Diabetic retinopathy: The FP’s role in preserving vision

,

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

By

Bryan Farford, DO

Evaluation and Tx of this debilitating complication falls to the eye specialist, but you play a central role in assessing risk and optimizing prevention strategies.

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PRACTICE RECOMMENDATIONS

› Refer patients with type 1 diabetes mellitus (DM) to an ophthalmologist or optometrist for a dilated and comprehensive eye examination within 5 years of disease onset. B

› Refer patients with type 2 DM to an ophthalmologist or optometrist for an initial dilated and comprehensive eye examination at time of diagnosis. B

› Control blood pressure—ideally, < 140/90 mm Hg—in patients with DM to reduce the risk of diabetic retinopathy. A

Strength of recommendation (SOR)

A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series

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.

27. Ahmed J, Ward TP, Bursell S-E, et al. The sensitivity and specificity of nonmydriatic digital stereoscopic retinal imaging in detecting diabetic retinopathy. Diabetes Care. 2006;29:2205-2209.

28. Taylor CR, Merin LM, Salunga AM, et al. Improving diabetic retinopathy screening ratios using telemedicine-based digital retinal imaging technology: the Vine Hill study. Diabetes Care. 2007;30:574.

29. Diabetic Retinopathy Clinical Research Network, Wells JA, Glassman AR, Ayala AR, et al. Aflibercept, bevacizumab, or ranibizumab for diabetic macular edema. N Engl J Med. 2015;372:1193-1203.

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

31. Ferris F. Early photocoagulation in patients with either type I or type II diabetes. Trans Am Ophthalmol Soc. 1996;94:505-537.

As of 2015, an estimated 30.2 million adults in the United States—12.2% of the population— had diabetes mellitus (DM). During that year, approximately 1.5 million new cases (6.7 cases for every 1000 people) were diagnosed in adults (≥ 18 years of age).¹

As the number of people with DM increases, so will the number of cases of diabetic retinopathy, the main cause of new cases of blindness in adults in the United States² and the leading cause of blindness among US working-age (20 to 74 years) adults.³ It is estimated that 4.1 million Americans have diabetic retinopathy³; it is projected that prevalence will reach 6 million this year.⁴

Blindness related to DM costs the United States approximately $500 million each year,⁵ including health care utilization: physician office visits, diagnostic testing, medication and other treatments, and hospitalization.⁶Impairment of vision also results in social isolation, dependence on others to perform daily functions, and a decline in physical activity.

Several professional organizations, including the American Diabetes Association and the American Academy of Ophthalmology, have developed practice guidelines for diabetic retinopathy screening. Guidelines notwithstanding, only about 55% of people with DM in the United States receive the recommended dilated eye examination at established intervals.^2,3In addition to screening by an ophthalmologist or optometrist, adherence to clinical guidelines for risk assessment, prevention, and early referral helps reduce the incidence and severity of retinopathy.⁵

The Wisconsin Epidemiologic Study of Diabetic Retinopathy found that the prevalence of diabetic retinopathy varied from 28.8% in people who had diabetes mellitus (DM) for < 5 years to 77.8% in people who had DM for ≥ 15 years.

This article describes how to assess the risk of diabetic retinopathy in your patients, details the crucial role that you, the primary care physician, can play in prevention, and emphasizes the importance of referral to an eye specialist for screening, evaluation, treatment (when indicated), and follow-up.

Pathophysiology and classification

Diabetic retinopathy, the result of progressive blood vessel damage to the retina, has 2 major forms: nonproliferative and proliferative. Those forms are distinguished by the absence or presence of new growth of blood vessels (retinal neovascularization).^3,7 To improve communication and coordination among physicians who care for patients with DM worldwide, the International Clinical Diabetic Retinopathy Disease Severity Scale for diabetic retinopathy was developed,^8-10 comprising 5 levels of severity that are based on findings on dilated ophthalmoscopy (Table 1^8-10):

Level 1. No apparent retinopathy. Funduscopic abnormalities are absent.
Level 2. Mild nonproliferative diabetic retinopathy (NPDR). Only a few microaneurysms are seen.
Level 3: Moderate NPDR. Characterized by microaneurysms and by intraretinal hemorrhage and venous beading, but less severe than what is seen in Level 4.
Level 4. Severe NPDR. More than 20 intraretinal hemorrhages in each quadrant of the retina, definite venous beading in > 2 quadrants, intraretinal microvascular abnormalities in > 1 quadrant, or any combination of these findings.
Level 5. Proliferative diabetic retinopathy. Characterized by neovascularization of the disc, retina, iris, or angle; vitreous hemorrhage; retinal detachment; or any combination of these findings. Further classified as “mild,” “moderate,” or “severe” if macular edema is present; severity is dependent on the distance of thickening and exudates from the center of the macula.⁹

Be attentive to risk factors

There are several risk factors for diabetic retinopathy, including duration of disease, type 1 DM, male gender, black race (non-Hispanic), elevated hemoglobin A1C(HbA1C) level, elevated systolic and diastolic blood pressure (BP), and insulin therapy.^4,5,11,12

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