What is Diabetes Related Retinopathy?
The American Diabetes Association defines diabetes as; ”a group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both. The chronic hyperglycemia of diabetes is associated with long-term damage, dysfunction, and failure of different organs, especially the eyes, kidneys, nerves, heart, and blood vessels” 1. Type 1 diabetes accounts for 5-10 % of diagnosed cases and is characterized by “an absolute deficiency of insulin secretion” 1. Type 2 diabetes accounts for 90-95% of diagnosed cases and is described as “a combination of resistance to insulin action and an inadequate compensatory insulin secretory response” 1.
The Centers for Disease Control and Prevention (CDC) estimate that 29.1 million people in the United States (US) have diabetes (diagnosed and undiagnosed) 2. As a percentage of the US population experts predict that diagnosed and undiagnosed diabetes will burgeon to 21-33% by 2050 3.
To avoid diabetes complications (e.g. such as retinopathy), individual behavior/lifestyle and self-management changes are recommended. Without self-care the risk of diabetes complications increase reducing the quality of life for the individual and increase the reliance on health care resourses. In the United States this cost was estimated at $197 billion dollars in 2010 outranking all other reporting countries worldwide 4.
Self-care skills are challenging. A person diagnosed with diabetes must cope with a gauntlet of daily life style and behavior changes to sustain optimal clinical and quality of life outcomes (e.g., healthy food choices, being physically active, monitoring blood glucose, taking medications). These demands can be overwhelming to a person diagnosed with this truculent disease 5. One complication is vision loss due to diabetes related retinopathy (DRR).
Diabetes related retinopathy (DRR)
The eye functions as the biological equivalent to a camera. The image is focused on the rod and cone receptor cells of the retina which convert the image into digital/pixel like impulses that are carried via nerve cells to the occipital cortex of the brain for decoding. DRR occurs when the vascular infrastructure of the retina is compromised by a variety of mechanisms (e.g., hyperglycemia, diabetes duration, insulin use or high systolic blood pressure) 6. DRR resulting from leakage of blood from retinal capillaries is referred to as mild, severe or proliferative retinopathy. DRR resulting from swelling in the area of central vision is categorized as macular edema.
Initially visual symptoms of DRR may be absent or appear innocuous in its presentation. Left unmanaged these factors can reach a critical mass, which in turn initiate a domino like process impacting neuro-sensory function, vision loss and potential blindness if left untreated 7.
Standards of Care
The American Diabetes Association recommends an initial comprehensive eye exam after diagnosis and within five years of onset for type 2 and type 1 respectively. After an unspecified number of annual eye exams the time between exams may vary (e.g., shorter intervals if DRR is present or longer intervals if DRR is absent) 5. If the standards of care were followed by persons with diabetes it is estimated that vision loss as a result of DRR could be reduced by 90% 7.
Diabetes Related retinopathy and eye exams
Only 50-60% of persons with diabetes currently have comprehensive dilated eye exams to check for DRR 8. It is also estimated that “one missed attendance at a retinal screening appointment is associated with a threefold increase in needing laser photocoagulation subsequently” 9. Explanations for this low figure can vary. Studies in the United Kingdom have found that socio-economic factors are only one of a varied number of variables that contribute to routine eye cadre for DDR 10. In the US these other factors include: a) no perceived need, b) cost/lack of insurance, c) lack of transportation, d) lack of eye care providers or appointment times, e) depression, f) insulin use, g) lack of diabetes education and h) (lack of) yearly foot examinations 11-14. [Interventions to increase DRR screening]
Incidence of Diabetes related retinopathy in USA
For persons over the age of 40 years old with diabetes the incidence of any DRR and sight threatening DRR is estimated to be 28.5% and 4.4% respectively 6. The National Eye Institute predicts that from 2010 to 2050 the rate of DRR in the US will increase from 7.7 million to 14.6 million individuals 15.
Independent risk factors for Diabetes related retinopathy
Although DRR is present in higher percentages of Black and Hispanic vs white populations, race is not a significant risk indicator of DRR 6,16. Both studies found longer duration of diabetes and hyperglycemia were significant independent risk factors for DRR. Other independent risk factors for DRR were a greater waist-hip ratio and a higher systolic blood pressure 16,20.
individual, health and Economic costs to the Community
In the US DRR is the leading cause of blindness of working adults between the ages of 20-74 years CDC, 17. The annual financial cost in the US as a result of DRR and related blindness is estimated at $500 million annually 6. A retrospective cohort study of individual direct/indirect health benefit costs and work sick days estimated the added annual cost of DRR between $6.5 - $8.3 thousand and 3.77-4.87 sick days more per capita then with diabetes alone respectively 18. The Office of Disease Prevention and Health Promotion has set a goal of increasing comprehensive eye examinations with dilation within a two year period (objective V-4.0) and decreasing vision impairment due to DRR (objective V-5.3) by 10% as a goal as part of Healthy People 2020 19.
Zhang et al. in a literature search of interventions centering on DRR found “Increasing patient awareness of diabetic retinopathy, improving provider and practice performance, and improving healthcare system infrastructure and processes, can significantly increase screening for diabetic retinopathy” 20. Accordingly, health education programs to achieve optimal success may be quite varied. Interventions include using language and culturally appropriate community educational awareness campaigns that emphasize the need of yearly eye exam/screening to detect and treat DRR. Other strategies use campaigns that target multidisciplinary healthcare professionals and diabetes patients. They emphasize the importance of health care physicians of different specialties partnering with each other and the person with diabetes to communicate the need for yearly screening/exams for diabetes. Still other strategies have employed multifaceted interventions with the community that reduce the barrier(s) of time, forgetting appointments, travel distance, lack of access to eye care. To lower such barriers, mobile clinics and trained community/health care personnel have been used to take retinal images that are read at remote locations for signs of DRR. Multiple educational screening/point of care interventions that include DRR screening, foot checks, healthy eating / increased activity have been employed to reduce barriers and emphasize the importance of multiple diabetes self-management habits.
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