Quick facts
- An AC-powered photostimulator supplies the controlled light stimulus used to measure retinal or visual function by perceptual or electrical methods — the stroboscope, ganzfeld or pattern stimulus at the front of an electroretinography or visual-evoked-potential set-up.
- In the United States it files under 21 CFR 886.1630, AC-powered photostimulator, at Class II, product code HLX.
- Canada keeps no named entry. The instrument is an active diagnostic device that supplies energy for monitoring a physiological process, so Rule 10(1) of Schedule 1 places it at Class II.
- Rule 10(2) would lift it to Class III only where the device is intended to monitor, assess or diagnose a condition and an erroneous reading could result in immediate danger.
- A mains-powered stimulus is a device, and a hand-held pen torch used as a rough stimulus is not; the classification follows the controlled output and the recording of a response.
- Entries, classes and product codes below were checked against the eCFR, the Regulations and the openFDA classification database on 2026-10-14.
A photostimulator is the light source at the front of an electrophysiology set-up: it delivers a defined flash, a full-field background or a patterned image to the eye while the recording electrodes measure the retina's or the visual pathway's response. It is the part of the chain that turns a clinical question into a reproducible stimulus, which is why its output has to be known rather than merely bright. The United States names it at Class II; Canada reaches the same class through the active-diagnostic rule. This article sets out both routes and what the class means for the check the unit is given, with the hypoallergenic paper tape the recording room keeps at the same bench.
What is an AC-powered photostimulator?
It is a device that provides light stimulus which allows measurement of retinal or visual function by perceptual or electrical methods. In practice the family covers the stroboscope that fires a defined flash, the ganzfeld dome that fills the field with a controlled background, and the pattern stimulator that presents a reversing checkerboard while the response is recorded. What they share is a controlled output: flash duration, luminance, background level and trigger timing are set by the instrument rather than by the operator's hand.
That is what separates a photostimulator from a pen torch. A torch can be waved at a patient as a rough check; a stimulator delivers a stated stimulus that a second laboratory can reproduce and that a report can quote. The instrument supplies energy to the eye, and it is an active device in both regulatory systems for that reason.
Is an AC-powered photostimulator a Class II device in the United States?
Yes. 21 CFR 886.1630 is titled AC-powered photostimulator and the identification reads: \"An AC-powered photostimulator is an AC-powered device intended to provide light stimulus which allows measurement of retinal or visual function by perceptual or electrical methods (e.g., stroboscope).\" The entry sits at Class II.
The openFDA device classification API lists product code HLX (Photostimulator, AC-powered) under that regulation number. The entry is written around the stimulus and the measurement it supports, not around the housing, which is why a dome, a stroboscope and a pattern generator with the same intended use sit together: the class attaches to the fact that a controlled light stimulus is delivered so that a physiological response can be measured.
| Item | Detail |
|---|---|
| US regulation | 21 CFR 886.1630 - AC-powered photostimulator |
| US class | Class II |
| Product code | HLX (Photostimulator, AC-powered) |
| Route to market | Premarket notification before commercial distribution |
| Stated intended use | To provide light stimulus that allows measurement of retinal or visual function by perceptual or electrical methods |
| Applied part | Light delivered into the eye; no contact with the globe |
How does Canada classify an AC-powered photostimulator?
Canada keeps no named entry, so the class is derived from Schedule 1 of the Medical Devices Regulations. The instrument delivers light into the eye, so it is not a passive optical element and Rule 7(1) does not govern it. Rule 10(1) states that an active diagnostic device, including any dedicated software, that supplies energy for the purpose of imaging or monitoring a physiological process is classified as Class II. A stimulator that fires a defined flash while the retinal or cortical response is recorded supplies energy for exactly that purpose, so the class is Class II — the same answer the United States gives.
Rule 10(2) is the subrule to read next: a device under subrule (1) is lifted to Class III where it is intended to monitor, assess or diagnose a disease, a disorder, an abnormal physical state or a pregnancy and erroneous readings could result in immediate danger. An electrophysiology stimulus that supports a diagnosis of retinal dysfunction does not by itself put a patient in immediate danger — the result is read by a clinician alongside the rest of the picture, and it does not drive an immediate intervention — so the lift does not apply on the reading taken here, and the class stays at Class II on both sides of the border.
| Item | Canada | United States |
|---|---|---|
| Named entry | None; classified by rule | 886.1630 - AC-powered photostimulator |
| Class | Class II (Rule 10(1), active diagnostic) | Class II |
| Governing text | Schedule 1, Part 1, Rule 10(1) | 21 CFR 886.1630 |
| Rule 10(2) lift? | No, on the reading taken here; the stimulus supports rather than drives an immediate decision | Not applicable |
| Route to market | Device licence (Class II) with quality-system evidence | Premarket notification |
How is a photostimulator different from a perimeter or an OCT instrument?
The three can be in the same room and can all be described as 'measuring vision', but they are three device families with three different working principles and three different entries. A perimeter maps the visual field by asking the patient to respond to stimuli at known positions. An optical coherence tomography instrument images the retina by interferometry. A photostimulator presents a controlled stimulus and the response is read from a recording rather than from the patient's report.
| Instrument | Working principle | Where the answer comes from | Class, Canada | Class, US |
|---|---|---|---|---|
| Photostimulator | Delivers a defined light stimulus | The recorded electrical or perceptual response | II (Rule 10(1)) | II (886.1630) |
| Perimeter | Presents stimuli at known field positions | The patient's reported detection | II (Rule 10(1)) if active | II (886.1605 range) |
| OCT instrument | Builds an image of the retina by interferometry | The image | II (Rule 10(1)) | II (886.1570 range) |
The practical point is that a single class does not mean a single routine. Each instrument has its own calibration, its own reference values and its own record of the check that was made. A laboratory that treats the three as interchangeable because they all end in 'vision testing' will end up with a folder that cannot show which instrument produced which result.
It is also worth noting what none of them is. None of the three touches the surface of the eye, so none of them is read against the eye-contact rule that governs a gonioscopy prism or a corneal electrode. The energy rule and the contact rule are different questions, and a device answers one or the other.
What should a practice check before ordering a stimulator?
Four checks. First, confirm the stimulus the unit delivers — flash duration, luminance range, background level and whether a pattern mode is offered — because those parameters decide which protocols the instrument can support. Second, confirm the trigger interface, since a stimulator that cannot be triggered by the recording system will be run by hand and the timing will not be reproducible. Third, confirm the calibration the maker states and the interval at which it should be repeated, because a stimulus whose output has drifted is a stimulus whose results cannot be compared with an earlier test. Fourth, confirm the manufacturer's stated software and version, since the analysis is part of the measurement.
A diagnostic imaging or electrophysiology service also restocks the consumables used at the same recording bench. 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 hypoallergenic paper tape sits in the same catalogue. Reselling? become a distributor.
How does the class affect the records a recording service keeps?
The class sets the market-entry path; the record is set by the protocol. An electrophysiology test is recorded with the protocol used, the stimulus settings, the electrode positions, the calibration date of the stimulator, any deviation in the patient's fixation or pupil state, and the version of the analysis software that produced the report. That set of fields is what lets a result taken this year be compared with one taken three years ago, and it is the part of the file that a reviewer asks for first.
Because the instrument is mains-powered and sits close to the patient, the routine also includes the maker's electrical-safety and cleaning instructions and the service interval. None of that changes with the class; it is the ordinary routine of a diagnostic electrophysiology service, and the record is what shows the stimulator was used as the maker 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 stimulus and calibration sheet for the recording room. Flash setting, background level, calibration date and the software version belong on one page that lives with the instrument. Open the compliance log centre and print the blank — no account and no sign-up, and the room can take as many copies as it runs sessions.
Generate the sheet, then keep it in the folder. Enter the service name, the instrument serial and the protocol list once, and the sterilization log generator lays out dated lines for the month, ready to print or file.
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
- Eye movement monitors in Canada vs the US
- Ophthalmic cameras in Canada vs the US
- Optical coherence tomography 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 an AC-powered photostimulator in the United States?
Class II, under 21 CFR 886.1630, AC-powered photostimulator, product code HLX.
What class is it in Canada?
Class II, under Rule 10(1) of Schedule 1 of the Medical Devices Regulations, which places an active diagnostic device that supplies energy for monitoring a physiological process in Class II.
Could Rule 10(2) make it Class III in Canada?
Only where the device is intended to monitor, assess or diagnose a condition and an erroneous reading could result in immediate danger. A stimulus that supports a diagnosis read by a clinician does not carry that consequence on the reading taken here.
Is a photostimulator the same as a perimeter?
No. A perimeter maps the visual field from the patient's reported detection; a photostimulator delivers a controlled stimulus whose response is recorded. They are separate entries.
What else is an AC-powered photostimulator called?
It is also written as stroboscope, flash stimulator, ganzfeld stimulator and pattern stimulator; the US regulation describes the same article as a device providing light stimulus for measuring retinal or visual function.
Does the class set the calibration interval?
No. The class sets the market-entry path. The calibration interval is set by the manufacturer's instructions and by the protocol the service runs, and the date of the last check belongs in the record.
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