Quick facts
- An Amsler grid is a printed chart held at a fixed reading distance to detect central and paracentral irregularities in the visual field, including the distortion known as metamorphopsia.
- United States: the Amsler grid has its own published device entry. Under 21 CFR 886.1330 it is a regulated device with a stated working distance and Class I status.
- Canada: the Medical Devices Regulations classify by rule rather than by named product line, so there is no matching entry to look up; the classification follows Schedule 1 and the labelling the manufacturer files.
- The distance is not a suggestion. The same US entry fixes the grid at 30 centimetres from the patient, which is why a chart scaled for a phone screen or a wall poster is not a substitute.
- The grid is a monitoring aid, not a diagnosis. A change on the grid is a prompt to be seen, not a result to be acted on alone.
- Clinics in both countries buy the same consumables around the test: charts, occluders, trial frames, mydriatic-safe paperwork and examination-room paper.
An Amsler grid is one of the least expensive items in eye care and one of the few that a patient uses unsupervised, at home, on a schedule. That combination is why the regulatory detail around it is worth knowing: two clinics can hand out what looks like the same card, and only one of them is handing out a chart that matches the device definition the test was built on.
This article sets out what the grid actually does, how each country files it, and what a buyer should be able to point at when a chart is ordered for a monitoring programme.
What does an Amsler grid actually test?
An Amsler grid is a square of straight lines printed on a page, usually with a small central fixation dot. The patient covers one eye, holds the chart at a fixed distance, looks at the dot and reports anything that is not straight: lines that bow, gaps that appear, an area that is blurred, or a patch that is simply missing.
Those reports map onto the macula. The grid is designed to catch central and paracentral change, which is the region that handles reading, recognition and fine detail. The American Academy of Ophthalmology describes it as a home monitor for people who already have a reason to watch the macula, particularly age-related macular degeneration, and the Academy's overview of macular degeneration explains why that region matters so much to function.
Two limits matter for how the chart is used in practice. First, the grid is subjective: the report comes from the patient, and a patient who is not sure what "distorted" means will under-report. Second, the grid is not a screening test for the general public. It tests a narrow function in a specific region, and a normal grid does not exclude eye disease.
Is an Amsler grid a regulated device in the United States?
Yes, and unusually specifically. The United States gives the grid its own device entry rather than leaving it as a generic chart.
Under 21 CFR 886.1330, an Amsler grid is identified as a device that is a series of charts with grids of different sizes, held at 30 centimetres distance from the patient, and intended to rapidly detect central and paracentral irregularities in the visual field. The same section classifies it as Class I (general controls) and exempts it from the premarket notification procedures of subpart E of part 807, subject to the limitations in § 886.9.
Three things follow for a buyer:
- The working distance is part of the device definition, not a clinical preference.
- "A series of charts with grids of different sizes" describes the product family, which is why chart sets that cover several grid densities sit inside the same entry.
- Exemption from premarket notification is not the same as being unregulated. Class I with general controls still carries labelling, record and reporting duties.
The same named-entry approach runs across US eye care: 21 CFR 886.1300 handles the afterimage flasher as a Class II device, so "eye test chart" is not one category in that rulebook.
Does Canada classify an Amsler grid the same way?
No. The difference is structural rather than a matter of degree.
In Canada, devices are classified under the Medical Devices Regulations, SOR/98-282, which works from definitions and a set of rules in Schedule 1 rather than from named product entries. The regulations define an invasive device as one intended to come into contact with the surface of the eye or to penetrate the body, and Rule 2(1) of Schedule 1 places the devices that meet that description in Class II. A printed chart held 30 centimetres away from a patient meets neither limb of that definition, so the invasive-device route does not reach it.
That is where the comparison gets interesting for a buyer. In the United States there is a published line to cite; in Canada the answer depends on applying the general rules and on what the manufacturer put in the labelling and licence application. The practical consequence is that a Canadian clinic cannot settle a specification question by quoting a Canadian entry, because none exists, and a supplier citing an FDA classification is describing the US pathway rather than the Canadian one.
| Item | Canada | United States |
|---|---|---|
| Classification approach | Rules in Schedule 1 of the Medical Devices Regulations, applied to device definitions | Named device entry per product line |
| Entry for an Amsler grid | No named entry; assessed against the general rules | 21 CFR 886.1330, Amsler grid |
| Named working distance | Not fixed in the regulation | 30 centimetres, stated in the device identification |
| Assigned class | Class I for a non-invasive chart that does not contact the eye | Class I (general controls) |
| Premarket route | Device licence where the class requires it; Class I is the lightest tier | Exempt from premarket notification, subject to the limits in § 886.9 |
| Who inspects practice | Provincial college and provincial health programmes | State boards and federal device rules |
The MDEL route matters on the supply side rather than the device side. CliniEco Medical holds Health Canada MDEL #35334 as an establishment, which is a licence to import and distribute devices in Canada; it is not a statement about any individual chart.
Why does the 30 centimetre working distance matter so much?
Because acuity and grid spacing are both angle-dependent, and the angle depends on distance.
A grid printed with a line spacing that subtends the intended angle at 30 centimetres subtends a different angle at arm's length or on a wall. The patient then either over-reports distortion, because normal print looks irregular at close range, or under-reports it, because the grid becomes too small to resolve. Either way the monitoring series loses its baseline, and the value of the test is the comparison between today and last month rather than any single sheet.
The same logic runs through vision standards, where the distance is also written into the rule. The United States eye standards for a first-class airman medical certificate specify distant visual acuity of 20/20 or better in each eye separately and near vision of 20/40 or better, Snellen equivalent, at 16 inches. The Canadian aviation rule expresses the same kind of requirement in metres: SOR/96-433 sets a distant visual acuity standard written as 6/12 (20/40) or better in each eye separately and binocular acuity of 6/9 (20/30) or better.
The commercial drawing standard for central vision is also a formal document rather than a preference. ISO 8596:2017 specifies a range of Landolt ring optotypes and a method for measuring distance visual acuity under photopic conditions for the purposes of certification or licensing, and states plainly that it is neither a standard for clinical measurement nor a route to certifying blindness. ISO 15004-1:2020 covers fundamental requirements for ophthalmic instruments, and lists the instrument types it excludes.
| Item | Canada | United States |
|---|---|---|
| Grid working distance | Set by the chart maker's instructions and the monitoring protocol | 30 centimetres, stated in the device identification |
| Aviation acuity notation | Metric first: 6/12 (20/40), binocular 6/9 (20/30) | Imperial: 20/20 distant, 20/40 near, Snellen equivalent |
| Near vision distance | Expressed in the same metric family as the acuity figure | Stated as 16 inches in the rule |
| Optotype reference | ISO 8596:2017 for certification and licensing work | ISO 8596:2017, plus the device entries for the instruments used |
| Commercial driving standard | Provincial medical fitness frameworks | 49 CFR 391.41, including the colour-recognition limb |
Who is the test for, and who pays for the visit around it?
The grid is handed out as part of an eye examination, so the funding model behind that examination shapes how often monitoring actually happens.
In Ontario, optometry services sit inside the public insurance structure. The Health Insurance Act, R.S.O. 1990, c. H.6 establishes insured services and entitlement to them at sections 11.2 and 12, and R.R.O. 1990, Regulation 552 works out the detail, including who counts as an optometrist and how services rendered in mobile vision and hearing vans are treated. The College of Optometrists of Ontario regulates practice in the province, and its eye-health library is written for patients rather than buyers.
In the United States the picture is fragmented. Where a patient sits for coverage depends on the plan, and the American Optometric Association's guidance on eye examinations and its macular degeneration condition page describe the clinical recommendations without a single national funding rule behind them.
The practical position for a clinic is the same on both sides of the border: hand out the grid with a written interval and a written instruction to report change, and record that you did it. The World Health Organization's blindness and visual impairment fact sheet is background on why follow-up decides outcomes.
Which consumables sit around an Amsler grid test in a clinic?
The grid is the least expensive item in the room and the least useful on its own. The items that make it work are the ones a buyer already stocks.
- Grid charts in a set. Different grid densities suit different patients, matching the "series of charts with grids of different sizes" described in the device identification.
- Occluders and eye patches. The test is monocular. An eye mask and warm compress is part of the same dry-eye and post-procedure conversation in many clinics, and occluders are needed for the grid itself.
- Examination room paper. Every eye examination consumes paper at the chin rest, the slit lamp table and the chair. Smooth examination table paper is a specification-driven purchase rather than an afterthought, and it is one of the lines clinics reorder on a cycle.
- Consumables that cross into every visit. Cotton swabs, gauze and tape are used across the eye clinic, and sterile gauze sponges are stocked for the same reason: there is never one indication.
- Eye protection where chemicals are handled. Where a clinic also handles disinfectants or irrigating fluids, eye and face protection requirements set out the hazard-assessment duty on the employer side of the border.
- Documentation. Monitoring only works if the result is written down: the chart handed out, the interval given and the report received.
For a practice buying these lines together, the ordering route is worth setting up once rather than re-negotiating each time.
Sources
- AAO, Amsler grid and how to use it
- AAO, age-related macular degeneration
- AAO, what is macular degeneration
- AAO, macular degeneration treatment
- AAO, lifestyle and macular degeneration
- AAO, eye exam frequency
- AOA, age-related macular degeneration
- AOA, macular degeneration
- College of Optometrists of Ontario
- Ontario eye-health library
- WHO, blindness fact sheet
- ISO 8596:2017, optotypes for distance visual acuity
- ISO 15004-1:2020
- 21 CFR 886.1330, Amsler grid
- 21 CFR 886.1300
- 14 CFR 67.103
- 49 CFR 391.41
- Canadian Aviation Regulations, SOR/96-433
- Medical Devices Regulations, SOR/98-282
- Health Insurance Act, R.S.O. 1990, c. H.6
- R.R.O. 1990, Reg. 552
- OSHA 29 CFR 1910.132
- Health Canada medical devices
Ordering for a clinic, lab or care home? Wholesale and multi-site ordering covers account setup and case pricing, and the B2B wholesale collection lists the lines stocked for institutional buyers. Clinics that also run an in-house sterilizer can start with the biological indicator 5-pack trial.
Related reading
- Snellen chart and eye test charts in Canada vs the US: which scale
- Eye masks in Canada vs the US: warm compress and dry eye
- Eye clinic consumables: gloves, swabs and tape for optometry
- Eye wash stations in Canada vs the US: ANSI Z358.1
- USB heated eye masks: graphene warm compress for dry eyes
Frequently Asked Questions
Is an Amsler grid the same device in Canada and the United States?
No. The United States publishes a named device entry for it under 21 CFR 886.1330, which fixes a 30 centimetre working distance and assigns Class I (general controls) with an exemption from premarket notification. Canada classifies devices by the rules in Schedule 1 of the Medical Devices Regulations applied to device definitions, so there is no matching named entry to look up.
How far from the eye should an Amsler grid be held?
At 30 centimetres. That distance is written into the US device identification rather than being a clinical preference, and it exists because grid spacing and acuity are both angle-dependent: a chart held at the wrong distance changes how much distortion the patient sees.
Does a clinic need a licence to hand out an Amsler grid in Canada?
The device itself is a non-invasive chart that does not contact the eye, so it does not meet the invasive-device definition used in the Medical Devices Regulations. The supply side is separate: an establishment that imports or distributes devices in Canada works under an establishment licence, and CliniEco Medical holds Health Canada MDEL #35334.
Can a phone app or a wall poster replace the printed grid?
Not if the point is a comparable series. A phone screen changes the angular size and the viewing distance, and a wall poster moves the chart too far away. Neither matches the working distance the test is built around, so readings stop being comparable between visits.
Does a normal Amsler grid rule out macular disease?
No. The grid is a monitoring aid for central and paracentral change, particularly the distortion known as metamorphopsia. It is subjective, it covers a narrow region, and a negative result does not exclude disease. Any reported change is a prompt to be examined.
What consumables does an eye clinic stock alongside the test?
Grid charts in a set of densities, occluders or patches for monocular testing, examination table paper, and the everyday consumables that cross every visit such as cotton swabs, gauze sponges and tape. Clinics that also handle disinfectants add eye and face protection.
CliniEco Medical supplies examination room consumables, eye care lines and the wider clinic catalogue described in this article. Health Canada MDEL #35334. This article is written for clinic, laboratory and procurement professionals and is not clinical guidance; diagnostic and monitoring decisions belong to the treating practitioner.
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