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Healio
Issue: February 2014
ByPaolo Lanzetta, MD
February 01, 2014
4 min read
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Reducing the burden of diabetic retinopathy: Prevention, screening, multidisciplinary approach and effective therapies

Issue: February 2014
ByPaolo Lanzetta, MD

Diabetes affects almost 350 million individuals worldwide and is becoming the epidemic of the 21st century. Half of those affected are in the working age group of 40 to 59 years old. Type 2 diabetes involves 6% of the world’s adult population, with 80% of the total in developing countries. The World Health Organization projects that diabetes will be the seventh leading cause of death in 2030. By this date, the number of individuals with diabetes will reach 552 million, and the global health care cost will be almost $500 billion.

Diabetic retinopathy (DR) is a primary complication of diabetes and a significant cause of blindness. Although its prevalence may have ethnic variations, it is a worldwide condition and a major public health burden. According to the Wisconsin Epidemiologic Study of Diabetic Retinopathy and the U.S. National Eye Institute, the prevalence of DR and sight-threatening diabetic retinopathy are, respectively, 86% and 42% in type 1 diabetes and 40% and 8.2% in type 2 diabetes.

Diabetic macular edema is a vision-threatening manifestation of DR. Prevalence ranges from 0% to 3% in recently diagnosed subjects and increases to 28% to 29% in subjects who have had diabetes for at least 20 years.

Recently, the American Diabetes Association released a position statement on the standards of medical care for diabetes. Strategies include a multidisciplinary, team-based approach, timely and evidence-based treatment decisions, and an active role by patients in the management of their condition.

Paolo Lanzetta

Today, well-established actions for prevention, screening and treatment of DR have been identified, and all efforts should be made to delay the onset and progression of this devastating complication.

Prevention may represent an important cost-saving step in the management of both diabetes and DR. Simple actions such as body weight control (loss of 7% of body weight), physical activity (150 minutes per week of moderate activity such as walking), healthy diet and nonsmoking may prevent or delay the onset of type 2 diabetes and related complications. Metformin therapy may be considered in specific high-risk categories. Annual monitoring in subjects with prediabetes is recommended, as well as screening for and treatment of modifiable risk factors for cardiovascular diseases. Blood glucose control, blood pressure control and serum lipid control are also important measures that can delay the onset or progression of DR.

Hyperglycemia is widely known as the key modifiable risk factor for the development of DR. Lowering glycated hemoglobin below 7% can reduce the risk of developing or worsening microvascular complications such as DR. More or less stringent glycated hemoglobin levels may be considered in specific patients.

Early recognition, timely referral, and prompt and effective treatment are pivotal components of DR management. Appropriate screening programs should be a major goal of national health care systems, resulting in significant cost and disability saving. Individuals with type 1 diabetes should be screened for DR within 5 years from the onset of diabetes, whereas patients with type 2 diabetes should be evaluated at the time of diagnosis and re-examined annually. Less or more frequent visits can be considered in case of stable or progressing retinopathy. Women with pre-existing diabetes who are pregnant or planning pregnancy should receive an eye examination during the first trimester and regular follow-up during pregnancy and 1 year postpartum.

Currently, major improvements in screening technologies are available, which allow faster, objective and more effective campaigns. Telemedicine with retinal photography and remote reading may also increase efficiency, reduce costs and, in future years, allow self-monitoring of retinal status.

Historically, laser photocoagulation has been the primary intervention to treat both proliferative diabetic retinopathy and DME even though, after decades of use, the exact mechanism of action of thermal laser irradiation on the pathogenic cascade of DR is still mostly unknown. Although the role of laser photocoagulation is still pivotal in the treatment of the proliferative stages of DR, large randomized trials have shown the efficacy and superiority of pharmacologic intravitreal therapies with either anti-VEGF or steroid compounds in the management of DME. New hope also resides in less-invasive applications of laser irradiation, the so-called subthreshold therapies.

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New pharmacological treatments address pivotal steps in DR pathogenesis: overexpression on VEGF and inflammatory cytokines. Unlike focal or grid laser therapy, VEGF inhibitors can improve visual acuity and recover retinal morphology as evaluated by optical coherence tomography in a significant proportion of subjects. Lucentis (ranibizumab, Genentech/Novartis) is currently approved for the treatment of DME, Eylea (aflibercept, Regeneron/Bayer) has recently shown promising results in phase 2 and 3 studies, and Avastin (bevacizumab, Genentech/Roche) is frequently used off label. Intravitreal steroids have also been evaluated in the treatment of DME due to their anti-inflammatory and anti-VEGF properties. In the past, triamcinolone acetonide was extensively used off label. Sustained delivery systems releasing dexamethasone (Ozurdex, Allergan) in a biodegradable matrix or fluocinolone acetonide (Iluvien, Alimera Sciences) contained in a non-biodegradable tube have also been studied. Iluvien is currently available in some European countries for the treatment of chronic edema not responding to other therapies.

The availability of effective therapies that greatly exceed the outcomes of laser photocoagulation therapies imposes common actions for prevention and screening of DR. Resources should be promptly made available by national health care systems for both timely identification and treatment of the vision-threatening stages of the disease.

  • References:
  • American Diabetes Association. Diabetes Care. 2013;doi:10.2337/dc13-S011.
  • Boyer DS, et al. Ther Adv Endocrinol Metab. 2013;doi:10.1177/2042018813512360.
  • Chan WC, et al. Eye (Lond). 2004;doi:10.1038/sj.eye.6701340.
  • Danaei G, et al. Lancet. 2011;doi:10.1016/S0140-6736(11)60679-X.
  • The Eye Diseases Prevalence Research Group. Arch Ophthalmol. 2004;doi:10.1001/archopht.122.4.552.
  • Fong DS, et al. Diabetes Care. 2004;doi:10.2337/diacare.27.2007.S84.
  • Global data on visual impairments 2010. World Health Organization website. www.who.int/blindness/GLOBALDATAFINALforweb.pdf. Published 2012.
  • Global status report on noncommunicable diseases 2010. World Health Organization website. www.who.int/nmh/publications/ncd_report_full_en.pdf. Published 2011.
  • Klein R, et al. Ophthalmology. 1984;doi:10.1016/S0161-6420(84)34102-1.
  • Klein R, et al. Ophthalmology. 1995;doi:10.1016/S0161-6420(95)31052-4.
  • Roy MS, et al. Arch Ophthalmol. 2004;doi:10.1001/archopht.122.4.546.
  • Wan KHN, et al. Asia Pac J Ophthalmol. 2013;doi:10.1097/APO.0b013e31829df4a3.
  • Wong TY, et al. Lancet. 2008;doi:10.1016/S0140-6736(08)60343-8.
  • Zhang P, et al. Diabetes Res Clin Pract. 2010;doi:10.1016/j.diabres.2010.01.026.
  • For more information:
  • Paolo Lanzetta, MD, OSN Europe Edition Board Member, can be reached at University of Udine, Department of Ophthalmology, Piazzale S. Maria della Misericordia; 33100 Udine, Italy; +39-0432-559-905; fax: +39-0432-559-904; email: paolo.lanzetta@uniud.it.

Disclosure: Lanzetta serves as a consultant for Alcon, Allergan, Bausch + Lomb, Bayer, Novartis, Roche and Teva.