Consensus terminology proposed to define widefield, ultra-widefield imaging
An international panel of researchers with expertise in retinal imaging published newly defined consensus terminology for widefield and ultra-widefield imaging.
Identified gaps in the literature and the lack of a properly accepted definition of ultra-widefield and widefield imaging led to the necessity of standardizing the language by the International Widefield Imaging Study Group, co-author Netan Choudhry, MD, FRCS(C), a member of the study group, told Ocular Surgery News.
“There were marketing terms that we saw on devices about widefield and ultra-widefield imaging, but it wasn’t really clear what their actual meaning was or how we could use them consistently in the literature. How do we standardize the language for the literature and even for devices? In the industry, what is widefield, what is ultra-widefield, and what are the goals for each?” Choudhry said.
A survey was circulated to the International Widefield Imaging Study Group, a panel of retina specialists with expertise in retinal imaging, containing a variety of images such as an OCT montage, pseudocolor images, a fundus photograph montage, fluorescein angiograms, a swept-source OCT B-scan, an asymmetric panretinal OCT montage and OCT angiography images from different vendors and providers. The members of the roundtable studied the images and were asked to apply a definition to each one, Choudhry said.
After defining each image, the researchers classified the definitions of widefield and ultra-widefield images based on anatomy landmarks. Previously, the terms were described and defined by degrees of field of view, which could be interpreted in different ways, he said.
“We wanted to focus on anatomy, thinking that it cuts through the ‘sciencey’ part of degrees of field but at the same time provides physicians with realistic, real-world landmarks they can use to corroborate what an image is showing and what they saw on their exams,” he said.
The collaborative group came to an agreement and defined widefield imaging as a single capture image with the focus on the fovea as the center, extending out in all four quadrants to capture, up to and including, the vortex vein ampullae, Choudhry said.
Comparatively, ultra-widefield imaging was defined as a single capture image in all four quadrants that captures the retina beyond the vortex vein ampullae. Anything beyond this landmark should be considered ultra-widefield imaging, he said.
The new standard of care
Ultra-widefield imaging is the new standard of care for fundus imaging in many retinal disorders, especially in patients with retinal vascular disease and diabetic retinopathy. A device that can capture ultra-widefield images in a single shot, without the need for image montaging, is an essential part of any retinal practice, Szilárd Kiss, MD, co-author of the guidelines, told Ocular Surgery News.
Ultra-widefield images of the fundus are “critical” for the accurate diagnosis and categorization of patients with diabetic retinopathy, he said.
“Without a complete view of the peripheral retina, not only can you miss areas of neovascularization and ischemia, but also not be able to follow patients who are actively receiving treatments, such as repeated anti-VEGF intravitreal injections, for their retinopathy,” he said.
The evidence for the importance of ultra-widefield imaging is greatest in patients with diabetes and diabetic retinopathy. In these cases, the traditional seven standard field imaging is insufficient, Kiss said.
There is also “ample” evidence from clinical practice, as well as from peer-reviewed sources, that the care of patients with posterior uveitis requires ultra-widefield imaging, he said.
“In my practice, there is not a patient for whom I would choose any other imaging modality over ultra-widefield imaging,” Kiss said.
Not all images
The International Widefield Imaging Study Group recommended the incorporation of the ultra-widefield and widefield definitions for color photographs, autofluorescence, multispectral images, fluorescein angiograms and en face OCTs.
However, the group felt the definitions created for widefield and ultra-widefield could not be applied to OCT imaging because no vortex vein ampullae can be shown in four quadrants in a single OCT capture. A single scan size does not represent an equivalent area of retina across all OCT devices, so no single scan size can define a widefield OCT scan universally, Choudhry said.
“It’s an inclusive report. Our goal is not to isolate ourselves to one single device in general but to use these devices to the best of their potential, and they all have excellent potential in various avenues. We wanted to create a language that we can all speak and reference back to. If I send an image to a colleague and say it’s a widefield image, he knows what he’s expected to get and what to look for,” he said.
The definition is “device agnostic,” as it is not catering to the science or technology of any one company and how it builds its machines. It is rooted in how doctors look at and evaluate their patients and how they use landmarks as a checkmark in their images, Choudhry said. – by Robert Linnehan
- Aiello LP, et al. JAMA Ophthalmol. 2018;doi:10.1001/jamaophthalmol.2018.4982.
- Choudhry N, et al. Ophthalmol Retina. 2019;doi:10.1016/j.oret.2019.05.007.
- Nale P. Ultra-widefield imaging visualizes DR outside ETDRS standard fields. www.healio.com/ophthalmology/retina-vitreous/news/online/%7B7fb142b8-b405-4cbb-89eb-ee88203797e6%7D/ultra-widefield-imaging-visualizes-dr-outside-etdrs-standard-fields. Published Jan. 19, 2016. Accessed Oct. 31, 2019.
- For more information:
- Netan Choudhry, MD, FRCS(C), can be reached at Vitreous Retina Macula Specialists of Toronto, 3280 Bloor St. West, Suite 310, Toronto, Ontario M8X 2X3, Canada; email: email@example.com.
- Szilárd Kiss, MD, can be reached at Department of Ophthalmology, Weill Cornell Medical College, 1305 York Ave., 11th Floor, New York, NY 10021; email: firstname.lastname@example.org.
Disclosures: Choudhry reports financial disclosures with Topcon, Optos, Bayer, Allergan, Novartis, Carl Zeiss Meditec and Ellex. Kiss reports he is a consultant for Adverum, Allergan, Alcon, Alimera, Fortress Bio, Genentech, Regenxbio, Novartis, Spark, Regeneron and Optos.