Quick facts
- A euthyscope is a modified ophthalmoscope that projects a bright light arc of about 30 degrees onto the fundus, with the centre of the bundle blocked so the fovea is spared.
- In the United States it files under 21 CFR 886.1250, Euthyscope, at Class I for the battery-powered version and Class II for the AC-powered version; the product codes are HML and HMK.
- Canada keeps no named entry. The identification describes a device used in amblyopia training, so it is an active therapeutic device and reaches Class II under Rule 9(1) of Schedule 1.
- Rule 10(1), the active diagnostic rule, gives the same Class II outcome; the governing reading follows the intended use stated in the identification, which is treatment.
- Rule 9(2) would lift the device to Class III only where the energy delivery were potentially hazardous given its intensity and the part of the body concerned.
- Entries, classes and product codes below were checked against the eCFR, the Regulations and the openFDA classification database on 2026-10-14.
A euthyscope is the instrument used in amblyopia and eccentric-viewing training. It is a modified ophthalmoscope that throws a bright arc of light onto the fundus while a small black disc blanks out the fovea, so the patient is trained to fix with a different part of the retina. The United States names the device and fixes one class for the battery version and another for the mains version; Canada keeps no entry and derives the class from a rule. This article sets out both routes and the records a treatment session supports, with the pre-perforated exam table roll that covers the treatment chair.
What is a euthyscope?
It is an ophthalmoscope modified for a specific treatment. A standard ophthalmoscope is a perforated mirror device used to inspect the interior of the eye; the euthyscope keeps that optical path but projects a bright light encompassing an arc of about 30 degrees onto the fundus instead of a narrow beam. The centre of the light bundle is blocked by a black disc that covers the fovea.
That geometry is the whole point. The fovea is left in shadow while the surrounding retina is bleached by the bright arc, and the patient practises taking up fixation with a non-foveal area. Because the patient must hold a steady gaze during the exposure, the session is recorded with the eye treated, the exposure used and the duration, so a later session can be compared with the earlier one when the question is whether fixation behaviour has changed.
What class is a euthyscope in the United States?
It is a named entry. 21 CFR 886.1250 is titled Euthyscope, and the regulation sets the class by power source: Class I (general controls) for the battery-powered device and Class II (special controls) for the AC-powered device. Both versions are exempt from the premarket notification procedures in subpart E of part 807, subject to the limitations in the ophthalmic-device section of that part.
The openFDA device classification API lists product code HML against the battery-powered device and HMK against the AC-powered device, both under 886.1250. The split is unusual and worth reading twice: the same instrument, doing the same job, sits in two different classes because of how it is powered.
| Item | Detail |
|---|---|
| US regulation | 21 CFR 886.1250 - Euthyscope |
| US class | Class I (battery-powered) / Class II (AC-powered) |
| Product codes | HML (battery-powered euthyscope), HMK (AC-powered euthyscope) |
| Route to market | Exempt from premarket notification under subpart E of part 807, subject to the limits of section 886.9 |
| Stated intended use | Treatment of amblyopia (dimness of vision without apparent disease of the eye) |
| Applied part | No contact with the eye; the light is projected onto the fundus |
How does Canada classify a euthyscope?
Canada keeps no named entry for a euthyscope. It applies the classification rules in Schedule 1 of the Medical Devices Regulations. The first thing the rules ask is what kind of device it is, and the identification answers that: the device is intended for use in the treatment of amblyopia. That makes it an active therapeutic device — an active device that administers energy to the body — so the governing rule is Rule 9(1): "Subject to subrules (2) and (3), an active therapeutic device, including any dedicated software, intended to be used to administer or withdraw energy to or from the body is classified as Class II."
The subrule worth reading next is Rule 9(2): a device under subrule (1) is lifted to Class III where the administration or withdrawal of energy is potentially hazardous, taking into account the nature of the delivery, the intensity of the energy and the part of the body concerned. A light arc of about 30 degrees projected onto the fundus for amblyopia training is not that case. The near miss is Rule 10(1), the active diagnostic rule, which also gives Class II for a device that supplies energy for imaging or monitoring; both readings reach the same class here, and the identification's own words are what decide which rule is quoted.
| Item | Canada | United States |
|---|---|---|
| Named entry | None; classified by rule | 886.1250 - Euthyscope |
| Class | Class II (Rule 9(1), active therapeutic) | Class I (battery) / Class II (AC) |
| Governing text | Schedule 1, Part 1, Rule 9(1) | 21 CFR 886.1250 |
| Route to market | Device licence (Class II) with quality-system evidence | Exempt from premarket notification, subject to section 886.9 |
| Class III lift? | Only under Rule 9(2) if the energy delivery were potentially hazardous | Handled inside the entry by power source |
Why does the two-country answer diverge?
The divergence is structural. The United States names the instrument and writes the class into the regulation text; a named entry does not move. Canada does not name it, and instead asks what kind of device it is — and because the identification says the device is for treatment, the Canadian route is the active-therapeutic rule rather than the active-diagnostic one.
The practical consequence is a real difference for one of the two versions: the battery-powered device is Class I in the United States and Class II in Canada, while the AC-powered device is Class II on both sides of the border. A purchaser who checks only the FDA database and then looks for a matching Canadian entry will not find one, and might wrongly conclude the instrument is unclassified or exempt. The correct reading is that the Canadian class is derived from a rule, not from a name.
What should a clinic check before ordering one?
Four checks. First, confirm the exact regulation number and product code on the supplier's labelling, and note the power source, because the US class turns on it. Second, confirm the intended-use statement the maker uses, since the Canadian route follows it. Third, confirm the calibration and lamp-replacement routine the maker states, because the treatment depends on the light arc being the size and brightness the protocol assumes. Fourth, confirm the training protocol the instrument supports matches the one the clinician intends to run.
An optometry or ophthalmology practice also reorders the room consumables used at the same treatment chair. Clinics that stock for a whole practice can order through the wholesale programme and request a bulk quote for a standing or annual order; the pre-perforated exam table roll sits in the same catalogue. Reselling? become a distributor.
How does the class affect a treatment routine?
The class sets who has to review the device before it reaches the market; it does not set the clinical routine. What the clinic does with the instrument is set by the maker's instructions and by the clinic's own quality routine. An amblyopia training session is recorded with the eye treated, the exposure field used, the duration of the exposure and the initials of the clinician who ran it, so the record shows the session was run the way the maker intended.
Because the patient must hold a steady gaze, the routine also depends on clear instruction and on a room that can be dimmed. None of that changes with the class; it is the ordinary routine of a patient-contact ophthalmic service. The class sets the licence path, and the record is what shows the session was run as intended.
Sources
- openFDA device classification API
- Medical Devices Regulations, SOR/98-282, full text and Schedule 1
- US FDA, medical device databases
- US FDA, overview of device regulation
- Health Canada, medical devices
- Health Canada, establishment licensing
- Standards Council of Canada
- CSA Group
- ISO 13485:2016, medical devices quality management
- ISO 14971:2019, application of risk management to medical devices
- ISO 15004-1:2020, ophthalmic instruments, general requirements
- ISO 17664:2017, processing of health care products, information to be provided
- Canadian Association of Optometrists
- College of Optometrists of Ontario, standards of practice
- Canadian Ophthalmological Society
- CCOHS, OSH answers
- Health Canada, medical device licence application guidance
A printable session sheet for the treatment room. The record an amblyopia training log has to hold — date, eye, exposure duration and the clinician who ran the session — fits on one page you can print and clip to the chart. Open the compliance log centre and take the blank sheet: no account and no sign-up, and you can print as many copies as your chair needs.
Build the month in one pass. Type the clinic name, the instrument serial and the protocol once, and the sterilization log generator lays out a dated set of cycle and session lines you can print or file straight into the quality manual.
Ask a compliance specialist. A classification question usually turns on how the device is used, not only on its name. Ask a compliance specialist — you get a written answer specific to your equipment and province, with the regulation or standard it is based on cited.
Related reading
- Ocular esthesiometers in Canada vs the US
- Maddox lenses in Canada vs the US
- Ophthalmic stereopsis tests in Canada vs the US
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 dental procurement professionals and is not legal advice; the class of a device and the records a practice keeps belong to the manufacturer and to the requirements that apply to it.
Frequently Asked Questions
What class is a euthyscope in the United States?
Class I for the battery-powered device and Class II for the AC-powered device, under 21 CFR 886.1250, product codes HML and HMK.
What class is it in Canada?
Class II. The instrument is an active therapeutic device intended for the treatment of amblyopia, so Rule 9(1) of Schedule 1 of the Medical Devices Regulations applies.
Why do the two answers differ for the battery version?
The United States fixes the class by power source in a named entry, where the battery-powered device is Class I. Canada asks what kind of device it is and finds an active therapeutic device, which Rule 9(1) sets at Class II.
Is a euthyscope the same thing as an ophthalmoscope?
No. It is built from an ophthalmoscope, but the euthyscope projects a wide light arc onto the fundus with the centre blocked over the fovea, and its stated use is treatment rather than inspection.
Would Rule 10(1) change the answer?
No. The active diagnostic rule also reaches Class II for a device that supplies energy to image or monitor a physiological process, so the class is the same either way. The identification's stated intended use is what decides which rule is quoted.
Does the class change what the clinic records?
No. The class sets the market-entry path. The record is set by the maker's instructions and the clinic routine: the eye treated, the exposure used, the duration and who ran the session.
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