By Dr. Paul Chous
This represents the first such update by the American Diabetes Association since 2002, and is notable for inclusion of the latest evidence and recommendations with respect to appropriate eye examination intervals, referral criteria, prevention of incidence and progression of diabetic retinopathy (DR), and treatment strategies with respect to preventing vision loss from vision-threatening diabetes-related retinal disease – proliferative diabetic retinopathy (PDR) and diabetic macular edema (DME).
Diabetes remains the leading cause of severe vision loss and blindness in Americans of working age, and though improved metabolic control of diabetes and advances in therapy have significantly diminished the probability of poor vision outcomes for individual patients, the increased prevalence of diabetes (despite plateauing incidence) combined with improved longevity of patients serve to sustain the impact of DR on a population level. 
With respect to prevention of DR and vision loss, the Statement continues to emphasize the importance of good diabetes control (blood glucose, blood pressure and lipids), including the benefits of good, early glycemic control (protective metabolic memory) even in patients with T2DM (based on findings from ACCORD-Eye). It also emphasizes the emerging benefit of fenofibrate therapy to prevent progression of mild to moderate non-proliferative diabetic retinopathy (NPDR) in patients with T2DM (based on findings from two RCTs, FIELD and ACCORD-Eye). In fact, fenofibrate is approved as first-line therapy for adults with T2DM and NPDR in Australia; the number needed to treat to prevent one patient from requiring laser photocoagulation or intraocular injection of anti-vascular endothelial growth factor (anti-VEGF) agents is a mere fourteen (NNT =- 14) . Trials are now underway to see if such preventative therapy is effective in patients with T1DM.
What is not discussed in the section, understandably because it is an enormous topic, is the importance of preventing diabetes in the first place. The fundamental impact of the Diabetes Prevention Program (DPP) and similar efforts to prevent insulin resistance and the development of T2DM through lifestyle modification and other therapies deserves at least some consideration, in my view. Put simply – patients won’t lose vision to diabetes-related eye disease if they don’t develop diabetes in the first place.
Eye examination frequency recommendations for people with diabetes are notable for the caveat that patients with no retinopathy and good metabolic control may be considered for dilated eye examinations every two years, rather than annually as has always been the US standard of care. This makes good economic sense, based on low probability of incidence and progression in such patients.
I believe this recommendation should be tempered based on patient history of compliance with recommended eye examination intervals as well as metabolic control – and the fact that emerging imaging modalities (adaptive optics, optical coherence tomography angiography) are showing that many patients with no apparent DR with normal examination techniques (dilated ophthalmoscopy and/or standard fundus photography) do indeed have structural abnormalities that likely increase the risk of vision loss (see figure 1). As use of these technologies becomes more widespread and evidence accumulates, we may very well find that the definition of DR and appropriate examination frequency and interventional targets will necessarily change.
The most significant change with respect to treatment is the recognition of anti-VEGF agents as the ‘gold standard’ for diabetic macular edema (DME), the leading cause of vision loss due to diabetes. A number of clinical trials have demonstrated that serial injection of these agents reduces swelling of the macula and preserves/improves visual acuity better than traditional focal laser therapy for patients with DME. Recent evidence (DRCR.net Protocol S) has shown that anti-VEGF therapy is non-inferior to panretinal photocoagulation for proliferative retinopathy (PDR), and also results in better visual function (night and peripheral vision).
My only caveat about anti-VEGF therapy is that these agents are known to increase the risk of thromboembolism when used systemically, and that even though they are quite safe and effective for DME, there is at least some evidence that patients at high cardiovascular risk (especially those with a prior history of MI or stroke) are at increased risk with higher cumulative exposure (i.e. more intraocular injections).
In conjunction with the emphasis on anti-VEGF therapy for ‘center-involved’ DME (i.e. involving the center of the macula, the fovea) is recognition that optical coherence tomography (OCT) has become the standard for assessing DME and response to therapy. In fact, OCT is the most sensitive tool for detecting DME, and although not all cases of DME identified by OCT require treatment, patients with subclinical DME are far more likely to develop more severe edema and require more careful follow-up. The bottom line for me is that patients with diabetes are best served by eye doctors who have and routinely use OCT.
The Position Statement ends with consideration of retinal telescreening to identify patients with DR and, most importantly, sight-threatening DR (STR). There is no doubt that such technology provides access to patients in remote areas without high quality eye care, and is becoming more critical for efficient use of resources as the Worldwide population of persons with diabetes and DR burgeons.
These benefits must be tempered with the reality that patients are often better-served by face to face contact with knowledgeable and experienced eye care providers, both optometrists and ophthalmologists. There is, I believe, an educative effect of receiving in-person examination and counsel from live health care providers who can answer questions, discuss preventative strategies and treatment options even and especially in patients who do not have STR. Moreover, patients with diabetes are at increased risk for ocular complications other than DR, including cataracts, glaucoma, dry eye disease, and significant changes in eyeglass prescription that often signal poor blood glucose control. There are many reasons for every American, especially those with or at-risk for diabetes (more than half the U.S. adult population per NHANES analysis) , to receive regular eye care distinct from detection of STR.
Overall, this new Position Statement does a wonderful job of succinctly summarizing the most important epidemiological and clinical studies regarding diabetic retinopathy and updates to ever-changing clinical practice recommendations. Hopefully, this will improve the quality and frequency of interactions amongst diabetes patients, eye care providers, and other members of the diabetes care team towards preventing catastrophic outcomes of this all-too-frequent complication.
 Lee R, Wong TY, Sabanayagam C. Epidemiology of diabetic retinopathy, diabetic macular edema and related vision loss. Eye and Vision. 2015;2:17.
 Wright AD, Dodson PM. Medical management of diabetic retinopathy: fenofibrate and ACCORD Eye studies. Eye. 2011;25(7):843-849.
 Menke A, Casagrande S, Geiss L, Cowie CC. Prevalence of and Trends in Diabetes Among Adults in the United States, 1988-2012.JAMA. 2015 Sep 8;314(10):1021-9.
(Advisory Board Member) Dr. Paul Chous received his undergraduate education at Brown University and the University of California at Irvine, where he was elected to Phi Beta Kappa in 1985. He received his Master’s Degree in 1986 and his Doctorate of Optometry in 1991, both with highest honors from the University of California at Berkeley. Dr. Chous has practiced optometry with a special emphasis on diabetic eye disease and diabetes education for 20 years in the State of Washington, winning the American Diabetes Association’s Distinguished Public Service Award in 1998.
Paul Chous, M.A., O.D. See list of articles.