By Omar S. Punjabi, MD
The retina is the part of the eye that sends light and visual signals to the brain for processing.
Ophthalmologists and optometrists are trained to diagnose retinal diseases, and retina specialists have the important task of treating potentially blinding eye conditions such as age-related macular degeneration (AMD) and diabetic eye disease, among others. AMD and diabetic retinopathy are the two leading causes of blindness in the United States, affecting millions of people. Retinal imaging is a vital part of diagnosing these conditions, and ultra-widefield (UWF) retinal imaging is a newer technique that has rapidly gained popularity and clinical application among eye doctors. OptosTM is the most commonly used camera to obtain UWF retinal images, although some other techniques are available.
Conventional photography can only capture a small portion of the human retina (approximately 35%), and hence miss a lot of pathology that is not imaged. Clinical data reviewed over 3 years of UWF imaging research suggest that 66% of pathology occurs outside of the field of view of standard fundus photography. The presence of this pathology and its margins are better documented with UWF imaging. These images can easily be digitally transferred between physician offices and hence shared between doctors. The ability to obtain, and then readily share high-resolution digital images of 200? (82%) of the retina in a single, noncontact capture has changed the way retina specialists approach screening, diagnosis and treatment selection of retinal diseases, and has even influenced the definition and grading of retinal disease.
Multimodal UWF photography includes color photography, red free photography, autofluoresence, fluorescein angiography and indocyanine green (ICG) angiography. These techniques permits evaluation of vascular lesions as well as their associated pathology, providing complementary information useful in differentiating choroidal nevi from tumor, examining intrinsic tumor vasculature, and assessing related pathology.
There is evidence-based research regarding the clinical utility of UWF retinal photography and angiography.
A comparison of the fields of view of UWF photography, standard fundus photography and slit lamp photography. Note that the field of view of UWF photography is significantly wider than other imaging modalities.
Patients with diabetes mellitus have the potential to develop retinal disease after several years of uncontrolled blood sugars and blood pressure. Early diagnosis, categorization and management of diabetic retinopathy are critical in prevention of sight threatening complications, and can potentially save Medicare millions of dollars.
Research at the Joslin Diabetes Center in Boston showed that the presence of predominantly peripheral retinal lesions in diabetics is predictive of over a 3-fold faster progression of diabetic retinopathy and development of blinding complications over time. Because these lesions are outside the area of the retina that can be visualized with traditional fundus photography and angiography, it is important to use UWF imaging to examine the periphery to accurately assess the severity of DR and evaluate the likelihood of progression. The Diabetic Retinopathy Clinical Research Network (DRCR) is a National Institute of Health (NIH) funded organization of over 400 retina specialists (CEENTA has been an integral part of this network) that performs groundbreaking clinical trials involving diabetic eye disease and is researching this exact question. The DRCR is trying to determine if UWF fluorescein angiography helps predict progression of eyes with moderate disease.
UWF Fluorescein Angiography (OptosTM) of a patient with diabetic retinopathy showing several areas of poor blood supply and areas of retinal microaneurysms, hemorrhages and other vascular abnormalities in the right and left corners of the picture
Retinal Vein Occlusion (RVO)
RVO is a common cause of vision loss in patients with high blood pressure. Many of these cases have retinal ischemia or non-perfusion (poor blood supply). In some research studies, the amount of peripheral ischemia at baseline correlated with the final vision and treatment responsiveness. In these cases, UWF photography and angiography allows evaluation of retinal blood supply in peripheral retina, which provides important diagnostic and prognostic information. Response to treatment can also be evaluated.
UWF fundus photograghy (OptosTM) of an eye with a retinal detachment with a retinal tear (seen in the top left corner of the picture)
Uveitis is a condition that involves inflammation of the inside of the eye, and may include retinal vasculitis (inflammation of retinal blood vessels). Studies have confirmed that UWF color and fluorescein angiography imaging reveal pathology associated with noninfectious uveitis or vasculitis that would be missed on standard fundus photography and fluorescein angiography. The enhanced quality and resolution of UWF images, even in the presence of vitreous haze, is also an advantage.
Peripheral Vascular Abnormalities
For the detection and monitoring of disorders that principally affect the retinal periphery, many of which appear in infancy or childhood, UWF imaging is increasingly indispensable. The use of UWF fluorescein angiography enhances evaluation and can guide treatment of peripheral vascular abnormalities, including rare congenital disorders such as Coats disease, retinal hemangiomas and other vascular tumors, and retinopathy of prematurity (seen in premature babies). Because the Optos UWF systems obtain a high-resolution digital angiogram of the retinal periphery in a single, rapid, noncontact capture, they may be particularly helpful for assessing babies or young children who are difficult to image via conventional means.
UWF Fluorescein Angiography (OptosTM) of a patient with sickle cell anemia with proliferative retinopathy showing leakage from new blood vessels (in the left corner of the picture).
Systemic Diseases and the Eye
There is a fair amount of research that shows modest to strong associations between retinal vascular signs and cardiovascular disease, particularly heart failure and stroke. Correlations between retinal pathology and the risk for development or progression of systemic diseases are now being tested, but the ability to examine the retinal vasculature in high resolution with multimodal UWF imaging will improve our understanding of this association.
Potential for screening for retinal diseases without dilation of the pupil
The ability to image a large portion of the retina has allowed retinal imaging through an undilated pupil in less than 1 second using the OptosTM. This allows eye doctors to screen for diseases rapidly and easily.
Teaching tool for patients
Patients are fascinated to see detailed pictures of their actual retinas. This improves the patient’s “eye exam” experience. Patients listen intently as eye doctors describe anatomical features and clinical findings. Patients who have had retinal pathology identified are more motivated to adhere to treatment and follow-up instructions, even lifestyle changes.
Potential for Telemedicine
This technology is easy to use. Non-eye physicians, technicians and photographers can easily capture these scans. Since these images are transferable, these scans can be sent to an ophthalmologist or retina specialist, allowing an efficient and cost-effective method of telemedicine.
Charlotte Eye Ear Nose and Throat Associates (CEENTA) is the leading eye and ear practice in the greater Charlotte region with multiple offices. OptosTM UWF retinal imaging is available to CEENTA patients and has improved patient care significantly. As more novel treatment options and approaches for retinal disease become available, and our understanding of the prognostic value of peripheral pathology for both ophthalmic and systemic disease improves, the clinical rationale for incorporating multimodal UWF retinal imaging into screening, diagnosis, monitoring, and management will continue to expand. UWF retinal imaging will likely play an increasingly central role in our daily clinical practice, ensuring that we do not miss critical signs in the retinal periphery.