The Ezer ERH-770 handheld autorefractor is a fully portable, pistol-grip refraction unit built on a Shack-Hartmann wavefront sensor, with a published spherical range of −20 D to +20 D, a cylinder range of −12 D to +12 D, and a stated capture time of under two seconds per eye. It exists to solve one problem a table-top instrument structurally cannot: getting an objective refraction on a patient who is not sitting at your lane.
This is a single-model deep dive. If you are still choosing between form factors and brands, start with our autorefractor buying guide — this page assumes you have already decided a portable unit belongs in your practice and want to know exactly what this one does, what it does not do, and what to confirm before you buy. For the underlying clinical rationale for objective refraction, see our companion article on the importance of autorefractors.
Shopping for handheld autorefractors? US Ophthalmic is a direct provider of handheld autorefractors to eye care practices across the US. Tell us how your lane is set up and we will come back with the configurations that fit, plus current availability and lead times.
Published specifications
These figures are taken directly from the current ERH-770 product page. Where a specification is not published, we say so rather than estimate it — and we tell you which ones to request in writing before you sign.
| Measurement principle | Shack-Hartmann aberrometer |
| Spherical range | −20 D to +20 D |
| Cylinder range | −12 D to +12 D |
| Axis range | 1° to 180° |
| Display | 2.80 inch touch screen |
| Data output | Bluetooth printer |
| Capture time | Under 2 seconds per eye (manufacturer stated) |
| Form factor | Fully handheld |
Not published on the product page — ask for these in writing: minimum measurable pupil diameter, working distance, vertex-distance settings, battery chemistry and runtime per charge, charging time, exact weight and dimensions, pupillary-distance measurement, and whether any keratometry is included. That last one matters more than buyers expect, and we cover it below.
What "Shack-Hartmann" actually means here
Shack-Hartmann is a wavefront-sensing method, not a marketing term, and it is worth understanding because it explains both the strengths and the limits of this instrument.
The sensor uses an array of small lenses — lenslets — all of the same focal length, each focused onto a photon sensor such as a CCD or CMOS array. Each lenslet samples one small piece of the light returning from the eye and focuses it to a spot. When the returning wavefront is perfectly flat, every spot lands in its reference position. When the wavefront is distorted by the eye's refractive error, the spots shift, and the displacement of each spot is proportional to the integrated gradient of the wavefront across that lenslet. Reading the whole grid of displacements at once lets the instrument reconstruct the wavefront and derive sphere, cylinder and axis.
Two practical consequences follow. First, this is a single-shot, whole-pupil sampling method, which is why sub-two-second capture is achievable at all. Second, the technique has a known boundary: a Shack-Hartmann sensor measures distortion across a continuous wavefront and cannot sense discontinuous steps in it. In plain terms, it is measuring the optics of the eye as an optical system — nothing in the measurement principle makes it a substitute for the rest of your examination.
Where a handheld genuinely wins
Patients who cannot reach the lane
This is the ERH-770's core case, and it is a real one. Writing in Review of Optometry, practitioners describe how handheld instruments "free practitioners to provide much-needed care for patients who cannot come to the office" — nursing facilities and hospital rooms, and patients who are bed-bound or have poor positioning from kyphosis. A chin rest and a forehead strap assume a patient who can sit upright, hold still, and be wheeled to a fixed instrument. A meaningful share of patients cannot do all three.
The same applies inside your own building. Wheelchair users, patients with tremor or limited neck extension, and anyone who cannot be transferred comfortably to the lane chair are all served by an instrument that travels to them.
Screening programs, outreach and mobile clinics
The manufacturer positions the ERH-770 for ophthalmology clinics, optical retail environments, vision screening programs, mobile eye clinics, home visits and post-operative follow-up. The throughput math is what makes screening work viable: at a stated sub-two-second capture per eye, the binding constraint on a screening line becomes patient flow and data handling, not the instrument.
Satellite lanes and second-instrument redundancy
A less obvious use is insurance. If your only autorefractor is a table-top unit and it goes down, pretesting stops until a technician arrives. A handheld is a fraction of the footprint and can keep pretesting moving through a service visit. For a second location that does not yet justify a full lane build-out, it is often the first objective-refraction instrument in the door.
Where it does not replace a table-top — an honest comparison
Portable and table-top units are complements, not substitutes. As the same Review of Optometry discussion puts it, "there is no reason clinicians would need to replace their in-office phoropter with a handheld one." The clearest way to see the trade is against the house-brand table-top sibling, the Ezer ERK-BH autorefractor/keratometer, using each unit's published figures.
| ERH-770 (handheld) | ERK-BH (table-top AR/K) | |
| Sphere | −20 to +20 D | −30.00 to +25.00 D |
| Cylinder | −12 to +12 D | 0.00 to ±10.00 D |
| Keratometry | Not published | Yes — corneal power 25.96–67.50 D, radius 5.0–13.0 mm |
| Contact-lens base curve mode | Not published | Yes (CLBC mode) |
| Vertex distance settings | Not published | 0.0 / 12.0 / 13.5 / 15.0 |
| Minimum pupil diameter | Not published | Ø2.0 mm |
| Pupillary distance | Not published | 10–88 mm |
| Display | 2.80 in touch screen | 7 in TFT-LCD, 800 × 480, tilt/swivel touch |
| Printing | Bluetooth printer | Internal thermal printer with auto-cutter |
| Power | Portable (battery; runtime not published) | AC 100–240 V, 50/60 Hz |
| Weight | Handheld (not published) | Approx. 44 lb (20 kg) |
Read that table as a division of labor rather than a scoreboard. The decisive line is keratometry: the ERK-BH publishes corneal power, corneal radius and a contact-lens base-curve mode, and the ERH-770 does not publish keratometry at all. If your contact-lens work depends on K readings, a handheld does not cover that job — you need an AR/K in the lane and the handheld for reach. The wider sphere range on the table-top matters at the extremes of your patient population; for most refractions, both instruments are comfortably in range.
What the handheld form factor costs you operationally
Three trade-offs deserve an honest look before you buy, and all three are manageable if you plan for them.
Operator technique matters more. There is no chin rest enforcing alignment, so the operator is the alignment system. As Review of Optometry notes, "less-than-careful alignment and timing on the moment of data collection will lead to inaccurate or poor quality information when using a portable device." Budget for real training rather than a five-minute handoff, and designate who owns the instrument.
Physical risk is higher. "Every use of a handheld instrument is an opportunity for it to be dropped, shaken or otherwise damaged." A hard case, a defined storage location and a charging home are not accessories — they are what keeps the unit in service. Ask what a drop does to your warranty position.
Data handling needs a decision up front. The ERH-770's published data output is a Bluetooth printer. That is fine for a paper-in-hand screening workflow, but it is not the same as a network path into a chart. Portable devices that rely on wireless or cloud transfer also carry information-security considerations. Decide before purchase whether readings will be keyed in, printed and scanned, or transferred — and confirm in writing what the unit supports.
Total cost of ownership: what to confirm before you sign
- Battery. Runtime per charge, charge time, whether the battery is user-replaceable, and what a replacement costs down the road. On a portable, the battery is the consumable that determines useful life.
- The printer. Bluetooth printing means a second device to charge, pair and stock with paper. Confirm whether the printer is included, which model it is, and what the paper costs.
- Case and charging. Confirm what ships in the box versus what is a line item.
- Calibration and service interval. Ask what the manufacturer specifies and what a service event requires.
- Warranty terms. Duration, what is covered, whether accidental damage is excluded, and turnaround time on a repair — including whether a loaner is available so pretesting does not stop.
- Training. Who trains your staff, and is it included.
Buying the ERH-770 from US Ophthalmic
The ERH-770 is part of the Ezer line, US Ophthalmic's own house brand, which changes the support picture in ways that matter on a portable instrument. Because we are the equipment provider rather than a middle layer, service, spare parts and warranty run through our own in-house technical department — the same team that supports the rest of the portable autorefractor line. On a device that lives in a bag and travels to nursing homes and screening events, the question is not whether it will eventually need attention, but who answers when it does. More on how we support what we sell is on our why choose US Ophthalmic page.
For current availability, configuration and a written quote including warranty terms, request a quote and a specialist will confirm the details above in writing.
Ready to spec your handheld autorefractors?
Send us your requirements and our equipment specialists will come back with a configuration built around how your practice actually works — including availability and lead time. US Ophthalmic is a direct provider to eye care practices nationwide.
Frequently asked questions
What is the measurement range of the Ezer ERH-770?
The published spherical range is −20 D to +20 D, the cylinder range is −12 D to +12 D, and the axis range is 1° to 180°.
How fast is the ERH-770?
The manufacturer states measurements in under two seconds per eye. In practice, patient positioning and data handling — not the capture itself — set the pace of a screening line.
Does the ERH-770 measure keratometry?
Keratometry is not published in the ERH-770's specifications. If you need K readings — for contact-lens fitting, for example — plan on an autorefractor/keratometer such as the table-top Ezer ERK-BH, which publishes corneal power, corneal radius and a contact-lens base-curve mode.
Can a handheld autorefractor replace a table-top unit?
For most practices, no — they do different jobs. A handheld reaches patients and locations a fixed instrument cannot, while a table-top AR/K generally offers a wider measurement range, keratometry, a larger display and an internal printer. Most practices run a handheld alongside a table-top rather than instead of one.
What technology does the ERH-770 use?
A Shack-Hartmann aberrometer. An array of lenslets samples the wavefront returning from the eye; the displacement of each focused spot is proportional to the local wavefront gradient, and reading the full grid at once allows the wavefront to be reconstructed and converted to sphere, cylinder and axis.
How does data get out of the instrument?
The published data output is a Bluetooth printer. Confirm any additional transfer options in writing before purchase, and decide in advance how readings will reach the patient record.
Who should operate it?
A trained technician can run it, but because there is no chin rest enforcing alignment, results depend on operator technique more than on a table-top unit. Assign a clear owner and budget for proper training.
What warranty and service come with it?
Warranty terms are confirmed on your written quote. US Ophthalmic supports the Ezer line through its own in-house technical and spare-parts department; ask specifically about repair turnaround and loaner availability, since a portable unit is the instrument most likely to take a knock.
