Review: Diabetic Retinopathy

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The VEHSS team conducted a review of published literature on examination-based population studies reporting the prevalence of diabetic retinopathy (DR).

Diabetic retinopathy (DR) occurs when high blood sugar damages the blood vessels below the retina. There are two primary types of DR: non-proliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR).(AOA, 2015)  With NPDR, the blood vessels of the retina leak, causing the macula to swell.(AOA, 2015)  There are three stages of NPDR: mild, moderate, and severe. Mild NPDR refers to the early stages where blood vessels begin to swell and leak.(NEI, 2015) In moderate cases of NPDR, blood vessels continue to swell and become unable to transport blood. NPDR is considered severe when the retina becomes oxygen deprived and signals growth factors to form new blood vessels.(NEI, 2015) In PDR, new blood vessels form, but are weak and prone to leakage. Scar tissue forms which may lead to retinal detachment and blindness).(AOA, 2015)  Nerve damage can also occur with diabetic retinopathy. Diabetic macular edema (DME) is the swelling of the macula and can occur at any stage. The term vision-threatening DR (VTDR) is defined as the presence of severe NPDR, proliferative DR, or clinically significant macular edema (CSME).(Wong T.Y., 2013)

In 1968, a group of experts developed a grading system for DR called the Arlie House Classification of DR.(Wu L, 2013) The system grades stereo photographs and classifies DR in 13 levels: level 10 indicates no retinopathy and level 85 signifies retinal detachment or severe vitreous hemorrhage. This system was modified in the Early Treatment of Diabetic Retinopathy Study (ETDRS). The term CSME was introduced by the ETDRS and refers to a specific form of DME. It was defined as the “(1) thickening of the retina at or within 500 μm of the center of the macula; or (2) hard exudate at or within 500 μm of the center of the macula associated with thickening of adjacent retina; or (3) a zone of retinal thickening 1 disc area or larger, any part of which is within 1 disc diameter of the center of the macula.”(Wu L, 2013)

Diabetic Retinopathy Literature Review Results

There were 18 studies conducted between 1992 and 2016 that examined the prevalence of diabetic retinopathy (DR). These studies examined a variety of demographics including race/ethnicity, age, sex, income, and education level. Various stages of DR were examined including mild, moderate, and severe NPDR, DME, and vision threatening DR (VTDR)

Table 1. Diabetic Retinopathy Prevalence Sources

Table 1. DR Prevalence Sources
Author Date of Publication Title Date of Data Collection Data Source Sample Size Prevalence Data Stratified by: Stage of AMD
Varma R, Wen G, et al. 2016 Prevalence of Diabetic Retinopathy in Adult Chinese American Individuals: The Chinese American Eye Study 2010-2013 The Chinese American Eye Study 665 Age, Sex, Race Any, Mild NPDR, Moderate NPDR, Severe NPDR, PDR
Kovarik JJ, Eller AW, et al. 2016 Prevalence of Undiagnosed Diabetic Retinopathy Among Inpatients with Diabetes: the Diabetic Retinopathy Inpatient Study 2011-2012 DRIPS 113 Not stratified by demographic variables Any, Mild NPDR, Moderate NPDR, Severe NPDR, PDR
Rodriguez N, Aguilar, S 2016 Prevalence of Diabetic Retinopathy in a Clinic Population from Puerto Rico 2001-2009 Retrospective Chart Review 411 Age, Sex Mild NPDR, Moderate NPDR, Severe NPDR, PDR
Park D, Mansberger SL, et al. 2016 Eye Disease in Patients with Diabetes Screened with Telemedicine 2006–2009 Telemedicine Screening Program 424 Not stratified by demographic variables Any, Mild NPDR, Moderate NPDR, Severe NPDR, PDR
Zhang X, Cotch MF, et al.  2012 Vision Health Disparities in the United States by Race/Ethnicity, Education, and Economic Status: Findings from Two Nationally Representative Surveys 2005–2008; 1988–1994 NHANES 2005-2008, NAHNES III 5,704; 8,208 Race/Ethnicity Any
Maa AY, Evans C, et al. 2013 Veteran Eye Disease after Eligibility Reform: Prevalence and Characteristics January 2008–February 2008 Atlanta VA Medical Center Chart Review 658 Not stratified by demographic variables NPDR, PDR
Zhang X, Saadine J, et al. 2010 Prevalence of Diabetic Retinopathy in the United States, 2005-2008 2005–2008 2005-2008 NHANES 1,006 Age, Sex, Race/Ethnicity Any, VTDR
Lim A, Stewart J, Chui TY, et al. 2008 Prevalence and Risk Factors of Diabetic Retinopathy in a Multi-Racial Underserved Population 2004–2006 SFGH Eye Van 1,073 Race/Ethnicity Any, Mild, Moderate, Severe
Wong TY, Klein R, Islam FM, et al. 2006 Diabetic Retinopathy in a Multi-Ethnic Cohort in the United States 2000–2002 MESA 778 Race/Ethnicity Any, Minimal, Early-moderate, Severe-proliferate, VTDR
 Mansberger SL, Romero FC, et al.  2005  Causes of Visual Impairment and Common Eye Problems in Northwest American Indians And Alaska Natives  Unknown  Northwest AIAN  288  Race  NPDR, PDR
 Varma R, Torres M, Pena F, et al.  2004  Prevalence of Diabetic Retinopathy in Adult Latinos: The Los Angeles Latino Eye Study  2000–2008  LALES   1,217   Age, Sex, Race/Ethnicity Any, Mild NPDR, Moderate NPDR, Severe NPDR, PDR
 Kempen JH, O’Colmain BJ, Leske MC, et al.  2004  The Prevalence of Diabetic Retinopathy Among Adults in the United States  1985–1998  EDPRG  N/A  Age, Race/Ethnicity, Sex  Any, VTDR
 Roy MS, Klein R, O’Colmain BJ, et al.  2004  The Prevalence of Diabetic Retinopathy Among Adult Type 1 Diabetic Persons in the United States 1980–1982, 1993–1998  WESDR, New Jersey 725  594, 790  Sex, Age, Race  Any, VTDR
Lee PP, Feldman ZW, Ostermann J, et al. 2003 Longitudinal Prevalence of Major Eye Diseases 1999 National Long-Term Care Survey Various Not stratified by demographic variables Any DR, PDR
West SK, Klein R, et al.  2001  Diabetes and Diabetic Retinopathy in a Mexican-American Population  1997–1999  Proyecto VER  1,044  Not stratified by demographic variables  Any, Moderate NPDR Severe NPDR, PDR
Harris MI, Klein R, Cowie CC, et al. 1998  Is the risk of Diabetic Retinopathy Greater in Non-Hispanic Blacks and Mexican Americans than in Non-Hispanic Whites with Type 2 Diabetes? A U.S. Population Study.  1988–1994  NHANES III Various  Race/Ethnicty  Any, Mild NPDR, Moderate NPDR, PDR
Haronian E, Wheeler NC, et al. 1993  Prevalence of Eye Disorders Among the Elderly in Los Angeles  1982–1990  UCLA MEC 431  Age, Sex  Any
Klein R, Klein B 1992  Epidemiology of Proliferative Diabetic Retinopathy  1980–1982  WESDR 2,366  Age, Sex  PDR

Overall Diabetic Retinopathy Prevalence Rates

Figure 1 below shows diabetic retinopathy (DR) prevalence rates from 11 of the selected studies that reported an overall rate.  The high degree of variation among the results in this figure is likely due to in part to methodological, disease definition and population differences among the studies. This figure excludes studies that did not report an overall rate for the study.  The figure is intended to illustrate the range of published prevalence values; direct comparison of the studies is impossible without considering the underlying differences in the studies. Detailed results from each individual study are available in the full report “Published Examination-based Prevalence of Major Eye Disorders.”

Most studies determined the prevalence of DR from a study sample of diabetic individuals (Figure 1), while some reported the prevalence rates among a general population including individuals with and without diabetes (Figure 2). The studies described throughout this section compared DR prevalence rates across race/ethnicity, age, education level, and income. Variation among these studies could be a result of the different distributions of sociodemographic characteristics among the study samples as well as differences in the prevalence of diabetes. Further, three of the studies reported estimates that were adjusted to a national standard.

Figure 1.  Overall Prevalence Rates of  Diabetic Retinopathy Among Populations with Diabetes.

Tables displays an approximate percentage for each of the following categories: Telemedicine Screening Program: 25%26#37;. CHES: 35%26#37;. DRIPS: 45%26#37;. Retrospective Chart Review: 38%26#37;. VA Chart review: 3%26#37;. NHANES 4%26#37;. SFGH Eye Van: 15%26#37;. MESA: 33%26#37;. AIAN Vision Impairment Study: 6%26#37;. LALES: 46%26#37;. EDPRG: 40%26#37;. National Long-Term Care Suvey: 17%26#37;. Proyecto VER: 47%26#37;. UCLA MEC: 2%26#37;.

*Age- or population- adjusted prevalence rate

Figure 2. Overall Prevalence Rates of Diabetic Retinopathy (not restricted to persons with diabetes).

Overall prevalence rates of diabetic retinopathy (not restricted to persons with diabetes) chart

*Age- or population- adjusted prevalence rate