Quick facts
- An exophthalmometer is a named Class I device in the United States at 21 CFR 886.1270.
- Canada names no exophthalmometer. A passive measuring instrument that does not touch the surface of the eye reaches Class I through Rule 7(1) of the Medical Devices Regulations.
- The class is the same on both sides; the route is not — the United States sorts by named entry, Canada by the contact and the energy source.
- An instrument that is connected to a Class II or higher active device is pulled up under Rule 7(2)(b).
- The reading is a distance in millimetres from the lateral orbital rim to the corneal apex, so the instrument has to be held the same way each visit.
- The regulation text quoted here is current to 2026-09-21 and was last amended on 2026-06-17.
An exophthalmometer measures how far the eye sits forward of the lateral orbital rim. It is used to follow a change in eye position over time, most often in thyroid eye disease, and it is read as a millimetre value that is compared with the previous visit. The instrument looks simple, and both countries place it in Class I, but the reasons are not the same.
What is an exophthalmometer?
It is a measuring instrument, usually a prism or a mirror scale mounted on a frame that rests against the outer rim of the orbit. The clinician sights along the scale to the corneal apex and reads the distance in millimetres. Some instruments use a small prism so that two eyes can be compared side by side; some use a mirror to reflect the corneal apex onto a scale.
The instrument produces a number, not an image, and it emits nothing. It does not touch the surface of the eye; the frame rests on the bony orbital rim and the skin over it. Those two facts — no contact with the eye surface and no source of energy — are what decide its class in Canada.
How do Canada and the United States classify an exophthalmometer?
The instrument lands in Class I on both sides of the border, but through two different doors.
| Item | Canada | United States |
|---|---|---|
| Exophthalmometer | Class I by Rule 7(1) | Class I, 21 CFR 886.1270 |
| Basis named in the rulebook | Rule and intended use | Device entry and product code (HLS) |
| What decides the class | Contact made and energy source | Which named entry it is filed under |
| Connected to a Class II active device | Class II by Rule 7(2)(b) | Depends on the entry and the accessory |
| Paired illuminator or camera | Class follows the higher device | Accessory to a named entry |
In the United States the exophthalmometer is a named entry at 21 CFR 886.1270, and a product filed under that entry is Class I. In Canada no entry names the instrument. It is a non-invasive device that is not a calibrator and not a quality-control support, so Rule 7(1) places all other non-invasive devices in Class I. The same instrument therefore reaches the same class by two routes, and the route is what decides how a supplier documents it.
Which documents differ between Canada and the United States for this instrument?
The class is identical, so the supplier might expect the paperwork to be identical too. It is not.
In the United States the named Class I entry carries the design and labelling controls that entry sets out, and a US supplier works from the entry number and product code. In Canada the instrument is a Class I medical device under Rule 7(1), and a Class I device sold in Canada is subject to the establishment and record requirements the Regulations set for that class, with the labelling rules applied to the instrument. The difference is not in the class number; it is in the reference the supplier cites when a buyer or a regulator asks why the device is Class I at all.
That is why two instruments that look the same can arrive with two different file references. One file cites a US entry and a product code; the other cites a rule and an intended use. Both are correct, and each is correct only in its own country.
Why does a passive instrument stay Class I in Canada?
Because the rulebook asks two questions in order: what does it touch, and where does its energy come from.
The instrument does not come into contact with the surface of the eye, so the invasive rules do not reach it and Rule 2(1) does not apply. It is not intended to channel or store gases or fluids into the body, so Rule 5 does not apply. It is not intended to modify the composition of blood or other body fluids, so Rule 6 does not apply. It is a non-invasive device that is not a calibrator, tester or quality-control support, and it is not connected to an active device in a higher class, so Rule 7(1) classifies all other non-invasive devices as Class I.
The threshold that matters most in practice is Rule 7(2)(b). An instrument that is connected to an active device classified as Class II, III or IV is classified as Class II. A stand-alone measuring instrument is one thing; the same instrument wired into a Class II imaging or monitoring unit is another, and the class follows the connection rather than the instrument.
A second threshold is easy to miss. An instrument that is intended to act as a calibrator, a tester or a quality-control support for another medical device is pulled to Class II under Rule 7(2)(a) even when it never touches a patient. A reference gauge kept on the bench to check a diagnostic instrument therefore carries its own class, and a supplier who lists it as an accessory to the instrument it checks has described the wrong device. The question to ask of any part is whether it measures the patient or measures another device, because the two answers lead to different rules.
Which consumables does an ophthalmic measurement room restock?
A room that runs measurements runs on the same bench supplies as any other lane. The smooth white exam table paper covers the headrest between patients, and the double-tipped cotton swabs handle the lid and lash cleaning that comes before a measurement is taken. Where a sample is collected at the bench, the sterile graduated 90 mL specimen cups carry it away, and a clinic that runs its own steriliser pairs the sterilization monitoring collection with the 24-hour monitoring five-pack trial. Clinics and multi-site groups ordering at case level use the wholesale ordering page, and the B2B wholesale collection lists the lines held for institutional buyers. Reselling? become a distributor.
What do the two rulebooks actually say?
The two texts are short, and reading them side by side explains why the same instrument is documented two ways.
| Rule or entry | Verbatim wording | Effect on an exophthalmometer |
|---|---|---|
| Rule 7(1), Canada | all other non-invasive devices are classified as Class I | The instrument is passive and non-invasive, so Class I |
| Rule 7(2)(b), Canada | to be connected to an active device that is classified as Class II, III or IV | Pulls a connected instrument up to Class II |
| Rule 2(1), Canada | come into contact with the surface of the eye | Does not apply, because the frame rests on the orbital rim |
| 21 CFR 886.1270, US | Exophthalmometer | Named Class I entry |
| Rule 12, Canada | any other active device is classified as Class I | Would apply only to a powered version |
Read together, the lines give a simple test. Ask what the device touches, then ask where its energy comes from, then ask what it is connected to. A passive instrument that touches only the orbital rim and nothing else stays where Rule 7(1) puts it.
Sources
- 21 CFR 886.1270, exophthalmometer
- 21 CFR 886.1040, ocular esthesiometer
- 21 CFR 886.1150, visual acuity chart
- 21 CFR 886.1415, ophthalmic trial frame
- 21 CFR 886.1420, ophthalmic lens gauge
- Medical Devices Regulations, SOR/98-282, full text
- openFDA device classification API
- ISO 15004-1:2020, ophthalmic instruments, general requirements
- ISO 13485:2016, medical devices quality management
- ISO 14971:2019, risk management for medical devices
- College of Optometrists of Ontario, standards of practice
- Opto, eye health library
- American Academy of Ophthalmology, eye health
- Public Health Ontario, laboratory services test index
- CCOHS, OSH answers
- Canadian Dental Association
- Royal College of Dental Surgeons of Ontario
- CLSI, clinical and laboratory standards
- Government of Canada, medical devices guidance
- Standards Council of Canada
A measurement that is not recorded cannot be compared with the next visit. The printable ophthalmic measurement log is a blank sheet with columns for the patient, the date, the instrument used and the reading in millimetres, so a change over time is a line on a page rather than a memory. The measurement record generator on the same page sizes the sheet to the number of lanes a clinic runs. No account and no sign-up are needed to open either one.
Every clinic layout is different. Ask a compliance specialist and you will get a written answer specific to your equipment and province, with the regulation or standard it is based on cited.
Related reading
- Eye Pads in Canada vs the US: Ophthalmic Dressing Pads
- Ophthalmic Cameras in Canada vs the US: Which Class Applies?
- Eye Bandages in Canada vs the US: Which Class Applies?
CliniEco Medical supplies eye care, laboratory and dental consumables of the kind described in this article. MDEL #35334. This article is written for optometry, laboratory and procurement professionals and is not legal advice; the class of a device and the records kept by a clinic belong to the manufacturer and to the requirements that apply to it.
Frequently Asked Questions
Is an exophthalmometer a Class I device in the United States?
Yes. An exophthalmometer is a named Class I entry at 21 CFR 886.1270, filed under product code HLS.
How does Canada reach the same class?
Canada names no exophthalmometer. The instrument is passive and does not touch the surface of the eye, so Rule 7(1) places all other non-invasive devices in Class I.
What moves the class up in Canada?
Rule 7(2)(b). An instrument connected to an active device that is Class II, III or IV is classified as Class II, so the connection, not the instrument, decides the class.
Does the instrument touch the eye?
No. The frame rests on the lateral orbital rim and the skin over it, and the scale is sighted to the corneal apex. The eye surface is not contacted.
What does the reading record?
A distance in millimetres from the lateral orbital rim to the corneal apex. The value is compared with previous visits, so the instrument must be held the same way each time.
Why do the two countries document it differently?
The United States files the instrument under a named entry and a product code; Canada cites a rule and an intended use. Both reach Class I, but the reference a supplier gives is different.
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