The prevalence of diabetes is expanding at an alarming rate. More than 133 million Americans are now living with diabetes or prediabetes—an increase of 11 million in the past 2 years (28). More concerning is that millions of these individuals are unaware of their diabetes or prediabetes status (28).
Given the sharp increase in diabetes, it is expected that the prevalence of diabetes-related eye disease— diabetes-related retinal disease (DRD) as well as glaucoma, cataracts, and other ocular disorders—will also continue to rise. DRD and its associated pathology, including diabetes-related macular edema (DME), is the leading cause of visual impairment and vision loss in adults between the ages of 20 and 74 years (16,18). DRD affects >7 million Americans, and the National Eye Institute projects an increase to >11 million people by 2030 (29).
Preventing or delaying the onset and slowing the progression of DRD is the goal of all eye care professionals (ECPs) and other health care professionals (HCPs) who participate in the care of people with diabetes. A crucial component of successfully meeting this goal is communication between ECPs and other diabetes HCPs to properly coordinate care. This chapter explains how to interpret eye examination reports for people with diabetes and reviews the latest information regarding diagnostic technologies, patient education, treatments, and telemedicine-based DRD screening. This information is necessary to facilitate collaborative care among ECPs and HCPs and ensure the best outcomes for their shared patients with diabetes.
Diabetes-Related Eye Disease Risks
It is estimated that ≥20% of people with diabetes first learn of their diabetes status through an eye exam (30). Thus, a diabetes-related eye exam record should include information about the person's diabetes status, ethnicity, age, duration of diabetes if present, and modifiable risk factors. These risk factors include the “ABCs of diabetes” (A1C, Blood pressure, Cholesterol, and Smoking status), as well as BMI/obesity status and nutritional concerns.
As observed in major diabetes clinical trials (19,20,31), lowering A1C to ≤7% is key to reducing the risk or slowing the progression of DRD and other diabetes complications (Table 1). Small reductions add up; even a 1% reduction in A1C can reduce microvascular and macrovascular complications. In addition, for people with diabetes who use continuous glucose monitoring (CGM), time in range and related CGM-derived parameters (32) should also be noted during eye exams.
Comorbidities such as hypertension and dyslipidemia should be addressed (33). The benefits of blood pressure and lipid-lowering medications in slowing the progression of DRD have been established for people with type 2 diabetes in clinical trials such as the FIELD (Fenofibrate Intervention and Event) study (34) and the ACCORD (Action to Control Cardiovascular Risk in Diabetes) Eye study (35).
Additionally, eye examination records should include information about medication use—particularly diabetes medications—to assess medication-taking consistency and engagement with the diabetes treatment plan.
Timing of Diabetes-Related Eye Exams
All people with diabetes should have regular dilated retinal exams to identify the presence of any diabetes-related eye diseases and ensure prompt treatment if they develop. However, many people with diabetes are unaware that they have the disease, making it unlikely that they will receive these exams. Additionally, many people with significant vision-threatening DRD remain asymptomatic and may therefore be unaware that they are even at risk for serious ocular complications. According to one recent study (36), ~60% of Americans with diabetes do not receive eye exams as recommended. For this reason, it is crucial for all diabetes care professionals to consistently reinforce the importance of getting regular dilated retinal exams.
A diabetes-related eye exam report will include symptoms that might indicate undiagnosed diabetes, including refractive changes, early-onset cataracts (especially posterior subcapsular cataracts), ocular surface disease (i.e., dry eyes), and other diabetes-related findings (Table 2).
As mentioned earlier in this compendium (p. 4), people with type 2 diabetes should have an initial dilated retinal exam near the time of diagnosis and generally annually thereafter. By the time a person is diagnosed with type 2 diabetes, the disease often has been present for several years; indeed, 33% of individuals who are newly diagnosed will already have some degree of DRD (37). The screening interval can be extended to 2 or 3 years in individuals with type 2 diabetes who reliably follow up, whose diabetes is well controlled, and who have had a normal dilated retinal exam previously (38). Individuals with DRD may require more frequent follow-up, depending on its severity.
DRD can progress rapidly during pregnancy. Therefore, all women with type 1 or type 2 diabetes who become pregnant should have a dilated retinal exam in the first trimester of pregnancy, with additional monitoring every trimester and for 1 year postpartum as indicated by the degree of DRD present.
Eye Exam Reports: What HCPs Need to Know
After a diabetes-related eye exam, the ECP should share a report with the person's HCP. This report will include information about the person's stage of DRD (Table 3) (39) and presence of DME, if applicable; a summary of retinal imaging results, telemedicine screening, and/ or other diagnostic tests; and treatment and follow-up recommendations, including the need for referral to a retinal specialist, if appropriate. Table 4 defines some of the common abbreviations ECPs often use in reporting findings of diabetes-related eye exams.
Retinal fundus photography (Figure 1) is considered the gold standard for DRD imaging, and recent advances in imaging technologies have significantly improved the ability to detect and treat DRD and maculopathy. Ultra-widefield imaging (Figure 2) provides a larger field of view, allowing ECPs to see more of the retina and detect peripheral changes, which in turn facilitates early detection of DRD and enhances patient education regarding the importance of screening and follow-up care.
The American Diabetes Association recognizes the potential of HCP clinic–based retinal photography with remote (telemedicine) review and interpretation by eye care experts as a way to overcome barriers to screening services in locations where qualified ECPs are not readily available (16). However, in-person exams are still necessary if retinal photos are of unacceptable quality and for follow-up if abnormalities are detected. Retinal photos are not a substitute for dilated comprehensive eye exams, which should be performed at least initially and at intervals thereafter as recommended by an ECP (16). U.S. Food and Drug Administration-approved artificial intelligence systems that detect more than mild DRD and DME are an alternative to traditional screening approaches. However, their benefits and optimal use have not yet been determined (16,40).
Optical coherence tomography (OCT) (Figure 3) has dramatically improved early detection and care of DRD and maculopathy. OCT allows for the early identification and management of DME. Based on OCT, DME is categorized as center-involved or non–center-involved. Center-involved DME is characterized by loss of foveal contour, cystoid macular edema involving the center of the fovea, neuro-sensory detachment involving the center of the fovea, and increased central subfield thickness. Non–center-involved DME is characterized by retinal thickening and/or cystic spaces not directly involving the center of the macula.
OCT angiography (OCTA) (Figure 4) is another modern imaging test that can detect other vascular anomalies such as vascular loops, tortuosity, and dilations of the vessels, as well as intraretinal microvascular abnormalities and superficial neovascularization. It also detects diabetes-related macular ischemia, with clinical signs of paramacular areas of capillary nonperfusion, impairment of the choriocapillaris flow, and enlargement of the foveal avascular zone (FAZ). Abnormalities in the structure or perfusion of the FAZ not only result in vision impairment, but also signify a poor prognosis because the condition cannot be treated.
Next Steps: What to Do After the Eye Exam
All people with severe nonproliferative diabetes-related retinal disease (NPDR), proliferative diabetes-related retinal disease (PDR), or DME should be referred to an ophthalmologist experienced in the management of DRD—even those with 20/20 vision and no visual complaints (16–18). Anti-vascular endothelial growth factor (VEGF) medications are the first-line treatment for most people with center-involved DME and PDR (41,42). In some cases of persistent edema after three to six injections, the retinal specialist may elect to switch anti-VEGF agents, add laser therapy, or initiate steroid treatment. For individuals with non–center-involved DME, the specialist may start treatment with focal laser therapy or anti-VEGF agents or decide on further observation if the vision is not compromised.
Reports of diabetes-related eye exams are an essential component of interprofessional communication between ECPs and HCPs who share patients with diabetes or prediabetes. These reports can be handwritten notes, forms developed and completed via an electronic medical record system, or based on templates obtained from various resources such as professional organizations. In addition to merely reporting their findings, ECPs should use these reports to alert HCPs if additional care such as a referral to a retinal specialist is warranted. Even when people have no notable ocular manifestations of diabetes upon examination, the ECP should still share a report to that effect in a timely manner.
Confronting the emerging epidemic of DRD and ensuring better ocular outcomes requires collaboration from all ECPs and HCPs involved in the care of people with diabetes. Bidirectional interprofessional communication is particularly important, and both ECPs and HCPs should be aware of their shared patients' overall medical status, individualized glycemic targets, and evolving eye health. Effective team care and ongoing communication can decrease the risk of sight-threating DRD, reduce systemic complications, improve clinical outcomes, and enhance quality of life for people with diabetes.
Editorial and project management services were provided by Debbie Kendall of Kendall Editorial in Richmond, VA.
Dualities of Interest
B.A.C. is a consultant for Genentech and Regeneron. S.A.R. is a speaker for Allergan, Inc., and VSP Vision Care. No other potential conflicts of interest relevant to this compendium were reported.
All authors researched and wrote their respective sections. Lead author T.W.G. reviewed all content and is the guarantor of this work.
The opinions expressed are those of the authors and do not necessarily reflect those of VSP Vision Care, Regeneron, or the American Diabetes Association. The content was developed by the authors and does not represent the policy or position of the American Diabetes Association, any of its boards or committees, or any of its journals or their editors or editorial boards.