Quick facts
- Frame sizing is a measured system, not a style preference. ISO 8624:2020 specifies a measuring system for spectacle frames and the related vocabulary, and it applies to frames whose fronts are intended to be symmetrical.
- The three numbers printed inside a temple come from that system: the horizontal size of the lens aperture, the bridge width and the temple length.
- United States: a prescription spectacle lens has its own entry. 21 CFR 886.5844 puts it in Class I, exempt from premarket notification, subject to limits. Spectacle frames themselves are not device entries.
- United States: prescription hand-over is a federal rule. 16 CFR 456.2 makes it an unfair act for an ophthalmologist or optometrist to fail to give the patient a copy of the prescription immediately after the examination and before offering to sell ophthalmic goods.
- Canada: there is no equivalent federal instrument. Dispensing and prescription handling sit with provincial college standards.
- Ophthalmic goods are defined broadly in the United States rule. 16 CFR 456.1 defines them as eyeglasses, any component of eyeglasses, and contact lenses.
A frame is the one item in an eye care purchase that patients choose for themselves and clinics still have to fit properly, and the fitting runs on numbers. Those numbers come from an international measuring system, while the paperwork that has to travel with them comes from different levels of government in the two countries. This article covers the measurement system, the device entries, the prescription duty and the consumables a dispensing bench goes through.
What do the numbers on a spectacle frame actually measure?
Open a temple and read the marking. It is a three-part size notation, and each part corresponds to a measurement the ISO 8624 system defines.
| Part of the notation | What it measures | Why it matters at the fitting |
|---|---|---|
| First number | Horizontal size of the lens aperture | Sets the lens size chosen for the frame front |
| Second number | Bridge width between the lens apertures | Decides how the frame sits on the nose |
| Third number | Temple length from the joint to the tip | Decides whether the frame stays in place |
The measuring system exists so that a 52 read on one bench means the same thing on another. That matters when a patient returns with a frame bought elsewhere, when a lens is ordered for a frame the practice did not supply, and when a second pair has to match a first. The system also gives the vocabulary for the parts of the frame, which is what a supplier needs when a practice orders a specific front or a specific temple.
Two practical consequences follow. First, a frame that is not symmetrical at the front is outside the scope of the measuring system as written, which is why a wrap or a strongly asymmetric front needs a fitting decision rather than a notation reading. Second, when a practice measures a frame it already owns, the measurement should be recorded on the same basis as the notation so the two can be compared later.
Does device classification of a frame and a lens differ between Canada and the United States?
The device treatment is closer than a buyer might expect, and the difference is in the mechanism rather than in the class.
| Item | Canada | United States |
|---|---|---|
| Named entry for a spectacle frame | None | None |
| Named entry for a prescription spectacle lens | None; class derived by rule | 21 CFR 886.5844, Class I |
| Premarket position for a prescription lens | Device licence where the derived class requires it | Exempt from premarket notification, subject to limits |
| Measuring system for the frame | ISO 8624 | ISO 8624 |
| Prescription hand-over duty | Provincial college standards | 16 CFR 456.2, a federal rule |
| Who may dispense | Provincially regulated opticians and optometrists | State-licensed dispensers under state law |
| Distributor obligation for the lens | Establishment licence held by the party placing it on the market | Establishment registration and device listing |
The lens entry is worth reading in full because it draws the line the way a lab needs it drawn. 21 CFR 886.5844 describes a prescription spectacle lens as "a glass or plastic device that is a lens intended to be worn by a patient in a spectacle frame to provide refractive corrections in accordance with a prescription", and it adds that the lens may be modified for sunlight, including reflective, tinted, polarizing or photosensitized forms. The frame is the carrier; the lens is the device.
Does prescription release work the same way in Canada and the United States?
In the United States the duty is written into a federal rule, and it is written in a way that a practice cannot work around by waiting to be asked.
16 CFR 456.2 makes it an unfair act or practice to "fail to provide to the patient one copy of the patient's prescription immediately after the refractive eye examination is completed and before offering to sell the patient ophthalmic goods, whether or not the prescription is requested by the patient". 16 CFR 456.1 supplies the definitions, including that a refractive eye examination is "the process of determining the refractive condition of a person's eyes or the presence of any visual anomaly by the use of objective or subjective tests", and that ophthalmic services are "the measuring, fitting, and adjusting of ophthalmic goods subsequent to a refractive eye examination".
There is no Canadian instrument with the same shape. Prescription handling in Canada is provincial college territory, which is why a practice operating in both countries needs two procedures rather than one, and why the United States procedure has to be written around a federal rule rather than a standard of practice.
The practical difference is what a practice writes down. In the United States the trigger is procedural: the copy goes to the patient at a defined moment, before any offer to sell. In Canada the trigger comes from the college's standards, which in most provinces address the examination, the dispensing and the record rather than a single hand-over event. A practice that serves patients from both countries therefore needs a release step that satisfies the federal timing rule and a college-compliant record, and the two can live in one workflow as long as the timing is the stricter of the two.
For the fitting side, the college that regulates optometrists publishes the expectations a practice has to meet. The College of Optometrists of Ontario standards of practice cover examination and dispensing expectations, and the national association's eye health library is a suitable source for the patient-facing explanation of what a frame measurement means.
Which consumables does a dispensing bench consume?
The bench consumes a short, predictable list, and the list is what a monthly order should be built from.
- Cleaning supplies for frames and trial frames. Cotton swabs and lens-safe wipes, used between patients.
- Gloves. Examination gloves for handling frames that have been on a patient's face.
- Surface cleaning. The bench, the tools and the measuring equipment.
- Patient-area supplies. Tissues, masks and hand hygiene supplies for the fitting area.
- Paperwork. The prescription and the fitting record, kept on the basis the practice's college requires.
The same double-tipped cotton swabs that a laboratory buys for bench work are the ones a dispensing bench uses on frames and trial frames, which is why a multi-site group can consolidate the line across both departments.
Practices that order these lines at case level can use the wholesale ordering page for account setup and case pricing, and the B2B wholesale collection for the lines held for institutional buyers. Clinics that also reprocess reusable instruments in house can start with the biological indicator 5-pack trial and review the sterilization monitoring collection.
Sources
- ISO 8624:2020, ophthalmic optics, spectacle frames, measuring system and vocabulary
- ISO 8624:2011, previous edition
- 21 CFR 886.5844, prescription spectacle lens
- 16 CFR 456.1, definitions under the eyeglass rule
- 16 CFR 456.2, separation of examination and dispensing
- 21 CFR 886.5925, soft (hydrophilic) contact lens
- Medical Devices Regulations, SOR/98-282, full text
- Health Canada, medical devices
- College of Optometrists of Ontario, standards of practice
- Opto, Canadian Association of Optometrists eye health library
- Opto, Canadian Association of Optometrists
- American Optometric Association
- American Academy of Ophthalmology, eye health
- Canadian Ophthalmological Society
- Ontario, what OHIP covers
- openFDA device classification database
- ISO 15189:2022, requirements for quality and competence in medical laboratories
- CCOHS, needlestick injuries
- Public Health Ontario, infectious diseases
- World Health Organization, laboratory biosafety manual
Related product: Related product: USB heated eye mask with three temperature settings (graphene heating element)
Related reading
- Comprehensive eye check-up in Canada vs the US: which exam interval applies
- Eye clinic consumables: gloves, swabs and tape for optometry
- Ophthalmic eye shields in Canada vs the US: which device rules apply
- Eye masks in Canada vs the US: which warm compress should a clinic recommend
CliniEco Medical supplies eye care, laboratory and clinic consumables of the kind described in this article. Health Canada MDEL #35334. This article is written for clinic, procurement and eye care professionals and is not clinical guidance; refraction, frame selection for a patient and dispensing decisions belong to the treating optometrist, optician or physician.
Frequently Asked Questions
Which standard defines how a spectacle frame is measured?
ISO 8624:2020 specifies a measuring system for spectacle frames and the related vocabulary, and it applies to frames whose fronts are intended to be symmetrical. The three-part size notation printed on a temple follows that system, which is what makes a size comparable between manufacturers and between practices.
Is a spectacle frame a regulated device?
Neither country names a spectacle frame in a device entry. The lens is the regulated part in the United States: 21 CFR 886.5844 places a prescription spectacle lens in Class I and exempts it from premarket notification subject to limits. In Canada the class of the lens is derived by rule rather than taken from a named entry.
Does a prescriber in Canada have to hand over the prescription?
There is no federal instrument in Canada with the same shape as 16 CFR 456.2. Prescription handling sits with provincial college standards, so a Canadian practice should write its procedure from its own college's requirements rather than from the United States rule.
What exactly does the United States rule require?
It makes it an unfair act or practice for an ophthalmologist or optometrist to fail to provide the patient one copy of the prescription immediately after the refractive eye examination is completed and before offering to sell ophthalmic goods, whether or not the patient asks for it. The definition of ophthalmic goods covers eyeglasses, any component of eyeglasses, and contact lenses.
Why does a frame size notation matter when a lens is ordered?
Because the notation is the only shared description of the frame front and the temple. If the lens is ordered against a size rather than against the physical frame, the notation is what keeps the order unambiguous, and it is also what lets a second pair match the first.
What should a dispensing bench keep in stock?
Cotton swabs and lens-safe wipes for frames and trial frames, examination gloves, surface cleaning supplies for the bench and measuring tools, patient-area supplies, and the paperwork that records the prescription and the fitting. Those lines, not the frame inventory, are what run out first.
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