A poorly centered frame doesn't show at the counter. It's discovered a week later, when the client comes back saying they "see blurry on the side" or get "headaches by the end of the day." By then, the cost of the error has already started to add up.
A poorly centered progressive lens can't be fixed in the workshop — it has to be reordered. Depending on the manufacturer and the coating, that typically means several tens to well over a hundred euros in lenses charged to the store, not counting the time spent reopening the file, the new fitting, and the readjustment.
Reopening a file means retaking a measurement, sometimes calling the client back, scheduling a second appointment, adjusting the frame a second time. In a busy week, that time is paid for in appointments not taken elsewhere.
A client who has to come back because their glasses don't work rarely remembers the technical excuse — they remember that "it didn't work the first time." For an independent store, whose local reputation and word of mouth carry real weight against chains and online retailers, that is the cost that's hardest to put a number on, and the hardest to win back.
IO Tech cross-checks multiple readings and flags risky postures before the error goes into production.
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