Dyslipidaemia and microvascular disease in the retina

Optical coherence tomography angiography quantitative analysis of retinal and choroidal microvasculature in patients with dyslipidemia

INTRODUCTION

The purpose of this investigation was to report swept source-optical coherence tomography angiography (SS-OCTA) quantitative information of retinal and choroidal microvascularization in patients with dyslipidemia (DL).

METHODS

We performed a retrospective study. The study enrolled 37 eyes of 20 patients with DL and 40 eyes of 23 healthy subjects. OCTA quantitative parameters (vessel density (VD) and foveal avascular zone (FAZ) area of superficial capillary plexus (SCP), middle capillary plexus (MCP), deep capillary plexus (DCP) and choriocapillaris (CC)) in 6 mm × 6 mm and 4,5 mm × 4,5 mm cubes were recorded.

RESULTS

No differences in VD in SCP, MCP and DCP were demonstrated between DL group and control group (p > 0,05). Conversely, VD in the central region at CC was diminished in patients with DL in both cubes (p < 0,05). Moreover, total VD in CC was decreased in the DL group in 6 mm × 6 mm cube (p < 0,05). Regarding FAZ area, we demonstrated and enlargement of FAZ in each retinal capillary plexus, but it did not reach statistical significance (p > 0,05).

CONCLUSION

We objectified a diminution of VD in the CC, suggesting that DL mainly affects the choroidal microvasculature. Nonetheless, further studies with a larger population are needed.

Lipids, hyperreflective crystalline deposits and diabetic retinopathy: potential systemic and retinal-specific effect of lipid-lowering therapies

The metabolically active retina obtains essential lipids by endogenous biosynthesis and from the systemic circulation. Clinical studies provide limited and sometimes conflicting evidence as to the relationships between circulating lipid levels and the development and progression of diabetic retinopathy in people with diabetes. Cardiovascular-system-focused clinical trials that also evaluated some retinal outcomes demonstrate the potential protective power of lipid-lowering therapies in diabetic retinopathy and some trials with ocular primary endpoints are in progress. Although triacylglycerol-lowering therapies with fibrates afforded some protection against diabetic retinopathy, the effect was independent of changes in traditional blood lipid classes. While systemic LDL-cholesterol lowering with statins did not afford protection against diabetic retinopathy in most clinical trials, and none of the trials focused on retinopathy as the main outcome, data from very large database studies suggest the possible effectiveness of statins. Potential challenges in these studies are discussed, including lipid-independent effects of fibrates and statins, modified lipoproteins and retinal-specific effects of lipid-lowering drugs. Dysregulation of retinal-specific cholesterol metabolism leading to retinal cholesterol accumulation and potential formation of cholesterol crystals are also addressed.

Higher prevalence of diabetic retinopathy among female Chinese diabetic patients with metabolic syndrome

PURPOSE

To investigate the association between metabolic syndrome (MetS) and diabetic retinopathy (DR), as well as the association between MetS and retinal vessel caliber, among Chinese patients with type 2 diabetes mellitus in north-eastern China.

STUDY DESIGN

Cross-sectional study.

PATIENTS AND METHODS

The patients were recruited from a community-based study, the Fushun Diabetic Retinopathy Cohort Study (FS-DIRECT). The presence of DR was determined using a modified version of the Early Treatment Diabetic Retinopathy Study (ETDRS) scale. The central retinal arteriolar equivalent (CRAE) and the central retinal venular equivalent (CRVE) were identified by use of Integrative Vessel Analysis software. The presence of MetS was defined according to the Joint Interim Statement proposed in 2009.

RESULTS

The prevalence of DR was significantly higher among female patients with MetS than among those without it (47.2% vs 30.9%, P = 0.002), and it increased as the number of MetS components increased (P = 0.003). Furthermore, the presence of MetS (odds ratio 2.43, 95% CI 1.39-4.26) as well as higher numbers of MetS components were significantly associated with DR in female patients, after adjustment for potential risk factors. Patients with MetS (multivariate β coefficient, 95% CI - 6.9, - 10.0, to - 3.8) or a higher number of Mets components tended to have significantly smaller CRAE.

CONCLUSION

In this study cohort, female patients with MetS had a higher prevalence of DR. Patients tended to have thinner central retinal arterioles as the number of MetS components increased.

LDL-Cholesterol versus Glucose in Microvascular and Macrovascular Disease

BACKGROUND

The causal relationships between increased concentrations of low density lipoprotein (LDL)-cholesterol and glucose and risk of ischemic heart disease are well established. The causal contributions of LDL-cholesterol and glucose to risk of peripheral micro- and macrovascular diseases are less studied, especially in prediabetic stages and in a general population setting.

CONTENT

This review summarizes the current evidence for a causal contribution of LDL-cholesterol and glucose to risk of a spectrum of peripheral micro- and macrovascular diseases and reviews possible underlying disease mechanisms, including differences between vascular compartments, and finally discusses the clinical implications of these findings, including strategies for prevention and treatment.

SUMMARY

Combined lines of evidence suggest that LDL-cholesterol has a causal effect on risk of peripheral arterial disease and chronic kidney disease, both of which represent manifestations of macrovascular disease due to atherosclerosis and accumulation of LDL particles in the arterial wall. In contrast, there is limited evidence for a causal effect on risk of microvascular disease. Glucose has a causal effect on risk of both micro- and macrovascular disease. However, most evidence is derived from studies of individuals with diabetes. Further studies in normoglycemic and prediabetic individuals are warranted. Overall, LDL-cholesterol-lowering reduces risk of macrovascular disease, while evidence for a reduction in risk of microvascular disease is inconsistent. Glucose-lowering has a beneficial effect on risk of microvascular diseases and on risk of chronic kidney disease and estimated glomerular filtration rate (eGFR) in some studies, while results on risk of peripheral arterial disease are conflicting.

Optic disc and peripapillary vessel density measured with optical coherence tomography angiography and its associations in Chinese adults: a large population-based study

PURPOSE

To investigate the optic disc and peripapillary vessel density, as well as its ocular and systemic associations, in healthy eyes among adult Chinese population.

METHODS

A population-based cross-sectional eye survey was conducted on Chinese adults residing in Hong Kong. 1891 eyes from 1891 participants who completed 4.5×4.5 mm optical coherence tomography angiography scans were recruited. Among the 1891 eyes, 404 were excluded due to low scan quality, optic disc or retinal disorders and non-Chinese ethnicity. The vessel densities (VDs) at nerve fibre layer plexus (NFLP) at both optic disc and peripapillary were collected for analysis. Multiple linear regression analysis was performed to determine the ocular and systemic associations of NFLP VD.

RESULTS

The study included 1487 participants (men: 41.2%) with a mean age of 48.8±15.4 years. The mean NFLP VD of the whole en face image, inside disc and peripapillary region was 53.8%, 42.7% and 60.3%, respectively. In the multivariable model, decreased NFLP VDs were significantly associated with older age, male gender, longer axial length (AL) and lower Signal Strength Index.

CONCLUSIONS

This large population-based cross-sectional study provided quantitative data of optic disc and peripapillary NFLP VD which may serve as a normative reference for clinical use. Apart from age, gender and AL, the scan signal strength also should be taken into consideration during the assessment of NFLP VD.

Radial Peripapillary Capillary Plexus Sparing and Underlying Retinal Vascular Impairment in Intermediate Age-Related Macular Degeneration

Purpose

To examine location-specific retinal vascular changes in intermediate age-related macular degeneration (iAMD) using age-matched, high-density en face optical coherence tomography angiography (OCTA) cluster analysis.

Methods

En face OCTA images of the 6 × 6 mm macular area were retrospectively acquired from 60 iAMD eyes and 60 age-matched normal eyes and then subdivided into 126 × 126 (47.62 × 47.62 µm) grids within the superficial and deep vascular complex. Grid-wise vessel perfusion (VP) were compared between iAMD and normal eyes from the corresponding 10-yearly age cohort, forming difference plots. Difference plots were further separated by normative topographical map spatial clusters (C_1-6), derived from normal_database eyes (n = 236, 20–81 years old).

Results

Overall difference plots showed decreased VP in the superficial (−12.19%) and deep vascular complex (−6.44%) of iAMD compared to normal eyes (P < 0.0001 both comparisons). Cluster-based difference plots highlighted nonuniform changes in the superficial vascular complex, with sparing of VP at the nasal macula (corresponding to the radial peripapillary capillary plexus) versus decreased VP toward the temporal macula and foveal avascular zone (FAZ) (C_1–6 all comparisons P < 0.0001, except C₁ vs. C₂P > 0.99 and C₄ vs. C₅P = 0.11). The deep vascular complex displayed diffusely decreased VP, greater at the FAZ (P < 0.0001).

Conclusions

High-density en face OCTA cluster analysis suggests relative sparing of the radial peripapillary capillary plexus and impairment of underlying retinal vasculature, supporting potential anterograde transsynaptic degeneration in iAMD. These location-specific data may better guide future diagnostic and management protocol of iAMD.

Impact of cardiometabolic factors on retinal vasculature: A 3 × 3, 6 × 6 and 8 × 8-mm ocular coherence tomography angiography study

BACKGROUND

Ocular coherence tomography angiography (OCTA) is available in varying size and resolution. We sought to characterise associations of cardiometabolic factors with retinal microvascular changes using 3 × 3, 6 × 6 and 8 × 8-mm OCTA scans to determine differences in detection with varying scan size.

METHODS

Cross-sectional study of 247 cardiovascular patients from a single-centre tertiary-care hospital. Demographic, comorbidity and medication data were obtained. Patients underwent 3 × 3, 6 × 6 and 8 × 8-mm macula OCTA scanning using Carl Zeiss CIRRUS HD-OCT Model 5000. Angioplex and AngioTool software was used to quantify vascular parameters in the superficial capillary plexus.

RESULTS

Increasing age, hypertension, dyslipidaemia, diabetes, chronic kidney disease, coronary artery disease and peripheral vascular disease were associated with reductions in vessel density, vessel perfusion, average vessel length and/or junction density in 3 × 3-mm OCTA (P < .05 for all). Conversely, smoking was associated with increased vessel density, vessel length and junction density in 3 × 3-mm OCTA (P < .05 for all). Associations of vessel abnormalities with cardiometabolic factors were progressively weakened and statistically attenuated in 6 × 6 and 8 × 8-mm OCTA scans. In multivariate analyses, dyslipidaemia remained an independent predictor of reduced vessel density, average vessel length and junction density (P < .05).

CONCLUSIONS

Cardiometabolic factors are associated with multiple retinal microvascular changes in 3 × 3-mm OCTA scans. These associations were weakened and progressively attenuated in OCTA scans of larger 6 × 6 and 8 × 8-mm size. These findings advance our understanding of microcirculatory dysfunction and may have future implications for the screening and management of patients with cardiometabolic risk factors. Additional studies are required to further investigate these important associations.

Six-year incidence and systemic associations of retinopathy in a multi-ethnic Asian population without diabetes

PURPOSE

We described the 6-year incidence and changes of retinopathy, and their associated risk factors in a multi-ethnic Asian population without diabetes.

METHODS

We included 4374 participants with non-diabetes from a population-based cohort, the Singapore Epidemiology of Eye Disease Study, with gradable retinal photographs at baseline and 6-year follow-up visit. Retinopathy was assessed according to the modified Airlie House classification system.

RESULTS

Over the 6-year period, the cumulative rates were 2.5% (106/4279) for retinopathy incidence, 1.0% (1/95) for retinopathy progression and 68.4% (65/95) for retinopathy regression. In multivariable analysis, higher diastolic blood pressure (DBP) (risk ratio (RR)=1.02; 95% CI: 1.00 to 1.04; per 10 mm Hg increase in DBP) and wider retinal arteriolar calibre (RR=1.36; 95% CI: 1.13 to 1.63; per SD increase in central retinal artery equivalent) were associated with higher risk of incident retinopathy, while higher level of high-density lipoprotein (HDL) was associated with lower risk of incident retinopathy (RR=0.56; 95% CI: 0.32 to 0.99; per mmol/L increase in HDL). Compared with Chinese, Malays were more likely to have retinopathy regression (RR=1.63; 95% CI: 1.20 to 2.22), while overweight (RR=0.47; 95% CI: 0.26 to 0.84) and higher glycosylated haemoglobin (HbA1c) level (RR=0.58; 95% CI: 0.37 to 0.93; per per cent increase in HbA1c) were associated with lower likelihood of retinopathy regression.

CONCLUSION

Risk of developing retinopathy in Asians without diabetes is generally low. However, regression of retinopathy over time is common, suggesting that these retinopathy signs may reflect subclinical reversible microvascular dysfunction. Several metabolic risk factors are associated with incidence or regression of retinopathy, suggesting that good metabolic control may still be important in the management of non-diabetic retinopathy.

Identification of aberrantly expressed circular RNAs in hyperlipidemia-induced retinal vascular dysfunction in mice

Hyperlipidemia-induced retinal vascular dysfunction is a complex pathological process. circRNAs are important regulators of biological processes and disease progression. However, the expression pattern of circRNAs in hyperlipidemia-induced retinal vascular dysfunction remains unclear. Herein, we used a murine model of hyperlipidemia and identified 317 differentially expressed circRNAs between hyperlipidemic retinas and normolipidemic retinas by circRNA microarrays. GO analysis indicated that the host genes of dysregulated circRNAs were targeted to cell differentiation (ontology: biological process), cytoplasm (ontology: cellular component), and protein binding (ontology: molecular function). Pathway analysis revealed that circRNAs-mediated network was mostly enriched in focal adhesion signaling. Notably, circLDB1 was significantly up-regulated in the serum of coronary artery disease patients and aqueous humor of age-related macular degeneration patients. circLDB1 regulated endothelial cell viability, proliferation, and apoptosis in vitro. Thus, circRNAs are the promising targets for the prediction and diagnosis of hyperlipidemia-induced vascular diseases.

Association of Fenofibrate and Diabetic Retinopathy in Type 2 Diabetic Patients: A Population-Based Retrospective Cohort Study in Taiwan

Background and Objectives: Fenofibrate, a PPAR-α agonist, has been demonstrated to reduce the progression of diabetic retinopathy (DR) and the need for laser treatment in a FIELD (Fenofibrate Intervention and Event Lowering in Diabetes) study. However, in the subgroup of patients without pre-existing DR, there was no significant difference in the progression of DR between the fenofibrate group and the placebo group. In this study, we aim to investigate whether fenofibrate can decrease the risk of incident DR in a population-based cohort study of type 2 diabetic patients in Taiwan. Materials and Methods: A total of 32,253 type 2 diabetic patients without previous retinopathy were retrieved from 892,419 patients in 2001-2002. They were then divided into two groups based on whether they were exposed to fenofibrate or not. The patients were followed until a diagnosis of diabetic retinopathy was made or until the year 2008. Results: With a follow-up period of 6.8 ± 1.5 years and 5.4 ± 2.6 years for 2500 fenofibrate users and 29,753 non-users, respectively, the Cox proportional hazard regression analysis revealed that the hazard ratio (HR) of new onset retinopathy was 0.57 (95% CI 0.57-0.62, p < 0.001). After adjusting for hypertension; the Charlson comorbidity index (CCI); and medications such as angiotensin-converting enzyme inhibitors (ACE-I), angiotensin receptor blockers (ARB), anticoagulants, gemfibrozil, statins, and hypoglycemic agents, the adjusted HR was 0.75 (95% CI 0.68-0.82, p < 0.001). The need for laser treatment has an HR and adjusted HR of 0.59 (95% CI 0.49-0.71, p < 0.001) and 0.67 (95% CI 0.56-0.81, p < 0.001), respectively. Conclusion: Our study showed that the long-term and regular use of fenofibrate may decrease the risk of incident retinopathy and the need for laser treatment in type 2 diabetic patients. Since there are limitations associated with our study, further investigations are necessary to confirm such an association.

Effects of Rosuvastatin and Aspirin on Retinal Vascular Structures in Hypercholesterolemic Patients with Low-to-Moderate Risk of Coronary Artery Disease

INTRODUCTION

Atherosclerosis erodes large elastic arteries and damages peripheral small vessels. Evaluating retinal vessel caliber enables exploration of the effect of improving microcirculation with statins.

OBJECTIVE

We investigated whether rosuvastatin therapy improves retinal vasculature in hypercholesterolemic patients with a low-to-moderate risk of coronary artery disease (CAD).

METHODS

This was a prospective, open-label, randomized study in which 127 patients were enrolled and randomized (ratio 1:1) into rosuvastatin and control groups.

RESULTS

Rosuvastatin increased retinal arteriolar calibers by 3.560 µm at 12 months, decreased retinal venular calibers by 3.110 µm at 6 months and by 5.860 µm at 12 months, and increased the artery-vein ratio (AVR) by 2.68% at 6 months and by 5.90% at 12 months. Meanwhile, in the control group, retinal arteriolar calibers decreased by 1.110 µm at 12 months, retinal venular calibers increased by 1.020 µm at 6 months and by 1.04 µm at 12 months, and AVR decreased by 1.12% at 6 months and by 1.73% at 12 months. All the above parameters were statistically significant between groups, but there was no significant change in retinal arteriolar calibers at 6 months. The increased AVR correlated significantly with decreased C-reactive protein (CRP) at 6 months and decreased low-density lipoprotein and CRP at 12 months.

DISCUSSION

For patients with a low-to-moderate risk of CAD, we found a significant effect of rosuvastatin on retinal microvasculature, including AVR increase, venular constriction, and arteriolar dilation after 6-12 months of treatment.

CLINICAL TRIAL REGISTRATION

Chinese Clinical Trial Registry identifier number ChiCTR-IOR-15006664.

Serum lipid profiles and dyslipidaemia are associated with retinal microvascular changes in children and adolescents

The present study aims to assess the relationship between serum lipid parameters and retinal microvascular calibres in children and adolescents. A total of 950 participants aged 7 to 19 years were recruited. Central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) were measured from digital retinal images. Serological testing was performed to obtain lipid profiles. Dyslipidaemia was defined according to the US national expert panel guideline. After adjusted for age, sex, mean arterial blood pressure, axial length, body mass index and the fellow retinal vascular calibre, no significant association was found between retinal vascular diameters and any lipid parameters (all P > 0.05) in children younger than 12 years. Among the adolescents 12 years and older, increased triglycerides, total cholesterol, low-density lipoprotein cholesterol, and apoB were associated with decrease in CRAE (β = −1.33, −1.83, −1.92 and −7.18, P = 0.031, 0.003, 0.006, and 0.009, respectively). Compared with normolipidemic counterparts, adolescents with dyslipidaemia had significantly narrower retinal arteriolar diameters. No significant relationship between lipid subclass levels and CRVE was revealed in adolescents. The present findings suggest that the elevation of atherogenic lipids in adolescents is closely related to the adverse changes of retinal arterioles. Dyslipidaemia may affect systemic microvasculature from childhood on.

Retinal Vessel Diameters and Their Relationship with Cardiovascular Risk and All-Cause Mortality in the Inter99 Eye Study: A 15-Year Follow-Up

Purpose. To describe associations between retinal vessel diameters and cardiovascular risk markers and mortality. Methods. The present study included 908 persons aged 30 to 60 years. Vessel diameters were expressed as central retinal venular equivalent (CRVE) and central retinal arteriolar equivalent (CRAE). Multiple linear regression analyses and Cox regression models were used. Results. Multiple linear regression analyses showed that narrower CRAE was associated with higher systolic blood pressure, age, and higher HDL cholesterol, whereas wider CRAE and CRVE were associated with smoking. Narrower CRVE was associated with higher HDL cholesterol. In an age-adjusted model, associations between wider CRVE and risk of ischemic heart disease were found (P < 0.001). Wider CRVE was associated with all-cause mortality (HR = 2.02, P = 0.033) in a model adjusted for age, gender, and blood pressure. However, the association was not statistically significant after additional adjustment for smoking. Conclusions. The associations between retinal vessel diameters and known cardiovascular risk factors were confirmed. All-cause mortality was not associated with retinal vessel diameters when adjusting for relevant confounders.

Lipids and Diabetic Retinopathy

The relationship between lipids and the development and/or severity of diabetic retinopathy (DR) is complex. Large epidemiologic studies suggest an inconsistent and overall modest association between serum triglycerides or major cholesterol species and the severity of DR; however, certain specific lipoprotein species may have stronger associations with DR severity, suggesting a pathophysiological role for lipoproteins analogous to that seen in atherosclerosis. In this lipoprotein-mediated DR pathogenesis model, damage to the blood-retinal barrier allows extravasation of lipoprotein species, which are modified in the intraretinal environment, creating substantial local damage. Additionally, hypolipidemic therapy with statins and fibrates--particularly the latter--have been shown to modulate DR in large-scale studies. Since serum lipid profile changes do not necessarily correlate with DR modulation, the efficacy of these agents may be due to their tissue-specific changes in lipoproteins and/or their anti-inflammatory, antioxidative, antiangiogenic, and antiapoptotic functions.

Retinal vessel structure measurement using spectral-domain optical coherence tomography

PURPOSE

To assess the reliability and validity of spectral-domain optical coherence tomography (SD-OCT) measurements of retinal vessel lumen diameters and wall thicknesses.

METHODS

SD-OCT was used to characterize the circular region around the optic disc of 40 eyes (20 subjects). The inner and outer sides (vitreal and choroidal sides) of the vessel wall and the luminal diameter were measured using intensity graphs.

RESULTS

Mean arterial and venous luminal diameters were 95.1±16.1 and 132.6±17.8 μm, respectively. The wall thicknesses of inner and outer sides of the artery were 23.9±4.9 and 21.2±3.5 μm, respectively. The wall thicknesses of the inner and outer sides of the vein were 20.7±4.2 and 16.3±4.3 μm, respectively. There were significant differences between the inner and outer wall thicknesses in both the artery and vein (P<0.01). Intra- and interobserver intraclass correlation coefficients (ICCs) for lumen measurements were >0.95, and for wall thicknesses were >0.85, except for the outer wall thickness measurements. The mean value of outer and inner wall thicknesses showed good reproducibility, with ICCs of >0.85.

CONCLUSION

Intensity graph-assisted measurements using SD-OCT provided more objective information in finding boundaries of vessels. Luminal diameters and wall thicknesses obtained with OCT showed good overall reproducibility, with inner wall thicknesses being thicker, and with better reproducibility compared with outer wall thicknesses, where ICC values were the lowest among the inner wall thicknesses, mean thicknesses of inner and outer walls, and luminal diameters. When using SD-OCT measurements, caution is therefore advised when using only the outer wall as representative of the wall thicknesses.

Body fat distribution, metabolic and inflammatory markers and retinal microvasculature in school-age children. The Generation R Study

OBJECTIVE

To examine the associations of body fatness, metabolic and inflammatory markers with retinal vessel calibers among children.

DESIGN

We performed a population-based cohort study among 4145 school-age children. At the median age of 6.0 years (95% range 5.8, 8.0 years), we measured body mass index, total and abdominal fat mass, metabolic and inflammatory markers (blood levels of lipids, insulin and C-peptide and C-reactive protein) and retinal vascular calibers from retinal photographs.

RESULTS

We observed that compared with normal weight children, obese children had narrower retinal arteriolar caliber (difference -0.21 s.d. score (SDS; 95% confidence interval (CI) -0.35, -0.06)), but not venular caliber. Continuous analyses showed that higher body mass index and total body fat mass, but not android/gynoid fat mass ratio and pre-peritoneal fat mass, were associated with narrower retinal arteriolar caliber (P<0.05 for body mass index and total body fat mass), but not with retinal venular caliber. Lipid and insulin levels were not associated with retinal vessel calibers. Higher C-reactive protein was associated with only wider retinal venular caliber (difference 0.10 SDS (95% CI 0.06, 0.14) per SDS increase in C-reactive protein). This latter association was not influenced by body mass index.

CONCLUSIONS

Higher body fatness is associated with narrower retinal arteriolar caliber, whereas increased C-reactive protein levels are associated with wider retinal venular caliber. Increased fat mass and inflammation correlate with microvascular development from school-age onwards.

Retinal vascular abnormalities in neovascular age-related macular degeneration

PURPOSE

To determine the prevalence of retinal vascular abnormalities (RVA) in neovascular age-related macular degeneration (AMD).

METHODS

A post hoc subanalysis of images acquired during a Phase III randomized controlled trial was undertaken, selecting images from participants with untreated, neovascular AMD in at least one eye. Protocol mandated fundus photographs and fluorescein angiograms were acquired at baseline and Year 2, from 107 sham-treated study eyes with neovascular AMD and 107 untreated fellow eyes. Images were reanalyzed by an independent reading center for the presence of RVA, defined as at least one of the following: microaneurysms, vessel staining or leakage, dilated or tortuous vessels, intraretinal hemorrhage, vessel sheathing or narrowing, capillary nonperfusion, or capillary infarcts.

RESULTS

The baseline prevalence of RVA in the sham-treated study eyes was 14.4% (15 of 104 gradable images) versus 8.3% (5 of 60) in the fellow eyes with dry AMD. The baseline prevalence of individual RVAs in study eyes was: microaneurysms (6.7%), vessel staining or leakage (6.7%), dilated or tortuous vessels (4.8%), intraretinal hemorrhage (4.8%), vessel sheathing or narrowing (2.9%), capillary nonperfusion (0%), and capillary infarcts (0%). Results were similar at 24 months.

CONCLUSION

Compared with several studies that relied solely on fundus photographs, this study included fluorescein angiography and found a higher prevalence of RVAs occurring in eyes with neovascular AMD.

The association between retinal vascular geometry changes and diabetic retinopathy and their role in prediction of progression--an exploratory study

Background

The study describes the relationship of retinal vascular geometry (RVG) to severity of diabetic retinopathy (DR), and its predictive role for subsequent development of proliferative diabetic retinopathy (PDR).

Methods

The research project comprises of two stages. Firstly, a comparative study of diabetic patients with different grades of DR. (No DR: Minimal non-proliferative DR: Severe non-proliferative DR: PDR) (10:10: 12: 19). Analysed RVG features including vascular widths and branching angles were compared between patient cohorts. A preliminary statistical model for determination of the retinopathy grade of patients, using these features, is presented. Secondly, in a longitudinal predictive study, RVG features were analysed for diabetic patients with progressive DR over 7 years. RVG at baseline was examined to determine risk for subsequent PDR development.

Results

In the comparative study, increased DR severity was associated with gradual vascular dilatation (p = 0.000), and widening of the bifurcating angle (p = 0.000) with increase in smaller-child-vessel branching angle (p = 0.027). Type 2 diabetes and increased diabetes duration were associated with increased vascular width (p = <0.05 In the predictive study, at baseline, reduced small-child vascular width (OR = 0.73 (95% CI 0.58-0.92)), was predictive of future progression to PDR.

Conclusions

The study findings suggest that RVG alterations can act as novel markers indicative of progression of DR severity and establishment of PDR. RVG may also have a potential predictive role in determining the risk of future retinopathy progression.

Retinal vascular caliber and metabolic syndrome in a Chinese population

BACKGROUND

Microvascular changes have been associated with the metabolic syndrome.

METHODS

We included 869 participants aged ≥ 40 years from the High-risk for Diabetes Changfeng Study, who had gradable fundus photographs. On digital photographs sum retinal arteriolar and venular calibers were measured with a semi-automated system. Metabolic syndrome was defined according to the International Diabetes Federation consensus.

RESULTS

A total of 286 (32.9%) participants was diagnosed with metabolic syndrome. Participants with narrower retinal arteriolar caliber were more often diagnosed with metabolic syndrome (odds ratio 1.78, 95% confidence interval 1.02 – 3.10; lowest vs highest quintile). Additionally adjusting for age, gender, education, smoking and weekly activity, and adding arteriolar and venular caliber simultaneously in the same models did not alter these associations. In the component analyses, participants with narrower retinal arteriolar caliber were more likely to have central obesity, dyslipidaemia or raised blood pressure, and less likely to have raised fasting plasma glucose. The association between wider venular caliber and metabolic syndrome was less pronounced and non-significant (odds ratio 1.34; 95% confidence interval 0.79 – 2.38; highest vs lowest quintile).

CONCLUSION

Retinal arteriolar narrowing and, to a lesser extent, retinal venular dilatation were associated with metabolic syndrome in this Chinese population. These vascular changes, although small in magnitude, may still be important in the pathophysiological mechanisms involved in the metabolic syndrome.

Review of the role of refined dietary sugars (fructose and glucose) in the genesis of retinal disease

This review examines the current evidence of the relationship between sugar consumption and the development of retinal and other eye diseases including diabetic retinopathy, hypertensive retinopathy, age-related macular degeneration, non-arteritic anterior ischaemic optic neuropathy and cataract. Sucrose is comprised of fructose and glucose. Sugar consumption has increased five-fold over the last century, with high quantities of sucrose and high-fructose corn syrup found in processed food and soft drinks. This increased consumption is increasingly recognized as a central factor in the rapidly rising rates of obesity and type 2 diabetes. The body metabolizes fructose and glucose differently, with fructose appearing to have the greater propensity to contribute to the metabolic syndrome. This review examines the effect of high rates of dietary consumption of refined carbohydrates on the eye, including the effect of chronic hyperglycaemia on microvascular disease in diabetic retinopathy, and the pathophysiological changes in the retinal circulation in hypertensive retinopathy.

Retinal vascular calibres are significantly associated with cardiovascular risk factors: the Tromsø Eye Study

PURPOSE

To describe the association between retinal vascular calibres and cardiovascular risk factors.

METHODS

Population-based cross-sectional study including 6353 participants of the Tromsø Eye Study in Norway aged 38-87 years. Retinal arteriolar calibre (central retinal artery equivalent) and retinal venular calibre (central retinal vein equivalent) were measured computer-assisted on retinal photographs. Data on blood pressure, body mass index (BMI), high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, glycosylated haemoglobin (HbA1c) and smoking were collected. Association between retinal vessel calibre and the cardiovascular risk factors was assessed by multivariable linear and logistic regression analyses.

RESULTS

Retinal arteriolar calibre was independently associated with age, blood pressure, HbA1c and smoking in women and men, and with HDL cholesterol in men only. Blood pressure had the strongest effect on arteriolar calibre, with a decrease in calibre of 3.6 μm (women)/4.1 μm (men) per standard deviation increase in mean arterial blood pressure. Retinal venular calibre was independently associated with age, blood pressure, BMI, HDL and LDL cholesterol and smoking in men and women. The effect of BMI and HDL cholesterol on venular calibre was sigifnicantly stronger in men than in women. Current smoking was the most important factor for venular calibre, where smokers had 13.2 μm (women)/15.2 μm (men) wider calibre than nonsmokers.

CONCLUSION

All the explored cardiovascular risk factors were independently associated with retinal vascular calibre, with stronger effect of HDL cholesterol and BMI in men than in women. Blood pressure and smoking contributed most to the explained variance.

Low HDL cholesterol and the risk of diabetic nephropathy and retinopathy: results of the ADVANCE study

OBJECTIVE

Although low HDL cholesterol (HDL-C) is an established risk factor for atherosclerosis, data on HDL-C and the risk of microvascular disease are limited. We tested the association between HDL-C and microvascular disease in a cohort of patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

A total of 11,140 patients with type 2 diabetes and at least one additional vascular risk factor were followed a median of 5 years. Cox proportional hazards models were used to assess the association between baseline HDL-C and the development of new or worsening microvascular disease, defined prospectively as a composite of renal and retinal events.

RESULTS

The mean baseline HDL-C level was 1.3 mmol/L (SD 0.45 mmol/L [range 0.1-4.0]). During follow-up, 32% of patients developed new or worsening microvascular disease, with 28% experiencing a renal event and 6% a retinal event. Compared with patients in the highest third, those in the lowest third had a 17% higher risk of microvascular disease (adjusted hazard ratio 1.17 [95% CI 1.06-1.28], P = 0.001) after adjustment for potential confounders and regression dilution. This was driven by a 19% higher risk of renal events (1.19 [1.08-1.32], P = 0.0005). There was no association between thirds of HDL-C and retinal events (1.01 [0.82-1.25], P = 0.9).

CONCLUSIONS

In patients with type 2 diabetes, HDL-C level is an independent risk factor for the development of microvascular disease affecting the kidney but not the retina.

Associations between metabolic syndrome and syndrome components and retinal microvascular signs in a rural Chinese population: the Handan Eye Study

BACKGROUND

Our purpose was to determine the relationship of metabolic syndrome (MetS) and its components with retinal microvascular abnormalities in a rural Chinese population.

METHODS

The Handan Eye Study, a population-based survey, recruited 6,830 (90.4 % of eligible) rural Chinese ≥30 years of age. A diagnosis of metabolic syndrome was based on the International Diabetes Federation definition. Retinal microvascular signs and arteriolar and venular diameters were assessed from fundus photographs by graders who were trained at the Retinal Vascular Imaging Centre, University of Melbourne.

RESULTS

After adjusting for age, gender, and smoking status, 5,519 participants with MetS, or with the specific components of large waist circumference, elevated blood pressure (BP), or elevated fasting blood glucose (FG), were more likely to have retinopathy, arteriovenous nicking, focal arteriolar narrowing, enhanced arteriolar wall reflex, and generalized retinal arteriolar narrowing than those without MetS or the corresponding component. Individuals with elevated triglycerides were significantly more likely to have arteriovenous nicking and retinopathy.

CONCLUSION

These results show that individual components of MetS are associated with different retinal microvascular signs and with changes in retinal arteriolar and venular diameters.

Fenofibrate - a potential systemic treatment for diabetic retinopathy?

PURPOSE

To review clinical and experimental data for fenofibrate as a possible systemic treatment for diabetic retinopathy.

DESIGN

Perspective.

METHODS

Review of clinical studies focused on 2 major randomized controlled trials: the FIELD (Fenofibrate Intervention and Event Lowering in Diabetes) and ACCORD (Action to Control Cardiovascular Risk in Diabetes)-Eye studies. Progression was defined in FIELD as laser treatment for proliferative retinopathy or macular edema or increase by ≥ 2 steps on the Early Treatment Diabetic Retinopathy Study (ETDRS) scale, and in ACCORD-Eye as ≥ 3 steps (ETDRS scale) or proliferative disease requiring laser or vitrectomy treatment. Experimental studies investigating the mode of action of fenofibrate were reviewed.

RESULTS

The 2 trials included 11 388 patients with type 2 diabetes mellitus, of whom 5701 were treated with fenofibrate (± statin) for up to 5 years. Fenofibrate reduced first laser treatment by 31% (P = .0002), and progression of diabetic retinopathy with absolute reductions of 5.0% over 5 years (P = .022, FIELD) and 3.7% over 4 years (P = .006, ACCORD-Eye). There was greater benefit in patients with than without preexisting retinopathy. The putative mechanisms implicated in the mode of action of fenofibrate involve lipid and nonlipid pathways, including beneficial effects on apoptosis, oxidative stress, inflammation, blood-retinal barrier breakdown, and neuroprotection.

CONCLUSIONS

There are now robust and consistent clinical data to recommend fenofibrate as an adjunctive treatment for early diabetic retinopathy in patients with type 2 diabetes mellitus, taking into account the risks vs benefits of therapy. Further elucidating its mode of action will help to refine how best to use fenofibrate in the management of diabetic retinopathy.

Association of retinal microvascular caliber with blood pressure levels

BACKGROUND

The most common ophthalmologic manifestation of hypertension is hypertensive retinopathy. Our study was designed to evaluate the factors that determine retinal vessel caliber in hypertensive subjects.

METHODS

During a 6-month period, retinal photographs were taken of participants during a routine yearly check-up. The photographs were evaluated by an ophthalmologist and the diameters of the individual retinal vessels were measured and summarized by a computer program. Data including patient's medical history, physical examination and laboratory evaluations were collected. The findings of the ophthalmologic examinations were analyzed with respect to the relevant systemic data.

RESULTS

We evaluated 285 subjects (43 women) with an average age of 62 ± 9 years (range 33-87). Hypertension was reported in 204 (71.6%) subjects and diabetes mellitus in 60 subjects (21%). The arteriolar calibers were inversely related to age (R = - 017; p = 0.01). Retinal arteriolar and venular calibers were wider in smokers and in subjects with dyslipidemia. History of hypertension was not associated with any vascular changes. However, retinal arteriolar caliber was inversely related to blood pressure levels. Diuretic treatment was associated with narrow retinal venular caliber.

CONCLUSION

The association between different cardiovascular risk factors and hypertensive retinopathy is complex. Effective blood pressure control has a beneficial effect on the vascular changes in the retina.

Dyslipidemia and eye diseases in the adult Chinese population: the Beijing eye study

To determine associations between dyslipidemia and ocular diseases, the population-based Beijing Eye Study 2006 examined 3251 subjects (age≥45 years) who underwent a detailed ophthalmic examination and biochemical blood analysis. Dyslipidemia was defined as any of the following: hypercholesterolemia (total cholesterol concentration≥5.72 mmol/L (220 mg/dL)) or hypertriglyceridemia (triglyceride concentration≥1.70 mmol/L (150 mg/dL)) or low high-density lipoprotein-cholesterol (HDL-C concentration≤0.91 mmol/L (35 mg/dL)). Biochemical blood examinations were available for 2945 (90.6%) subjects. After adjustment for age, gender, habitation region, body mass index, self reported income, blood glucose concentration, diastolic blood pressure and smoking, dyslipidemia was significantly associated with higher intraocular pressure (P<0.001) and beta zone of parapapillary atrophy (P = 0.03). Dyslipidemia was not significantly associated with the prevalence of glaucoma (P = 0.99), retinal vein occlusions (P = 0.92), diabetic retinopathy (P = 0.49),presence of retinal vascular abnormalities such as focal or general arteriolar narrowing, age-related macular degeneration(P = 0.27), nuclear cataract (P = 0.14), cortical cataract (P = 0.93), and subcapsular cataract (P = 0.67). The results make one conclude that, controlled for systemic and socioeconomic parameters, dyslipidemia was not associated with common ophthalmic disorders including glaucoma and age-related macular degeneration.

Window to the brain: Can retinopathy be used to assess cognitive function

OBJECTIVE

Retinopathy status as a screening method to predict cognitive health is limited. The objective of this study was to examine the association between retinopathy and lowered cognitive performance in a Canadian First Nations population.

METHODS

Eligible individuals were assessed by the Clock Drawing Test (CDT) and the Trail Making Test Parts A and B, which were combined into an executive function score (TMT-exec). Digital fundus photographs were taken for both eyes to assess retinopathy. Anthropometric, vascular and metabolic risk factors were assessed by interview, clinical examinations and blood tests. Carotid atherosclerosis was assessed by Doppler ultrasonography.

RESULTS

Retinopathy was detected in 7.1% of the population. Individuals classified as having a previous history of cardiovascular disease, insulin resistance and diabetes were more likely to have retinopathy. No other cardiovascular risk factors were associated. In unadjusted analysis, there were no associations between retinopathy and lowered cognitive performance (CDT, odds ratio [OR]: 0.86, 95% confidence interval [CI]: 0.30–2.53; TMT-exec, OR: 1.79, 95% CI: 0.60–5.33). Multivariable adjusted analysis also showed no associations, although sample size may be limiting.

CONCLUSIONS

Retinopathy was not associated with lowered cognitive performance. Associations for microvascular risk factors suggest a panel of cognitive tests is needed for future studies.

The relationship between retinal arteriolar and venular calibers is genetically mediated, and each is associated with risk of cardiovascular disease

PURPOSE

Retinal arteriolar and venular calibers are highly heritable and associated with cardiovascular disease. This study was designed to investigate the relative influence of genetic and environmental factors on the high phenotypic correlation (r = 0.59) between these two traits and to assess the shared and specific influence of established and novel cardiovascular disease risk factors on them.

METHODS

A total of 1463 Caucasian female twins (706 monozygotic and 757 dizygotic), between 24 and 79 years of age, underwent retinal photography from which retinal arteriolar (mean, 153.75 ± 22.1 μm, SD) and venular (mean, 232.1 ± 36.6 μm) calibers were measured with semiautomated software. A bivariate heritability model was used to assess the genetic and environmental influences underlying both specific trait variance and the covariance between the vessel traits. The investigation was an assessment of phenotypic associations between retinal arteriolar and venular calibers and cardiovascular disease risk factors.

RESULTS

Additive genetic factors accounted for approximately three fourths of the covariance between retinal arteriolar and venular calibers within the cohort. This finding was replicated in a sample of 1981 twins from the Australian Twins Eye Study. The partial correlation showed that known risk factors accounted for only 5% of the covariance between arteriolar and venular calibers. Novel associations were found between venular caliber and β-cell function (P = 0.011) and insulin sensitivity (P = 0.002).

CONCLUSIONS

These results suggest that future gene-mapping studies may identify pleiotropic genetic variants influencing both retinal arteriolar and venular calibers. Genetic variants associated with retinal caliber and (risk factors for) cardiovascular disease should provide new etiologic insights into this complex disease.

Prevention of diabetic eye disease: the commonest cause of blindness in individuals younger than 65 years

There has been a considerable advancement in the treatment of diabetes and understanding of the biochemical mechanisms underlying diabetic complications in the last 20 years. However, this advancement has not translated into a consistent reduction in diabetic retinopathy, one of the most frightening complications of diabetes mellitus. It is probable that greater attention to preventive intervention will help reduce the damage load in the next future, and that several drugs for the treatment of more advanced stages of diabetic retinopathy will become available. Competent strategies targeting prevention based on screening programs should be proposed to reduce the burden and to improve the clinical outcome of this devastating diabetes complication.

Alterations in retinal microvascular geometry in young type 1 diabetes

OBJECTIVE

To describe retinal microvascular geometric parameters in young patients with type 1 diabetes.

RESEARCH DESIGN AND METHODS

Patients with type 1 diabetes (aged 12-20 years) had clinical assessments and retinal photography following standardized protocol at a tertiary-care hospital in Sydney. Retinal microvascular geometry, including arteriolar and venular tortuosity, branching angles, optimality deviation, and length-to-diameter ratio (LDR), were measured from digitized photographs. Associations of these geometric characteristics with diabetes duration, A1C level, systolic blood pressure (SBP), and other risk factors were assessed.

RESULTS

Of 1,159 patients enrolled, 944 (81.4%) had gradable photographs and 170 (14.7%) had retinopathy. Older age was associated with decreased arteriolar (P = 0.024) and venular (P = 0.002) tortuosity, and female subjects had larger arteriolar branching angle than male subjects (P = 0.03). After adjusting for age and sex, longer diabetes duration was associated with larger arteriolar branching angle (P <or= 0.001) and increased arteriolar optimality deviation (P = 0.018), higher A1C was associated with increased arteriolar tortuosity (>8.5 vs. <or=8.5%, P = 0.008), higher SBP was associated with decreased arteriolar LDR (P = 0.002), and higher total cholesterol levels were associated with increased arteriolar LDR (P = 0.044) and decreased venular optimality deviation (P = 0.044). These associations remained after controlling for A1C, retinal vessel caliber, and retinopathy status and were seen in subjects without retinopathy.

CONCLUSIONS

Key diabetes-related factors affect retinal microvascular geometry in young type 1 diabetes, even in those without evidence of retinopathy. These early retinal alterations may be markers of diabetes microvascular complications.

Quantitative genetic analysis of the retinal vascular caliber: the Australian Twins Eye Study

Research into the genetic effects and specific genes associated with retinal vascular caliber, a risk marker of cardiovascular diseases, may provide new insights into the genetic contribution of early microvascular disease. A combined 374 monozygotic and 536 dizygotic twin pairs and 322 siblings from the Twins Eye Study in Tasmania and the Brisbane Adolescent Twin Study underwent complete ophthalmic examinations, including retinal photography, and bilateral retinal vascular caliber was measured. Structural equation modeling was used to estimate the heritability. Genome-wide linkage analysis was conducted on 836 individuals from 381 Brisbane Adolescent Twin Study families, with adjustments for age, sex, and other covariates. The heritabilities for the retinal arteriolar caliber were 59.4% (95% CI: 53.2% to 64.7%) and 56.5% (95% CI: 50.1% to 61.9%) in the Twins Eye Study in Tasmania and the Brisbane Adolescent Twin Study, respectively, and for venular caliber they were 61.7% (95% CI: 55.6% to 67.0%) and 64.2% (95% CI: 58.7% to 68.8%), respectively, after adjusting for age, sex, and body mass index. Two multipoint peaks detected on chromosomes 3p12.3 and 8p23.1 for retinal arteriolar caliber had suggestive linkage, with the highest multipoint peak logarithm of odds score of 2.24 on chromosome 8p23.1 (genome-wide P=7.0 x 10(-4)). Two suggestive logarithm of odds scores for venular caliber were identified on chromosomes 2p14 and 9q21.13. The largest multipoint logarithm of odds score was 2.69 on chromosome 2p14 (genome-wide P=2.0 x 10(-4)). In this large twin population, genetic factors appear to play a significant role in the variation of retinal vascular caliber. Several putative loci were identified for the retinal vascular caliber.

Retinal vessel abnormalities are associated with elevated fasting insulin levels and cerebral atrophy in nondiabetic individuals

OBJECTIVE

To determine the impact of insulin resistance short of diabetes on the arteriolar-to-venular ratio (AVR) and whether AVR is related to cerebral atrophy.

DESIGN

Cross-sectional study.

PARTICIPANTS

Forty-six nondiabetic subjects with normal glucose tolerance and varying degrees of insulin resistance ranging in age from 43 to 77 years.

METHODS

Insulin resistance was assessed by fasting insulin and the homeostasis model assessment. Arteriolar-to-venular ratio was determined using digital retinal photography with a nonmydriatic camera, and retinal data were analyzed using a reliable semiautomated method. Cerebral atrophy was derived by means of manual tracing and thresholding procedures on structural magnetic resonance images.

MAIN OUTCOME MEASURES

Arteriolar-to-venular ratio and cerebral atrophy.

RESULTS

Hyperinsulinemia negatively impacted AVR. Furthermore, AVR was associated with cerebral atrophy. Both of these findings were independent of the effects of age and hypertension.

CONCLUSIONS

These novel findings indicate that insulin resistance short of diabetes and independent of age and hypertension has a negative impact on retinal vessel health. Moreover, impaired retinal vessel health related to brain atrophy also was independent of hypertension and white matter hyperintensities. Given the connections between retinal and cerebral vasculature, this may offer a partial explanation for the presence of cognitive and brain abnormalities among individuals with insulin resistance.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Apolipoprotein A1 is overexpressed in the retina of diabetic patients

PURPOSE

To compare apolipoprotein A1 (ApoA1) expression in the retina from diabetic and nondiabetic donors.

DESIGN

Case-control study.

METHODS

Diabetic postmortem eyes (n = 8) were compared with eyes (n = 8) from nondiabetic donors matched by age. Messenger ribonucleic acid (mRNA) of ApoA1 (quantitative reverse-transcriptase polymerase chain reaction) was measured separately in the neuroretina and retinal pigment epithelium (RPE). ApoA1 was assessed by immunofluorescence (confocal laser microscopy) and Western blot analysis. The presence of early diabetic retinal damage was evaluated by measuring the rate of apoptosis and glial activation.

RESULTS

ApoA1 mRNA levels and ApoA1 immunofluorescence obtained in RPEs and in neuroretinas from diabetic donors were significantly higher than those obtained from nondiabetic donors. ApoA1 was expressed in all retina layers and it was more abundant in RPE than in the neuroretina in both diabetic and nondiabetic donors. In addition, ApoA1 immunofluorescence was significantly higher in all the layers of the neuroretina from diabetic patients. Densitometric analysis of immunoblots showed higher ApoA1 in the retinas from diabetic donors in comparison with nondiabetic donors, but the differences were at significant levels only for the RPE.

CONCLUSIONS

ApoA1 overexpression is an early event in the retina of diabetic patients and can be involved in the physiopathology of diabetic retinopathy. In addition, RPE is the main source of ApoA1 within the retina. These findings my be relevant to aiming new treatment strategies toward reducing the development of diabetic retinopathy.

Relative importance of systemic determinants of retinal arteriolar and venular caliber: the atherosclerosis risk in communities study

OBJECTIVE

To examine the relative contributions of systemic cardiovascular factors to retinal arteriolar and venular caliber in men and women and in whites and African Americans.

METHODS

In the Atherosclerosis Risk in Communities study, retinal arteriolar caliber (central retinal arteriolar equivalent), and venular caliber (central retinal venular equivalent) were measured from digitized retinal photographs of 8794 participants.

RESULTS

The main systemic determinants of narrower central retinal arteriolar equivalent were, in order of relative decreasing contribution, higher current mean arterial blood pressure, lower serum albumin level, current alcohol consumption, and higher body mass index (calculated as weight in kilograms divided by height in meters squared). The main systemic determinants of wider central retinal venular equivalent were current cigarette smoking and higher current mean arterial blood pressure, followed by higher white blood cell count, body mass index, and plasma low-density lipoprotein cholesterol levels. These associations were generally similar in whites and African Americans and in men and women.

CONCLUSIONS

The major systemic determinant of narrower retinal arteriolar caliber is higher blood pressure, while those of wider retinal venular caliber are cigarette smoking, higher blood pressure, systemic inflammation, and obesity. These data offer further insights into the systemic processes influencing arteriolar and venular characteristics and may help explain the observed associations of retinal vascular caliber and the risk of clinical cardiovascular disease.

Effect of fenofibrate on the need for laser treatment for diabetic retinopathy (FIELD study): a randomised controlled trial

BACKGROUND

Laser treatment for diabetic retinopathy is often associated with visual field reduction and other ocular side-effects. Our aim was to assess whether long-term lipid-lowering therapy with fenofibrate could reduce the progression of retinopathy and the need for laser treatment in patients with type 2 diabetes mellitus.

METHODS

The Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) study was a multinational randomised trial of 9795 patients aged 50-75 years with type 2 diabetes mellitus. Eligible patients were randomly assigned to receive fenofibrate 200 mg/day (n=4895) or matching placebo (n=4900). At each clinic visit, information concerning laser treatment for diabetic retinopathy-a prespecified tertiary endpoint of the main study-was gathered. Adjudication by ophthalmologists masked to treatment allocation defined instances of laser treatment for macular oedema, proliferative retinopathy, or other eye conditions. In a substudy of 1012 patients, standardised retinal photography was done and photographs graded with Early Treatment Diabetic Retinopathy Study (ETDRS) criteria to determine the cumulative incidence of diabetic retinopathy and its component lesions. Analyses were by intention to treat. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN64783481.

FINDINGS

Laser treatment was needed more frequently in participants with poorer glycaemic or blood pressure control than in those with good control of these factors, and in those with a greater burden of clinical microvascular disease, but the need for such treatment was not affected by plasma lipid concentrations. The requirement for first laser treatment for all retinopathy was significantly lower in the fenofibrate group than in the placebo group (164 [3.4%] patients on fenofibrate vs 238 [4.9%] on placebo; hazard ratio [HR] 0.69, 95% CI 0.56-0.84; p=0.0002; absolute risk reduction 1.5% [0.7-2.3]). In the ophthalmology substudy, the primary endpoint of 2-step progression of retinopathy grade did not differ significantly between the two groups overall (46 [9.6%] patients on fenofibrate vs 57 [12.3%] on placebo; p=0.19) or in the subset of patients without pre-existing retinopathy (43 [11.4%] vs 43 [11.7%]; p=0.87). By contrast, in patients with pre-existing retinopathy, significantly fewer patients on fenofibrate had a 2-step progression than did those on placebo (three [3.1%] patients vs 14 [14.6%]; p=0.004). An exploratory composite endpoint of 2-step progression of retinopathy grade, macular oedema, or laser treatments was significantly lower in the fenofibrate group than in the placebo group (HR 0.66, 95% CI 0.47-0.94; p=0.022).

INTERPRETATION

Treatment with fenofibrate in individuals with type 2 diabetes mellitus reduces the need for laser treatment for diabetic retinopathy, although the mechanism of this effect does not seem to be related to plasma concentrations of lipids.

Three-year incidence and cumulative prevalence of retinopathy: the atherosclerosis risk in communities study

PURPOSE

To describe the three-year incidence and cumulative prevalence of retinopathy and its risk factors.

DESIGN

Population-based, prospective cohort study in four US communities.

METHODS

In the Atherosclerosis Risk in Communities (ARIC) Study, 981 participants had retinal photography of one randomly selected eye at the third examination (1993 to 1995) and three years later at the fourth examination (1996). Photographs were graded on both occasions for retinopathy signs (for example, microaneurysm, retinal hemorrhage, and/or cotton-wool spots). Incidence was defined as participants without retinopathy at the third examination who developed retinopathy at the fourth examination, and cumulative prevalence was defined to include incident retinopathy as well as participants who had retinopathy at both the third and fourth examinations.

RESULTS

The three-year incidence and cumulative prevalence of any retinopathy in the whole cohort was 3.8% and 7.7%, respectively. In multivariable analysis, incident retinopathy was related to higher mean arterial blood pressure (odds ratio [OR] 1.5, 95% confidence interval [CI] 1.0 to 2.3, per standard deviation increase in risk factor levels), fasting serum glucose (OR 1.6, 95% CI 1.3 to 2.1), serum total cholesterol (OR 1.4, 95% CI 1.0, 2.0), and plasma fibrinogen (OR 1.4, 95% CI 1.1 to 1.9). Among persons without diabetes, the three-year incidence and cumulative prevalence of nondiabetic retinopathy was 2.9% and 4.3%, respectively. Incident nondiabetic retinopathy was related to higher mean arterial blood pressure (OR 1.4, 95% CI 0.9 to 2.3) and fasting serum glucose (OR 1.5, 95% CI 1.0 to 2.3). Among persons with diabetes, the three-year incidence and cumulative prevalence of diabetic retinopathy was 10.1% and 27.2%, respectively.

CONCLUSIONS

Retinopathy signs occur frequently in middle-aged people, even in those without diabetes. Hypertension and hyperglycemia are risk factors for incident retinopathy.