Ultra-widefield imaging: Coming into its own

Take-home message: Ultra-widefield (UWF) imaging provides clinicians a much broader view of the retinal periphery. The Optos California uses multiple UWF imaging modalities, including color, autofluorescence, fluorescein angiography (FA), and indocyanine green (ICG) angiography in a 200° picture.

By Michelle Dalton, ELS

Ultra-widefield (UWF) imaging provides clinicians a much broader view of the retinal periphery, which can translate to earlier recognition of disease progression and (possibly) treatment intervention. The Optos California is one example of a technology that uses multiple UWF imaging modalities, including color, autofluorescence, fluorescein angiography (FA), and indocyanine green (ICG) angiography in a 200° picture.

The Optos California uses multiple ultra-widefield imaging modalities, including color autofluorescence, fluorescein angiography, and indocyanine green angiography in a 200 degree picture. The imaging device's footprint is smaller and has new optical design. (Photos courtesy of Optos)The scanning laser approach does not require pupil dilation and the speed of the laser beam is able to capture more than 80% of the retina in a single capture, explained Derek Swan, vice president of research.

The California includes both hardware and software changes “that improve the visualization of the retina all the way to the very far periphery as well as enhancing the way that the retina’s visualized in its review software,” Mr. Swan said. Among its other features, the California’s footprint is significantly smaller than other devices. The device also has a new optical design “that optimizes the resolution by maintaining a spot on the eye as the laser images the whole retina.”

The process from initial design concept through commercial introduction was about 2 years, Mr. Swan said. The device incorporates scanning laser ophthalmoscopy (SLO) that helps clinicians visualize the retina even through scatter and other obstructions (such as cataract).

Clinicians “have to see everything before they can be sure they’re making effective clinical decisions. That goes all the way from disease detection into making decisions around treatment planning and importantly follow up and advancement of disease,” Mr. Swan said.

Clinical implications

In diabetic retinopathy, Harvard researchers have now shown “that patients whose peripheral retina looks worse than the central retina tend to progress faster overall,”¹ said SriniVas Sadda, MD, Doheny Eye Institute (Los Angeles). Couple UWF with FA, ICG angiography, and autofluorescence, and “we’ve now found there is a lot of important information in the periphery,” Dr. Sadda said.

FA in particular has helped identify “large areas of nonperfusion” that may have relevance in determining patient outcomes, he added. Things like drusen, atrophy, and pigmentary alterations are “very common in patients with age-related macular degeneration (AMD),” Dr. Sadda said. “We observed that these color photo abnormalities correspond to autofluorescence changes, which are even more striking and easier to detect. We found that certain patterns, especially hyperautofluorescence, were more common in patients with more advanced AMD. Those studies have highlighted a shifting disease concept that AMD may not just be a macular disease, but rather a panretinal disorder.”

Several studies are under way that should help guide what clinicians should do with the information they can now gather, including the SCORE 2, LEAVO, and Clarity studies, Dr. Sadda said. The Diabetic Retinopathy Clinical Research Network also is evaluating widefield imaging in some of its ongoing studies. 

For anterior specialist David Goldman, MD (Palm Beach Gardens, FL), using UWF “has improved my efficiency. Patients come in postop month 1 after cataract surgery or after YAG laser, and typically we would dilate them to get a good peripheral retina exam. With UWF, if the patient is asymptomatic, we don’t have to dilate. It saves us time, it saves the patient time.” Plus, imaging itself takes about 1-2 seconds, and avoids the flash most patients find distasteful. Other devices mandate multiple images (and multiple flashes) to image an equivalent amount of the retina.

Having such high-resolution images also has helped in patient education, he said. Some patients know they have had a retinal tear or scleral buckle, but have never seen it. “Being able to put the image up on our TV screens really helps the patient understand what's going on in their eye,” Dr. Goldman said.

From his perspective, being able to superimpose images of a cataract over the retina “clearly helps show patients how their vision is being impacted by the cataract.” The California renders “a kind of 3D representation of the eye, with the back of the eye being filled in by the retina image. We can add or subtract things like the cornea or the cataract. You can rotate the image and zoom in and zoom out,” he said.

“So, we would put in an image of a cataract and rotate the eye so it’s a bird’s eye view through the cataract to show patients how the view of the retina through that cataract is diminished. Then we can remove that cataract image and replace it with a mock monofocal IOL to show how the peripheral and posterior eye is clear. And we can do that with multifocal IOL image and contact lens images as well,” Dr. Goldman continued.

The California also boasts a chin rest and headrest, which makes it easier for elderly patients, he added. Dr. Goldman said the small footprint made the California easy to bring into the practice, into the same room as most of his other diagnostic equipment.

Uveitis

Uveitis is another retinal pathology where UWF is having an impact, Dr. Sadda said.

“Some uveitis patients may have relatively few lesions in the posterior; most of the activity is in the peripheral retina. So we’ve been hindered in the past with not knowing if the disease is active,” he said.

In another example, a patient had been referred after complaining about a visual field problem thought to be the result of a droopy eyelid.

“We took a quick undilated autofluorescence image that showed subtle abnormalities,” he said. “It turned out this patient had early retinitis pigmentosa.”

Widefield imaging also can be used to monitor vein occlusions and central serous chorioretinopathy, he said, and monitor and document tumors as well.

“Some clinicians have noted that the color is not exactly the same as a white-light color so it can be a little more of a learning curve, but once clinicians become used to the images UWF provides, it can be incredibly useful for monitoring tumor growth,” he said.

Dr. Sadda has not yet altered treatment algorithms or management strategies, but may once the clinical studies on the UWF devices are published. “I practice a truly evidence-based approach,” he said. “I like to have the randomized clinical trial data.”

However, some pioneers in the field, including Prof. Paulo Stanga, has used UWF to analyze targeted laser treatment, where Prof. Stanga uses the images from the UWF device to “evaluate which areas are non-perfused and lasers only those areas,” Dr. Sadda said. That initial work has shown how valuable the information gleaned from the peripheral retina can be, and may lead to even more individualized treatments in the future.

Reference

• Silva PS, Cavallerano JD, Haddad NM, et al. Peripheral lesions identified on ultrawide field imaging predict increased risk of retinopathy progression over 4 years. Ophthalmology. 2015;122(5):949-56.

David Goldman, MD

E: david@goldmaneye.com

SriniVas Sadda, MD

E: ssadda@doheny.org

Derek Swan

E: dswan@optos.com

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