Individualised screening for diabetic retinopathy: the ISDR study-rationale, design and methodology for a randomised controlled trial comparing annual and individualised risk-based variable-interval screening

Artificial Intelligence-Based Screening System for Diabetic Retinopathy in Primary Care

BACKGROUND

This study aimed to test an artificial intelligence-based reading system (AIRS) capable of reading retinographies of type 2 diabetic (T2DM) patients and a predictive algorithm (DRPA) that predicts the risk of each patient with T2DM of developing diabetic retinopathy (DR).

METHODS

We tested the ability of the AIRS to read and classify 15,297 retinal photographs from our database of diabetics and 1200 retinal images taken with Messidor-2 into the different DR categories. We tested the DRPA in a sample of 40,129 T2DM patients. The results obtained by the AIRS and the DRPA were then compared with those provided by four retina specialists regarding sensitivity (S), specificity (SP), positive predictive value (PPV), negative predictive value (NPV), accuracy (ACC), and area under the curve (AUC).

RESULTS

The results of testing the AIRS for identifying referral DR (RDR) in our database were ACC = 98.6, S = 96.7, SP = 99.8, PPV = 99.0, NPV = 98.0, and AUC = 0.958, and in Messidor-2 were ACC = 96.78%, S = 94.64%, SP = 99.14%, PPV = 90.54%, NPV = 99.53%, and AUC = 0.918. The results of our DRPA when predicting the presence of any type of DR were ACC = 0.97, S = 0.89, SP = 0.98, PPV = 0.79, NPV = 0.98, and AUC = 0.92.

CONCLUSIONS

The AIRS performed well when reading and classifying the retinographies of T2DM patients with RDR. The DRPA performed well in predicting the absence of DR based on some clinical variables.

Referable Diabetic Retinopathy Prediction Algorithm Applied to a Population of 120,389 Type 2 Diabetics over 11 Years Follow-Up

(1) Background: Although DR screening is effective, one of its most significant problems is a lack of attendance. The aim of the present study was to demonstrate the effectiveness of our algorithm in predicting the development of any type of DR and referable DR. (2) Methods: A retrospective study with an 11-year follow-up of a population of 120,389 T2DM patients was undertaken. (3) Results: Applying the results of the algorithm showed an AUC of 0.93 (95% CI, 0.92-0.94) for any DR and 0.90 (95% CI, 0.89-0.91) for referable DR. Therefore, we achieved a promising level of agreement when applying our algorithm. (4) Conclusions: The algorithm is useful for predicting which patients may develop referable forms of DR and also any type of DR. This would allow a personalized screening plan to be drawn up for each patient.

Appropriate design and reporting of superiority, equivalence and non-inferiority clinical trials incorporating a benefit-risk assessment: the BRAINS study including expert workshop

Background

Randomised controlled trials are designed to assess the superiority, equivalence or non-inferiority of a new health technology, but which trial design should be used is not always obvious in practice. In particular, when using equivalence or non-inferiority designs, multiple outcomes of interest may be important for the success of a trial, despite the fact that usually only a single primary outcome is used to design the trial. Benefit-risk methods are used in the regulatory clinical trial setting to assess multiple outcomes and consider the trade-off of the benefits against the risks, but are not regularly implemented in publicly funded trials.

Objectives

The aim of the project is to aid the design of clinical trials with multiple outcomes of interest by defining when each trial design is appropriate to use and identifying when to use benefit-risk methods to assess outcome trade-offs (qualitatively or quantitatively) in a publicly funded trial setting.

Methods

A range of methods was used to elicit expert opinion to answer the project objectives, including a web-based survey of relevant researchers, a rapid review of current literature and a 2-day consensus workshop of experts (in 2019).

Results

We created a list of 19 factors to aid researchers in selecting the most appropriate trial design, containing the following overarching sections: population, intervention, comparator, outcomes, feasibility and perspectives. Six key reasons that indicate a benefit-risk method should be considered within a trial were identified: (1) when the success of the trial depends on more than one outcome; (2) when important outcomes within the trial are in competing directions (i.e. a health technology is better for one outcome, but worse for another); (3) to allow patient preferences to be included and directly influence trial results; (4) to provide transparency on subjective recommendations from a trial; (5) to provide consistency in the approach to presenting results from a trial; and (6) to synthesise multiple outcomes into a single metric. Further information was provided to support the use of benefit-risk methods in appropriate circumstances, including the following: methods identified from the review were collated into different groupings and described to aid the selection of a method; potential implementation of methods throughout the trial process were provided and discussed (with examples); and general considerations were described for those using benefit-risk methods. Finally, a checklist of five pieces of information that should be present when reporting benefit-risk methods was defined, with two additional items specifically for reporting the results.

Conclusions

These recommendations will assist research teams in selecting which trial design to use and deciding whether or not a benefit-risk method could be included to ensure research questions are answered appropriately. Additional information is provided to support consistent use and clear reporting of benefit-risk methods in the future. The recommendations can also be used by funding committees to confirm that appropriate considerations of the trial design have been made.

Limitations

This research was limited in scope and should be considered in conjunction with other trial design methodologies to assess appropriateness. In addition, further research is needed to provide concrete information about which benefit-risk methods are best to use in publicly funded trials, along with recommendations that are specific to each method.

Study registration

The rapid review is registered as PROSPERO CRD42019144882.

Funding

Funded by the Medical Research Council UK and the National Institute for Health and Care Research as part of the Medical Research Council-National Institute for Health and Care Research Methodology Research programme.

Development of an Instrument for the Assessment of Health-Related Multi-sectoral Resource Use in Europe: The PECUNIA RUM

BACKGROUND

Measuring objective resource-use quantities is important for generating valid cost estimates in economic evaluations. In the absence of acknowledged guidelines, measurement methods are often chosen based on practicality rather than methodological evidence. Furthermore, few resource-use measurement (RUM) instruments focus on the measurement of resource use in multiple societal sectors and their development process is rarely described. Thorn and colleagues proposed a stepwise approach to the development of RUM instruments, which has been used for developing cost questionnaires for specific trials. However, it remains unclear how this approach can be translated into practice and whether it is applicable to the development of generic self-reported RUM instruments and instruments measuring resource use in multiple sectors. This study provides a detailed description of the practical application of this stepwise approach to the development of a multi-sectoral RUM instrument developed within the ProgrammE in Costing, resource use measurement and outcome valuation for Use in multi-sectoral National and International health economic evaluAtions (PECUNIA) project.

METHODS

For the development of the PECUNIA RUM, the methodological approach was based on best practice guidelines. The process included six steps, including the definition of the instrument attributes, identification of cost-driving elements in each sector, review of methodological literature and development of a harmonized cross-sectorial approach, development of questionnaire modules and their subsequent harmonization.

RESULTS

The selected development approach was, overall, applicable to the development of the PECUNIA RUM. However, due to the complexity of the development of a multi-sectoral RUM instrument, additional steps such as establishing a uniform methodological basis, harmonization of questionnaire modules and involvement of a broader range of stakeholders (healthcare professionals, sector-specific experts, health economists) were needed.

CONCLUSION

This is the first study that transparently describes the development process of a generic multi-sectoral RUM instrument in health economics and provides insights into the methodological aspects and overall validity of its development process.

Thirty-Year Time Trends in Diabetic Retinopathy and Macular Edema in Youth With Type 1 Diabetes

OBJECTIVE

To examine trends in diabetic retinopathy (DR) and diabetic macular edema (DME) in adolescents with type 1 diabetes between 1990 and 2019.

RESEARCH DESIGN AND METHODS

We analyzed 5,487 complication assessments for 2,404 adolescents (52.7% female, aged 12-20 years, diabetes duration >5 years), stratified by three decades (1990-1999, 2000-2009, 2010-2019). DR and DME were graded according to the modified Airlie House classification from seven-field stereoscopic fundal photography.

RESULTS

Over three decades, the prevalence of DR was 40, 21, and 20% (P < 0.001) and DME 1.4, 0.5, and 0.9% (P = 0.13), respectively, for 1990-1999, 2000-2009, and 2010-2019. Continuous subcutaneous insulin infusion (CSII) use increased (0, 12, and 55%; P < 0.001); mean HbA1c was bimodal (8.7, 8.5, and 8.7%; P < 0.001), and the proportion of adolescents meeting target HbA1c <7% did not change significantly (8.3, 7.7, and 7.1%; P = 0.63). In multivariable generalized estimating equation analysis, DR was associated with 1-2 daily injections (odds ratio 1.88, 95% CI 1.42-2.48) and multiple injections in comparison with CSII (1.38, 1.09-1.74); older age (1.11, 1.07-1.15), higher HbA1c (1.19, 1.05-1.15), longer diabetes duration (1.15, 1.12-1.18), overweight/obesity (1.27, 1.08-1.49) and higher diastolic blood pressure SDS (1.11, 1.01-1.21). DME was associated with 1-2 daily injections (3.26, 1.72-6.19), longer diabetes duration (1.26, 1.12-1.41), higher diastolic blood pressure SDS (1.66, 1.22-2.27), higher HbA1c (1.28, 1.03-1.59), and elevated cholesterol (3.78, 1.84-7.76).

CONCLUSIONS

One in five adolescents with type 1 diabetes had DR in the last decade. These findings support contemporary guidelines for lower glycemic targets, increasing CSII use, and targeting modifiable risk factors including blood pressure, cholesterol, and overweight/obesity.

Real-world outcomes of a clinical decision support system for diabetic retinopathy in Spain

Objective

The aim of present study was to evaluate our clinical decision support system (CDSS) for predicting risk of diabetic retinopathy (DR). We selected randomly a real population of patients with type 2 diabetes (T2DM) who were attending our screening programme.

Methods and analysis

The sample size was 602 patients with T2DM randomly selected from those who attended the DR screening programme. The algorithm developed uses nine risk factors: current age, sex, body mass index (BMI), duration and treatment of diabetes mellitus (DM), arterial hypertension, Glicated hemoglobine (HbA1c), urine–albumin ratio and glomerular filtration.

Results

The mean current age of 67.03±10.91, and 272 were male (53.2%), and DM duration was 10.12±6.4 years, 222 had DR (35.8%). The CDSS was employed for 1 year. The prediction algorithm that the CDSS uses included nine risk factors: current age, sex, BMI, DM duration and treatment, arterial hypertension, HbA1c, urine–albumin ratio and glomerular filtration. The area under the curve (AUC) for predicting the presence of any DR achieved a value of 0.9884, the sensitivity of 98.21%, specificity of 99.21%, positive predictive value of 98.65%, negative predictive value of 98.95%, α error of 0.0079 and β error of 0.0179.

Conclusion

Our CDSS for predicting DR was successful when applied to a real population.

Validation of a Diagnostic Support System for Diabetic Retinopathy Based on Clinical Parameters

Purpose

To validate a clinical decision support system (CDSS) that estimates risk of diabetic retinopathy (DR) and to personalize screening protocols in type 2 diabetes mellitus (T2DM) patients.

Methods

We utilized a CDSS based on a fuzzy random forest, integrated by fuzzy decision trees with the following variables: current age, sex, arterial hypertension, diabetes duration and treatment, HbA1c, glomerular filtration rate, microalbuminuria, and body mass index. Validation was made using the electronic health records of a sample of 101,802 T2DM patients. Diagnosis was made by retinal photographs, according to EURODIAB guidelines and the International Diabetic Retinopathy Classification.

Results

The prevalence of DR was 19,759 patients (19.98%). Results yielded 16,593 (16.31%) true positives, 72,617 (71.33%) true negatives, 3165 (3.1%) false positives, and 9427 (9.26%) false negatives, with an accuracy of 0.876 (95% confidence interval [CI], 0.858–0.886), sensitivity of 84% (95% CI, 83.46–84.49), specificity of 88.5% (95% CI, 88.29–88.72), positive predictive value of 63.8% (95% CI, 63.18–64.35), negative predictive value of 95.8% (95% CI, 95.68–95.96), positive likelihood ratio of 7.30, and negative likelihood ratio of 0.18. The type 1 error was 0.115, and the type 2 error was 0.16.

Conclusions

We confirmed a good prediction rate for DR from a representative sample of T2DM in our population. Furthermore, the CDSS was able to offer an individualized screening protocol for each patient according to the calculated risk confidence value.

Translational Relevance

Results from this study will help to establish a novel strategy for personalizing screening for DR according to patient risk factors.

Factors associated with non-attendance in the Irish national diabetic retinopathy screening programme (INDEAR study report no. 2)

AIMS

We aimed to determine the patient and screening-level factors that are associated with non-attendance in the Irish National Diabetic Retinal screening programme (Diabetic RetinaScreen). To accomplish this, we modelled a selection of predictors derived from the historical screening records of patients with diabetes.

METHODS

In this cohort study, appointment data from the national diabetic retinopathy screening programme (RetinaScreen) were extracted and augmented using publicly available meteorological and geospatial data. A total of 653,969 appointments from 158,655 patients were included for analysis. Mixed-effects models (univariable and multivariable) were used to estimate the influence of several variables on non-attendance to screening appointments.

RESULTS

All variables considered for analysis were statistically significant. Variables of note, with meaningful effect, were age (OR: 1.23 per decade away from 70; 95% CI: [1.22-1.24]), type 2 diabetes (OR: 1.10; 95% CI: [1.06-1.14]) and socio-economic deprivation (OR: 1.12; 95% CI: [1.09-1.16]). A majority (52%) of missed appointments were from patients who had missed three or more appointments.

CONCLUSIONS

This study is the first to outline factors that are associated with non-attendance within the Irish national diabetic retinopathy screening service. In particular, when corrected for age and other factors, patients with type 2 diabetes had higher rates of non-attendance. Additionally, this is the first study of any diabetic screening programme to demonstrate that weather may influence attendance. This research provides unique insight to guide the implementation of an optimal and cost-effective intervention strategy to improve attendance.

Safety and cost-effectiveness of individualised screening for diabetic retinopathy: the ISDR open-label, equivalence RCT

AIMS/HYPOTHESIS

Using variable diabetic retinopathy screening intervals, informed by personal risk levels, offers improved engagement of people with diabetes and reallocation of resources to high-risk groups, while addressing the increasing prevalence of diabetes. However, safety data on extending screening intervals are minimal. The aim of this study was to evaluate the safety and cost-effectiveness of individualised, variable-interval, risk-based population screening compared with usual care, with wide-ranging input from individuals with diabetes.

METHODS

This was a two-arm, parallel-assignment, equivalence RCT (minimum 2 year follow-up) in individuals with diabetes aged 12 years or older registered with a single English screening programme. Participants were randomly allocated 1:1 at baseline to individualised screening at 6, 12 or 24 months for those at high, medium and low risk, respectively, as determined at each screening episode by a risk-calculation engine using local demographic, screening and clinical data, or to annual screening (control group). Screening staff and investigators were observer-masked to allocation and interval. Data were collected within the screening programme. The primary outcome was attendance (safety). A secondary safety outcome was the development of sight-threatening diabetic retinopathy. Cost-effectiveness was evaluated within a 2 year time horizon from National Health Service and societal perspectives.

RESULTS

A total of 4534 participants were randomised. After withdrawals, there were 2097 participants in the individualised screening arm and 2224 in the control arm. Attendance rates at first follow-up were equivalent between the two arms (individualised screening 83.6%; control arm 84.7%; difference -1.0 [95% CI -3.2, 1.2]), while sight-threatening diabetic retinopathy detection rates were non-inferior in the individualised screening arm (individualised screening 1.4%, control arm 1.7%; difference -0.3 [95% CI -1.1, 0.5]). Sensitivity analyses confirmed these findings. No important adverse events were observed. Mean differences in complete case quality-adjusted life-years (EuroQol Five-Dimension Questionnaire, Health Utilities Index Mark 3) did not significantly differ from zero; multiple imputation supported the dominance of individualised screening. Incremental cost savings per person with individualised screening were £17.34 (95% CI 17.02, 17.67) from the National Health Service perspective and £23.11 (95% CI 22.73, 23.53) from the societal perspective, representing a 21% reduction in overall programme costs. Overall, 43.2% fewer screening appointments were required in the individualised arm.

CONCLUSIONS/INTERPRETATION

Stakeholders involved in diabetes care can be reassured by this study, which is the largest ophthalmic RCT in diabetic retinopathy screening to date, that extended and individualised, variable-interval, risk-based screening is feasible and can be safely and cost-effectively introduced in established systematic programmes. Because of the 2 year time horizon of the trial and the long time frame of the disease, robust monitoring of attendance and retinopathy rates should be included in any future implementation.

TRIAL REGISTRATION

ISRCTN 87561257 FUNDING: The study was funded by the UK National Institute for Health Research. Graphical abstract.

Prevalence of diabetic retinopathy in children and adolescents at an urban tertiary eye care center

BACKGROUND

Diabetic retinopathy (DR) is a serious complication that can progress to sight-threatening disease. The prevalence of DR in youth with diabetes has been reported to be 3.8% to 20%.

OBJECTIVE

We aimed to evaluate the prevalence of DR among youth with diabetes at a large ophthalmologic referral center. Secondary goals were to determine the risk factors for DR and severity of disease.

METHODS

Retrospective chart review of 343 patients with diabetes, <21 years of age, seen at a tertiary referral eye care center from 2013 to 2018.

RESULTS

The study included 343 patients, of which 293 had type 1 diabetes (T1D) and 50 had type 2 diabetes (T2D). Thirteen of 343 patients had DR, with an overall incidence of 3.8% (3.4% in T1D and 6% T2D). DR severity included nine with mild non-proliferative, three moderate non-proliferative, and one with proliferative DR. Patients with hemoglobin A1c (HbA1c) > 8% had a higher risk of DR (P = .049). In this cohort, none of the patients with an HbA1c <8% had DR. In the multivariate analysis, a higher systolic blood pressure was marginally associated with risk for DR (P = .07).

CONCLUSIONS

We found lower prevalence of DR in youth with diabetes than previously reported. The incidence of DR was higher among patients with T2D and occurred with a shorter duration of disease, as compared with T1D. While the incidence of DR in youth with T1D is low, with the increasing incidence of T2D in adolescents and early risk for DR, early screening must be emphasized.

Adherence to eye examination guidelines among individuals with diabetes: An analysis of linked health data

IMPORTANCE

Screening for diabetic retinopathy for early detection and treatment can prevent vision loss.

BACKGROUND

We aimed to assess rates of eye examination of people with diabetes, adherence with national guidelines and investigate characteristics of those who do not adhere.

DESIGN

We used data from the 45 and Up Study, a cohort study of 267 153 randomly selected residents aged ≥45 years from New South Wales, Australia. Individual survey data collected in 2006 to 2009 were linked to corresponding national Medicare Benefits Schedule claims data for 2006 to 2016.

PARTICIPANTS

The study sample included 24 832 participants who reported having diabetes and at least 5 years of observation.

METHODS

Claims for visits to optometrists or ophthalmologists were assessed to estimate rates of eye examination. Poisson regression models were used to investigate factors associated with non-adherence.

MAIN OUTCOME MEASURE

Participants were classified as adherent if the average time between eye care claims was consistent with national guideline of having an eye exam every 2 years.

RESULTS

Of 50% to 75% people with diabetes met the biennial eye examination guidelines and only 21% to 28% with diabetes duration ≥10 years were adherent to the annual eye examination guideline. Characteristics associated with greatest (~1.3-fold) risk of non-adherence were smoking, age <60 years and higher income.

CONCLUSIONS AND RELEVANCE

There is a clear need to improve rates of adherence to eye examination guidelines among people with diabetes to reduce the personal and societal burden of diabetic retinopathy.

Ten-year incidence and assessment of safe screening intervals for diabetic retinopathy: the OPHDIAT study

BACKGROUND

To estimate the 10-year incidence of referable diabetic retinopathy (DR) in a French population with type 1 and 2 diabetes mellitus (DM). A secondary objective was the assessment of safe screening intervals in patients with diabetes without retinopathy.

METHODS

Observational, prospective and multicentric study between June 2004 and September 2017 based on a regional screening programme for DR in the Paris region. The incidence of referable DR in patients without retinopathy at baseline was calculated by the Turnbull survival estimator. A safe screening interval was defined as a 95% probability of remaining without referable DR.

RESULTS

Among the 25 745 participants with type 1 (n=6086) or type 2 (n=19 659) DM, the 10-year cumulative incidence of referable DR was 19.10% (95% CI 17.21% to 21.14%) and 17.03% (15.78% to 18.35%), median (IQR) follow-up=3.33 (4.24) years. The safe screening interval for patients without DR at the first examination for type 1 and 2 DM was 2.2 (95% CI 2.0 to 2.4) and 3.0 (2.9 to 3.1) years, respectively. In a subgroup of low-risk patients with type 2 DM, the safe screening interval was 4.2 (3.8 to 4.6) years.

CONCLUSIONS

These data suggest that in Paris area, a 2-year, 3-year and 4-year screening interval was considered safe for type 1 DM, type 2 DM and for low-risk patients with type 2 DM, respectively, without DR at the first examination. While these data might be used to support the consideration of extending screening intervals, a randomised clinical trial would be suitable to confirm the safety for patients with DM.

Personalising screening of sight-threatening diabetic retinopathy - qualitative evidence to inform effective implementation

BACKGROUND

Internationally, systematic screening for sight-threatening diabetic retinopathy (STDR) usually includes annual recall. Researchers and policy-makers support extending screening intervals, citing evidence from observational studies with low incidence rates. However, there is little research around the acceptability to people with diabetes (PWD) and health care professionals (HCP) about changing eye screening intervals.

METHODS

We conducted a qualitative study to explore issues surrounding acceptability and the barriers and enablers for changing from annual screening, using in-depth, semistructured interviews analysed using the constant comparative method. PWD were recruited from general practices and HCP from eye screening networks and related specialties in North West England using purposive sampling. Interviews were conducted prior to the commencement of and during a randomised controlled trial (RCT) comparing fixed annual with variable (6, 12 or 24 month) interval risk-based screening.

RESULTS

Thirty PWD and 21 HCP participants were interviewed prior to and 30 PWD during the parallel RCT. The data suggests that a move to variable screening intervals was generally acceptable in principle, though highlighted significant concerns and challenges to successful implementation. The current annual interval was recognised as unsustainable against a backdrop of increasing diabetes prevalence. There were important caveats attached to acceptability and a need for clear safeguards around: the safety and reliability of calculating screening intervals, capturing all PWD, referral into screening of PWD with diabetic changes regardless of planned interval. For PWD the 6-month interval was perceived positively as medical reassurance, and the 12-month seen as usual treatment. Concerns were expressed by many HCP and PWD that a 2-year interval was too lengthy and was risky for detecting STDR. There were also concerns about a negative effect upon PWD care and increasing non-attendance rates. Amongst PWD, there was considerable conflation and misunderstanding about different eye-related appointments within the health care system.

CONCLUSIONS

Implementing variable-interval screening into clinical practice is generally acceptable to PWD and HCP with important caveats, and misconceptions must be addressed. Clear safeguards against increasing non-attendance, loss of diabetes control and alternative referral pathways are required. For risk calculation systems to be safe, reliable monitoring and clear communication is required.

Screening for diabetic retinopathy: new perspectives and challenges

Although the prevalence of all stages of diabetic retinopathy has been declining since 1980 in populations with improved diabetes control, the crude prevalence of visual impairment and blindness caused by diabetic retinopathy worldwide increased between 1990 and 2015, largely because of the increasing prevalence of type 2 diabetes, particularly in low-income and middle-income countries. Screening for diabetic retinopathy is essential to detect referable cases that need timely full ophthalmic examination and treatment to avoid permanent visual loss. In the past few years, personalised screening intervals that take into account several risk factors have been proposed, with good cost-effectiveness ratios. However, resources for nationwide screening programmes are scarce in many countries. New technologies, such as scanning confocal ophthalmology with ultrawide field imaging and handheld mobile devices, teleophthalmology for remote grading, and artificial intelligence for automated detection and classification of diabetic retinopathy, are changing screening strategies and improving cost-effectiveness. Additionally, emerging evidence suggests that retinal imaging could be useful for identifying individuals at risk of cardiovascular disease or cognitive impairment, which could expand the role of diabetic retinopathy screening beyond the prevention of sight-threatening disease.

European Association for the Study of Diabetes 2019 Conference: Podcast Overview of the Conference

Podcast recording of Editorial Board Members Uazman Alam and Shazli Azmi live from the EASD 2019 conference in Barcelona (MP4 377292 kb).

Advances in the treatment of diabetic retinopathy

As the diabetes epidemic in the United States continues to worsen, so too does the prevalence of diabetic retinopathy (DR). DR is divided broadly into nonproliferative and proliferative stages, with or without vision-threatening macular edema. Progression to proliferative DR is associated with vision loss that is often irreparable, and a rapid decline in health-related quality of life. Vascular endothelial growth factor (VEGF)-A is upregulated in the diabetic eye, and has been identified as a key driver of DR pathogenesis. With this perspective, we review the published phase III clinical trial data of anti-VEGF therapies approved for the treatment of DR in the United States. Using the Early Treatment Diabetic Retinopathy Study Diabetic Retinopathy Severity Scale, in which an improvement of ≥2 steps is considered clinically significant, approximately one-third of patients with DR and macular edema experience this level of improvement after 1 year of treatment with either ranibizumab or aflibercept. The rates of clinically significant DR improvement with ranibizumab could be twice that in the subgroup of patients with moderately severe or severe nonproliferative DR and macular edema. These clinical trial data indicate that intraocular inhibition of VEGF is a rational approach for the management of DR.