Diabetic retinopathy is the number one cause of blindness in people 20-74 years of age, and healthcare professionals can decrease the risk of blindness in about two thirds of these patients if diagnosed and treated in the early stages. The National Committee for Quality Assurance states that only 40% of the diabetic population are screened for diabetic retinopathy using traditional screening methods.
In addition to the inadequate screening methods for diabetic retinopathy, the ratio of eyecare professionals to diabetic patients is shockingly disproportionate. According to the American Optometric Association, as of 2015 there were an estimated 30 million adults with diabetes within the U.S. The incidence of diabetes in the U.S. is increasing at roughly 1.4 million cases per year, with only an average of 2000 eyecare professionals emerging each year. These rates suggest that we will need at least one eyecare provider for every 700 diabetic patients to screen and evaluate for vision-threatening diabetic retinopathy!
Screening methods aren’t reaching enough of the diabetic population, and now there aren’t enough eyecare professionals available to fill in the gaps. How can we meet these future demands and properly manage such a large volume of diabetic patients? This course will emphasize how diagnostic imaging can efficiently assist eyecare providers in staging diabetic retinopathy for better management, and how telemedicine screenings can increase accessibility to care and make detection of diabetic retinopathy earlier.
Reviewing the Stages and Management of Diabetic Retinopathy
It’s important to recognize the stages of retinopathy in order to determine an appropriate follow-up and treatment plan. Diabetic retinopathy falls into two main classes: nonproliferative and proliferative, the latter having a greater potential for serious visual consequences. Decades of clinical research from major studies including the Diabetic Retinopathy Study (DRS) and the Early Treatment Diabetic Retinopathy Study (ETDRS) has led to the development of a severity scale and management plan for diabetic retinopathy, which is summarized in the American Academy of Ophthalmology’s Preferred Practice Pattern (Figure 1 & 2).
Diabetic Retinopathy Disease Severity Scale and International Clinical Diabetic Retinopathy Disease Severity Scale
|Disease Severity Level||Findings Observable upon Dilated Ophthalmoscopy|
|No apparent retinopathy||No abnormalities|
|Mild NPDR (see Glossary)||Microaneurysms only|
|Moderate NPDR (see Glossary)||More than just microaneurysms but less than severe NPDR|
|Severe NPDR (U.S. definition)||Any of the following (4-2-1 rule) and no signs of proliferative retinopathy:
|Severe NPDR (International definition)|| Any of the following and no signs of proliferative retinopathy:
|PDR||One or both of the following:
IRMA = intraretinal microvascular abnormalities; NPDR = nonproliferative diabetic retinopathy; PDR = proliferative diabetic retinopathy
Figure 1. Severity scale of diabetic retinopathy found in AAO’s Preferred Practice Pattern for Diabetic Retinopathy. Further information can be found on Table 1, pages 81-82.
Remember that diabetic macular edema may be present at any severity level of nonproliferative or proliferative retinopathy, and if untreated, can also increase the risk of vision loss.
Initial Management Recommendations for Patients with Diabetes
|Severity of Retinopathy||Presence of Macular Edema||Follow-up (Months)||Panretinal Photocoagulation (Scatter) Laser||Focal and/or Grid Laser||Intravitreal Anti-VEGF Therapy|
|Normal or minimal NPDR||No||12||No||No||No|
Anti-VEGF = anti-vascular endothelial growth factor; CI-DME =center-involved diabetic macular edema; NCI-DME= noncenter-involved diabetic macular edema; NPDR =nonproliferative diabetic retinopathy; PDR =proliferative diabetic retinopathy
Figure 2. Retinip. Further information can be found on Table 5, page 90.
Widefield and Ultra Widefield Fundus Imaging
Widefield and Ultra Widefield CLARUS fundus imaging can detect mid-peripheral and peripheral retinopathy lesions. What’s the difference between the two imaging techniques?
Figure 3: Image courtesy of Carolyn Majcher, OD, FAAO and Munish Sharma, MD, OD, MBA, FAAO.
Widefield imaging (shown on the left) reaches up to the vortex vein ampullae in one shot, obtaining 133 degrees in diameter of retinal views. Ultra-widefield imaging(shown on the right) reaches at least four vortex vein ampullae, covering a diameter of 200 degrees. These images can be montaged to demonstrate up to 80% of the retinal surface in one image.
OCT-A Angioplex Montage
OCT Angiography (OCT-A)evaluates retinal vascularity and capillary function. The high image quality provides fine detail of the vasculature and is a great non-invasive alternative to fluorescein angiography. Also, areas of neovascularization and nonperfusion are identified easily with OCT-A when compared to standard fundus photography.
Patients with diabetic retinopathy often show early signs of nonperfusion within the mid-periphery and periphery of the retina. Individual 8x8mm cube scans of the OCT-A can be combined into a 14x14mm OCT Angioplex montage (Figure 4) to identify areas of retinal nonperfusion further into the periphery of all four quadrants. Areas of nonperfusion indicate an increased risk of developing proliferative diabetic retinopathy, therefore these patients would likely benefit from early treatment with PRP or anti-VEGF injections.
Figure 4: Example of an OCT-A Angioplex 14x14mm montage (five 8mm cube scans) showing areas of nonperfusion in the mid-periphery in all four quadrants that could be missed on standard posterior pole photography. Image courtesy of Carolyn Majcher, OD, FAAO.
Figure 5: Another example of a patient with peripheral nonperfusion that puts them at high risk for developing proliferative diabetic retinopathy. Patients in this scenario tend to benefit from early treatment with PRP and/or anti-VEGF therapy to prevent progression. Image courtesy of Carolyn Majcher, OD, FAAO.
Figure 6: This image shows the difference between mature, involuted neovascularization along the superior arcades versus active, growing neovascularization along the inferior arcades. Active neovascularization appears as leaves on tree branches, while old neovascularization appears as long naked branches. Image courtesy of Carolyn Majcher, OD, FAAO.
The OCT-A offers vitreoretinal interface imaging which is specifically designed to show areas of pre-retinal neovascularization around the optic disc. OCT-A imaging can also identify enlarged foveal avascular zones which can explain the level of central vision loss diabetic patients may experience from retinopathy, even if there is an absence of macular edema or thinning on a regular macular OCT scan.
OCT Macular and Optic Nerve Cube Scan
OCT scans are an excellent way to monitor the status of the posterior hyaloid and retinal changes for progression over time. Early changes to the vitreous or retinal structures may indicate a higher risk for a tractional retinal detachment. High resolution OCT scans can even highlight subtle vitreous hemorrhaging that may not be observed on normal fundoscopy.
Figure 7. The macular OCT scan on the left shows a V-shaped vitreoretinal traction without complications. Two months later, the updated scan on the right shows a vitreous hemorrhage that is decreasing the quality of the scan, and a pocket of subretinal fluid underneath the area of vitreoretinal traction. This patient would now benefit from a referral to a retina specialist for further management and close monitoring. Image courtesy of Carolyn Majcher, OD, FAAO.
Macular cube OCT scans are also used to detect macular edema and changes to the retinal tissue thickness. The high resolution images with a 21 line raster can highlight cystic pockets of fluid, suggesting a risk for retinal detachment.
Increasing Accessibility to Care with Telemedicine
Another approach to tackling the increasing volume of diabetic patients is telemedicine. The future requires decentralizing diabetic retinopathy screening methods to smaller optometric practices across the nation to reach more eyecare professionals. In addition to that, offline cameras for imaging should be available in other healthcare settings where diabetic patients are managed, such as family doctors and endocrinologists. This way, all healthcare providers can efficiently contribute to the patient’s care.
Current telemedicine programs involve imaging of diabetic patients at their primary care physician or endocrinologist’s office. The images are then interpreted by an optometrist who determines whether the patient can be monitored or referred for further treatment. This method increases the number of diabetic patients that have access to optometric care. This also provides an opportunity to converse with the patient on the importance of an eye examination for diabetic management.
Implementing Imaging in the Management of Diabetic Retinopathy
Patient Case Example #1
- 29yo American Indian male
- CC: Routine DM exam, wants glasses
- OHx: Severe NPDR OU dx 5 yrs ago
- MHx: DM Type 2 dx 20 yrs ago, last HbA1c 8.2%. Two toes amputated due to DM ulcer
- BCVA OS: 20/30-1
Ultra Widefield CLARUS imaging of the left eye shows neovascularization elsewhere along the superior temporal arcade and extensive hemorrhaging within the periphery of the retina.
Figure 8: Image courtesy of Carolyn Majcher, OD, FAAO.
OCT Angiography imaging shows large regions of nonperfusion which are not easily detected with standard fundus photography. Areas of neovascularization are well defined within the arcades, as well as around the optic disc.
Figure 9: Image courtesy of Carolyn Majcher, OD, FAAO.
Looking at the macular OCT scans, we can see an absence of macular edema. So why is the patient experiencing decreased vision if the macular tissue appears fairly intact? OCT-A imaging revealed the contour of the foveal avascular zone being much larger than a normal, healthy patient. So the reason for decreased vision in this patient’s left eye is likely due to having an enlarged foveal avascular zone secondary to macular ischemia.