Diabetic retinopathy: The FP’s role in preserving vision

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doi:10.1038/nphys1170

Applied Evidence

Diabetic retinopathy: The FP’s role in preserving vision

J Fam Pract. 2020 April;69(3):120-126 | 10.1038/nphys1170

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References

1. National Diabetes Statistic Report 2020: Estimates of Diabetes and Its Burden in the United States. Atlanta, GA: US Department of Health and Human Services, Centers for Disease Control and Prevention. www.cdc.gov/diabetes/pdfs/data/statistics/national-diabetes-statistics-report.pdf. Accessed March 20, 2020.

2. Fitch K, Weisman T, Engel T, et al. Longitudinal commercial claims-based cost analysis of diabetic retinopathy screening patterns. Am Health Drug Benefits. 2015;8:300-308.

3. Centers for Disease Control and Prevention. Common eye disorders. September 29, 2015. www.cdc.gov/visionhealth/basics/ced/index.html. Accessed March 20, 2020.

4. American Academy of Ophthalmology PPP Retina/Vitreous Committee, Hoskins Center for Quality Eye Care. Diabetic Retinopathy PPP 2019. San Francisco, CA: American Academy of Ophthalmology. October 2019. https://www.aao.org/preferred-practice-pattern/diabetic-retinopathy-ppp. Accessed March 20, 2020.

5. Zhang X, Saaddine JB, Chou C-F, et al. Prevalence of diabetic retinopathy in the United States, 2005-2008. JAMA. 2010;304:649-656.

6. Stewart MW. Socioeconomic cost of diabetic retinopathy and therapy. In: Diabetic Retinopathy. Singapore: Adis; 2017:257-268.

7. Tarr JM, Kaul K, Chopra M, et al. Pathophysiology of diabetic retinopathy. ISRN Ophthalmol. 2013;2013:343560.

8. Wilkinson CP, Ferris FL 3rd, Klein RE, et al. Proposed International Clinical Diabetic Retinopathy and Diabetic Macular Edema Disease Severity Scales. Ophthalmology. 2003;110:1677-1682.

9. Wu L, Fernandez-Loaiza P, Sauma J, et al. Classification of diabetic retinopathy and diabetic macular edema. World J Diabetes. 2013;4:290-294.

10. American Academy of Ophthalmology. International Clinical Diabetic Retinopathy Disease Severity Scale detailed table. October 2002. http://www.icoph.org/downloads/Diabetic-Retinopathy-Detail.pdf. Accessed March 20, 2020.

11. Klein R, Klein BE, Moss SE, et al. The Wisconsin Epidemiologic Study of Diabetic Retinopathy. Arch Ophthalmol. 1984;102:527-532.

12. Klein R, Klein BE, Moss SE, et al. The Wisconsin Epidemiologic Study of Diabetic Retinopathy. Ten-year incidence and progression of diabetic retinopathy. Arch Ophthalmol. 1994;112:1217-1228.

13. Klein R, Knudtson MD, Lee KE, et al. The Wisconsin Epidemiologic Study of Diabetic Retinopathy XXII. The twenty-five-year progression of retinopathy in persons with type 1 diabetes. Ophthalmology. 2008;115:1859-1868.

14. Emanuele N, Sacks J, Klein R, et al. Ethnicity, race, and baseline retinopathy correlates in the Veterans Affairs Diabetes Trial. Diabetes Care. 2005;28:1954-1958.

15. Effect of pregnancy on microvascular complications in the diabetes control and complications trial. The Diabetes Control and Complications Trial Research Group. Diabetes Care. 2000;23:1084-1091.

16. Diabetes Control and Complications Trial Research Group; Nathan DM, Genuth S, Lachin J, et al. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med. 1993;329:977-986.

17. Mohamed Q, Gillies MC, Wong TY. Management of diabetic retinopathy: a systematic review. JAMA. 2007;298:902-916.

18. American Diabetes Association. Standards of Medical Care in Diabetes—2019 abridged for primary care providers. Clin Diabetes. 2019;37:11-34.

19. Do DV, Wang X, Vedula SS, et al. Blood pressure control for diabetic retinopathy. Cochrane Database Syst Rev. 2015;(1):CD006127.

20. UK Prospective Diabetes Study Group. Tight blood pressure control and risk of macrovascular and microvascular complications in type 2 diabetes: UKPDS 38. UK Prospective Diabetes Study Group. BMJ. 1998;317:703-713.

21. Colhoun HM, Betteridge DJ, Durrington PN; CARDS Investigators. Primary prevention of cardiovascular disease with atorvastatin in type 2 diabetes in the Collaborative Atorvastatin Diabetes Study (CARDS): multicentre randomised placebo-controlled trial. Lancet. 2004;364:685-696.

22. Chew EY, Davis MD, Danis RP, et al. Action to Control Cardiovascular Risk in Diabetes Eye Study Research Group. The effects of medical management on the progression of diabetic retinopathy in persons with type 2 diabetes: The Action to Control Cardiovascular Risk in Diabetes (ACCORD) Eye Study. Ophthalmology. 2014;121:2443-2451.

23. Fong DS, Aiello L, Gardner TW, et al American Diabetes Association. Retinopathy in diabetes. Diabetes Care. 2004;27(suppl 1):S84-S87.

24. 11. Microvascular complications and foot care: Standards of Medical Care in Diabetes—2019. Diabetes Care. 2019;42(suppl 1):S124-S138.

25. Moss SE, Klein R, Kessler SD, et al. Comparison between ophthalmoscopy and fundus photography in determining severity of diabetic retinopathy. Ophthalmology. 1985;92:62-67.

26. Kirkizlar E, Serban N, Sisson JA, et al. Evaluation of telemedicine for screening of diabetic Retinopathy in the Veterans Health Administration. Ophthalmology. 2013;120:2604-2610.

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30. Early photocoagulation for diabetic retinopathy. ETDRS Report Number 9. Early Treatment Diabetic Retinopathy Study Research Group. Ophthalmology. 1991;98(5 suppl):766-785.

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Proven primary prevention strategies

Glycemic control. Optimal glycemic control is an essential component of prevention of diabetic retinopathy. From 1983 to 1993, the Diabetes Control and Complications Trial randomized 1441 patients with type 1 DM to receive intensive therapy (median HbA1C level, 7.2%) or conventional therapy (median HbA1C level, 9.1%). During a mean of 6 years of follow-up, intensive therapy reduced the adjusted mean risk of retinopathy by 76% (95% CI, 62%-85%).^16,17 A 2007 systematic review of 44 studies of the treatment of diabetic retinopathy found that strict glycemic control was beneficial in reducing the incidence and progression of retinopathy.¹⁷

The American Diabetes Association’s Standards of Medical Care in Diabetes—2019 Abridged for Primary Care Providers recommends that most nonpregnant adults maintain an HbA1Clevel < 7%. For patients with a history of hypoglycemia, limited life expectancy, advanced microvascular or macrovascular disease, other significant comorbid conditions, or longstanding DM in which it is difficult to achieve the optimal goal, a higher HbA1clevel (< 8%) might be appropriate.¹⁸

Control of BP. Strict control of BP is a major modifier of the incidence and progression of diabetic retinopathy.^17,19In the United Kingdom Prospective Diabetes Study, 1148 patients with type 2 DM and a mean BP of 160/94 mm Hg at the onset of the study were randomly assigned to either (1) a “tight” blood pressure group (< 150/85 mm Hg) or (2) a “less-tight” group (< 180/105 mm Hg). The primary therapy for controlling BP was captopril or atenolol. After 9 years of follow-up, the tight-control group had a 34% mean reduction in risk in the percentage of patients with deterioration of retinopathy (99% CI, 11%-50%; P = .0004) and a 47% reduction in risk (99% CI, 7%-70%; P = .004) of deterioration in visual acuity.²⁰

Most patients with DM and hypertension should be treated to maintain a BP < 140/90 mm Hg. Although there is insufficient evidence to recommend a specific antihypertensive agent for preventing diabetic retinopathy, therapy should include agents from drug classes that have a demonstrated reduction in cardiovascular events in patients with DM. These include angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, thiazide diuretics, and dihydropyridine calcium channel blockers.¹⁸

Lipid management. The benefit of targeted therapy for lowering lipids for the prevention of diabetic retinopathy is not well established.¹⁷ In the Collaborative Atorvastatin Diabetes Study, 2838 patients with type 2 DM were randomized to atorvastatin (10 mg) or placebo; microvascular endpoint analysis demonstrated that patients taking atorvastatin needed less laser therapy (P = .14); however, progression of diabetic retinopathy was not reduced.²¹Similarly, in the Action to Control Cardiovascular Risk in Diabetes Eye Study, slowing of progression to retinopathy was observed in patients with type 2 DM who were treated with fenofibrate (ie, progression in 6.5%, compared with progression in 10.2% of untreated subjects [odds ratio = 0.60 (95% CI, 0.42-0.87); P = .0056]).²²

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