you can't use it. The frame has no scratches and the lenses aren't chipped. But when you put them on, the floor seems to float, or your computer screen looks doubled. Problems like this rarely count as initial defects, so each shop's policy decides the outcome. Before ordering, check these three boundaries.
"Prescription guarantee" and "returns" are separate policies
What many online glasses shops offer is a prescription exchange or prescription guarantee (度数交換・度数保証) that remakes your lenses within a set period. This isn't a return; only the lenses are replaced with a new prescription, and your frame stays the same. Check the period (days from receipt), how many times (once or multiple), and who pays shipping and processing fees. In particular, remakes that change the astigmatism axis mean grinding the lenses from scratch, so some shops exclude them.
Straight returns, on the other hand, are generally not accepted once prescription lenses are fitted, since they're treated as custom orders. Non-prescription fashion glasses, sunglasses or frame-only purchases can often be returned unused. That boundary is why it works to buy just the frame first, check how it feels, and order lenses once you're satisfied.
If you entered the values from your prescription or clinic records as-is, there's no way to tell whether the "hard to see" problem comes from the prescription or the lenses. When requesting a prescription exchange, describe as specifically as possible at what distance and in what way you have trouble seeing (distance is blurry / text looks smudged / the floor seems tilted when walking) to improve the accuracy of the remake.
What counts as an initial defect?
The places to check are fixed. When your glasses arrive, check the following in a bright place first.
- Debris and scratches on the lens surfaceBubbles in the coating, fingerprint-like haze, circular polishing marks. Reflecting light off the lens at an angle makes them easier to spot.
- Left–right asymmetry of the framePlace them upside down on a flat desk and see whether both temple (arm) tips touch the surface. If one lifts, the frame is twisted even before fitting.
- How the lenses are mountedGaps between rim and lens, or looseness in plastic frames. For semi-rimless (nylor) or rimless frames, also check for loose screws or nylon thread.
- Logo and model number matchWhether the markings and size inside the frame match the model number and size you ordered.
These are likely to qualify for exchange, but "doesn't suit my face," noticed after wearing them, is not a defect. Symptoms like nose pads digging in or temples pressing on your ears are often fixed by adjustment, and how much effort it takes after purchase depends on whether the brand has a network of physical stores that handle fittings for online orders, or whether you'll pay a local optical shop to adjust them.
Who can you ask for adjustments and repairs?
Loose screws and nose pad replacement are normal wear and tear, and you or a local optical shop can usually handle them. The problem is how glasses bought online are treated when you bring them to another shop. Some shops help for free, while others charge or refuse items bought elsewhere. When choosing a frame, checking whether nose pads are screw-on or molded in, and whether the temples are adjustable metal or acetate that needs heat to bend, gives you more flexibility later. Rimless (two-point) frames in particular are mounted by drilling holes in the lenses, which tends to limit lens replacement and repair options, so it's best to avoid them for your first online purchase.
Your warranty card or email records are the only documents showing your lens prescription, PD and the lens type used. They also serve as a reference for your next purchase, so don't delete your order confirmation email.
Single vision, progressive, intermediate — lens types change with your life stage
Lenses differ not only by power but also by "which distances they're designed for." When you're young, one pair of distance single-vision lenses is enough, but from around age 40, when close-up vision gets harder (presbyopia), you start wanting one lens that covers multiple distances. Get this wrong and even new glasses may leave you thinking, "only close-up things are oddly hard to see."
- Single vision: A simple lens set for one distance. Usually for distance, though some people make reading-only pairs. Few adjustment issues, and easy to order online.
- Progressive (bifocal-style, 遠近両用): One lens for both distance and close-up. The top is for distance and the bottom for near; you switch by moving your eyes up and down. Moving your gaze takes getting used to, and some people feel a sideways swaying effect. Higher extra charge.
- Intermediate/near (indoor progressives, 中近・近々): Optimized for close-up to room distance. For people who mainly do desk work or housework. Distance vision is weak, so not suited as your main pair when out.
Progressive lenses vary by design grade in how little peripheral distortion they have and how easy they are to adapt to, with big price differences. Your first progressives take time to get used to how you move your eyes, so rather than jumping straight to a high grade online, you'll have fewer failures if you try them on in store and test shifting your gaze before deciding. Once you're used to them, choosing an equivalent design online for your second pair onward is a realistic plan. If close-up text starts looking blurry or looking at things up close tires you out, it's a good idea to have your eyes checked at an eye clinic.
Frame turnover and lens campaigns run on different cycles
Glasses mean buying two different things at once—frames and lenses—so the deals come on two separate tracks. Watch only one and you may get a cheap frame, only to lose the savings on lens options.
Frames follow twice-yearly collection changes
Many eyewear brands switch collections for spring/summer and fall/winter, and store and online stock generally moves to that rhythm. Old-collection colors and sizes get cleared out just before the next season launches. During this period, edge sizes (very small lens widths, very long temples) tend to drop in price before the best-selling sizes. If you know your measurements from the frame markings, you can pick up cases where one of these edge sizes turns out to be exactly what you wanted.
Frames are also often kept on sale in new colors. If you love the model itself, waiting for other colors of the same model to be cleared out makes sense. On the other hand, limited colors and special-order models may never be remade, so waiting can backfire.
Lens sales come as "free option upgrades"
Since lenses are made to order for each prescription, rather than discounts the standard campaign is upgrading to thin lenses or coatings at no extra cost. These help people with high myopia who need high-index lenses anyway, and people who want to add blue light filtering, water-repellent coating or photochromic lenses. People with weak prescriptions for whom standard lenses are enough get little benefit from these campaigns. Knowing which lens range your prescription falls into lets you judge whether a sale is worth waiting for.
With progressives, the "lens design grade" is the core of the price difference. Even among progressive lenses, there are tiers based on field of view and how little swaying there is, so upgrade campaigns are worth the most to people getting progressives for the first time.
A rough picture of the yearly cycle
| Type of period | What tends to happen | Best way to buy |
| Around the new school/work year | Entry-level sets move with demand from new students and employees | Your first pair, or a spare second pair |
| Collection changeover | Old models in edge sizes and other colors get cleared out | Targeting specific frames using your size numbers |
| Big sale periods | Lens option upgrade campaigns tend to overlap | High myopia, progressives, functional coatings |
| Before pollen and UV season | More promotions for photochromic, anti-fog and UV features | A second pair for outdoors, glasses that double as sunglasses |
When not to wait
Waiting for the right time assumes your current pair is still usable. In situations like these, getting new glasses soon instead of waiting for a sale pays off in the end.
- Your prescription no longer fits and you get headaches or stiff shoulders in the evening
- The coating is peeling and blotchy patterns appear in your view (they don't wipe off)
- The frame is bent so the left and right lenses are misaligned and the optical centers are off from your pupils
The third one in particular is a classic case where the prescription itself is correct but your vision gets worse; if metal fatigue has gone too far for adjustment to fix, replacement is the only option. Eye measurements also have a shelf life. If time has passed since your prescription, getting re-measured before buying is more reliable than ordering with old numbers just to catch a sale.
When to replace your glasses, and when deals are likely
Glasses aren't just "buy new when they break"—it's time to replace them based on how well you see and the condition of the frame. Frames can last several years with care, but lenses are closer to consumables, so reconsider when you see these signs.
- Lens scratches or coating wear: Fine scratches or peeling coating (rainbow-colored blotches) make it harder to see. If you still like the frame, you can replace just the lenses.
- Prescription no longer fits: Seeing worse than before or eye fatigue in the evening are signs your prescription has changed. Eyesight changes, so check it regularly.
- Frame bent or loose: Slipping no matter how often it's adjusted, screws loosening often, paint wearing off, etc.
If you want to keep costs down, paying attention to when demand shifts can make it easier on your wallet. The new school/work year season (early spring) tends to bring offers for students and new employees, and campaigns may also overlap during the New Year holidays and big sale periods. If you want to rack up points together with everyday purchases, timing your buy with sales on the major online marketplaces is another option. However, point-back rates and coupon conditions change constantly, so don't take anything for granted and always check the latest official information. Also, if you're not in a hurry, you could wait for a lens-replacement-only campaign.
A few tips for making them last. Don't rub lenses hard with a dry cloth; rinse off dust with water first, then wipe with a lens cloth to avoid scratches. Keep them in a case when not in use, don't set them down lens-first with the arms open, and don't put them on or take them off with one hand—this prevents bending. If the nose pads or arms start slipping, the shop where you bought them or a nearby optical shop can often adjust them for free or cheaply, so have them looked at early when they start feeling less comfortable.
Checklist to avoid regrets after your online glasses arrive
Here are the key points so far, in the order to check before ordering. Tick them off one by one and you'll greatly lower the chance of "can't see, keeps slipping, needs remaking" after delivery.
- Is your prescription current, and are the signs correct?Don't order with an old prescription. Mistakes with the plus/minus of S and with AX (astigmatism axis) are especially common.
- Does your PD match the intended use?Distance or near? If self-measured, watch out for errors. The stronger the prescription, the safer an in-store measurement is.
- Does the index match your prescription?The highest index for a weak prescription is poor value. Consider frame size and rims too.
- Did you check the 3 numbers on the frame?Choose lens width, bridge width and temple length close to your current glasses.
- Did you add only the coatings you need?Only add anti-reflective or blue light filtering if you have a reason. Piling them on gets expensive.
- Did you check warranty, prescription exchange and return terms?Before buying, confirm whether you can get a remake or return if they don't feel right.
- Are you planning to get them adjusted when they arrive?Having nose pads and arms fitted in store or by bringing them in makes them noticeably more comfortable.
Warranty and prescription exchange terms in particular vary widely between online shops. Conditions like "free prescription exchange for your first order" or "returns accepted within a set period" make a huge difference to how secure your first online purchase feels. Choosing not just on price but also on whether you have a way out if they don't fit means fewer regrets.
Real mistakes with online glasses, and how to stop them before they happen
Here are mistakes specific to buying glasses online—the kind you won't notice on the order screen. All of them can be prevented with 30 minutes of checking before you order.
Mixing up monocular and binocular PD
This is the most common one. Pupillary distance comes as binocular PD, a single number for the distance between your pupil centers, and monocular PD (R/L), written separately as the distance from the center of your nose to each pupil. If your prescription says "32.0/31.0" and you enter only one of them, the order goes in at half your actual value. Conversely, entering a monocular value in the binocular PD field without adding them gives you extremely narrow lenses. You can tell just by the size of the number: adult binocular PD is roughly around 60, and monocular values are about half that. On the confirmation screen after entering, check that a number in the 20s or 30s hasn't ended up in the "binocular PD" field.
It's not unusual for monocular PD to be asymmetric. Your face's center line isn't as even as you might think, so treat asymmetry as normal rather than a sign of a measuring mistake.
Leaving the astigmatism axis "0" or "180" blank
The astigmatism axis (AXIS) is a number from 0 to 180, and if there's a cylinder value (CYL), there's always an axis too. Whether your prescription says "180" or "0," it's optically the same direction. The problem is when the CYL field is blank but an axis is entered, or vice versa. Entering only one means the lenses either can't be made or are processed as having no astigmatism. Remember that CYL and axis are either both filled in or both blank—nothing else, and you'll avoid accidents.
Using your contact lens prescription for glasses
Contact lenses sit directly on your cornea, while glasses lenses sit about 12 mm in front of your eyes. Because of this difference in distance (vertex distance), the power you need isn't the same. The stronger the prescription, the bigger the gap; with high myopia, glasses actually need a numerically stronger power. If you only have a contact lens prescription, the rule is don't enter those numbers as your glasses prescription.
Choosing a frame just because the lens width matches
Even if only the lens width of the three printed numbers matches your current pair, the fit won't be the same. What matters is bridge width (nose width) and the distance between the lens centers, determined by lens width + bridge width. If this center distance is far off from your PD, you'll end up looking through the edges of the lenses, which causes distortion and eye strain, especially with strong prescriptions. If you've ever felt that the clear zone of your current glasses is off-center, match the center distance next time.
Temple length is also often overlooked. Even the same model can have different temple lengths by size; too short and they hit in front of your ears and slide forward, too long and they don't hold from behind. Comparing the third printed number with a pair you currently find comfortable keeps you safe.
Ordering progressives with just your current nearsighted prescription
Progressive lenses create the near zone by adding an "addition" (ADD) to the distance power. Single-vision prescriptions don't include ADD, so if you order progressives with only the distance power, you'll get something close to plain single-vision lenses that don't let you see up close. ADD changes with age, and entering a guessed number can cause a swaying field of view or motion-sickness-like discomfort. If you're ordering progressives online, assume you need a prescription that includes ADD.
Ordering progressives without considering frame tilt
With progressive lenses, the usable position of the near zone changes depending on the angle at which the frame sits on your face. Strongly curved sporty frames and slim frames with short lens height don't have enough vertical room for the near zone. For progressives, choosing a model with a reasonable lens height makes failure less likely, and since this isn't in the printed numbers, you need to check the lens height in the size details on the product page.
FAQ
Is it OK to measure my PD (pupillary distance) myself?
For a weak prescription, self-measuring is generally fine, but the stronger your prescription, the more a PD error affects your vision, so people with strong nearsightedness, farsightedness or astigmatism should get measured in store. Measuring with a mirror and ruler can easily be off by 1–2 mm from a tilted face or closing one eye. Also, distance and near PD differ, so note that close-up-only glasses use near PD. If you can, have it measured at an optical shop.
My prescription doesn't list a PD. What should I do?
Eye clinic prescriptions list your power and astigmatism but often don't include PD. That's because PD is a lens-fitting value used to align the lenses with your eyes, and it's usually measured by the optical shop. If you need it for an online order, you can have just your PD measured at an optical shop, or ask for a measurement when trying frames on in store. If you measure it yourself, watch out for errors, and prioritize a proper measurement if your prescription is strong.
How do I choose a lens refractive index?
The basic rule is to choose an index that matches your prescription—thinner isn't always better. With a weak prescription, standard (around 1.50) lenses rarely look thick, and for moderate prescriptions around 1.60 gives a good balance. The stronger your prescription, the more worthwhile a high index is for reducing edge thickness. Smaller, full-rim frames hide thickness easily, so decide together with your frame choice to avoid wasting money.
How do I check frame size?
The most reliable way is to read the numbers printed on your current glasses (e.g. 52□18-140). They show lens width, bridge width and temple length, and choosing a frame with similar numbers makes it hard to get the size wrong online. Your actual face measurements alone don't determine bridge width or arm length, so relying on the printed numbers is safer. If you have a low nose bridge, frames with adjustable nose pads are easier to fit.
Can I decide using online (AR) try-on alone?
AR try-on is handy for narrowing down colors and shapes, but it can't show actual fit, weight or how easily they slip. If you're just torn between colors, AR is enough, but when how the frame sits on your face is key—like trying a bigger frame—it's safer to use a home try-on loan or try them on once in store. Narrow down with AR first and confirm with the real thing: this two-step approach cuts down on mistakes.
Can I order progressive lenses online if it's my first pair?
You can, but progressive lenses take getting used to how you move your eyes, and some people feel a sideways swaying effect. For your first progressives, you'll have fewer failures if you try them on in store and test shifting your gaze, rather than jumping straight to a high grade online. Once you're used to them, choosing an equivalent design online for your second pair onward is realistic. If close-up blurriness starts bothering you, it's reassuring to have your eyes checked at an eye clinic first.
What should I check before buying online?
Before ordering, check: ① your prescription is current, with signs and astigmatism axis entered correctly; ② your PD suits the intended use; ③ the index matches your prescription; and ④ you've noted the three numbers printed on your frame. Also, warranty, prescription exchange and return terms vary widely between online shops, so be sure to check them. Seeing whether you can get a remake or return if they don't fit lets you buy with confidence, even the first time.
Can I order using a PD I measured myself with a ruler and mirror?
For weak single-vision lenses it can work in practice, but self-measurements are easily off by about 1–2 mm, and the stronger the prescription, the bigger the effect. Especially with progressives or high myopia, the lens's optical center ends up off from your pupil, creating a prism effect that causes eye strain and distortion. It's more reliable to refer to the lens center distance of your current glasses or use a professionally measured value.
Will a local optical shop adjust glasses I bought online?
It depends on the shop. Many accept glasses bought elsewhere for a fee, but some refuse, so it's safer to ask in advance. Tightening screws on metal frames or replacing nose pads is relatively easy to request, but shops may refuse to handle acetate frames that need heat to bend, or rimless frames with lenses drilled for mounting. Thinking about ease of adjustment when choosing a frame is the safe approach.
Can I have just the lenses replaced in my own frame?
Yes, at shops that offer lens replacement, but you need to mail in your frame so they can trace its shape, so you'll be without those glasses in the meantime. Also, frames whose plastic has hardened with age can crack during processing, and shop terms usually exclude liability for such damage. For a favorite pair or an expensive frame, first decide whether you can accept that risk.
* This article is for reference only. Sale dates, point rates and campaign terms can change, so check each store's official page for the latest details.