Ultra-widefield imaging contributes to earlier disease detection
The management of diabetic retinopathy (DR) presents a formidable and growing challenge to the ophthalmic community. According to the U.S. Centers for Disease Control (CDC), more than 30 million Americans (9.4% of the U.S. population) are diabetic,1 a number that is predicted to rise by 54% to 54.9 million by 2030.2
As a result, DR and other diabetic eye diseases are projected to follow a similar trend.3 DR is a silent disease that can manifest initially with few if any symptoms. While 40 to 45% of Americans diagnosed with diabetes are affected, only about half of these patients are aware they have diabetic eye disease.4 Consequently, many go untreated for far too long, losing vision and in some cases, going blind. Thus, early detection particularly of those whose disease is most likely to progress, is critical for successful disease management. In my experience, the addition of ultra-widefield (UWF) imaging to screening and evaluation protocols offers advantages that improve our ability to diagnose earlier and treat more effectively
In recent decades, the standard for evaluating DR disease severity has been Early Treatment Diabetic Retinopathy Study (ETDRS) photography. These 35-mm colour images, comprised of 7 stereoscopic pairs of photographs per eye (ETDRS 7 standard fields), are assessed using the extended modified Airlie House classification system, which evaluates the location and degree of retinal lesions in the posterior pole.5 The ETDRS 7 standard fields includes the central posterior 90° of the retina, which equates to about 30% of the entire retina surface.
For years this has been the gold standard for identifying vascular pathology in DR. However, relying solely on this limited field of view means we risk missing a pathology present in the periphery that may contribute to the progression and outcome of the disease. DR studies have shown that pathology often exists outside the ETDRS 7 standard fields and in some cases, peripheral pathology is associated with greater disease severity and higher risk of disease progression.6–8
This has long been suspected, but recent research has begun to illuminate the role of peripheral pathology in early disease detection and determination of the risk of progression. Ischemia, which is an important factor in DR progression, may appear in the periphery first and has been associated with the presence of peripheral lesions on color images.9 One study found that predominantly peripheral lesions (PPLs) are present in up to 40% of patients with early nonproliferative diabetic retinopathy (NPDR) were linked to a nearly 5-fold DR progression over 4 years.10 Defining UWF imaging UWF images are defined as a single image capture that includes vortex ampullae in all four quadrants.11
Hundreds of published, peer-reviewed clinical studies have supported the value of the Optos 200° UWF based on its ability to improve screening for and identification of retinal disease. In addition to the clinical and diagnostic benefits, because these images can be captured in less than ½ a second and without dilation, routine use of the technology can contribute to practice efficiency by facilitating assessment and documentation and allowing more patients to be screened in less time. The images are easily annotated, stored and shared, serving as a useful resource for making treatment decisions and referrals when necessary. Other systems on the market capture varying degrees of the periphery using montaging techniques but they have not yet been widely adopted or validated versus gold-standard technologies.
UWF images also create a valuable tool for patient engagement and education. The ability to show patients the areas of concern or changes since a previous visit makes both their condition and your recommendations easier to explain and easier for the patient to understand. Seeing the damage to their retina first-hand may even encourage compliance with treatment recommendations or inspire behavior modification, such as taking steps to improve blood glucose control. UWF images equal to ETDRS While UWF imaging should not be considered a replacement for a dilated fundus exam, several published clinical studies have demonstrated its equivalence to ETDRS in the evaluation of DR severity.
Recently, a large, multicentre, cross-sectional observational study conducted by the Diabetic Retinopathy Clinical Research Network (DRCRnet) found moderate to substantial agreement between ETDRS and Optos 200 degree UWF images. Masked readers graded more than 700 subjects for DR level. When evaluated, the images agreed exactly in 435 eyes (59%) and were within one level in 96.9% (714 eyes).
Additionally, the results indicated that UWF images were better for assessing DR level in 27% of eyes than ETDRS. PPL were observed in 41% of these eyes and indicated increased DR severity by 2 steps or more in 11%. The authors concluded that these findings could support the use of UWF to evaluate DR severity in future clinical studies.12 UWF for telemedicine UWF has also begun to be evaluated for its use in telemedicine environments given the ease of use, seamless integration with EMR and value of additional information captured. When implemented in one large telemedicine system, UWF detected double the amount of DR, reduced ungradable rates by up to 81%, due to the ability to easily image through small pupils and media opacity.13 Another study in a diabetic screening program found in eyes without diabetic retinopathy, approximately 20% may have ocular findings identified on UWF imaging.14
In our own Cleveland Clinic Executive Health Clinic, UWF imaging detected peripheral pathology in 18.4% of eyes not visualised by traditional small field imaging in a population of health screening subjects.15
Conclusion
The body of research supporting the value of UWF imaging technology is considerable and continuously growing; as a result, UWF is fast becoming the standard of care for retinal vascular disorders, especially DR. In my practice, we rely heavily on both the clinical and practical advantages that this technology provides. Given the evidence and my experience, I believe that we have a responsibility to adopt technology that has the potential to detect disease earlier, treat it more effectively and ultimately, provide better care to more of our patients.