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New scan for diabetic eye disease is better, but at a cost

Verónica Hackethal, M

Results from a national telehealth program in the United States have shown that employing a new technology, ultra wide field imaging (UWF), for diabetic retinopathy screening could cut unnecessary referrals for full eye exams, potentially benefiting many patients who live in remote areas.

The study was published online March 1 in Ophthalmology.

"These data demonstrate that when we deploy this technology in a community-based setting, we can achieve the same magnitude of reduction in ungradable images and increased identification of eye disease as we saw in the academic research environment," comments first author Paolo Silva, MD, staff ophthalmologist and assistant chief of telemedicine at Beetham Eye Institute, Joslin Diabetes Center, Boston, Massachusetts, in a press release issued by his institution.

"Utilizing this new type of camera technology, we can more easily obtain the images, we can read the retinal images faster, we have fewer images that are unusable, and we pick up more disease than we could in the past …and we have now shown this substantial benefit in a large real-world setting," adds senior author Lloyd Paul Aiello, MD, PhD, director of the Beetham Institute and professor of ophthalmology at Harvard Medical School.

Reducing the ungradable image rate is important because ungradable images often result in referral for comprehensive eye exams, which many patients may not need. In remote areas that can translate into considerable expense and travel time — for example, some patients may need to travel by plane just to reach a specialist who can do the exam.

But although UWF is more efficient and captures over twice the retinal surface as the current gold standard, nonmydriatic multifield fundus photography (NMFP), it is very expensive — often in excess of $70,000 for one machine — so the question remains whether the benefits outweigh the costs.

Asked to comment on these new findings, Thomas M Johnson, MD, FRCSC, an attending vitreoretinal surgeon at the Retinal Group of Washington, DC, said that the cost is probably the biggest issue with UWF imaging at the moment.

"UWF is still somewhat prohibitively expensive, given that it's not like telescreening really reimburses much to support the cost of it," he told Medscape Medical News. "If you try to extrapolate this into the country as a whole, it's hard to know whether you'd really save any money in that ungradable rating."

UWF Reduces Ungradable Imaging Rate for Diabetic Retinopathy by 90%

The new research was conducted in the Indian Health Service (IHS), which provides care for 2.2 million Alaskan Natives and American Indians. Forty-two percent of the populations live in remote areas like the Arctic Circle and the Grand Canyon, with limited access to medical specialists.

Within the IHS, Joslin Diabetes Center runs a telemedicine vision-screening program called Joslin Vision Network, which operates in 97 clinics in 25 states. Images are scanned at a central reading center in Phoenix, Arizona.

The study took a nonrandomized approach and included 17,526 IHS patients who had imaging with NMFP and 8109 patients who had UWF imaging between May 2014 and August 2015. During this time UWF imaging was used at 21 sites within the IHS.

Trained, certified imagers identified ungradable images at the point of care.

Licensed optometrists supervised by an ophthalmologist-graded images using a standardized, validated protocol at the central reading center.

Results showed that UWF imaging reduced the ungradable imaging rate for diabetic retinopathy by 89.6% per patient, compared with standard NMFP imaging. Results remained significant after adjustment for potential confounders like age and diabetes duration (P < .0001).

Using UWF also resulted in a twofold improvement in identification of patients with diabetic retinopathy or referable diabetic retinopathy.

And UWF produced a lower rate of ungradable images even among older individuals — older diabetic patients are more likely to have cataracts, which can increase ungradable imaging rates for both UWF and standard NMFP.

Of the images, 2.3% were ungradable for UWF in the group aged 50 to 70 years vs. 28.3% for NMFP; for those over 70, these figures were 12% vs 53.6%, respectively.

Furthermore, UWF imaging detected predominantly peripheral lesions suggestive of more severe disease in 9.6% of patients. These peripheral lesions usually lie outside the field viewed by standard NMFP imaging and can indicate whether the patient's eye disease will progress, say the researchers.

Wider Testing Required

Although UWF imaging seems to offer advantages over standard screening, the one major drawback is the cost of the equipment.

However, the steep up-front costs of the camera may balance out over the long run, according to the authors, because the lower ungradable rate reduces the numbers, and consequently costs, of people referred for second eye exams.

The results therefore point to "substantial public-health benefit" that may result from using UWF imaging in telehealth programs, they add.

However, they acknowledge that the new technology requires testing in wider, more diverse populations.

To this end, a national comparison study run by the Diabetic Retinopathy Clinical Research Network is currently under way, with initial reporting expected in late 2016.

"If that study also shows that we can use this technology reliably, we expect this type of imaging will be used much more commonly," Dr. Aiello commented.

Standard Screening Pretty Good for Detecting Peripheral Lesions

Besides the issue of the cost of UWF, Dr. Johnson said another unanswered question concerns whether UWF does indeed have an advantage over standard screening in detecting retinopathy more peripherally.

In the current study, the number of people with clinically significant disease in need of treatment was relatively low.

Only about 10% of patients (7% of eyes imaged) had more severe disease based on detection of peripheral lesions with UWF imaging compared with NMDR, he pointed out.

"It's somewhat reassuring that standard nonmydriatic images are at least capturing these people and that what we're doing in most cases is still pretty good. That goes along with other literature that's been published," he concluded.

The study was supported in part by grant funding from the Massachusetts Lions Eye Research Fund to the Joslin Diabetes Center. Optos provided "temporary loan of two ultrawide field imaging devices to the Joslin Diabetes Center, but the devices were not used in this study." Dr Aiello reports financial support from Optos; the coauthors have no relevant financial relationships. Dr Johnson reports no relevant financial relationships.
Source: American Academy of Ophthalmology, march 2016
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