Ultra-Widefield Retinal Imaging: What It Adds and How to Evaluate a Camera

Ultra widefield retinal imaging captures the retina well beyond the posterior pole, out toward the far periphery, often in one capture. A standard 45° photo shows only the central retina. For a practice choosing its next retinal camera, the hard part is not the idea. It is comparing the numbers. Manufacturers measure field of view in different ways, single shots and montages get mixed together on spec sheets, and the image-quality trade-offs only show up once a camera is in your lane. This guide explains how the categories are defined, how to read a field-of-view spec, and what to check before you buy. It uses the Ezer Panorama ultra-widefield retinal camera as the worked example.

Scope note: this article covers imaging capability and equipment selection only. It makes no clinical or regulatory claims.

Widefield vs ultra-widefield: the definitions are anatomical

In 2019 the International Widefield Imaging Study Group proposed a consistent nomenclature built on normal anatomical landmarks rather than degree counts, applicable across imaging methods. Their recommendation, published in Ophthalmology Retina:

• Widefield: images showing retinal features beyond the posterior pole but posterior to the vortex vein ampullae, in all four quadrants.
• Ultra-widefield: images showing retinal features anterior to the vortex vein ampullae, in all four quadrants.
• Panretinal: a complete 360°, ora-to-ora view. A review notes that, as of 2019, no technology could do this in a single capture.

That review also tabulates the approximate degree ranges these labels usually map to: about 50° for the posterior pole, about 60° to 100° for widefield, and about 110° to 220° for ultra-widefield. Use those ranges as a rough guide only. The definitions themselves are anatomical on purpose, because degree numbers depend on how they are measured.

How field of view is measured: internal vs external angle

This is the single most useful idea for anyone comparing ultra-widefield cameras, and spec sheets don't always state which method they use.

• External (visual) angle. Conventional fundus cameras measure the angle of light entering the eye, at the pupil. A geometric analysis of widefield imaging notes that this is the ISO convention for fundus cameras, and that it tops out at almost 180°.
• Internal (eye) angle. Most widefield systems measure the angle from the spherical center of the eye. For the same patch of retina, that number is larger than the pupil-based figure.

The size of the gap matters. A 2019 review of Optos imaging gives a worked example: 200° measured from the center of the eye corresponds to roughly 125° measured the conventional way. ZEISS labels the CLARUS 500 field "measured from the center of the eye." So when one brochure says 133° and another says 200°, check first that both use the same convention. If they don't, you are not comparing like with like.

One practical rule follows from the table. When a spec sheet doesn't state its convention, ask for it in writing before you compare cameras. It is a fair question, and a good supplier will answer it.

Single capture vs montage

Many headline figures are montages: several captures at different fixation points, stitched into one panorama. The AAO's summary of the consensus work expects montage to remain popular. But it changes the workflow. The Patel review notes that montaging widefield images up to an ultra-widefield field "requires significantly more time for capture and montaging." When you evaluate a camera, separate three numbers:

1. Single-capture field. What one press of the button records.
2. Montage field. The maximum stitched field, and how many captures it takes.
3. Who does the stitching. Automatic in real time, automatic after capture, or manual in software.

On the Ezer Panorama, the product page lists a 170° single shot and up to 260° by montage. Nine internal fixation targets guide the patient, and stitching is listed as real-time, automatic or manual. On the CLARUS 500, ZEISS lists 133° for one image, 200° for two, and up to 267° for a montage of up to six images.

Why scanning-laser designs can image through a small pupil

Several ultra-widefield systems, including Optos and the Ezer Panorama, are scanning laser ophthalmoscopes rather than flash-based fundus cameras; the Panorama is listed as a confocal scanning laser ophthalmoscope (cSLO). The difference is in how they handle light. A conventional fundus camera records all the light reflected from the eye. A cSLO places a small aperture at a point optically conjugate with the retina. It passes light from the plane in focus and blocks scattered light and glare from elsewhere. Patent literature on confocal ophthalmoscopes describes this as rejecting light from the region around the object being viewed. It also credits this design with letting the fundus be observed without dilating drops, despite a relatively small pupil.

In practice this shows up as a minimum pupil spec, and it is worth comparing directly. The Ezer Panorama lists a 2.5 mm minimum pupil with mydriasis not required. ZEISS lists 2.5 mm for the CLARUS 500. For comparison, our Ezer EFC-2600 non-mydriatic retinal camera review covers a conventional 45° design with a 4.0 mm minimum pupil.

The image-quality trade-offs to test before you buy

Ultra-widefield imaging is not free. Peer-reviewed reviews name the same trade-offs again and again. Each one is worth testing on a demo unit with your own staff.

Eyelash, eyelid and nose artifacts

A review of ultra-wide field imaging lists artifacts from the eyelashes, lid margin and nose as common. It also notes that simple measures, holding the lid and centering the eye at a suitable distance, reduce them. ZEISS's partially confocal optics are described in the literature as reducing lash and lid artifacts. Ask any vendor to show you raw, unedited peripheral captures, not curated marketing images.

Peripheral distortion and measurement

The retina is curved and the image is flat. Projecting one onto the other distorts and magnifies the periphery, which "leads to errors especially in peripheral measurements," according to the same review. Software can correct for this. Optos, for example, offers a tool that reprojects images stereographically on a model eye 24 mm in diameter. If your doctors will measure anything in the periphery, ask whether the software corrects the projection, and how.

Color rendering

Some laser systems produce a pseudocolor image rather than a true-color photo. The Patel review lists pseudocolor imaging among the limitations of Optos systems, alongside peripheral distortion and lash artifact. ZEISS states that CLARUS 500 images closely resemble the coloration seen during clinical examination. Whatever you are evaluating, look at the color images with the clinicians who will read them, before you sign.

A worked example: what the Ezer Panorama spec sheet tells you

The Ezer Panorama is US Ophthalmic's house-brand ultra-widefield camera. These are the figures published on its product page, grouped by the questions above:

Two things are worth noting from a buyer's side. First, the selectable fields run from 8° to 170°. One instrument can produce a narrow, detailed view and a full overview, so the camera is not limited to peripheral work. Second, Ezer's product page states that a single capture covers 82% of the total retinal area. Optos uses the same 82% figure for its 200° field measured from the center of the eye. Because the two degree figures differ, ask for the angle convention behind the 170° figure before you set the cameras side by side. That way you compare the systems on the same basis.

Where an ultra-widefield camera fits next to a 45° camera

An ultra-widefield camera does not automatically replace a conventional camera. The practical questions are about workflow and budget:

• Which images do your doctors want by default? If most of the imaging is posterior-pole work, a conventional non-mydriatic camera such as the Ezer EFC-2600 may cover the need. Our fundus camera buying guide compares non-mydriatic, mydriatic and handheld designs.
• Are you dilating to see the periphery today? If so, the minimum-pupil spec and how long montage capture takes become the main points to compare.
• Who will operate it? Heavy automation, like the Panorama's automatic alignment, focus and capture, can matter most in lanes where technicians rotate.
• Where will the images live? Confirm export formats, EHR or DICOM integration, and storage needs with the vendor in writing. At 4096 × 4096 pixels per image across several modes, storage adds up.

To see where the leading non-mydriatic and widefield systems sit against each other, see our comparison of the best non-mydriatic fundus and retinal cameras for 2026.

Evaluation checklist: ask these before you sign

1. Is the field of view measured from the center of the eye or at the pupil? Get it in writing.
2. What is the single-capture field, and what is the maximum montage field? How many captures does the montage need?
3. Is stitching automatic, real-time, or a manual software step?
4. What is the minimum pupil diameter for full-field capture?
5. Is the color image true-color or a laser composite? Review sample images with your doctors.
6. How does the system handle lash and lid artifacts? Ask to see unedited peripheral captures.
7. Does the software correct peripheral projection distortion for measurements?
8. Which imaging modes are included as standard, and which are options?
9. What refractive compensation range does autofocus cover?
10. How do images reach your EHR, and how many viewing stations are included?
11. What warranty, on-site service and spare-parts support come with it in the US?

US Ophthalmic is the provider behind the Ezer house brand, with an in-house technical and spare-parts department. We can walk your team through the Panorama's full spec sheet, including the field-of-view convention, and quote it alongside a conventional camera so you can compare both options. Request a quote to start.

Frequently asked questions

What is the difference between widefield and ultra-widefield retinal imaging?

The International Widefield Imaging Study Group defines both terms by anatomy, not by degrees. A widefield image shows the retina beyond the posterior pole but posterior to the vortex vein ampullae in all four quadrants. An ultra-widefield image shows retinal features anterior to the vortex vein ampullae in all four quadrants.

Why do two cameras with similar degree numbers capture different amounts of retina?

Because field of view can be measured two ways. Conventional fundus cameras quote the angle at the pupil (the external, or visual, angle). Most widefield systems quote the angle from the center of the eye (the internal, or eye, angle), which gives a larger number for the same area. One published example: 200 degrees measured from the center of the eye corresponds to roughly 125 degrees by the conventional method.

How much of the retina does a standard 45-degree photo cover?

A peer-reviewed overview puts a single 45-degree image at about 15% of the retinal surface. The seven standard ETDRS fields together are cited at about 30% to 35%, depending on the source.

Does an ultra-widefield camera need pupil dilation?

Not necessarily. Patent literature credits confocal scanning designs with imaging the fundus without dilating drops despite a small pupil. The Ezer Panorama lists a 2.5 mm minimum pupil with mydriasis not required, and the ZEISS CLARUS 500 also lists a 2.5 mm minimum pupil.

What are the main image-quality trade-offs of ultra-widefield imaging?

Published reviews name three: eyelash, eyelid and nose artifacts in the periphery; distortion and magnification at the edges from projecting a curved retina onto a flat image, which affects peripheral measurements unless the software corrects it; and, on some laser systems, pseudocolor rather than true-color rendering.

What field of view does the Ezer Panorama capture?

Ezer lists a 170-degree single-shot field and up to 260 degrees by automatic montage across nine internal fixation targets, with seven selectable fields from 8 to 170 degrees. Ask for the spec sheet that states which angle convention those figures use, so you can compare them directly with other systems.

Sources

• Choudhry N, et al. Classification and Guidelines for Widefield Imaging. Ophthalmology Retina, 2019 (abstract, PMID 31302104): europepmc.org/article/MED/31302104
• AAO EyeNet, "Nomenclature and Guidelines for Widefield Imaging," 2019: aao.org
• Patel SN, et al. Ultra-widefield retinal imaging: an update on recent advances: europepmc.org/article/PMC/PMC6971964
• Oishi A, et al. Int J Retina Vitreous, 2019 (Optos angle convention; cSLO aperture): europepmc.org/article/PMC/PMC6907101
• Widefield and Ultra-Widefield Retinal Imaging: A Geometrical Analysis: europepmc.org/article/PMC/PMC9867331
• Ghasemi Falavarjani K, et al. Ultra-wide-field imaging overview (45° coverage): europepmc.org/article/PMC/PMC4909710
• 2026 review of ultra-widefield color photography (ETDRS seven-field coverage): europepmc.org/article/PMC/PMC13271908
• Ultra-wide field retinal imaging: A wider clinical perspective (artifacts, distortion, color): europepmc.org/article/PMC/PMC8012972
• Optos, Benefits of optomap: optos.com
• ZEISS CLARUS 500 specifications: zeiss.com
• Confocal ophthalmoscope patents US5867251A and US5430509A: patents.google.com
• Ezer Panorama product page and specifications: usophthalmic.com