Mistakes When Ordering Glasses Online and How to Avoid Them — Lenses, PD, Frames
Common mistakes when ordering glasses online: incorrect PD, wrong index, ill-fitting frames, missing measurements for multifocal lenses — suggestions for checking before payment and when to visit a store.
Optometrist Vũ Văn Tiệp
March 28, 2026
Ordering glasses online is convenient, with transparent prices and sometimes attractive flash sales — but one wrong number on the order (PD, axis, index) can turn a pair of glasses into something unwearable or cause prolonged eye strain. This article outlines common mistakes and how to avoid them, supplementing is online eye measurement accurate? and shopping guide.
1. Incorrect PD or careless self-measurement using an app
PD (pupillary distance) off by 2–3 mm is enough to cause lens misalignment — especially dangerous with multifocal and high myopia. PD measurement apps using selfie photos can be inaccurate due to shooting angle and screen scale. Solution: measure in-store or use a prescription with PD noted by the optician; read what is PD.
2. Choosing index just because "higher number = fancier"
1.74 is not always necessary — it can be expensive and sometimes causes color distortion or optical aberration if the eyes are sensitive. For moderate myopia, 1.60 or 1.67 + edge-covering frames look great. See high-index, lenses for high myopia.
3. Beautiful frames in photos but measurements don’t fit nose and ears
Lens width, bridge, temple length determine slippage / tightness. Slipping frames → misaligned vision → eye strain. Learn how to read frame sizes and try on frames if possible.
4. Ordering multifocal lenses with only a written prescription, without lens height
Lacking fitting height and consultation on corridor → high failure rate. See multifocal lenses. It’s advisable to visit a store for progressive lenses for the first time.
5. Believing “strong blue light filter = maximum protection”
Too dark filters → color distortion, tiring when doing design work. Choose based on blue light protection, not based on slogans.
6. Not reading return and warranty conditions
Ask clearly about returns if unwearable, who bears lens costs, time limits. Related to return policy.
7. Mistyping + / − signs or Axis
A silly mistake but very common when typing by hand. Cross-check each box with the prescription before payment.
When should you prioritize visiting a store instead of online?
Multifocal, height, high astigmatism, first-time glasses wearers, children, or needing frame adjustments after fitting.
Checklist before payment
Cross-check SPH/CYL/AXIS/ADD/PD; save chat confirming lens model; take a screenshot of the policy.
8. Confusing lens types: single vision, anti-fatigue, multifocal, photochromic
Websites often have dropdowns that are easy to misselect: you need single vision but click office / relax (which have different viewing areas); or select photochromic and then complain about dark indoors. Each type has its own viewing range and trade-offs — read Eyezen / anti-fatigue for screens and photochromic before ordering.
9. Overlooking frame curvature (wrap) when ordering sports glasses / curved faces
Frames that wrap around create misaligned viewing angles compared to flat frames; some online orders do not ask and lenses are not optimized for high wrap. With high myopia + large wrap, it’s advisable to visit a store to measure vertex, pantoscopic tilt if needed — avoid self “guessing”.
10. Not saving transaction proof when there’s an error
Keep order emails, screenshot of lens configuration, chat confirming PD. If the lenses are incorrect due to shop data entry, proof helps exchange faster — related to return policy.
11. Expecting super thin edges even with too wide frames
Some landing pages illustrate thin edges on small DAO and full rim frames; you may choose oversized frames. Result: still thick. Ask for advice on appropriate diameter or read lens materials.
12. Ordering genuine lenses but not checking labels / COA
High-end lenses can easily be confused without clear warranty labels, lot numbers, or shipping slips. When buying online, ask for serial / label and how to register warranty — refer to comparison Essilor–Zeiss–Rodenstock to know the line name that needs to be printed on the invoice.
13. Overlooking edge cutting / polish and edge treatment for rimless frames
Rimless require safety edges, appropriate edge thickness; ordering online cheaply sometimes means standard cuts that do not fit drilled holes. If you choose drilled screws, it’s best to do it at a place with an optician to measure holes on the actual frame.
14. Not having a plan for frame adjustments after receiving
Online glasses offer little after-sales service: frames tightening, slipping, slight misalignment need on-site adjustments. If you are sensitive to slight misalignments, consider buying at a store that offers free adjustments — see lens cutting process.
15. Ordering pupillary distance (PD) as “average” for everyone
Some online forms allow leaving PD blank and the system auto-fills 63 mm or male/female PD. This mistake causes lens misalignment — particularly dangerous if the eyes are asymmetrical (different PDs) or you tend to look through the edge due to habit. Always use accurate PD measurements; if not available, stop ordering progressive or height until measured.
16. Not checking unit of measurement (mm vs cm) and sign conventions
Some prescriptions state -3.00, others -3,00; less common is miscopying 0.25 diopter when typing by hand. Cross-check with old glasses or scan slips; if the shop enters incorrectly, you need photos of the original prescription to exchange for free. With ADD, mistaking +1.50 for +2.50 makes the near zone uncomfortable right away — don’t “endure” too long due to neck strain.
17. Buying sale frames but premium lenses — weight doesn’t match
Too heavy frames + thin high-index lenses can sometimes throw off balance, causing slippage; too flimsy frames + thick lenses can cause ear pinching. Online rarely advises combos — ask the shop for the expected total weight or choose O2O: order lenses after trying frames in-store.
18. Not verifying axis units according to shop conventions
Some systems enter axis 90 instead of 180 if copied incorrectly; high astigmatism is very sensitive. Send a photo of the prescription to the shop for double-checking before cutting, and request a lensometer photo (if the store allows) upon receipt — especially with complex prescriptions.
19. Not asking about cutting diameter (ED / decentration) when comparing prices for “the same 1.67”
Two shops may report 1.67 but one has a smaller DAO or less decentration will provide thinner edges even with the same index. If you compare prices online, also ask about the planned diameter and whether there are charges for super wide frames — avoid receiving unexpectedly thick glasses.
Conclusion
Ordering glasses online is safe when you control the data, understand multifocal limits, and choose frames with clear measurements. Mistakes focus on PD, index, frames, and marketing expectations. Contact the store to measure / confirm before ordering remotely; continue choosing lenses · articles.
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