This compendium, “A Practical Guide to Diabetes-Related Eye Care,” follows a 2019 compendium titled “Prevention and Management of Diabetes-Related Eye Disease” (1). The first publication focused on the medical and ocular features of diabetes-related eye disease and its diagnosis and treatment. The current publication builds on that foundation to address pragmatic approaches to improving bidirectional communication between eye care professionals (ECPs) and primary and specialty diabetes health care professionals (HCPs) and reducing barriers to diabetes-related eye care.
In this compendium, we have chosen to use the term “diabetes-related retinal disease” (DRD) to reflect the involvement of the entire retina, including both vascular and neural elements. The principles set forth in the first compendium remain the basis for the clinical practice of ECPs when treating people with diabetes. Here, we describe the health status information ECPs need from HCPs, and the eye examination reports HCPs need from ECPs to improve diabetes and eye health outcomes for the patients they share. We also discuss the challenges of and opportunities to improve the detection and timely treatment of DRD in all people with diabetes, with a particular emphasis on individuals who are socioeconomically disadvantaged or face other significant impediments to obtaining recommended eye care services.
Vision loss from DRD is preventable, as was demonstrated in the Diabetes Control and Complications Trial (DCCT) and its ongoing follow-up Epidemiology of Diabetes Interventions and Complications (EDIC) study. After 18 years of follow-up, DRD categorized as mild nonproliferative disease or less was maintained without further progression in 68% of people in the DCCT's intensive therapy cohort and 49% of those in the conventional treatment cohort (2,3). Thus, the technical means to maintain good vision are available now. Analogous long-term benefits also persist for diabetes-related kidney disease (4). Nevertheless, DRD remains a leading cause of vision impairment and blindness worldwide (5), and, crucially, is a major concern of people with diabetes and their families.
The alarming increase in diabetes prevalence worldwide has resulted in large part from the growing prevalence of obesity, although prevalence rates of both type 1 diabetes and type 2 diabetes have increased, suggesting that other causes are also at play. The International Diabetes Federation (6) estimates that the total number of people with diabetes globally will increase from 536.6 million (10.5% of the world's population) in 2021 to 783.2 million by 2045. Approximately one in five people with diabetes worldwide have some degree of DRD—an estimated 103.12 million individuals—of whom ~28.5 million have vision-threatening DRD. The challenges presented by diabetes are illustrated by the fact that youth and young adults with the disease in the United States have mean A1C levels of 8.8% for those with type 1 diabetes and 8.6% for those type 2 diabetes (7). It is not surprising, then, that youth with type 1 or type 2 diabetes already have mild DRD, peripheral neuropathy, and nephropathy (8,9) and thus the predicate conditions for development of vision-threatening DRD in early adulthood.
The United Kingdom, Denmark, Sweden, Ireland, Thailand, and Iceland have uniform, government-funded screening and treatment programs. Because of the success of the United Kingdom program, DRD in 2010 ceased being the leading cause of blindness in working-age adults there (10). The United States does not yet have widespread DRD screening programs, but telemedicine initiatives are expanding, and one system that uses artificial intelligence to interpret diagnostic imaging has been approved by the U.S. Food and Drug Administration (11). The economic costs of DRD and diabetes-related macular edema (DME) are substantial for people with diabetes and their employers (12).
The ocular manifestations of diabetes are readily detected by standard ophthalmic exams conducted by optometrists and ophthalmologists and include primarily cataracts and DRD. The scopes of practice of ophthalmologists and optometrists overlap considerably. Ophthalmologists are physicians with M.D. (doctor of medicine) or D.O. (doctor of osteopathic medicine) credentials who have completed medical school, an internship, and a 3-year residency in ophthalmology. Slightly fewer than 500 physicians complete ophthalmology training per year in the United States (13), and about half of them complete additional fellowship training in specialty areas such as glaucoma, corneal diseases, and retinal diseases. Surgery is an intrinsic aspect of ophthalmology but not optometric training. Retinal specialists are ophthalmologists whose practice focuses on medical and surgical diseases of the retina and vitreous. They typically perform intravitreal (intraocular) injections of medications, laser surgery for retinal diseases, and vitrectomies to treat advanced DRD and retinal detachments. Optometrists, with O.D. (doctor of optometry) credentials, attend 4 years of optometry school after college. In 2017, ~400 of the 1,658 optometry school graduates also completed 1-year residencies (14,15). The scope of practice for ophthalmologists, including medical and surgical diagnosis and therapy, is uniform across the United States. The scope of practice of optometrists varies based on state legislation, with topical medication-prescribing privileges in all 50 states and anterior segment laser privileges in fewer than 10 states, with ongoing lobbying efforts to gain surgical privileges. Both optometrists and ophthalmologists provide DRD screening exams and treatment in the earliest stages of the disease. Although the guidelines of relevant professional organizations differ in specifics, all advise referral to an ophthalmologist knowledgeable in the management of DRD as the disease progresses (16–18).
Throughout this compendium, we review the practical aspects of diabetes-related eye screenings and DRD treatment and offer suggestions to facilitate successful collaboration between ECPs and HCPs.
In our first chapter, Blake A. Cooper, MD, MPH, explains how HCPs can prepare their patients for what to expect during DRD screenings. He details the 10 standard components of a complete eye exam and the information each one yields regarding a person's ocular and systemic health. This information will be of substantial value to HCPs who are unfamiliar with ophthalmic tests or the jargon used to describe their findings. Dr. Cooper describes the various diagnostic procedures people may undergo and what they might expect, such as blurry vision after pupil dilation or yellow urine after undergoing fluorescein angiography. He provides a succinct list of suggestions for people with diabetes to follow before, during, and after their eye exams.
Next, Sherrol A. Reynolds, OD, FAAO, reviews the information included in a typical ocular exam report and guides HCPs on how to interpret such findings in light of their patients' systemic health. Her chapter also includes several helpful tables. The first summarizes the reductions in rates of diabetes complications, including DRD, resulting from A1C lowering in the landmark DCCT/EDIC trial in type 1 diabetes (19) and UK Prospective Diabetes Study in type 2 diabetes (20). Additional tables summarize the signs and symptoms of and tests for various diabetes-related ocular conditions, describe the classification of DRD severity, and define terms commonly used in the context of diabetes-related eye care.
In our third chapter, Michael Huvard, MD, looks at communications in the opposite direction and how the information from HCPs' records can be interpreted by ECPs to guide diagnoses and treatment decisions. Specifically, he discusses the advantages of electronic medical record (EMR) systems to facilitate communication among the various professionals who care for people with multifaceted, chronic conditions such as diabetes. EMR systems can provide reminders for periodic screening exams, transmit information to both patients and other ECPs or HCPs via secure messaging, enable quantitative monitoring of care quality, and facilitate the collection and analysis of data for research to improve care. Dr. Huvard cites three important references (21–23) that emphasize the value of secure messaging, decision-support tools, and metrics of care available within EMR systems.
Finally, Anjali R. Shah, MD, and Rebecca A. Wu, MD, provide a thought-provoking discussion of disparities in rates of both DRD and diabetes-related eye screening. They describe existing disparities among racial/ethnic groups, including the higher diabetes prevalence rates among Blacks, Hispanics, and Native Americans and their higher rates of DME, proliferative diabetes-related retinal disease (PDR), and visual impairment. Moreover, they note that people living in distressed counties of the Appalachian “diabetes belt” (24) have substantially higher rates of both diabetes and DRD and that socioeconomically disadvantaged people are less likely to undergo recommended DRD screening and more likely to be unaware of their risk of DRD. Drs. Shah and Wu propose a focus on improving system-level factors, including expanding access to DRD screening through telemedicine. For now, however, the challenges of minimal reimbursement for remote disease detection and monitoring continue to limit widespread implementation of this beneficial technology.
Preparing People with Diabetes for DRD Treatment
In his chapter, Dr. Cooper provides tips for preparing people with diabetes for routine diabetes-related eye exams. Here, we add some brief information to help prepare people for ensuing DRD treatment, if needed.
Intraocular injection of anti-vascular endothelial growth factor (VEGF) drugs (i.e., bevacizumab, ranibizumab, and aflibercept) and corticosteroids is now the most common form of treatment for advanced DRD. People with this condition are understandably apprehensive about undergoing this therapy, but most tolerate it well once they learn what to expect. Thus, providing a clear explanation of the process can alleviate some of their fear and reluctance.
A person receiving intraocular injections is placed in a comfortable seated or reclining position, and the eye is anesthetized by installation of eyedrops (proparacaine) and topical or subconjunctival application of lidocaine or a similar agent. A povidone-iodine solution is applied, although soap solutions can be substituted for people with iodine allergies. Some ophthalmologists insert an eyelid speculum, and they may or may not wear sterile gloves. The person is asked to look to the side, and the very small needle (usually 30-gauge or smaller) is inserted, which may cause a brief pressure sensation but little pain. The medication injection lasts only a couple of seconds, and then the speculum is removed and saline solution is used to irrigate the eye. Most people do not receive topical antibiotics or need an eye patch. Rarely, a person's vision may temporarily dim if the intraocular pressure exceeds the retinal perfusion pressure. If vision does not recover within in a few minutes, aqueous fluid from the anterior chamber can be removed. Most people describe some irritation and blurred vision throughout the day of the procedure. The greatest risk of this procedure is endophthalmitis, which is quite rare, occurring with fewer than 1 in 1,000 injections.
Panretinal photocoagulation is also still used widely to treat PDR because it creates a more durable regression of neovascularization than does anti-VEGF therapy. The procedure requires pupil dilation. Topical or subconjunctival anesthesia usually suffices to minimize pain from the contact lens that focuses the laser light and the stimulation of ocular sensory nerves by the laser energy. However, a minority of people receiving this treatment require retrobulbar anesthetic injection or even systemic sedation for the procedure. Vision is often blurred for a day or two after the procedure.
Vitrectomy to remove blood and/or scar tissue in the eye can be very effective in restoring vision in people with PDR. This procedure takes place in an operating room under intravenous or general anesthesia, and patients wear an eye patch for a day or more and usually apply steroid and/or antibiotic eyedrops for about 2 weeks. Postoperative pain is usually mild.
We hope this compendium will facilitate better communication between ECPs and HCPs, improving both the quality of and their satisfaction with the care they provide and—most importantly—the eye health of people with diabetes.
Acknowledgments
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.
Author Contributions
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.
