Factors influencing the onset and progression of diabetic retinopathy in subjects with insulin-dependent diabetes mellitus

Association between resistivity index of central retinal artery and severity of diabetic retinopathy

Purpose

Diabetic retinopathy (DR) is a leading cause of ocular morbidity. Its progression depends mainly on retinal vasculature and ocular blood flow. Color Doppler imaging (CDI) is a noninvasive imaging technique that measures blood flow velocity. The resistivity index (RI), calculated by the CDI, reflects the vascular resistance distal to the measuring location. RI is independent of the doppler angle and position of the patient, making it a reliable and reproducible parameter. To the best of our knowledge, there is only one study in literature studying the association between resistivity index (RI) of the central retinal artery (CRA) and severity of DR.

Aim

To determine the association between RI of CRA and severity of DR. To determine the association between RI of CRA and spectral-domain optical coherence tomography (SD-OCT) biomarkers for DR.

Methods

Type II diabetics visiting our OPD underwent DR screening and were graded into three categories according to ETDRS classification which include Group A-No diabetic retinopathy (No DR), Group B-Nonproliferative diabetic retinopathy (Moderate-Severe-Very Severe NPDR), and Group C-Proliferative diabetic retinopathy (PDR). SD-OCT was performed. Ultrasonic color doppler imaging was done. RI of the CRA was noted. It was compared between the three groups and its association with severity of DR and OCT biomarkers (central subfield thickness, cube average thickness and ellipsoid zone disruption) was studied.

Results

56 eyes of 28 patients were included in our study with 20 in Group A,14 in Group B, and 22 in Group C. RI of CRA compared within groups showed statistically significant association with severity of DR (P < 0.001). The presenting BCVA (LogMar) showed positive correlation with RI in all groups. OCT biomarker central subfield thickness showed a positive correlation with RI in Groups A (P < 0.001) and B. Ellipsoid zone (EZ) disruption showed a statistically significant association with RI in Group C (P < 0.001).

Conclusion

The RI of CRA is a reliable biomarker for the assessment of the severity of DR. Patients with high RI of CRA had higher chances of EZ disruption and presented with poor visual acuity.

Prognostic factors for the development and progression of proliferative diabetic retinopathy in people with diabetic retinopathy

BACKGROUND

Diabetic retinopathy (DR) is characterised by neurovascular degeneration as a result of chronic hyperglycaemia. Proliferative diabetic retinopathy (PDR) is the most serious complication of DR and can lead to total (central and peripheral) visual loss. PDR is characterised by the presence of abnormal new blood vessels, so-called "new vessels," at the optic disc (NVD) or elsewhere in the retina (NVE). PDR can progress to high-risk characteristics (HRC) PDR (HRC-PDR), which is defined by the presence of NVD more than one-fourth to one-third disc area in size plus vitreous haemorrhage or pre-retinal haemorrhage, or vitreous haemorrhage or pre-retinal haemorrhage obscuring more than one disc area. In severe cases, fibrovascular membranes grow over the retinal surface and tractional retinal detachment with sight loss can occur, despite treatment. Although most, if not all, individuals with diabetes will develop DR if they live long enough, only some progress to the sight-threatening PDR stage.  OBJECTIVES: To determine risk factors for the development of PDR and HRC-PDR in people with diabetes and DR.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; which contains the Cochrane Eyes and Vision Trials Register; 2022, Issue 5), Ovid MEDLINE, and Ovid Embase. The date of the search was 27 May 2022. Additionally, the search was supplemented by screening reference lists of eligible articles. There were no restrictions to language or year of publication.  SELECTION CRITERIA: We included prospective or retrospective cohort studies and case-control longitudinal studies evaluating prognostic factors for the development and progression of PDR, in people who have not had previous treatment for DR. The target population consisted of adults (≥18 years of age) of any gender, sexual orientation, ethnicity, socioeconomic status, and geographical location, with non-proliferative diabetic retinopathy (NPDR) or PDR with less than HRC-PDR, diagnosed as per standard clinical practice. Two review authors independently screened titles and abstracts, and full-text articles, to determine eligibility; discrepancies were resolved through discussion. We considered prognostic factors measured at baseline and any other time points during the study and in any clinical setting. Outcomes were evaluated at three and eight years (± two years) or lifelong.  DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data from included studies using a data extraction form that we developed and piloted prior to the data collection stage. We resolved any discrepancies through discussion. We used the Quality in Prognosis Studies (QUIPS) tool to assess risk of bias. We conducted meta-analyses in clinically relevant groups using a random-effects approach. We reported hazard ratios (HR), odds ratios (OR), and risk ratios (RR) separately for each available prognostic factor and outcome, stratified by different time points. Where possible, we meta-analysed adjusted prognostic factors. We evaluated the certainty of the evidence with an adapted version of the GRADE framework.   MAIN RESULTS: We screened 6391 records. From these, we identified 59 studies (87 articles) as eligible for inclusion. Thirty-five were prospective cohort studies, 22 were retrospective studies, 18 of which were cohort and six were based on data from electronic registers, and two were retrospective case-control studies. Twenty-three studies evaluated participants with type 1 diabetes (T1D), 19 with type 2 diabetes (T2D), and 17 included mixed populations (T1D and T2D). Studies on T1D included between 39 and 3250 participants at baseline, followed up for one to 45 years. Studies on T2D included between 100 and 71,817 participants at baseline, followed up for one to 20 years. The studies on mixed populations of T1D and T2D ranged from 76 to 32,553 participants at baseline, followed up for four to 25 years.  We found evidence indicating that higher glycated haemoglobin (haemoglobin A1c (HbA1c)) levels (adjusted OR ranged from 1.11 (95% confidence interval (CI) 0.93 to 1.32) to 2.10 (95% CI 1.64 to 2.69) and more advanced stages of retinopathy (adjusted OR ranged from 1.38 (95% CI 1.29 to 1.48) to 12.40 (95% CI 5.31 to 28.98) are independent risk factors for the development of PDR in people with T1D and T2D. We rated the evidence for these factors as of moderate certainty because of moderate to high risk of bias in the studies.  There was also some evidence suggesting several markers for renal disease (for example, nephropathy (adjusted OR ranged from 1.58 (95% CI not reported) to 2.68 (2.09 to 3.42), and creatinine (adjusted meta-analysis HR 1.61 (95% CI 0.77 to 3.36)), and, in people with T1D, age at diagnosis of diabetes (< 12 years of age) (standardised regression estimate 1.62, 95% CI 1.06 to 2.48), increased triglyceride levels (adjusted RR 1.55, 95% CI 1.06 to 1.95), and larger retinal venular diameters (RR 4.28, 95% CI 1.50 to 12.19) may increase the risk of progression to PDR. The certainty of evidence for these factors, however, was low to very low, due to risk of bias in the included studies, inconsistency (lack of studies preventing the grading of consistency or variable outcomes), and imprecision (wide CIs). There was no substantial and consistent evidence to support duration of diabetes, systolic or diastolic blood pressure, total cholesterol, low- (LDL) and high- (HDL) density lipoproteins, gender, ethnicity, body mass index (BMI), socioeconomic status, or tobacco and alcohol consumption as being associated with incidence of PDR. There was insufficient evidence to evaluate prognostic factors associated with progression of PDR to HRC-PDR.  AUTHORS' CONCLUSIONS: Increased HbA1c is likely to be associated with progression to PDR; therefore, maintaining adequate glucose control throughout life, irrespective of stage of DR severity, may help to prevent progression to PDR and risk of its sight-threatening complications. Renal impairment in people with T1D or T2D, as well as younger age at diagnosis of diabetes mellitus (DM), increased triglyceride levels, and increased retinal venular diameters in people with T1D may also be associated with increased risk of progression to PDR. Given that more advanced DR severity is associated with higher risk of progression to PDR, the earlier the disease is identified, and the above systemic risk factors are controlled, the greater the chance of reducing the risk of PDR and saving sight.

The Integration of Diabetic Eye Screening into Hemodialysis Units in Northern Ireland

Background

Diabetes is rising globally and is the most common cause of both end-stage renal disease and blindness. People on hemodialysis have to attend several dialysis appointments per week, which can affect their attendance at diabetic eye screening. In addition, previous literature suggests patients on hemodialysis are more likely to have sight-threatening diabetic eye disease. This study aims to determine attendance at the Diabetic Eye Screening Program in Northern Ireland, diabetic retinopathy severity, and use of handheld retinal imaging in people with diabetes attending hemodialysis units in Northern Ireland.

Methods

All patients with diabetes attending hemodialysis clinics regionally were screened and graded by the Diabetic Eye Screening Program in Northern Ireland using a handheld and/or conventional nonmydriatic fundus camera.

Results

All eligible people (N=149) were offered a Diabetic Eye Screening Program in Northern Ireland appointment, 132 attended, 34% of whom had not been seen in >3 years and 15% of whom had never attended the Diabetic Eye Screening Program in Northern Ireland despite multiple previous appointments. Altogether, 13% required urgent referral to hospital eye services, which is significantly higher than the national average of 0.4%.

Conclusions

Those on hemodialysis are at high risk for sight-threatening diabetic retinopathy. Implementing the Diabetic Eye Screening Program in Northern Ireland in hemodialysis clinics enables timely diagnosis and referral.

Ocular Surface Squamous Neoplasia Managed With Primary Interferon α2b: A Comparative Analysis of 212 Tumors in Smokers Versus Nonsmokers

PURPOSE

To explore clinical features and outcomes of ocular surface squamous neoplasia (OSSN) treated with primary interferon (IFN)-α2b, based on patient cigarette smoking status.

METHODS

Retrospective nonrandomized, interventional cohort study on 212 consecutive tumors in 194 patients, all of whom were treated with topical and/or injection IFNα2b.

RESULTS

There were 88 tumors in 76 patients with current or past smoking history (smokers) and 124 tumors in 118 nonsmoking patients (nonsmokers). A comparison (smokers vs. nonsmokers) revealed smokers with more frequent bilateral disease (16% vs. 3%, P = 0.003), more frequent involvement of inferior forniceal (34% vs. 21%, P = 0.03) and inferior tarsal conjunctiva (38% vs. 24%, P = 0.04), greater mean number of clock hour involvement (4.1 vs. 3.5 clock hours, P = 0.04), and greater dome growth pattern (30% vs. 15%, P = 0.01). There was no difference regarding method of IFNα2b administration as topical (61% vs. 71%, P = 0.14), injection (10% vs. 6%, P = 0.32), or combination topical/injection (28% vs. 23%, P = 0.33). A comparison revealed smokers with more frequent recurrence after initial response (23% vs. 13%, P = 0.04). There was no difference regarding initial tumor response or time to response, treatment side effects, or systemic outcomes.

CONCLUSIONS

Regarding ocular surface squamous neoplasia, smokers more often display bilateral, dome-shaped tumors with inferior forniceal or tarsal involvement, and greater extent than nonsmokers. After treatment with topical and/or injection IFNα2b, control is equivalent, but smokers show greater recurrence.

Birth Weight and Diabetic Retinopathy: Results From the Population-Based Gutenberg Health Study (GHS)

PURPOSE

This study investigates the relationship between diabetic retinopathy (DR) and birth weight (BW) in diabetic subjects sampled from the general population.

METHODS

The Gutenberg Health Study (GHS) is a population-based, observational cohort study in participants aged from 35 to 74 years. Criteria for diabetes diagnosis were HbA1c ≥6.5% at study entry, a doctor-diagnosis of diabetes, or diabetes medication. The presence of DR was determined by evaluating fundus photographs. BW was assessed by self-reports. GHS participants were divided into three different BW groups (low: <2500 g; normal: 2500-4000 g; high:>4000 g). Logistic regression analysis was conducted as uni- and multivariable analysis with adjustment for age and sex. Effect mediators were separately investigated.

RESULTS

A total of 1,124 GHS participants (7.5% of the cohort) had diabetes at study entry. Of these, 402 subjects (35.8%) had gradable fundus photographs, reported BW data and were included into this study. Overall, 91/402 subjects (23%) had DR. With regard to BW groups, DR was descriptively more frequent in subjects with low (28.1% [95%-CI: 14.4-47.0%; n = 32]) and high BW (30.8% [95%-CI: 19.1-45.3%; n = 52]) compared to normal BW (20.8% [95%-CI: 16.5-25.7%; n = 318]). Both high and low BW were associated with DR in multivariable analysis (high: OR = 1.68, p = .037; low: OR = 1.81, p = .05). The BW effect was mediated by duration of diabetes in both BW groups and by arterial hypertension in the low BW group.

CONCLUSION

Low and high BW in persons with diabetes is related to higher risk of diabetic retinopathy. Longer duration of diabetes and higher prevalence of arterial hypertension are factors in these subjects explaining the elevated risk.

Change in peripapillary and macular choroidal thickness change in children with type 1 diabetes mellitus without visual impairment or diabetic retinopathy

PURPOSE

To study the characteristics of choroid thickness (CT) of the optic disc and macula in children with type 1 diabetes mellitus (T1DM) without visual impairment and diabetic retinopathy (DR) and analyse associated factors.

METHODS

A square area of 6 × 6 mm around the centre of the optic disc and macula was scanned. The indices analysed mainly included CT at the macular centre (1 mm), and temporal, superior, nasal or inferior aspect of the inner ring (1-3 mm) and outer ring of (3-6 mm) optic disc and macula. Independent risk factors were analysed using multifactor linear regression.

RESULTS

A total of 44 children with T1DM and 48 healthy subjects were enrolled. The diabetic group showed significant increase in the inferior inner ring of parapapillary CT (100.99 ± 30.42 μm versus 89.41 ± 34.00 μm, p = 0.04) and nasal outer ring of parapapillary CT (157.02 ± 47.35 μm versus 131.15 ± 35.17 μm, p = 0.01) as compared to those values in the healthy controls. Spherical equivalent refraction and family history of hypertension are independent factors of both peripappillary choroid thickness (PPCT) and macular choroid thickness (PMCT). Spherical equivalent refraction (p = 0.01) and serum cholesterol (p = 0.03) were independent factors of the inferior inner ring of parapapillary CT, whereas family history of hypertension was an independent factor of the nasal outer ring of parapapillary CT (p = 0.001).

CONCLUSION

In children with diabetes without DR or visual impairment, the CT increase in nasal outer ring of parapapillary (PPNO) and the inferior inner ring of parapapillary (PPII) may be the characteristic pre-DR alteration at the early stage of DM. For children with higher serum cholesterol and family history of hypertension, the change of the nasal outer ring of parapapillary CT and the inferior inner ring of parapapillary CT may be more advanced.

Applications of Artificial Intelligence for the Detection, Management, and Treatment of Diabetic Retinopathy

Rates of diabetic retinopathy (DR) and diabetic macular edema (DME), a common ocular complication of diabetes mellitus, are increasing worldwide. There is a substantial burden concerning the detection and management of this condition, particularly in low-resource settings, due to limitations such as the time, cost, and labor associated with current screening and treatment methods. Artificial intelligence (AI) is a modality of pattern recognition that has the potential to combat these limitations in a reliable and cost-effective way. This review explores the various applications of AI on the screening, management, and treatment of DR and DME. AI applications for detecting referable DR and DME have been the most thoroughly researched applications for this condition. While some studies exist using AI to stratify DR patients based on the risk of progression, predict treatment outcomes to anti-VEGF therapy, and explore the utilization of AI for clinical trials to develop new treatments for DR, further validation studies on larger datasets are warranted.

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

INTRODUCTION

Currently, all people with diabetes (PWD) aged 12 years and over in the UK are invited for screening for diabetic retinopathy (DR) annually. Resources are not increasing despite a 5% increase in the numbers of PWD nationwide each year. We describe the rationale, design and methodology for a randomised controlled trial (RCT) evaluating the safety, acceptability and cost-effectiveness of personalised variable-interval risk-based screening for DR. This is the first randomised trial of personalised screening for DR and the largest ophthalmic RCT in the UK.

METHODS AND ANALYSIS

PWD attending seven screening clinics in the Liverpool Diabetic Eye Screening Programme were recruited into a single site RCT with a 1:1 allocation to individualised risk-based variable-interval or annual screening intervals. A risk calculation engine developed for the trial estimates the probability that an individual will develop referable disease (screen positive DR) within the next 6, 12 or 24 months using demographic, retinopathy and systemic risk factor data from primary care and screening programme records. Dynamic, secure, real-time data connections have been developed. The primary outcome is attendance for follow-up screening. We will test for equivalence in attendance rates between the two arms. Secondary outcomes are rates and severity of DR, visual outcomes, cost-effectiveness and health-related quality of life. The required sample size was 4460 PWD. Recruitment is complete, and the trial is in follow-up.

ETHICS AND DISSEMINATION

Ethical approval was obtained from National Research Ethics Service Committee North West - Preston, reference 14/NW/0034. Results will be presented at international meetings and published in peer-reviewed journals. This pragmatic RCT will inform screening policy in the UK and elsewhere.

TRIAL REGISTRATION NUMBER

ISRCTN87561257; Pre-results.

Personalized risk-based screening for diabetic retinopathy: A multivariate approach versus the use of stratification rules

AIMS

To evaluate our proposed multivariate approach to identify patients who will develop sight-threatening diabetic retinopathy (STDR) within a 1-year screen interval, and explore the impact of simple stratification rules on prediction.

MATERIALS AND METHODS

A 7-year dataset (2009-2016) from people with diabetes (PWD) was analysed using a novel multivariate longitudinal discriminant approach. Level of diabetic retinopathy, assessed from routine digital screening photographs of both eyes, was jointly modelled using clinical data collected over time. Simple stratification rules based on retinopathy level were also applied and compared with the multivariate discriminant approach.

RESULTS

Data from 13 103 PWD (49 520 screening episodes) were analysed. The multivariate approach accurately predicted whether patients developed STDR or not within 1 year from the time of prediction in 84.0% of patients (95% confidence interval [CI] 80.4-89.7), compared with 56.7% (95% CI 55.5-58.0) and 79.7% (95% CI 78.8-80.6) achieved by the two stratification rules. While the stratification rules detected up to 95.2% (95% CI 92.2-97.6) of the STDR cases (sensitivity) only 55.6% (95% CI 54.5-56.7) of patients who did not develop STDR were correctly identified (specificity), compared with 85.4% (95% CI 80.4-89.7%) and 84.0% (95% CI 80.7-87.6%), respectively, achieved by the multivariate risk model.

CONCLUSIONS

Accurate prediction of progression to STDR in PWD can be achieved using a multivariate risk model whilst also maintaining desirable specificity. While simple stratification rules can achieve good levels of sensitivity, the present study indicates that their lower specificity (high false-positive rate) would therefore necessitate a greater frequency of eye examinations.

The prevalence of retinopathy among type 2 diabetic patients in Iran: A systematic review and meta-analysis

Diabetic retinopathy is one of the most major causes of blindness and disability in diabetic patients and imposes very high cost on Health Care System. Studies conducted in the country showed different and inconsistent prevalence of the disease. The study aims to determine the overall prevalence of retinopathy in patients with type 2 diabetes in Iran through a systematic review and meta-analysis. The present study was conducted via meta-analysis method during March, 2000 to October, 2018. The articles related to the subject under study were obtained from Magiran, SID, Medline (PubMed), Science Direct, Scopus and Google Scholar databases. I2 index was used to examine the heterogeneity of articles studied; and the data was analyzed by Comprehensive Meta-Analysis Software. Through the study of 34 articles and 17,079 individuals with age range of 5-83, the overall prevalence of retinopathy for type 2 diabetic patients in Iran and on the basis of meta-analysis, was obtained that was 37.8% (32.84-43%, 95% confidence interval); the highest prevalence of retinopathy for type 2 diabetic patients was in Tehran province with 78% (68.8-85.1%, 95% confidence interval) in 2006 and the lowest prevalence of retinopathy for type 2 diabetic patients was in Isfahan province with 9% (7.1-11.4, 95% confidence interval) in 2006; furthermore, the prevalence of retinopathy for type 2 diabetic patients in Iran increases with increased sample size that it was statistically significant (P < 0.05). Regarding the high prevalence of retinopathy for type 2 diabetic patients in the country, it is essential that health policy makers take effective measures to reduce the disease incidence in diabetic patients.

The association of smoking and risk of diabetic retinopathy in patients with type 1 and type 2 diabetes: a meta-analysis

PURPOSE

To clarify the relevance between smoking and diabetic retinopathy in patients with type 1 and type 2 diabetes mellitus.

METHODS

Published evidence were searched in MEDLINE and EMBASE from the databases began until Feb. 2017. Studies evaluating the association between smoking and diabetic retinopathy or evaluating the risk factors of diabetic retinopathy including smoking were included.

RESULTS

Totally 73 studies were identified, among which 19 studies included type 1 diabetes patients and 56 studies included type 2 diabetes patients. In type 1 diabetes, compare with non-smokers, the risk of diabetic retinopathy significantly increased in smokers (risk ratio (RR) = 1.23, 95% CI 1.14, 1.33, P < 0.001), and the risk of proliferative diabetic retinopathy also significantly increased in smokers (RR = 1.48, 95% CI 1.20, 1.81, P < 0.001). In type 2 diabetes, compare with non-smokers, the risk of diabetic retinopathy significantly decreased in smokers (RR = 0.92, 95% CI 0.86, 0.98, P = 0.02) and the risk of proliferative diabetic retinopathy also significantly decreased in smokers (RR = 0.68, 95% CI 0.61, 0.74, P < 0.001).

CONCLUSIONS

Compare with non-smokers, the risk of diabetic retinopathy significantly increased in smokers with type 1 diabetes while significantly decreased in smokers with type 2 diabetes. However, this result did not change the importance of smoking cessation for public health.

Progression of diabetes, ischemic heart disease, and chronic kidney disease in a three chronic conditions multistate model

BACKGROUND

Diabetes mellitus, ischemic heart disease, and chronic kidney disease are three major chronic conditions that develop with increasing risks among adults as they get older. The interconnectedness of these three chronic conditions is well known, while each condition acts as a prognostic risk factor for the other two. It is important to understand the progressive relationships of these three conditions over time in terms of transitioning between clinical states and the impact on patients' survival.

METHODS

We investigate the survival characteristics of a Medicare population aged 65 years and above in a multistate system that contained clinical states specified by death and diagnosis combinations of three chronic conditions. The study was conducted using Hawaii Medicare claims data from 2009 to 2013. To evaluate the progression of a subject with one of the newly diagnosed chronic conditions, we analyzed quantities such as state occupation probabilities in eight states and hazards of sixteen transition types. We quantified effects and significances of potential covariates such as age, gender, race/ethnicity, comorbidity burden and financial status on these temporal functions. Nonparametric method of estimating state occupation probabilities and pseudo-value based method for estimating covariate effects of a survival system were utilized.

RESULTS

We found a range of age, gender, race/ethnicity and financial status based interesting covariate influences on transitions and state occupation probabilities of the system.

CONCLUSION

Survival characteristics of the disease system are influenced by subject-specific effects. Subgroup-specific interventions/screenings should be considered for the optimal prevention and care.

The long-term effect of community-based health management on the elderly with type 2 diabetes by the Markov modeling

The aim of this study was to assess the long-term effects of community-based health management on elderly diabetic patients using a Markov model. A Markov decision model was used to simulate the natural history of diabetes. Data were obtained from our randomized trials of elderly with type 2 diabetes and from the published literature. One hundred elderly patients with type 2 diabetes were randomly allocated to either the management or the control group in a one-to-one ratio. The management group participated in a health management program for 18 months in addition to receiving usual care. The control group only received usual care. Measurements were performed on both groups at baseline and after 18 months. The Markov model predicted that for every 1000 diabetic patients receiving health management, approximately 123 diabetic patients would avoid complications, and approximately 37 would avoid death over the next 13 years. The results suggest that the health management program had a positive long-term effect on the health of elderly diabetic patients. The Markov model appears to be useful in health care planning and decision-making aimed at reducing the financial and social burden of diabetes.

Associations and interactions between lipid profiles, retinopathy and nephropathy in patients with type 1 diabetes: the FinnDiane Study

OBJECTIVES

The aim of this study was to investigate the associations between lipid profiles and retinopathy in the large nationwide FinnDiane Study and to examine interactions and correlations between retinopathy, nephropathy and lipid variables.

DESIGN AND SUBJECTS

A total of 1465 patients with type 1 diabetes, available lipid profiles, ophthalmic records and fundus photographs were included in the study. The Early Treatment of Diabetic Retinopathy Study scale was used to assess the severity of retinopathy. In an independent cohort of 1100 patients, laser treatment was used to define severe diabetic retinopathy.

RESULTS

HDL cholesterol was associated with proliferative retinopathy (PDR), and triglycerides were associated with mild nonproliferative retinopathy (NPDR) independently of nephropathy and other conventional risk factors (P < 0.01). Significant interactions were seen between albumin excretion rate (AER), retinopathy status and lipid parameters (including triglycerides, non-HDL cholesterol and apolipoprotein B; P < 0.001). Highly different correlations between AER and lipid variables were observed in patients without retinopathy or with mild NPDR compared with patients with moderate to severe NPDR or PDR. Similar interactions and correlations were observed in an independent cohort stratified by laser treatment. In patients without retinopathy or with mild NPDR, AER was low despite HDL cholesterol in the lowest or triglycerides, total cholesterol or LDL cholesterol in the highest quartiles.

CONCLUSIONS

Nephropathy had a strong effect on the associations between lipid variables and retinopathy, whilst dyslipidaemia was associated with nephropathy only in the presence of retinopathy. This finding suggests the existence of shared pathogenic mechanisms between retinopathy and nephropathy which could be targeted to prevent complications in patients with metabolic risk factors.

Diabetic retinopathy in sub-Saharan Africa: meeting the challenges of an emerging epidemic

BACKGROUND

Sub-Saharan Africa faces an epidemic of diabetes. Diabetes causes significant morbidity including visual loss from diabetic retinopathy, which is largely preventable. In this resource-poor setting, health systems are poorly organized to deliver chronic care with multiple system involvement. The specific skills and resources needed to manage diabetic retinopathy are scarce. The costs of inaction for individuals, communities and countries are likely to be high.

DISCUSSION

Screening for and treatment of diabetic retinopathy have been shown to be effective, and cost-effective, in resource-rich settings. In sub-Saharan Africa, clinical services for diabetes need to be expanded with the provision of effective, integrated care, including case-finding and management of diabetic retinopathy. This should be underpinned by a high quality evidence base accounting for differences in diabetes types, resources, patients and society in Africa. Research must address the epidemiology of diabetic retinopathy in Africa, strategies for disease detection and management with laser treatment, and include health economic analyses. Models of care tailored to the local geographic and social context are most likely to be cost effective, and should draw on experience and expertise from other continents. Research into diabetic retinopathy in Africa can drive the political agenda for service development and enable informed prioritization of available health funding at a national level. Effective interventions need to be implemented in the near future to avert a large burden of visual loss from diabetic retinopathy in the continent.

SUMMARY

An increase in visual loss from diabetic retinopathy is inevitable as the diabetes epidemic emerges in sub-Saharan Africa. This could be minimized by the provision of case-finding and laser treatment, but how to do this most effectively in the regional context is not known. Research into the epidemiology, case-finding and laser treatment of diabetic retinopathy in sub-Saharan Africa will highlight a poorly met need, as well as guide the development of services for that need as it expands.

Diabetic retinopathy and VEGF

Diabetic retinopathy remains the leading vascular-associated cause of blindness throughout the world. Its treatment requires a multidisciplinary interventional approach at both systemic and local levels. Current management includes laser photocoagulation, intravitreal steroids, and anti-vascular endothelial growth factor (VEGF) treatment along with systemic blood sugar control. Anti-VEGF therapies, which are less destructive and safer than laser treatments, are being explored as primary therapy for the management of vision-threatening complications of diabetic retinopathy such as diabetic macular edema (DME). This review provides comprehensive information related to VEGF and describes its role in the pathogenesis of diabetic retinopathy, and in addition, examines the mechanisms of action for different antiangiogenic agents in relation to the management of this disease. Medline (Pubmed) searches were carried out with keywords “VEGF”, “diabetic retinopathy”, and “diabetes” without any year limitation to review relevant manuscripts used for this article.

Lack of effect of short-term treatment with amlodipine and lisinopril on retinal autoregulation in normotensive patients with type 1 diabetes and mild diabetic retinopathy

PURPOSE

Diabetic retinopathy is characterized by morphological changes in the retina secondary to disturbances in retinal blood flow. It has been shown that antihypertensive treatment has a protective effect on the development of diabetic retinopathy, and evidence suggests that inhibitors of the renin-angiotensin system have a protective effect beyond the antihypertensive effect. The background for this additional effect is unknown but might be related to an effect on retinal autoregulation.

METHODS

In a double-blinded, two-way cross-over study, 25 normotensive patients with type 1 diabetes (T1D) aged 20.6-33.9 (mean 27.9) with mild retinopathy were randomized to receive either 5 mg of the calcium channel blocker (CCB) amlodipine for 14 days followed by a washout period and treatment with 10 mg of the angiotensin converting enzyme (ACE) inhibitor lisinopril for another 14 days or the two treatments in the reverse order. Using a Dynamic Vessel Analyzer (DVA), the diameter response of retinal arterioles during an acute increase in the blood pressure induced by isometric exercise, during flicker stimulation and during both stimulus conditions simultaneously was studied before and during the two treatments periods.

RESULTS

Amlodipine and lisinopril induced a similar non-significant decrease in the arterial blood pressure. At baseline, the arterial diameter decreased by 2.4 ± 0.9% (p = 0.004) during isometric exercise, increased by 2.2 ± 0.9% (p = 0.019) during flicker stimulation and increased by 1.8 ± 0.9% (p = 0.03) during the combined stimulus conditions. Neither of the antihypertensive drugs amlodipine (p = 0.76) or lisinopril (p = 0.11) changed the diameter response of retinal vessels significantly; however, the two treatments induced a different response in the veins during combined exercise and flicker (p = 0.021).

CONCLUSIONS

Short-term treatment with amlodipine and lisinopril had no significant effect on retinal autoregulation in young normotensive patients with T1D and mild retinopathy, and this lack of effect was similar for the two drugs. A possible normalizing effect of antihypertensive treatment on retinal autoregulation was not observed; however, it might take longer time to improve autoregulation than to reduce the arterial blood pressure.

Identification of independent risk factors for the development of diabetic retinopathy requiring treatment

INTRODUCTION

Diabetic retinopathy is screened by fundus photography and screening intervals are defined according to general rules to ensure that vision threatening complications are detected even if the progression of the disease is fast. The resulting superfluous examinations of patients with slow disease progression can be reduced by a more exact decision model that allows an adjustment of the screening interval to each patient's individual risk profile. This requires an identification of independent risk factors for reaching treatment end points for diabetic retinopathy.

METHODS

Clinical data from 5365 patients who had undergone 23 324 examinations at the Department of Ophthalmology, Århus University Hospital between Jan 1st 1994 and Dec 31st 2007 were used to identify independent risk factors for progression of treatment requiring retinopathy.

RESULTS

The risk of reaching a treatment end point was in both diabetes types independently affected by retinopathy grade and HbA1c. Furthermore, in type 1 diabetic patients the risk of reaching a treatment end point was independently affected by disease duration and by a recommended control interval of less than 3 months, in spite of correction for retinopathy grade and other studied confounders, whereas in type 2 diabetes this risk was affected by increasing age of diagnosis of the disease.

CONCLUSIONS

Only a subset of known risk factors for development and progression of diabetic retinopathy should be used to construct a decision model for optimizing screening intervals for diabetic retinopathy.

Evolution of β-Cell Replacement Therapy in Diabetes Mellitus: Pancreas Transplantation

Diabetes mellitus remains one of the leading causes of morbidity and mortality worldwide. According to the Centers for Disease Control and Prevention, approximately 23.6 million people in the United States are affected. Of these individuals, 5-10% have been diagnosed with type 1 diabetes mellitus (TIDM), an autoimmune disease. Although it often appears in childhood, T1DM may manifest at any age. The effects of T1DM can be devastating, as the disease often leads to significant secondary complications, morbidity, and decreased quality of life. Since the late 1960s, surgical treatment for diabetes mellitus has continued to evolve and has become a viable alternative to chronic insulin administration. In this review, the historical evolution, current status, graft efficacy, benefits, and complications of pancreas transplantation are explored.

Effect of systemic medications on onset and progression of diabetic retinopathy

Diabetic retinopathy remains a leading cause of visual loss worldwide. Patients with diabetes mellitus commonly have multiple comorbidities treated with a wide variety of medications. Systemic medications that target glycemic control and coexisting conditions may have beneficial or deleterious effects on the onset or progression of diabetic retinopathy. In addition, data is accumulating to suggest that the use of systemic therapy primarily to address ocular complications of diabetic retinopathy may be a promising therapeutic approach. This article reviews our current understanding of the ocular-specific effects of systemic medications commonly used by patients with diabetes mellitus, including those directed at control of hyperglycemia, dyslipidemia, hypertension, cardiac disease, anemia, inflammation and cancer. Current clinical evidence is strongest for the use of angiotensin-converting enzyme inhibitors and angiotensin-2 receptor blockers in preventing the onset or slowing the progression of early diabetic retinopathy. To a more limited extent, evidence of a benefit of fibrates for diabetic macular edema exists. Numerous other agents hold considerable promise or potential risk. Thus, these compounds must undergo further rigorous study to determine the actual clinical efficacy and adverse effects before definitive therapeutic care recommendations can be offered.

Sex steroid and tropic hormone levels may be associated with postoperative prognosis of vitrectomy in Korean postmenopausal women: a pilot study

OBJECTIVE

The aim of this study was to evaluate the postoperative prognostic value of sex hormones and related biochemical markers for vitrectomy in postmenopausal Korean women.

METHODS

Twenty-three postmenopausal women undergoing vitrectomy who had not received hormone therapy were recruited. Before vitrectomy, hormonal profile such as follicle-stimulating hormone, estradiol, testosterone, tumor markers, and biochemical markers including homocysteine, glycosylated hemoglobin, protein, albumin, and lipid panel was measured. These parameters were correlated with ophthalmologic outcomes such as intraocular pressure, preoperative and postoperative visual acuity, and the visual improvement after surgery.

RESULTS

Follicle-stimulating hormone showed a positive correlation with the logarithm of the minimal angle of resolution value of postoperative visual acuity (Pearson's correlation, 0.583; P = 0.009). This significance was maintained after age or preoperative visual acuity was adjusted (P = 0.006 and P = 0.013, respectively). Testosterone also showed a positive correlation with intraocular pressure before and after adjustment for age (P = 0.027 and P = 0.033, respectively).

CONCLUSIONS

Sex steroid and tropic hormones may be associated with postoperative ophthalmologic outcomes in the postmenopausal women undergoing vitrectomy. Further larger scale studies will be necessary to confirm these preliminary results.

Serum lipid profile in diabetic macular edema

PURPOSE

To evaluate the correlation of lipid profile and clinical presentation of macular edema in Type 2 diabetes mellitus (DM) patients.

MATERIALS AND METHODS

The study included 20 patients with chronic diabetic macular edema and plaque-like hard exudates (Group 1), 20 patients with diabetic macular edema (Group 2), and 20 DM patients but without retinopathy (Group 3). Diabetic retinopathy was classified according to the Early Treatment Diabetic Retinopathy Study grading system. Sample t test was used to evaluate the association between the fasting serum lipid [total cholesterol, triglyceride, low-density lipoprotein (LDL), high-density lipoprotein (HDL)], glycosylated hemoglobin (HbA1c), fasting blood glucose, creatinine levels, and the clinical findings. P values <.05 were considered statistically significant.

RESULTS

There was no difference between fasting serum lipids and HbA1c levels. Duration of diabetes was shorter in Group 3 than in Groups 1 and 2. Patients in Group 1 had longer duration of diabetes than others (P<.05). Creatinine levels in Group 1 were higher than in other groups (P<.05). Although there was no correlation between fasting blood glucose and HbA1c levels, HbA1c was higher in all three groups from the baseline-normal limits (P<.05).

CONCLUSION

No correlation was found between serum lipid levels and macular edema severity, but the duration of diabetes was demonstrated as a significant factor in the progression of macular edema. High HbA1c levels in all patients highlight the importance of intense glycemic control in diabetic patients.

Role of blood pressure in development of early retinopathy in adolescents with type 1 diabetes: prospective cohort study

OBJECTIVE

To examine the relation between blood pressure and the development of early retinopathy in adolescents with childhood onset type 1 diabetes.

DESIGN

Prospective cohort study.

SETTING

Diabetes Complications Assessment Service at the Children's Hospital at Westmead, Sydney, Australia.

PARTICIPANTS

1869 patients with type 1 diabetes (54% female) screened for retinopathy with baseline median age 13.4 (interquartile range 12.0-15.2) years, duration 4.9 (3.1-7.0) years, and albumin excretion rate of 4.4 (3.1-6.8) microg/min plus a subgroup of 1093 patients retinopathy-free at baseline and followed for a median 4.1 (2.4-6.6) years.

MAIN OUTCOME MEASURES

Early background retinopathy; blood pressure.

RESULTS

Overall, retinopathy developed in 673 (36%) participants at any time point. In the retinopathy-free group, higher systolic blood pressure (odds ratio 1.01, 95% confidence interval 1.003 to 1.02) and diastolic blood pressure (1.01, 1.002 to 1.03) were predictors of retinopathy, after adjustment for albumin excretion rate (1.27, 1.13 to 1.42), haemoglobin A(1c) (1.08, 1.02 to 1.15), duration of diabetes (1.16, 1.13 to 1.19), age (1.13, 1.08 to 1.17), and height (0.98, 0.97 to 0.99). In a subgroup of 1025 patients with albumin excretion rate below 7.5 microg/min, the cumulative risk of retinopathy at 10 years' duration of diabetes was higher for those with systolic blood pressure on or above the 90th centile compared with those below the 90th centile (58% v 35%, P=0.03). The risk was also higher for patients with diastolic blood pressure on or above the 90th centile compared with those below the 90th centile (57% v 35%, P=0.005).

CONCLUSIONS

Both systolic and diastolic blood pressure are predictors of retinopathy and increase the probability of early retinopathy independently of incipient nephropathy in young patients with type 1 diabetes.

Rationale, design, and methods of the Action to Control Cardiovascular Risk in Diabetes Eye Study (ACCORD-EYE)

Diabetic retinopathy (DR) is a major microvascular complication of diabetes mellitus. The Action to Control Cardiovascular Risk in Diabetes Eye Study (ACCORD-EYE), a prospective study of a subset of patients in the randomized controlled clinical ACCORD trial, is being conducted at enrollment and after 4 years of follow-up to assess the progression of DR with standardized comprehensive eye exams and fundus photography of 7 standard stereoscopic fields. This study aims to assess the effects of the ACCORD medical treatment strategies of tight control of glycemia and blood pressure and management of dyslipidemia on the course of DR in patients with type 2 diabetes. Photographs will be evaluated at a centralized location using the modified Early Treatment Diabetic Retinopathy Study (ETDRS) classification. The primary outcome of ACCORD-EYE, which will measure the development and progression of DR, is a composite of (1) progression of DR (> or = 3 steps on the ETDRS scale), (2) photocoagulation for DR, or (3) vitrectomy for DR. Specifically, the following questions will be addressed: (1) Does a therapeutic strategy targeting a glycosylated hemoglobin (HbA(1c)) level <6.0% reduce development and progression of DR more than one targeting an HbA(1c) level of 7.0%-7.9% (target median level, 7.5%)? (2) In the context of good glycemic control, does a strategy using a fibrate to increase high-density lipoprotein cholesterol and lower triglyceride levels and a statin to maintain the level of low-density lipoprotein (LDL) cholesterol at <2.59 mmol/L (100 mg/dL) reduce development and progression of DR compared with one using placebo and a statin to treat LDL cholesterol? (3) In the context of good glycemic control, does a strategy targeting a systolic blood pressure level <120 mm Hg reduce development and progression of DR compared with one targeting a level <140 mm Hg? Secondary outcome variables include various levels of loss of visual acuity at 4 years versus baseline, cataract extraction, and the development or progression of diabetic macular edema. Methods to measure DR progression have been incorporated into ACCORD, and complete baseline data have been collected on 3,537 participants. These data will provide valuable information regarding the effects of medical treatment on the prevention and progression of DR.

[Epidemiology of diabetic retinopathy in Lebanon]

AIMS

To assess the prevalence of diabetic retinopathy, evaluate risk factors underlying its development, and assess the epidemiological characteristics of documented diabetes in the Lebanese population.

PATIENTS AND METHOD

The population-based study was conducted in three regions in Lebanon from January 2nd 2000 until June 30th 2000. The study group comprised 112 known diabetic patients who had previously been identified among 4,063 randomly selected individuals. All known diabetic patients underwent an interview, a physical examination, and a thorough retinal examination that included evaluation for the absence or presence of diabetic retinopathy. Retinal examination was performed by an ophthalmologist using direct and indirect ophthalmoscopy through dilated pupils. Several risk factors were then evaluated in order to delineate those related to occurrence of diabetic retinopathy.

RESULTS

The prevalence of known diabetes was 2.95%. Of the 120 known diabetic patients, 112 accepted to be examined. The sex ratio (m:f) was 1.43, the mean patient age was 60.98 years, the mean age at onset of diabetes was 51.75 years, and the mean duration of diabetes was 9.19 years. Type 1 diabetes was found in 1.8% of the patients, whereas 98.2% had type 2 diabetes. Diabetic retinopathy was detected in 19 patients (16.96%). Duration of diabetes, frequency of fundoscopic surveillance, and altered vision were found to be significantly related to the occurrence of diabetic retinopathy.

CONCLUSION

In our study, diabetic retinopathy was found in 16.96% of known diabetic patients, a lower rate than in most of other countries. Most of the diabetic patients (84.82%) were aware that diabetes causes ocular disease, yet only a few (17.85%) were under regular fundoscopic surveillance.

Ambulatory blood pressure monitoring and progression of retinopathy in normotensive, normoalbuminuric type 1 diabetic patients: a 6-year follow-up study

To investigate the relationship between diabetic retinopathy (DR) and 24-h ambulatory blood pressure (ABP) in a cohort of normotensive, normoalbuminuric type 1 diabetic patients. This is a 6.1+/-3.3 year prospective study of 44 normotensive, normoalbuminuric type 1 diabetic patients. ABP was measured at the beginning and at the end of the study. Measurements of urinary albumin excretion rate (UAER) and direct and indirect ophthalmoscopy after mydriasis were performed at the start and end of the study and at least once a year. DR was observed in 12 patients at baseline. At the end of the study, eight of these patients had progressed to more advanced stages of retinopathy. Four patients developed retinopathy after the study began. These patients were grouped and classified as progressors. At baseline, progressors were older, had longer duration of diabetes, higher levels of UAER, and higher 24-h diastolic (P=0.03) and diurnal diastolic blood pressure (P=0.03). UAER and diastolic blood pressure (24h or day) remained significantly associated with development and progression of DR after multivariate analysis. High normal ABP was associated with the development or progression of DR in this cohort of normotensive, normoalbuminuric type 1 diabetic patients. Abnormalities in blood pressure homeostasis could indicate higher susceptibility to DR.

Association of serum lipids with diabetic retinopathy in urban South Indians--the Chennai Urban Rural Epidemiology Study (CURES) Eye Study--2

AIMS

To study the association of serum lipids with diabetic retinopathy (DR) in Type 2 diabetic subjects.

METHODS

Type 2 diabetic subjects (n = 1736) were randomly selected from the Chennai Urban Rural Epidemiology Study (CURES), which was carried out on a representative population of Chennai in South India. DR was diagnosed by retinal colour photography and classified according to the Early Treatment Diabetic Retinopathy Study (ETDRS) grading system. Classification of lipid abnormalities was done according to the National Cholesterol Education Programme-Adult Treatment Panel III (NCEP-ATP III) Guidelines.

RESULTS

The mean serum cholesterol (P = 0.024), serum triglycerides (P = 0.017) and non-high-density lipoprotein (HDL)-cholesterol (P = 0.025) concentrations were higher in subjects with DR compared with those without DR. Multiple logistic regression analysis revealed that after adjusting for age, gender, duration of diabetes, total cholesterol Standardised regression estimate (SRE) = 1.178, 95% confidence interval (CI) 1.042, 1.331, P = 0.014), non-HDL-cholesterol (SRE = 1.169, 95% CI 1.040, 1.313, P = 0.012) and serum triglycerides (SRE = 1.292, 95% CI 1.136, 1.467, P = 0.001) were associated with DR and non-HDL-cholesterol (SRE = 1.264, 95% CI 1.000, 1.592, P = 0.045) and low-density lipoprotein (LDL)-cholesterol (SRE = 1.453, 95% CI 1.107, 1.896, P = 0.005) with diabetic macular oedema (DME). After adjusting for HbA(1c) and body mass index, only triglycerides maintained a significant association with DR (SRE = 1.137, 95% CI 1.000, 1.291, P = 0.007) and LDL-cholesterol with macular oedema (SRE = 1.358, 95% CI 1.034, 1.774, P = 0.026).

CONCLUSIONS

There is a significant association of serum triglycerides with DR and LDL-cholesterol with DME.

The prevention of diabetic microvascular complications of diabetes: is there a role for lipid lowering?

The role of hyperglycemia in the development of microvascular complications of diabetes, such as nephropathy, retinopathy and neuropathy, has been well documented. Evidence is accumulating to support the concept that dyslipidemia can also contribute to the development of these complications. Lipid-lowering agents, such as statins, have been shown to prevent cardiovascular events in patients with diabetes. However, in addition to preventing macrovascular diseases, statins may also be able to retard the progression of microvascular complications of diabetes. Indeed, in addition to reducing lipid levels, these agents can improve endothelial function and reduce oxidative stress, which can improve microvascular function. These findings would provide further support for the use of lipid-lowering agents in patients with diabetes.

Funduscopic findings following cataract extraction by means of phacoemulsification in diabetic dogs: 52 cases (1993-2003)

OBJECTIVE

To determine prevalence of retinal hemorrhages and microaneurysms in dogs with diabetes mellitus following cataract extraction by means of phacoemulsification and identify potential risk factors.

DESIGN

Retrospective study.

PROCEDURE

Medical records of dogs undergoing phacoemulsification between 1993 and 2003 were reviewed, and information was recorded on signalment, history, physical examination findings, ophthalmic examination findings, results of laboratory testing, electroretinographic findings, and surgical findings. Glycemic control was classified as poor, intermediate, or good on the basis of baseline blood glucose concentration, perioperative body weight loss, daily insulin dosage, and presence of glucosuria and ketonuria. Data from diabetic and nondiabetic dogs were analyzed to determine prevalence and risk factors for development of retinal hemorrhages or microaneurysms following phacoemulsification.

RESULTS

11 of the 52 (21%) dogs with diabetes mellitus developed ophthalmoscopic signs of retinal hemorrhages or microaneurysms, compared with 1 of the 174 (0.6%) nondiabetic dogs. Median time from onset of diabetes mellitus to diagnosis of retinopathy was 1.4 years (range, 0.5 to 3.2 years). No risk factors for development of retinopathy were identified.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that retinal hemorrhages and microaneurysms may be more common and develop earlier in diabetic dogs than previously reported. This may affect treatment, as diabetic dogs survive longer with improved glycemic control.

The role of lipids in the development of diabetic microvascular complications: implications for therapy

Dyslipidemia is a major factor responsible for coronary heart disease and its reduction decreases coronary risk in patients with diabetes mellitus. However, the association of dyslipidemia with microvascular complications and the effect of intervention with lipid-lowering therapy in diabetes have been less investigated. We present the systematic review of association and intervention studies pertaining to dyslipidemia and microvascular disease in diabetes and also review possible mechanisms. Dyslipidemia may cause or exacerbate diabetic retinopathy and nephropathy by alterations in the coagulation-fibrinolytic system, changes in membrane permeability, damage to endothelial cells and increased atherosclerosis. Hyperlipidemia is associated with faster decline in glomerular filtration rate and progression of albuminuria and nephropathy. Recent evidence also suggests a role of lipoprotein(a) in progression of retinopathy and nephropathy in patients with diabetes mellitus. Lipid-lowering therapy, using single agents or a combination of drugs may significantly benefit diabetic retinopathy and diabetic nephropathy. In particular, hydroxymethyl glutaryl coenzyme A reductase inhibitors may be effective in preventing or retarding the progression of microvascular complications because of their powerful lipid-lowering effects and other additional mechanisms. However, most of the data are based on short-term studies, and need to be ascertained in long-term studies. Until more specific guidelines are available, aggressive management of diabetic dyslipidemia, according to currently accepted guidelines, should be continued for the prevention of macrovascular disease which would also benefit microvascular complications.

Growth factors and protein kinase C inhibitors as novel therapies for the medical management diabetic retinopathy

Diabetic retinopathy is a leading cause of acquired visual loss. Current treatment modalities are not effective in all cases and may have side effects. Investigation of the biochemical basis of diabetic retinopathy suggests that future treatments may reverse or halt the progression of diabetic retinopathy, or actually prevent the development of diabetic retinopathy. Pharmacological manipulation of protein kinase C and various growth factors may form the basis of future treatments for diabetic retinopathy.

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.

The Singapore impaired glucose tolerance follow-up study: does the ticking clock go backward as well as forward?

OBJECTIVE

To 1). document the change in glucose tolerance for subjects with normal glucose tolerance (NGT) and impaired glucose tolerance (IGT) over time, 2). identify baseline factors associated with worsening of glucose tolerance, and 3). determine whether cardiovascular disease (CVD) risk factors associated with IGT improved in tandem with glucose tolerance.

RESEARCH DESIGN

Subjects with IGT and NGT (matched for age, sex, and ethnic group) were identified from a cross-sectional survey conducted in 1992. Subjects with IGT (297) and NGT (298) (65.0%) were reexamined in 2000. Glucose tolerance (assessed by 75-g oral glucose tolerance test), anthropometric data, serum lipids, blood pressure, and insulin resistance were determined at baseline and at the follow-up examination.

RESULTS

For NGT subjects, 14.0% progressed to IGT and 4.3% to diabetes over 8 years. For IGT subjects, 41.4% reverted to NGT, 23.0% remained impaired glucose tolerant, and 35.1% developed diabetes. Obesity, hypertriglyceridemia, higher blood pressure, increased insulin resistance, and lower HDL cholesterol at baseline were associated with worsening of glucose tolerance in both IGT and NGT subjects. Those with IGT who reverted to NGT remained more obese and had higher blood pressure than those with NGT in both 1992 and 2000. However, serum triglyceride, HDL cholesterol, and insulin resistance values in 2000 became indistinguishable from those of subjects who maintained NGT throughout the study period.

CONCLUSIONS

Some, but not all, CVD risk factors associated with IGT and with the risk of future diabetes normalize when glucose tolerance normalizes. Continued surveillance and treatment in subjects with IGT, even after they revert to NGT, may be important in the prevention of CVD.

Epidemiology of diabetic retinopathy

Diabetic retinopathy is associated with a number of systemic risk factors, namely hyperglycaemia, elevated blood pressure and dyslipidaemia. Patients with diabetes should be vigorously treated for these modifiable risk factors to prevent the development and progression of diabetic retinopathy.

Haemodynamics in microvascular complications in type 1 diabetes

Type 1 diabetes is commonly associated with microvascular complications. Most of the microvascular blood vessels are involved but those in the kidney, retina and large nerves exhibit the more significant pathology. Haemodynamic and metabolic factors both alone and through the activation of a common pathway contribute to the characteristic dysfunction observed in diabetic vasculopathy. The haemodynamic abnormalities in type 1 diabetes are characterized by increased systemic blood pressure and altered blood flow with subsequent activation of various vasoactive factors, which can contribute to the maintenance of the haemodynamic alterations and to the development and progression of the microvascular complications. These vasoactive factors include vasoconstrictors such as angiotensin II, and endothelin, as well as vasodilators such as nitric oxide (NO). Systemic hypertension and vasoactive factors independently and in interaction with the metabolic pathway activate intracellular second messengers, nuclear transcription factors and various growth factors which lead to the typical functional and structural alterations of diabetic microvascular complications. Therapeutic strategies involved in the management and prevention of diabetic complications currently include antihypertensive agents, particularly those that interrupt the renin-angiotensin system. Further understanding of the interactions among the vasoactive factors, the intracellular second messengers and the growth factors may help to identify novel strategies to influence the action of the vasoactive factors. These novel therapies, together with specific inhibitors of the metabolic pathway or the common pathway, may provide the possibility of preventing or even reversing the progression of diabetic microvascular complications.

Diabetic retinopathy, visual acuity, and medical risk indicators: a continuous 10-year follow-up study in Type 1 diabetic patients under routine care

The objective of this study was to describe incidence and progression of diabetic retinopathy in relation to medical risk indicators as well as visual acuity outcome after a continuous follow-up period of 10 years in a Type 1 diabetic population treated under routine care. The incidence and progression of retinopathy and their association to HbA(1c), blood pressure, urinary albumin, serum creatinine levels, and insulin dosage were studied prospectively in 452 Type 1 diabetic patients. The degree of retinopathy was classified as no retinopathy, background, or sight-threatening retinopathy, i.e. clinically significant macular edema, severe nonproliferative, or proliferative retinopathy. Impaired visual acuity was defined as a visual acuity <0.5 and blindness as a visual acuity < or =0.1 in the best eye. In patients still alive at follow-up (n=344), 61% (69/114) developed any retinopathy, 45% (51/114) background retinopathy, and 16% (18/114) sight-threatening retinopathy. Progression from background to sight-threatening retinopathy occurred in 56% (73/131). In 2% (6/335), visual acuity dropped to <0.5 and in less than 1% (3/340) to < or =0.1. Patients who developed any retinopathy and patients who progressed to sight-threatening retinopathy had higher mean HbA(1c) levels over time compared to those who remained stable (P<.001 in both cases). Patients who developed any retinopathy had higher levels of mean diastolic blood pressure (P=.036), whereas no differences were seen in systolic blood pressure levels between the groups. Cox regression analysis, including all patients, showed mean HbA(1c) to be an independent risk indicator for both development and progression of retinopathy, whereas mean diastolic blood pressure was only a risk indicator for the incidence of retinopathy. Metabolic control is an important risk indicator for both development and progression of retinopathy, whereas diastolic blood pressure is important for the development of retinopathy in Type 1 diabetes. The number of patients who became blind during 10 years of follow-up was low.

Systemic considerations in the management of diabetic retinopathy

PURPOSE

To highlight the systemic factors which affect onset and/or progression of diabetic retinopathy (DR) and to emphasize the role and responsibilities of ophthalmologists and other eye care providers to ensure that appropriate systemic medical evaluation of the patient with diabetes is being pursued.

DESIGN

Literature review of publications relevant to diabetic retinopathy, blood glucose control, diabetes mellitus type, hypertension, renal disease, elevated serum lipids, exercise, pregnancy, anticoagulation, thrombolysis, smoking, anemia and antioxidant ingestion.

FINDINGS

Intensive blood glucose control and control of systemic hypertension reduce the risk of new onset DR and slow the progression of existing DR. Severe DR may be an indicator of renal disease while severe renal disease and its treatment can affect the progression of DR. Elevated serum lipids are associated with macular exudate and moderate visual loss. Certain types of excessive exercise in patients with advanced stages of retinopathy may aggravate vitreous hemorrhage. During pregnancy, DR should be monitored closely as transient progression of DR can occur. Therapeutic anticoagulation and thrombolysis are not contraindicated at any stage of DR. Anemia can result in progression of DR, smoking in general should be discouraged, and the role of antioxidant therapy requires further study.

CONCLUSIONS

Blindness from diabetic retinopathy is now largely preventable with timely detection and appropriate interventional therapy. Routine, repetitive, lifelong, expert clinical retinal examination is essential for the fundamental ophthalmic care of the patient with diabetes. However, diabetes mellitus is a systemic disease and thus optimal ophthalmic care must include diligent evaluation and treatment of concomitant systemic disorders that influence the development, progression and ultimate outcome of diabetic retinopathy. Optimization of these systemic considerations through an intensive, multi-disciplinary, healthcare team-based approach will maximize the ophthalmic and general health of these patients. Ophthalmologists and other eye care providers are critical members of this team with unique responsibilities to ensure that appropriate systemic medical evaluation is being pursued.

Association of plasma fibrinogen level and blood pressure with diabetic retinopathy, and renal complications associated with proliferative diabetic retinopathy, in Type 2 diabetes mellitus

AIM

To clarify the association of several clinical parameters, including plasma fibrinogen level, with diabetic retinopathy in patients with Type 2 diabetes mellitus (DM).

METHODS

A total of 294 Japanese patients with Type 2DM were studied; 53 patients with no diabetic retinopathy (NDR), 90 with background diabetic retinopathy (BDR), and 151 with proliferative diabetic retinopathy (PDR). Multiple logistic regression analysis was performed to assess variables independently associated with diabetic retinopathy in two settings: presence of retinopathy of any severity and presence of advanced retinopathy.

RESULTS

The following parameters were identified as independent factors associated with the presence of diabetic retinopathy (NDR vs. BDR + PDR): type of therapy (P<0.0005), log-transformed plasma fibrinogen level (P < 0.05), mean blood pressure (P < 0.05), and duration of diabetes (P < 0.05). The independent variables associated with advanced retinopathy were type of therapy (P<0.00005), age (P<0.0005) and nephropathy (P<0.05). Body mass index, smoking and hypertensive status, HbA1c and total cholesterol levels were not independently associated.

CONCLUSIONS

These data suggest that in patients with Type 2 DM, an increased blood viscosity due to high fibrinogen level as well as an elevated intravessel pressure play a role in the development of diabetic retinopathy, and that the progression to PDR is influenced or accompanied by the deterioration of renal status.

Monitoring for retinopathy in children and adolescents with type 1 diabetes

In children with an average diabetes onset at 11 y of age, the first retinal changes can be expected after a median diabetes duration of 9 y, while the median time until clinically relevant background retinopathy is 14 y. Periodic examinations of the retinal status become necessary with the onset of puberty or after 5 y of diabetes duration. Only sensitive methods should be used for retinopathy screening; the minimum recommended standard is a stereoscopic slit-lamp biomicroscopic examination in mydriasis. The degree of glycaemic control, both before and after puberty, appears to be of outstanding importance for the development of retinopathy, but the contribution of other factors (arterial blood pressure, lipid abnormalities, sex steroids, smoking and genetic factors) may be of varying relevance in the individual patient. Thus, to improve the long-term prognosis for children with diabetes appropriate screening for retinopathy and associated risk factors is mandatory.

Prevalence and risk factors for diabetic retinopathy among Omani diabetics

AIMS

To study the prevalence of diabetic retinopathy in a population of patients attending a diabetic clinic and to evaluate the medical risk factors underlying its development.

METHODS

500 randomly selected diabetic patients attending the diabetes clinic in Al Buraimi hospital were referred to the ophthalmology department where they were fully evaluated for the absence or presence of retinopathy. Any retinopathy present was graded as mild non-proliferative retinopathy (NPR), moderate-severe NPR, and proliferative retinopathy. Several risk factors were then evaluated in order to delineate those related to occurrence of retinopathy in general as well as to the different grades of retinopathy in particular.

RESULTS

Diabetic retinopathy was detected in 212 patients (42.4%), with mild NPR present in 128 patient (25.6% of the total population), moderate-severe NPR in 20 patients (4%), and proliferative diabetic retinopathy present in 64 patients (12.8%). Factors significantly related to occurrence of retinopathy were age of the patient, duration of diabetes, presence of ischaemic heart disease, presence of hypertension, a high fasting capillary glucose level as well as elevated serum levels of urea, creatinine, cholesterol, and triglycerides. After adjustment for covariates, it was found that duration of diabetes was the only risk factor associated with mild NPR, while high diastolic blood pressure and high levels of serum creatinine, cholesterol, and triglycerides were significantly associated with the occurrence of proliferative retinopathy.

CONCLUSIONS

In addition to glycaemic control, lowering of blood lipids as well as diastolic blood pressure (in hypertensive patients) may be effective in lowering the incidence of retinopathy in compromised patients.

The association between cigarette smoking and ocular diseases

Tobacco smoke is composed of as many as 4,000 active compounds, most of them toxic on either acute or long-term exposure. Many of them are also poisonous to ocular tissues, affecting the eye mainly through ischemic or oxidative mechanisms. The list of ophthalmologic disorders associated with cigarette smoking continues to grow. Most chronic ocular diseases, with the possible exception of diabetic retinopathy and primary open-angle glaucoma, appear to be associated with smoking. Both cataract development and age-related macular degeneration, the leading causes of severe visual impairment and blindness, are directly accelerated by smoking. Other common ocular disorders, such as retinal ischemia, anterior ischemic optic neuropathy, and Graves ophthalmopathy, are also significantly linked to this harmful habit. Tobacco smoking is the direct cause of tobacco-alcohol amblyopia, a once common but now rare disease characterized by severe visual loss, which is probably a result of toxic optic nerve damage. Cigarette smoking is highly irritating to the conjunctival mucosa, also affecting the eyes of nonsmokers by passive exposure (secondhand smoking). The dangerous effects of smoking are transmitted through the placenta, and offspring of smoking mothers are prone to develop strabismus. Efforts should be directed toward augmenting the campaign against tobacco smoking by adding the increased risk of blindness to the better-known arguments against smoking. We should urge our patients to quit smoking, and we must make them keenly aware of the afflictions that can develop when smoke gets in our eyes.