A four-year follow-up study on the incidence of diabetic retinopathy in older onset diabetes mellitus

Incidence and progression of diabetic retinopathy: a systematic review

Diabetic retinopathy is a leading cause of vision impairment and blindness. We systematically reviewed studies published from Jan 1, 1980, to Jan 7, 2018, assessed the methodological quality, and described variations in incidence of diabetic retinopathy by region with a focus on population-based studies that were conducted after 2000 (n=8, including two unpublished studies). Of these eight studies, five were from Asia, and one each from the North America, Caribbean, and sub-Saharan Africa. The annual incidence of diabetic retinopathy ranged from 2·2% to 12·7% and progression from 3·4% to 12·3%. Progression to proliferative diabetic retinopathy was higher in individuals with mild disease compared with those with no disease at baseline. Our Review suggests that more high-quality population-based studies capturing data on the incidence and progression of diabetic retinopathy with stratification by age and sex are needed to consolidate the evidence base. Our data is useful for conceptualisation and development of major public health strategies such as screening programmes for diabetic retinopathy.

One-Hour Plasma Glucose Compared With Two-Hour Plasma Glucose in Relation to Diabetic Retinopathy in American Indians

OBJECTIVE

We compared the ability of 1- and 2-h plasma glucose concentrations (1h-PG and 2h-PG, respectively), derived from a 75-g oral glucose tolerance test (OGTT), to predict retinopathy. 1h-PG and 2h-PG concentrations, measured in a longitudinal study of an American Indian community in the southwestern U.S., a population at high risk for type 2 diabetes, were analyzed to assess the usefulness of the 1h-PG to identify risk of diabetic retinopathy (DR).

RESEARCH DESIGN AND METHODS

Cross-sectional (n = 2,895) and longitudinal (n = 1,703) cohorts were assessed for the prevalence and incidence of DR, respectively, in relation to deciles of 1h-PG and 2h-PG concentrations. Areas under the receiver operating characteristic (ROC) curves for 1h-PG and 2h-PG were compared with regard to predicting DR, as assessed by direct ophthalmoscopy.

RESULTS

Prevalence and incidence of DR, based on direct ophthalmoscopy, changed in a similar manner across the distributions of 1h-PG and 2h-PG concentrations. ROC analysis showed that 1h-PG and 2h-PG were of similar value in identifying prevalent and incident DR using direct ophthalmoscopy. 1h-PG cut points of 230 and 173 mg/dL were comparable to 2h-PG cut points of 200 mg/dL (type 2 diabetes) and 140 mg/dL (impaired glucose tolerance), respectively.

CONCLUSIONS

1h-PG is a useful predictor of retinopathy risk, has a predictive value similar to that of 2h-PG, and may be considered as an alternative glucose time point during an OGTT.

Ophthalmic and clinical factors that predict four-year development and worsening of diabetic retinopathy in type 1 diabetes

AIMS

To investigate the role of ophthalmic imaging markers - namely retinal thickness measures and corneal nerve morphology - in predicting four-year development and worsening of diabetic retinopathy (DR) in type 1 diabetes (T1DM).

METHODS

126 eyes of 126 participants with T1DM were examined at baseline and after four years. Diabetic retinopathy (DR) was graded using the Early Treatment Diabetic Retinopathy Study scale. HbA_1c, nephropathy, neuropathy, cardiovascular factors, and retinal thickness using optical coherence tomography (OCT) and corneal nerve fiber length (CNFL) using corneal confocal microscopy at baseline were assessed by univariate and step-wise multiple logistic regression, and their diagnostic capabilities for single and combined measures.

RESULTS

Four-year development of DR was 19% (13 of 68 without DR at baseline). Worsening of DR was seen in 43% (25 of 58 with DR at baseline). When adjusted for potential confounders, a lower CNFL (AUC=0.637, p=0.040, 64% sensitivity and 64% specificity at 14.9mm/mm² cut-off), higher triglycerides (AUC=0.669, p=0.012, 64% sensitivity, 62% specificity at 0.85mmol/L) and an elevated vibration threshold (AUC=0.708, p=0.002, 96% sensitivity, 40% specificity at 3.55Hz) were significant predictors for four-year worsening of DR.

CONCLUSIONS

Reduced CNFL, elevated vibration perception threshold and higher triglycerides can predict future worsening of DR.

Diabetic Retinopathy in Patients with Diabetic Nephropathy: Development and Progression

The purpose of current study aims to investigate the development and progression of diabetic retinopathy (DR) in patients with diabetic nephropathy (DN) in a nationwide population-based cohort in Taiwan. Newly diagnosed DN patients and age- and sex-matched controls were identified from the Taiwanese Longitudinal Health Insurance Database from 2000 to 2010. We studied the effects of age, sex, hypertension, dyslipidemia, diabetic polyneuropathy (DPN), and medications on the development of nonproliferative DR (NPDR), proliferative DR (PDR), and diabetic macular edema (DME) in patients with DN. Cox proportional hazard regression analyses were used to estimate the adjusted hazard ratios (HRs) of the development of DR. Our results show that the adjusted HRs of NPDR and PDR were 5.01 (95% confidence interval (CI) = 4.68-5.37) and 9.7 (95% CI = 8.15-11.5), respectively, in patients with DN as compared with patients in the non-DN cohort. At 5-year follow-up, patients with DN showed an increased HR of NPDR progression to PDR (HR = 2.26, 95% CI = 1.68-3.03), and the major comorbidities were hypertension (HR = 1.23, 95% CI = 1.10-1.38 with NPDR; HR = 1.33, 95% CI = 1.02-1.72 with PDR) and DPN (HR = 2.03, 95% CI = 1.72-2.41 in NPDR; HR = 2.95, 95% CI = 2.16-4.03 in PDR). Dyslipidemia increased the HR of developing NPDR but not PDR or DME. Moreover, DN did not significantly affect DME development (HR = 1.47, 95% CI = 0.87-2.48) or progression (HR = 0.37, 95% CI = 0.11-1.20). We concluded that DN was an independent risk factor for DR development and progression; however, DN did not markedly affect DME development in this study, and the potential association between these disorders requires further investigation.

Circulating Biomarkers of Diabetic Retinopathy: An Overview Based on Physiopathology

Diabetic retinopathy (DR) is the main cause of working-age adult-onset blindness. The currently available treatments for DR are applicable only at advanced stages of the disease and are associated with significant adverse effects. In early stages of DR the only therapeutic strategy that physicians can offer is a tight control of the risk factors for DR. Therefore, new pharmacological treatments for these early stages of the disease are required. In order to develop therapeutic strategies for early stages of DR new diagnostic tools are urgently needed. In this regard, circulating biomarkers could be useful to detect early disease, to identify those diabetic patients most prone to progressive worsening who ought to be followed up more often and who could obtain the most benefit from these therapies, and to monitor the effectiveness of new drugs for DR before more advanced DR stages have been reached. Research of biomarkers for DR has been mainly based on the pathogenic mechanism involved in the development of DR (i.e., AGEs, oxidative stress, endothelial dysfunction, inflammation, and proangiogenic factors). This review focuses on circulating biomarkers at both early and advanced stages that could be relevant for the prediction or detection of DR.

Genetics in diabetic retinopathy: current concepts and new insights

There is emerging evidence which indicates the essential role of genetic factors in the development of diabetic retinopathy (DR). In this regard it should be highlighted that genetic factors account for 25-50% of the risk of developing DR. Therefore, the use of genetic analysis to identify those diabetic patients most prone to developing DR might be useful in designing a more individualized treatment. In this regard, there are three main research strategies: candidate gene studies, linkage studies and Genome-Wide Association Studies (GWAS). In the candidate gene approach, several genes encoding proteins closely related to DR development have been analyzed. The linkage studies analyze shared alleles among family members with DR under the assumption that these predispose to a more aggressive development of DR. Finally, Genome-Wide Association Studies (GWAS) are a new tool involving a massive evaluation of single nucleotide polymorphisms (SNP) in large samples. In this review the available information using these three methodologies is critically analyzed. A genetic approach in order to identify new candidates in the pathogenesis of DR would permit us to design more targeted therapeutic strategies in order to decrease this devastating complication of diabetes. Basic researchers, ophthalmologists, diabetologists and geneticists should work together in order to gain new insights into this issue.

Incidence of diabetic retinopathy in a Hong Kong Chinese population

BACKGROUND

The aim was to examine the progression and regression of diabetic retinopathy within a four-year period in a Chinese population with type 2 diabetes mellitus in a community optometry clinic in Hong Kong.

METHODS

During the period May 2005 to November 2009, 5,160 patients with type 2 diabetes mellitus who had attended at least two diabetic retinopathy screening sessions at a community optometry clinic were included as subjects in this study. All had retinal photographs taken of both eyes, which were of sufficiently good quality for grading. For the purpose of this study, diabetic retinopathy grading was based on the results of the worst eye. The main outcomes were the within four-year incidence of diabetic retinopathy and the incidence of progression and regression of diabetic retinopathy.

RESULTS

Of the 5,160 subjects in this study, 3,647 had no diabetic retinopathy, while 1,513 had diabetic retinopathy at the baseline visit. Of those 3,647 subjects with no diabetic retinopathy, the within four-year cumulative incidence of any diabetic retinopathy, mild or moderate non-proliferative diabetic retinopathy and sight-threatening diabetic retinopathy was 15.16 per cent, 14.45 per cent, 0.69 per cent and 0.03 per cent, respectively. Of those 1,513 subjects with diabetic retinopathy at baseline, the within four-year progression incidence of diabetic retinopathy was 6.61 per cent and the regression incidence of diabetic retinopathy was 45.54 per cent.

CONCLUSION

The high regression incidence of diabetic retinopathy suggests that it might not be necessary for all patients with diabetes to be screened annually. Other methods to determine the screening frequency for an individual patient should be explored.

Probability based approach for predicting the course of disease in diabetic retinopathy patients

The number of Diabetes patients has risen in both the developing and the developed nations. It is associated with lot complications retinopathy, nephropathy, neuropathy etc. Diabetic retinopathy is one of the leading causes of preventable blindness. Diabetic patients have to be monitored at regular intervals to detect any signs of retinopathy and deterioration of vision and timely intervention. This requires lot of time and cost both on the part of the patient and the specialist. Therefore there is a need to differentiate the ‘ high risk ’ patients from the ‘ low risk ’ patients, so that the high risk ones can be managed more rigorously while the low risk patients can be referred for less frequent screenings and checkups. Data of around 100 patients with Grade 1 retinopathy was collected. Their physiological parameters with their DR grading after 3 years was recorded. Physiological parameters which were having a higher impact on the course of Retinopathy were taken (e.g. Mild blood urea, Hypertension and Smoking in this case). Transition probabilities of going from one stage to other were calculated. Probability of having a single physiological parameter in a given stage of DR at a given point of time was calculated. Probability of various combinations of these physiological parameters in a given stage of disease was calculated. Then by knowing the present stage of that disease future stage (3 years later in this case) of the disease can be predicted. Based on these predictions, the ‘ high risk ’ patients are differentiated from the ‘ low risk ’ patients and are accordingly referred for screenings and interventions.

Four years incidence of diabetic retinopathy and effective factors on its progression in type II diabetes

PURPOSE

To study the 4 years incidence of diabetic retinopathy in patients with type II diabetes and effective factors on its progression.

METHODS

Among diabetic patients referred to Yazd Diabetes Research Center, 120 patients with type II diabetes without diabetic retinopathy were selected. After complete ophthalmic examination, fasting blood sugar (FBS), postprandial blood sugar, triglyceride, and cholesterol were measured and height, weight, and blood pressure (BP) were recorded. Then patients were followed with eye examination yearly for 4 years.

RESULTS

Four-year cumulative incidence of diabetic retinopathy was 47.5% (95% CI: 38.6-56.4). The retinopathy was mild nonproliferative diabetic retinopathy (NPDR) in 43 (35.8%) whereas 10 (8.3%) patients had moderate NPDR, 3 (2.5%) patients had severe NPDR, and only one patient had proliferative diabetic retinopathy. The incidence of diabetic retinopathy was 5.8% in first year, 20.3% in the second year, 24.4% in the third year, and 7.4% in the fourth year. Duration of diabetes, FBS, and systolic BP had statistically significant relation with grades of diabetic retinopathy. However, there was no significant association between age, sex, body mass index, triglyceride, cholesterol, method of treatment, smoking, and diastolic BP with grades of diabetic retinopathy.

CONCLUSIONS

These data provide 4-year cumulative incidence of diabetic retinopathy in defined type 2 diabetic patients. The present study shows that duration of diabetes, hyperglycemia, and systolic BP appear to be the major factors associated with the development of any level of retinopathy in type 2 diabetic patients.

Genome-wide linkage analyses to identify Loci for diabetic retinopathy

Hyperglycemia and long duration of diabetes are widely recognized risk factors for diabetic retinopathy, but inherited susceptibility may also play a role because retinopathy aggregates in families. A genome-wide linkage analysis was conducted in 211 sibships in which > or =2 siblings had diabetes and retinal photographs were available from a longitudinal study. These sibships were a subset of 322 sibships who had participated in a previous linkage study of diabetes and related traits; they comprised 607 diabetic individuals in 725 sibpairs. Retinal photographs were graded for presence and severity of diabetic retinopathy according to a modification of the Airlie House classification system. The grade for the worse eye was adjusted for age, sex, and diabetes duration and analyzed as a quantitative trait. Heritability of diabetic retinopathy in this group was 18% (95% CI 2-36). A genome-wide linkage analysis using variance components modeling found evidence of linkage on chromosome 1p. Using single-point analysis, the peak logarithm of odds (LOD) was 3.1 for marker D1S3669 (34.2 cM), whereas with multipoint analysis the peak LOD was 2.58 at 35 cM. No other areas of suggestive linkage were found. We propose that an area on chromosome 1 may harbor a gene or genes conferring susceptibility to diabetic retinopathy.

Five-year incidence and progression of diabetic retinopathy in a defined older population: the Blue Mountains Eye Study

AIMS

To determine 5-year incidence and progression of diabetic retinopathy in an older Australian population-based cohort.

METHODS

During the period 1992-1994, the Blue Mountains Eye Study examined 3654 residents aged 49+years (82.4% of those eligible), living in two urban postcode areas, west of Sydney, Australia. Participants were subsequently invited to attend 5-year follow-up exams. After excluding 543 (14.8%) who died during the follow-up period, 2334 persons (75.0%) were re-examined during 1997-1999. The examination included a comprehensive questionnaire, blood pressure measurement, standardised refraction, Zeiss stereo retinal photographs, and estimation of fasting blood glucose. Diabetic retinopathy was graded from the retinal photographs, using the modified Early Treatment Diabetic Retinopathy Scale classification (15-step scale).

RESULTS

Of participants with diabetes diagnosed at baseline, 150 were re-examined, including 139 with gradable fundus photographs. The cumulative 5-year incidence of diabetic retinopathy was 22.2% before 95% confidence interval (CI) 14.1-32.2%. Retinopathy progression (1+ steps) was documented in 25.9% (95% CI 18.8-34.0%) of participants with retinopathy and gradable photographs at both visits; in 58.3% of these cases, a 2+ -step progression was documented. Progression to proliferative retinopathy occurred in only 4.1% of those with retinopathy at baseline. The only baseline risk factors associated with retinopathy progression, after adjusting for age and gender, were increase in fasting blood glucose, odds ratio (OR) 1.2 (95% CI 1.1-1.4)/mmol/l, and increase in diabetes duration, OR 2.3 (95% CI 1.0-5.3)/10 years.

CONCLUSIONS

These data provide 5-year cumulative incidence of diabetic retinopathy in a defined older population. Increase in diabetes duration and elevated baseline fasting blood glucose level predicted retinopathy incidence.

A community-based follow-up study on diabetic retinopathy among type 2 diabetics in Kinmen

The purpose of this follow-up study was conducted to assess the incidence and risk factors of diabetic retinopathy (DR) among type 2 diabetics in Kinmen, Taiwan. A penal of eye screening regimes were performed yearly for 971 type 2 diabetics by two senior ophthalmologists using indirect ophthalmoscopy and 45-degree color fundus photography to examine fundus after dilating pupils from 1999 to 2002. 74.7% (725/971) of diabetics had been screened at least two times during this period. Among the 548 type 2 diabetics who had no DR at first screening, 93 subjects developed any type of DR. The 3-year 18.2% cumulative incidence was (95% CI: 14.8-21.5%) and incidence density was 6.62% per year (95% CI: 5.36-8.06% per year). Using Cox regression model, HbAlc revealed the significantly dose response relationship to the development of DR (chi2-test for trend = 9.41, p < 0.05) after controlling for confounding factors. Other independent predictors related to the development of DR included duration of diabetes (RR: 1.09, 95% CI: 1.05-1.13), higher systolic blood pressure (>140 vs. < 140 mm Hg, RR: 1.96, 95% CI: 1.23-3.12), and higher triglyceride (> 200 vs. < 200 mg/dl, RR: 1.60, 95% CI: 1.01-2.54). In conclusion, in addition to poor glycemic control of which is the most significant risk factor for the development of DR, longer duration of diabetes, higher systolic blood pressure, and elevated serum triglyceride levels were also associated with the development of DR among type 2 diabetics in Kinmen.

Epidemiology of diabetic retinopathy and macular oedema: a systematic review

AIMS

To systematically review the literature on the prevalence and incidence of diabetic retinopathy (DR) and macular oedema (MO).

METHODS

A search of the bibliographic databases (Medline, Embase, CINAHL) was conducted up to October 2001. Selected relevant studies were scrutinized and included in the review.

RESULTS

A total of 359 studies were included. The studies were reported in nearly 100 different journals and in over 50 countries. The majority of the studies were US-based, with large studies such as the Wisconsin Epidemiologic Study of Diabetic Retinopathy dominating the literature. The studies were quite dated and highly heterogeneous in nature in terms of patient selection with variable inclusion criteria (age range, gender, diabetes duration and type, ethnicity, comorbidity, and DR status, assessment, and classification).

CONCLUSIONS

There are inconsistencies between epidemiological studies, and differences in study methods may contribute to conflicting reports of prevalence and incidence of DR and MO in diabetic populations. As new therapies for DR and its associated complications emerge, the need to capture and monitor new epidemiological data becomes increasingly important to be able to assess the impact and effectiveness of these therapies. Robust, longitudinal capture of patient data is, therefore, essential to evaluate the impact of current practice on the epidemiology of diabetic eye complications.

Development of evidence-based clinical practice guidelines for diabetes: the Department of Veterans Affairs/Department of Defense guidelines initiative

OBJECTIVE

To describe the Veterans Affairs (VA)/Department of Defense (DoD) Clinical Practice Guidelines for diabetes and contrast selected recommendations with those of the American Diabetes Association (ADA).

RESEARCH DESIGN AND METHODS

We summarize the general structure of the VA/DoD Guidelines and describe the rationale for recommendations issued in 2003 for glycemic control, management of hypertension, and retinopathy screening. We compare the synthesis of evidence and resulting recommendations for these content areas with the 2004 American Diabetes Association Clinical Practice Recommendations.

RESULTS

The VA/DoD Guidelines and the ADA Clinical Practice Recommendations reported similar strength of evidence findings by content area, but clinical recommendations varied. The VA/DoD Guidelines and practice recommendations emphasize the use of data on absolute risk reduction from available published randomized clinical trials rather than relative risk reduction from observational analyses. The VA/DoD Guidelines employ an algorithm-based methodology to guide clinicians through a risk-stratified approach to managing individual patients rather than promoting a single standard for most or all patients without explicit consideration of competing comorbidities.

CONCLUSIONS

The VA/DoD Guidelines are intended to guide diabetes care by providing Internet-ready, evidence-based annotations in algorithmic form to help clinicians set and revise individual treatment goals for their patients.

Five-year incidence of diabetic retinopathy in the Melbourne Visual Impairment Project

BACKGROUND

The purpose of the present paper was to describe the 5-year incidence and progression of diabetic retinopathy in the Melbourne Visual Impairment Project (VIP) cohort.

METHODS

Baseline examinations were conducted from 1992 to 1994 and follow-up data were collected 5 years later. Data collected during the baseline and follow-up studies included medical history (including previous diagnosis of diabetes mellitus) and dilated fundus examination. Two 30 degrees stereoscopic fundus photographs were taken with a Topcon TRC fundus camera, one centred on the optic disc and the other centred on the fovea. Photographs from participants who reported having diabetes were graded for diabetic retinopathy based on an extension of the Modified Airlie House Classification. Grouping of participant data into retinopathy grades was based on the results of the worst eye.

RESULTS

The follow-up survey included 82% (n = 121) of those with diabetes at baseline. Prevalence of any retinopathy was 35.7% and macular oedema was 13% at follow up. Diabetic retinopathy was newly detected in 8/73 (5-year incidence = 11.0%, 95% confidence interval (CI) = 3.8-18.1). Disease progression was seen in 9/31 participants (29.0%, 95%CI = 14.9-47.8) who had diabetic retinopathy at baseline. The 5-year incidence of proliferative diabetic retinopathy in people without proliferative diabetic retinopathy at baseline was 2.9% (3/104, 95%CI = 0-6.4). The 5-year incidence of macular oedema in people who did not have macular oedema at baseline was 8.0% (8/100, 95%CI = 2.7-13.3). All people with proliferative diabetic retinopathy at baseline had received laser treatment by the follow-up survey. Twenty-four per cent of people without diabetic retinopathy reported never having had a dilated fundus examination (excluding the VIP examinations).

CONCLUSION

The 5-year incidence of diabetic retinopathy was 11% in the Melbourne Visual Impairment Project. Most people with proliferative diabetic retinopathy or macular oedema are receiving treatment. However, many people with diabetes are not having regular dilated fundus examinations.

Incidence of diabetic retinopathy in the Barbados Eye Studies

PURPOSE

To examine the 4-year incidence and risk factors for diabetic retinopathy (DR) among black participants with diabetes in the Barbados Eye Studies (BES).

DESIGN

Population-based incidence study.

SETTING AND PARTICIPANTS

Four hundred ten persons with diabetes mellitus (DM) from the BES cohort, which was based on a simple random sample of Barbadians, 40 to 84 years of age at baseline.

MAIN OUTCOME MEASURES

Development of DR, assessed by independent gradings of 30 degrees color stereo fundus photographs of the disc and macula. Associations were evaluated by logistic regression analyses.

RESULTS

After 4 years, DR developed in 92 of 306 (30.1%; 95% confidence interval, 25.0%, 35.5%) persons unaffected at baseline. The incidence of DR was 31.9% in those with known DM at baseline and 20.9% in newly diagnosed DM. Clinically significant macular edema developed in 16 (4.5%) of 353 individuals at risk. Seven (6.9%) of the 101 persons with minimum or moderate DR at baseline progressed to proliferative DR. Age-specific incidence declined from 36.2% at age 40 to 49 years to 28.8% and 24.2% over the subsequent two decades, increasing to 38.2% among those >/=70 years. Risk factors for DR were increased systolic blood pressure (relative risk [RR], 1.16 [1.03, 1.31]/10 mmHg increase); use of oral hypoglycemics (RR, 2.4 [1.3, 4.2]); and use of insulin (RR, 6.1 [1.7, 22.1]) (vs. no treatment or diet only); and elevated glycated hemoglobin (GHb; RR, 6.4 [2.5, 16.0]); GHb >11.5% vs. GHb </=8%).

CONCLUSIONS

High rates of incident DR were evident in the black BES population, also known to have high rates of DM. Prevention of visual loss caused by DR in this population has high priority, including optimal glycemic and blood pressure control.

Longitudinal studies of incidence and progression of diabetic retinopathy assessed by retinal photography in pima indians

OBJECTIVE

To examine incidence and progression of retinopathy using retinal photographs in Pima Indians and to compare the results with those obtained when retinopathy is assessed by direct ophthalmoscopy.

RESEARCH DESIGN AND METHODS

We undertook an analysis of examinations conducted between 1 April 1982 and 31 December 1990 in residents of the Gila River Community in central Arizona. Data were taken from 411 people with diabetes who had at least two examinations during this period. Incidence and progression of retinopathy were evaluated by retinal photography and fundoscopy, and hazard rate ratios were calculated for various potential risk factors measured at baseline.

RESULTS

Previously diagnosed retinopathy tended to progress, except in individuals with minimal nonproliferative retinopathy, among whom follow-up examinations were more likely to show no retinopathy. Diabetes duration (hazard rate ratio [HRR], 1.06 per year difference [P = 0.007]), hyperglycemia (HbA(1) HRR, 1.27 per 1% difference [P < 0.0001]), the type of treatment for diabetes (insulin use HRR, 3.06 [P = 0.0007], and oral hypoglycemic use HRR, 2.40 [P = 0.0034], compared with individuals on no pharmacotherapy), and macroalbuminuria (HRR, 2.86, compared with individuals without macroalbuminuria [P = 0.0486]) were associated with the development of retinopathy. Although fundoscopy detected fewer cases of retinopathy, HRRs for most risk factors were similar when retinopathy was assessed by fundoscopy rather than retinal photography.

CONCLUSIONS

Although retinopathy tends to worsen over time, some eyes show improvement, especially in patients with minimal nonproliferative retinopathy. As in other populations, glycemic control is the major modifiable risk factor for the development and progression of retinopathy.

The evaluation of screening policies for diabetic retinopathy using simulation

AIMS

To develop a model for evaluating screening strategies and to use it to determine the cost effectiveness of varying the screening method and the screening interval.

METHODS

A discrete event simulation was designed, validated and run for a population of 500000. Most parameters were derived from peer-reviewed publications.

RESULTS

Standard methods of screening save up to 50% of the potential sight years lost. They give up to 85% of the sight years saved by an idealized gold standard programme using mydriatic seven-field photography reported by an ophthalmologist. The mobile camera, used for annual screening and 6-month follow-up after the detection of background retinopathy, had an estimated cost of pound 449200 per year with pound 2842 per sight year saved. It is less efficient to screen Type 2, rather than Type 1 diabetes mellitus patients, but they contributed to almost three-quarters of the sight years saved.

CONCLUSIONS

The model can evaluate screening intervals and methods on a national or health authority basis. Results indicate that it appears more cost effective to continue to screen outside an ophthalmology clinic, until treatment is needed. Programmes with annual screening, and more frequent screening for those with background retinopathy, are robust to realistic fluctuations in compliance and screening sensitivity.

Evaluating screening policies for the early detection of retinopathy in patients with non-insulin dependent diabetes

Retinopathy is a common complication of insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) diabetes, but serious visual loss may be prevented or delayed with sufficiently early diagnosis and treatment. Screening for early signs of retinopathy is clearly beneficial for some people, but there is no established consensus about who should be screened, by whom, by what technique and with what frequency, especially for NIDDM. The model described in this paper simulates the development of eye disease in a population of NIDDM patients and the effects of different screening schemes in terms of years of sight saved and the numbers of people prevented from suffering severe visual loss. The initial results indicate that blanket screening of all NIDDM patients may not be effective.

Retinal examination intervals in diabetic patients on diet treatment only

PURPOSE

The aim of the present study was to examine whether type 2 diabetic patients with good metabolic control achieved on diet treatment only, developed sight-threatening retinopathy during a four-year follow-up period.

METHODS

A retrospective four-year follow-up study was carried out including all diabetic patients on diet treatment only, registered at the out-patient clinic at the Department of Medicine and referred for fundus photography to the Department of Ophthalmology in 1989 as well as all patients referred from primary care units for fundus photography during 1988 and 1989. One hundred and seventeen diabetic patients treated with diet only were examined with fundus photography after remittance, and after two and four years.

RESULTS

Age at diabetes diagnosis was 58.8 +/- 13.8 years (mean +/- SD), age at baseline was 61.5 +/- 13.6 years, and diabetes duration was 2.7 +/- 3.1 years. During the four-year follow-up period, 48 of the patients (41%) remained on diet treatment only whereas diabetes treatment was changed in 66 (56%), from diet to oral agents only in 57 (49%), and from diet to insulin alone or in combination with oral agents in 9 (8%) of the patients. One hundred and six patients (91%) did not have any retinopathy at baseline and 11 patients (9%) had minimal background retinopathy. At follow-up, there were no signs of retinopathy in 93 patients (79%), 22 (19%) had minimal background retinopathy, and two had developed moderate background retinopathy. Out of those patients who were still on diet at follow-up, five (10%) had developed minimal background retinopathy. Mean blood glucose and HbA1c levels, registered every year during the observation period, were higher at most time points in patients who received oral agents or insulin treatment compared to those who were treated with diet only during the entire observation period. No differences were observed between patients who received oral agents and those who received insulin alone or in combination with oral agents.

CONCLUSION

It is suggested, that if the initial retinal examination reveals no or minimal diabetic retinopathy at the time of diagnosis of type 2 diabetes mellitus, the second examination can be postponed at least 4 years in patients with good metabolic control on diet treatment only.

Progression of retinopathy is related to glycaemic control even in patients with mild diabetes mellitus

To study the progression of retinopathy in patients with mild diabetes mellitus, we examined, in a cohort study, 347 patients treated with diet alone at baseline. The patients participated in an ophthalmological screening and control programme, and diet-treated patients who were examined between January 1990 and July 1992 were included in the study and followed until October 1995. Mean follow-up was 3.4 +/- 1.1 years. The alternative classification of the Wisconsin study was used to classify retinopathy, and the mean HbA1c values for the study period, to estimate the level of glycaemic control. At baseline, 314 of the patients (90.5%) had no retinopathy, and 33 (9.5%) had mild non-proliferative diabetic retinopathy. In 296 patients there was no retinopathy progression, in 27 patients there was progression by 1 level in the retinopathy scale, and in 24 patients by 2 levels or more. In 2 patients there was progression to proliferative diabetic retinopathy. The mean HbA1c (%) was 6.5 +/- 1.3. Higher HbA1c correlated to increased progression (r = 0.16; p = 0.005), and in a multivariate analysis, HbA1c remained associated with a progression of retinopathy by 2 levels or more, with a relative risk of 1.4 per percent increase in HbA1c (95% CI 1.1-2.0; p = 0.02). Furthermore, the presence of any retinopathy at baseline was associated with progression with a relative risk of 1.7 (95% confidence interval 1.1-2.8; (p = 0.02). These data indicate that even slightly elevated levels of HbA1c might be associated with a risk of retinopathy progression.

The importance of early diagnosis of treatable diabetic retinopathy for the four-year visual outcome in older-onset diabetes mellitus

The four-year visual outcome was retrospectively studied in patients with older-onset diabetes mellitus and diabetic retinopathy in need of laser treatment. Visual acuity in 53 patients examined by ophthalmologists who referred the patients for an evaluation of retinopathy before laser treatment, was compared to that of 47 patients examined by ophthalmologists who also performed the photocoagulation. The number of eyes that became blind (visual acuity < or = 6/60) during the four-year period was higher (23/90 vs 9/91; p < 0.01) among referred patients, whereas the number of retinal examinations per patient during the three-year period prior to laser treatment did not differ between the two groups. Among referred patients, 13% had not been ophthalmologically examined before the treatment-requiring retinopathy was found. Corresponding figure for those examined at the laser centre was 23%. Severe macular oedema in regularly examined patients was more common among referred patients (9/30 vs 1/32; p < 0.01). The results indicate that screening for diabetic retinopathy in older-onset diabetes was not performed satisfactorily. In addition, laser treatment was delayed in older-onset diabetic patients controlled by ophthalmologists who referred patients for photocoagulation, resulting in an increased incidence of legally blind eyes. The study also stresses the importance of carrying out knowledge of when and how to diagnose early sight-threatening diabetic retinopathy to ophthalmologists referring patients for laser treatment.