Coming to terms with ‘ultra-widefield’ and ‘widefield’ imaging

Figure 2. Anatomic examples of expert panel nomenclature recommendations.

The International Widefield Imaging Study Group (IWISG)-a physician panel with expertise in retinal imaging-has released recommendations for classifications and guidelines for defining “widefield” and “ultra-widefield” imaging.

The International Widefield Imaging Study Group (IWISG)-a physician panel with expertise in retinal imaging-has released recommendations for classifications and guidelines for defining “widefield” and “ultra-widefield” imaging.

Although ultra-widefield is the new standard of care for fundus imaging in patients with retinal vascular diseases, no standardized definition existed, leading to potential confusion among retinal specialists when trying to interpret the peer-review journal articles on the topic.

The IWISG held a consensus meeting with the goal of creating universal nomenclature to describe these terms, introduced for the first time at this year’s American Society of Retinal Specialists’ meeting (and published online at https://www.ncbi.nlm.nih.gov/pubmed/31302104). The IWISG also created a new term: panretinal (to represent a 360-degree ora-to-ora view of the retina).

Guideline development

Netan Choudhry, MD, FRCS, Vitreous Retina Macula Specialists of Toronto, noted inconsistencies in how “widefield” and “ultra-widefield” were used in the literature, which inspired the goal of standardization.

Before the expert panel convened, a set of seven images, including a variety of imaging methods of both healthy and diseased eyes, were circulated to the group.

IWISG members were asked to define each image and classify the definitions of “widefield” and “ultra-widefield” based on anatomic markers. The definitions were gathered and used as the foundation of discussion during the consensus meeting. Anatomic location, field of view, and perspective for each of the seven sets of images were reviewed.

Recommendations

Field-of-view interpretation is subjective due to the different angles (external, internal) and clinician perception. The expert panel determined that the field of view should include the macula at the center. Field-of-view cut points for widefield and ultra-widefield should correspond to common anatomical features (Figure 1).

The expert panel defined “widefield” as a single capture image centered on the fovea, capturing the retina in all four quadrants posterior to and including the vortex vein ampullae. In contrast, the panel defined “ultra-widefield” as a single capture view of the retina in the far periphery in all four quadrants.

The expert panel developed new term, “panretinal,” to define a single capture, 360-degree, ora-to-ora view of the retina (Figure 2).

The panelists defined several other terms, including:

• Posterior pole: Retina within and just slightly beyond the arcades;
• Midperiphery: Region of retina up to the posterior edge of the vortex vein ampulla; and 
• Far Periphery: Region of retina anterior to the vortex vein ampulla.

Optical coherence tomography (OCT) B-scans are primarily used for cross-sectional examination of the retina.

The expert panel found variances with OCT use; field of view was not always applied, and the OCT could include variable pixels and aspect ratios. To address these inconsistencies, the expert panel recommended that the description of the B-scan should include the size of the B-scan, the location, the scan time, and symmetry.

Further, to be considered “widefield,” OCT-angiography (OCT-A) images must capture the retina in all four quadrants and include the retina up to the posterior edge of the vortex vein ampullae. To be considered “ultra-widefield,” OCT-A images must capture all four quadrants beyond the anterior edge of the vortex vein ampullae.

In summary, the IWISG panel recommends basing definitions on anatomical landmarks to better reflect the clinical exam. The group also calls for improved inter-device consistency, the incorporation of montage into the image description for precision, and the incorporation of asymmetry in view into the description for all imaging modalities.

These recommendations should bring much needed uniformity to clinical exams, Dr. Choudhry said.

Including Dr. Choudhry, the International Widefield Imaging Study Group consisted of the following thought-leaders in retina:

• Jay S. Duker, MD, professor and chairman of ophthalmology, Tufts Medical Center and Tufts University School of Medicine, Boston;
• K. Bailey Freund, MD, clinical professor of ophthalmology, New York University School of Medicine, and in practice with Vitreous Retina Macula Consultants of New York;
• Szilard Kiss, MD, director of clinical research, Department of Ophthalmology, Weill Cornell Medical College;
• Giuseppe Querques, MD, associate professor, University Vita-Salute, IRCCS Ospedale San Raffaele, Milan, Italy;
• David Sarraf, MD, full-time faculty member, Stein Eye Institute at UCLA and a member of the Retinal Disorders and Ophthalmic Genetics Division at JSE UCLA;
• Richard Rosen, MD, vitreoretinal surgeon and consultant at the New York Eye and Ear Infirmary, where he serves as vice chairman and director of ophthalmology research, as well as surgeon director and chief of retinal services;
• Eric Souied, MD, head of Department of Ophthalmology at both “Hopital Intercommunal de Creteil” and “Henri Mondor” hospital, in France;
• Paulo Stanga, MD, consultant ophthalmologist and vitreoretinal surgeon, Manchester Royal Eye Hospital, Manchester, UK:
• Giovanni Staurenghi, MD, professor of ophthalmology and chairman, University Eye Clinic, and director, University Eye Clinic Department of Biomedical and Clinical Science “Luigi Sacco” at the Luigi Sacco Hospital in Milan, Italy; and
• SriniVas Sadda, MD, president and chief scientific officer, Doheny Eye Institute, the Stephen J. Ryan – Arnold and Mabel Beckman Endowed Chair, and professor of ophthalmology, University of California – Los Angeles (UCLA), David Geffen School of Medicine.