Diabetic eye disease

Disease burden, risk factors, and temporal trends of eye cancer: A global analysis of cancer registries

BACKGROUND

This study aims to investigate the global disease burden, risk factors, and temporal trends of eye cancer by sex and age group.

METHODS

Databases including Cancer Incidence in Five Continents volumes I-XI, the Nordic Cancer Registries, the Surveillance, Epidemiology, and End Results Program and the WHO IARC mortality database were accessed to extract incidence and mortality data. Joinpoint regression analyses were conducted to evaluate the Average Annual Percentage Change of the incidence and mortality.

RESULTS

The age-standardised rates of eye cancer incidence and mortality were 0.49 and 0.08 globally in 2020. Higher incidence rates were observed in Sub-Saharan Africa (ASR = 4.06), Western Europe (ASR = 0.89), and Northern Europe (ASR = 0.84), but higher mortality was observed only in Sub-Saharan Africa (ASR = 1.59). Lower HDI, higher prevalence of UV exposure and lower prevalence of several lifestyle habits and metabolic syndromes were associated with higher incidence and mortality. There was an overall stable incidence trend and a decreasing mortality trend. Notably, all countries reporting decreasing trend in mortality were in the Asian or European region.

CONCLUSIONS

Although higher incidence was observed in both African and European regions, only the Sub-Saharan Africa region reported high mortality, indicating inequity in the access of healthcare and treatment resource. Higher prevalence of UV exposure was associated with both higher incidence and mortality. Education should be provided to increase the awareness of eye protection. An overall declining mortality trend was found, but it was limited to only Asian and European countries.

A robust activatable two-photon fluorescent probe for endogenous formaldehyde biomarker visualization diagnosis and evaluation of diabetes mellitus

Diabetes mellitus and its complications are one of the largest healthcare burdens in the world and are increasing every year. However, the lack of effective biomarkers and non-invasive real-time monitoring tools remains a great challenge for the early diagnosis of diabetes mellitus. Endogenous formaldehyde (FA) represents a key reactive carbonyl species in biological systems, and altered metabolism and functions of FA have been closely related to the pathogenesis and maintenance of diabetes. Among various noninvasive biomedical imaging techniques, the identification-responsive fluorescence (FL) imaging could greatly benefit the comprehensive multi-scale assessment of some diseases such as diabetes. Herein, we have designed a robust activatable two-photon probe DM-FA for the first highly selective monitoring of fluctuations in FA levels during diabetes mellitus. Through the density functional theory (DFT) theoretical calculations, we elucidated the rationality of the activatable fluorescent probe DM-FA turning on the FL before and after the reaction with FA. In addition, DM-FA has excellent high selectivity, high growth factor and good photostability in the process of recognizing FA. Due to the brilliant two-photon and one-photon FL imaging capabilities of DM-FA, it has been successfully used to visualize of exogenous and endogenous FA in cells and mice. Remarkably, as a powerful FL imaging visualization tool, DM-FA was introduced for the first time to visually diagnose and explore diabetes through the fluctuation of FA content. The successful application of DM-FA in two-photon and one-photon FL imaging experiments found elevated FA levels in high glucose-stimulated diabetic cell models. We successfully visualized upregulation of FA levels in diabetic mice and decreased of FA levels in diabetic mice scavenged by NaHSO₃ from multiple perspectives using multiple imaging modalities. This work may provide a novel strategy for the initial diagnosis of diabetes mellitus and the evaluation of the efficacy of drug therapy for treating diabetes mellitus, which will likely have a positive impact on clinical medicine.

VEGF-Trap Modulates Retinal Inflammation in the Murine Oxygen-Induced Retinopathy (OIR) Model

Anti-Vascular Endothelial Growth Factor (VEGF) agents are the first-line treatment for retinal neovascular diseases, which represent the most prevalent causes of acquired vision loss world-wide. VEGF-Trap (Aflibercept, AFL), a recombinant decoy receptor recognizing ligands of both VEGFR-1 and -2, was recently reported to be highly efficient in improving visual acuity and preserving retinal anatomy in individuals affected by diabetic macular edema. However, the precise molecular and cell biological mechanisms underlying the beneficial effects of this novel tool have yet to be elucidated. Using the mouse oxygen-induced retinopathy (OIR) model as a surrogate of retinopathies with sterile post-ischemic inflammation, such as late proliferative diabetic retinopathy (PDR), retinopathy of prematurity (ROP), and diabetic macular edema (DME), we provide evidence that AFL modulates inflammation in response to hypoxia by regulating the morphology of microglial cells, a parameter commonly used as a proxy for changes in their activation state. We show that AFL administration during the hypoxic period of OIR leads to an increased number of ramified Iba1⁺ microglial cells/macrophages while subsequently limiting the accumulation of these cells in particular retinal layers. Our results suggest that, beyond its well-documented beneficial effects on microvascular regeneration, AFL might exert important modulatory effects on post-ischemic retinal inflammation.

Association of Alpha-Crystallin with Fiber Cell Plasma Membrane of the Eye Lens Accompanied by Light Scattering and Cataract Formation

α-crystallin is a major protein found in the mammalian eye lens that works as a molecular chaperone by preventing the aggregation of proteins and providing tolerance to stress in the eye lens. These functions of α-crystallin are significant for maintaining lens transparency. However, with age and cataract formation, the concentration of α-crystallin in the eye lens cytoplasm decreases with a corresponding increase in the membrane-bound α-crystallin, accompanied by increased light scattering. The purpose of this review is to summarize previous and recent findings of the role of the: (1) lens membrane components, i.e., the major phospholipids (PLs) and sphingolipids, cholesterol (Chol), cholesterol bilayer domains (CBDs), and the integral membrane proteins aquaporin-0 (AQP0; formally MIP26) and connexins, and (2) α-crystallin mutations and post-translational modifications (PTMs) in the association of α-crystallin to the eye lens's fiber cell plasma membrane, providing thorough insights into a molecular basis of such an association. Furthermore, this review highlights the current knowledge and need for further studies to understand the fundamental molecular processes involved in the association of α-crystallin to the lens membrane, potentially leading to new avenues for preventing cataract formation and progression.

The Usefulness of Monocyte-to-High Density Lipoprotein and Neutrophil-to-Lymphocyte Ratio in Diabetic Macular Edema Prediction and Early anti-VEGF Treatment Response

Purpose: To determine the association of monocyte-to-high-density lipoprotein ratio (MHR) and neutrophil-to-lymphocyte ratio (NLR) with diabetic macular edema (DME) and early anti-VEGF treatment response.Material methods: This was a retrospective and cross-sectional study conducted with 143 patients with diabetes mellitus (53 diabetic retinopathy with DME, 38 diabetic retinopathy without DME, and 52 without diabetic retinopathy).Results: 13.9 was the best cutoff value to predict DME for MHR, and 2 was for NLR (59% and 75% sensitivity and 81% and 59% specificity, respectively). Logistic regression analysis showed that NLR≥2 and MHR≥13.9 were significantly associated with DME prediction. However, neither NLR≥2 nor MHR≥13.9 was associated with central retinal thickness(CRT) or best corrected visual acuity(BCVA) outcomes after anti-VEGF treatment. On the other hand, increased NLR was associated with inferior CRT outcomes.Conclusion: MHR and NLR were simple and cost-effective biomarkers to predict DME. Moreover, higher NLR may contribute to poor CRT outcomes.

Interaction of alpha-crystallin with four major phospholipids of eye lens membranes

It is well-studied that the significant factor in cataract formation is the association of α-crystallin, a major eye lens protein, with the fiber cell plasma membrane of the eye lens. The fiber cell plasma membrane of the eye lens consists of four major phospholipids (PLs), i.e., phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), and sphingomyelin (SM). Despite several attempts to study the interaction of α-crystallin with PLs of the eye lens membrane, the role of individual PL for the binding with α-crystallin is still unclear. We recently developed the electron paramagnetic resonance (EPR) spin-labeling method to study the binding of α-crystallin to the PC membrane (Mainali et al., 2020a). Here, we use the recently developed EPR method to explicitly measure the binding affinity (K_a) of α-crystallin to the individual (PE*, PS, and SM) and two-component mixtures (SM/PE, SM/PS, and SM/PC in 70:30 and 50:50 mol%) of PL membranes as well as the physical properties (mobility parameter and maximum splitting) of these membranes upon binding with α-crystallin. One of the key findings of this study was that the K_a of α-crystallin binding to individual PL membranes followed the trends: K_a(PC) > K_a(SM) > K_a(PS) > K_a(PE*), indicating PE* inhibits binding the most whereas PC inhibits binding the least. Also, the K_a of α-crystallin binding to two-component mixtures of PL membranes followed the trends: K_a(SM/PE) > K_a(SM/PS) > K_a(SM/PC), indicating SM/PC inhibits binding the most whereas SM/PE inhibits binding the least. Except for the PE* membrane, for which there was no binding of α-crystallin, the mobility parameter for all other membranes decreased with an increase in α-crystallin concentration. It represents that the membranes become more immobilized near the headgroup regions of the PLs when more and more α-crystallin binds to them. The maximum splitting increased only for the SM and the SM/PE (70:30 mol%) membranes, with an increase in the binding of α-crystallin. It represents that the PL headgroup regions of these membranes become more ordered after binding of α-crystallin to these membranes. Our results showed that α-crystallin binds to PL membranes in a saturable manner. Also, our data suggest that the binding of α-crystallin to PL membranes likely occurs through hydrophobic interaction between α-crystallin and the hydrophobic fatty acid core of the membranes, and such interaction is modulated by the PL headgroup's size and charge, hydrogen bonding between headgroups, and PL curvature. Thus, this study provides an in-depth understanding of α-crystallin interaction with the PL membranes made of individual and two-component mixtures of the four major PLs of the eye lens membranes.

Six-Year Incidence and Causes of Low Vision and Blindness in a Rural Chinese Adult Population: The Handan Eye Study

PURPOSE

To determine the six-year incidence, risk factors, and causes of visual impairment in a Chinese population.

METHODS

This was a population-based study of eye disease in Chinese adults in a rural district of Handan in China. 6,830 individuals were invited to participate in 2006 and 5,394 returned for follow-up in 2012. All participants underwent standardized eye examinations. Visual impairment was defined according to WHO criteria. The incidence of visual impairment was age- and gender-standardized to the 2010 China Census. Multivariable logistic regression analysis was used to determine risk factors for visual impairment.

RESULTS

The leading causes of visual impairment were cataract and refractive error. Based on presenting visual acuity (PVA), the six-year incidence rates of low vision and blindness were 5.2% and 0.5%, respectively. Incidence of low vision was associated with older age (p < .001), less education (p < .001), diabetes (p < .05), and lower BMI (p < .001). The incidence of blindness was associated with diabetes (p < .05). Based on best-corrected visual acuity (BCVA), the six-year incidence rates of low vision and blindness were 0.8% and 0.1%, respectively. Incidence of low vision was associated with older age (p < .001) and lower BMI (p < .05). None of these factors were associated with the incidence of blindness.

CONCLUSION

In Handan, the incidence of visual impairment was high and associated with older age, less education, diabetes, and lower BMI. The majority of cases were due to unoperated cataract and uncorrected refractive error, reflecting the need for improved eye care in this region.

Activation of Factor XII and Kallikrein-Kinin System Combined with Neutrophil Extracellular Trap Formation in Diabetic Retinopathy

BACKGROUND

In diabetic retinopathy (DR), neutrophil extracellular traps (NET) and kallikrein-kinin system are considered as contributing factors. However, the detail activation mechanisms has not been fully understood. Since the NET could provide negative-charged surface for factor XII activation and the activated factor XII (XIIa) can initiate kallikrein-kinin system, this study investigated whether patients with DR show activation of NET, factor XII and kallikrein-kinin system.

METHODS

The markers related to NET (DNA-histone complex) and kallikrein-kinin system (high-molecular-weight kininogen, prekallikrein, bradykinin) and factor XIIa were measured in 253 patients with diabetes. To access ex vivo effect of glucose, DNA-histone complex and factor XIIa were measured in whole blood stimulated by glucose.

RESULTS

The circulating level of DNA-histone complex and factor XIIa were significantly higher in patients with DR than those without DR. In logistic regression analysis, DNA-histone complex, factor XIIa, and high-molecular-weight kininogen were the risk factors of DR. In recursive partitioning analysis, among patients with diabetes duration less than 10 years, patients with high level of DNA-histone complex (>426 AU) showed high risk of DR. In ex vivo experiment, glucose significantly elevated both DNA-histone complex and factor XIIa.

CONCLUSION

Our findings suggest that activation of factor XII and kallikrein-kinin system combined with NET formation actively occur in patients with DR and circulating levels of DNA-histone complex, factor XIIa and HMWK can be potential biomarkers to estimate the risk of DR. Strategies against factor XII activation may be beneficial to inhibit DR.

Current perspectives on established and novel therapies for pathological neovascularization in retinal disease

Neovascularization is a hallmark pathology of numerous retinal diseases from diabetic retinopathy (DR) to age-related related macular degeneration (AMD). Over the past 2 decades, the rise of anti-VEGF based medications for neovascular eye conditions has revolutionized the treatment paradigm for patients and preserved the vision of millions. With any form of therapy however, there remain pitfalls and areas for improved interventions. Here, we succinctly present some current views on treatment options for patients with retinal and choroidal neovascularization. We also highlight some of the most promising therapeutic strategies currently being developed and where these therapies may fit with the current clinical standard of care.

Leukocyte Lipid Peroxidation, Superoxide Dismutase and Catalase Activities of Type 2 Diabetic Patients with Retinopathy

Increased oxidative stress might play an important role in the initiation and progression of diabetic complications. The present study has been undertaken to investigate whether there is any relationship between retinopathy degree and leukocyte superoxide dismutase (SOD) and catalase (CAT) activities and lipid peroxidation (LPO) in diabetic individuals with type 2 diabetic retinopathy. Patients were groupped with respect to the degree of retinopathy. Leukocyte malondialdehyde (MDA) levels, and SOD and CAT activities were measured in patients with type 2 diabetes mellitus (n=41) and nondiabetic healthy controls (n=23). Leukocyte LPO of the type 2 diabetic patients with retinopathy was significantly increased (p< 0.001), whereas SOD and CAT activities were decreased (p<0.001 and p<0.001, respectively) compared to those of controls. MDA concentrations rose while SOD and CAT activities fell with increasing severity of diabetic retinopathy, altough there was no significant difference in comprasion of the parameters mentioned above between the diabetic patients with and without retinopathy. Our results show that leukocytes in patients with type 2 diabetic retinopathy are affected by oxidative stress which might be contribute to pathogenesis of diabetic retinopathy. Prospective studies are needed to evaulate the relationship between the leukocyte antioxidants status and DR.

A randomised trial of non-mydriatic ultra-wide field retinal imaging versus usual care to screen for diabetic eye disease: rationale and protocol for the Clearsight trial

INTRODUCTION

Suboptimal screening for diabetic eye disease is a major cause of preventable vision loss. Screening barriers include mydriasis and the extra time patients need to attend dedicated eye screening appointments. In the Clearsight trial, we are testing whether screening by non-mydriatic ultra-wide field (NM UWF) imaging on the day patients attend their diabetes outpatient clinic visit improves detection of clinically important eye disease compared with usual screening.

METHODS AND ANALYSIS

Patients with diabetes due for a screening eye exam by the 2013 Canadian Diabetes Association (CDA) practice guidelines are being randomised to on-site screening by NM UWF imaging on the day of their clinic visit or to usual screening where, per CDA guidelines, they are encouraged to arrange an exam by an optometrist. The primary outcome is actionable eye disease (AED) based on a need for referral to ophthalmology and/or increased ocular surveillance. The primary analysis will use an intention-to-screen approach that compares the proportions of detected AED between on-site and usual screening groups under a superiority hypothesis in favour of on-site screening. With 740 randomised participants, the study will have 80% power to detect ≥5% absolute increase in the AED rate among on-site screening versus usual screening participants. This difference translates into a number-needed-to-screen by on-site screening of 20 to detect 1 additional person with AED.

ETHICS AND DISSEMINATION

The protocol was approved by the institutional review board of Western University. The findings of the trial will be disseminated directly to participants and through peer-reviewed publications and conference presentations.

TRIAL REGISTRATION NUMBER

ClinicalTrials.Gov NCT02579837 (registered 16 October 2015).

PROTOCOL ISSUE DATE

18 November 2015.

What factors influence uptake of retinal screening among young adults with type 2 diabetes? A qualitative study informed by the theoretical domains framework

AIMS

Young adults with type 2 diabetes (T2D, 18-39years) face increased risk of vision loss from diabetic retinopathy (DR). Retinal screening is essential to detect DR, yet screening rates for this group are low and little is known about the underlying factors influencing this important behavior. Using the theoretical domains framework (TDF) to guide data collection and analysis, we explored screening barriers and facilitator, contrasting them with a comparator group of older adults with T2D (40+ years).

METHODS

Thirty semi-structured telephone interviews (10 younger, 20 older adults) were conducted. Data were coded into TDF domains with salience identified by "frequency" of reference. Screening facilitators and barriers were systematically compared between groups.

RESULTS

Although many screening facilitators and barriers were shared by younger and older adults, additional factors highly relevant to the former included: social comparison with others ('social influences'); concern for the impact on the family unit, unrealistic optimism and perceived invulnerability ('beliefs about consequences'); lack of time and financial resources ('environmental context and resources'), and DR misconceptions ('knowledge').

CONCLUSIONS

This study demonstrated that young adult retinal screening behavior was influenced by additional social cognitive factors compared to older adults, providing a first-step evidence base for clinicians and other health professionals, and potential targets for future eye health and retinal screening interventions.

Live imaging of primary ocular vasculature formation in zebrafish

Ocular vasculature consists of the central retinal and ciliary vascular systems, which are essential to maintaining visual function. Many researchers have attempted to determine their origins and development; however, the detailed, stepwise process of ocular vasculature formation has not been established. In zebrafish, two angioblast clusters, the rostral and midbrain organizing centers, form almost all of the cranial vasculature, including the ocular vasculature, and these are from where the cerebral arterial and venous angioblast clusters, respectively, differentiate. In this study, we first determined the anatomical architecture of the primary ocular vasculature and then followed its path from the two cerebral angioblast clusters using a time-lapse analysis of living Tg(flk1:EGFP)k7 zebrafish embryos, in which the endothelial cells specifically expressed enhanced green fluorescent protein. We succeeded in capturing images of the primary ocular vasculature formation and were able to determine the origin of each ocular vessel. In zebrafish, the hyaloid and ciliary arterial systems first organized independently, and then anastomosed via the inner optic circle on the surface of the lens by the lateral transfer of the optic vein. Finally, the choroidal vascular plexus formed around the eyeball to complete the primary ocular vasculature formation. To our knowledge, this study is the first to report successful capture of circular integration of the optic artery and vein, lateral transfer of the optic vein to integrate the hyaloidal and superficial ocular vasculatures, and formation of the choroidal vascular plexus. Furthermore, this new morphological information enables us to assess the entire process of the primary ocular vasculature formation, which will be useful for its precise understanding.

The Role of Plasma Kallikrein-Kinin Pathway in the Development of Diabetic Retinopathy: Pathophysiology and Therapeutic Approaches

Diabetic retinal disease is characterized by a series of retinal microvascular changes and increases in retinal vascular permeability that lead to development of diabetic retinopathy (DR) and diabetic macular edema (DME), respectively. Current treatment strategies for DR and DME are mostly limited to vascular endothelial growth factor (VEGF) inhibitors and laser photocoagulation. These treatment modalities are not universally effective in all patients, and potential side effects persist in a significant portion of patients. The plasma kallikrein-kinin system (KKS) is one of the pathways that has been identified in the vitreous in proliferative DR and DME. Preclinical studies have shown that the activation of intraocular KKS induces retinal vascular permeability, vasodilation, and retinal thickening. Proteomic analysis from vitreous of eyes with DME has shown that KKS and VEGF pathways are potentially independent biologic pathways. Furthermore, proteins associated with DME in the vitreous were significantly more correlated with the KKS pathway compared to VEGF pathway. Preclinical experiments on diabetic animals showed that inhibition of KKS components was found to be an effective approach to decrease retinal vascular permeability. An initial phase I human trial of a novel plasma kallikrein inhibitor for the treatment of DME is currently ongoing to test the safety of this approach and serves as an initial step in the translation of basic science discovery into an innovative clinical intervention.

The role of Toll-like receptors in retinal ischemic diseases

Toll-like receptors (TLRs) are commonly referred to a series of evolutionary conserved receptors which recognize and respond to various microbes and endogenous ligands. Growing evidence has demonstrated that the expression of TLRs in the retina is regulated during retinal ischemic diseases, including ischemia-reperfusion injury, glaucoma, diabetic retinopathy (DR) and retinopathy of prematurity (ROP). TLRs can be expressed in multiple cells in the retina, such as glial cells, retinal pigment epithelium (RPE), as well as photoreceptor cells and endothelium cells. Activation of TLRs in retina could initiate a complex signal transduction cascade, induce the production of inflammatory cytokines and regulate the level of co-stimulatory molecules, which play prominent roles in the pathogenesis of retinal ischemic diseases. In this review, we summarized current studies about the relationship between TLRs and ischemic retinopathy. A greater understanding of the effect of TLRs on ischemic injuries may contribute to the development of specific TLR targeted therapeutic strategies in these conditions.

Alpha-lipoic acid: molecular mechanisms and therapeutic potential in diabetes

Diabetes is a chronic metabolic disease with a high prevalence worldwide. Diabetes and insulin resistance are associated with the development of cardiovascular and nervous diseases. The development of these disorders reflects complex pathological processes in which the oxidative stress caused by reactive oxygen species (ROS) and reactive nitrogen species (RNS) plays a pivotal role. It is widely accepted that diabetes impairs endothelial nitric oxide synthase (eNOS) activity and increases the production of ROS, thus resulting in diminished NO bioavailability and increased oxidative stress. Alpha-lipoic acid (LA) possesses beneficial effects both in the prevention and in the treatment of diabetes. LA is a potent antioxidant with insulin-mimetic and anti-inflammatory activity. LA in the diet is quickly absorbed, transported to the intracellular compartments, and reduced to dihydrolipoic acid (DHLA) under the action of enzymes. LA, which plays an essential role in mitochondrial bioenergetic reactions, has drawn considerable attention as an antioxidant for use in managing diabetic complications such as retinopathy, neuropathy and other vascular diseases.

Systemic and Intravitreal Delivery of Dendrimers to Activated Microglia/Macrophage in Ischemia/Reperfusion Mouse Retina

PURPOSE

Microglial activation and associated neuroinflammation play a key role in the pathogenesis of many diseases of the retina, including viral infection, diabetes, and retinal degeneration. Strategies to target activated microglia and macrophages and attenuate inflammation may be valuable in treating these diseases. We seek to develop dendrimer-based formulations that target retinal microglia and macrophages in a pathology-dependent manner, and deliver drugs, either intravenously or intravitreally.

METHODS

Retinal uptake of cyanine dye (Cy5)-conjugated dendrimer (D-Cy5) was assessed in normal and ischemia/reperfusion (I/R) mouse eyes. Microglia/macrophage uptake of the dendrimer was assessed with immunofluorescence using rabbit Iba-1 antibody with Cy3-tagged secondary antibody (microglia/macrophage). Uptake in retina and other organs was quantified using fluorescence spectroscopy.

RESULTS

Clearance of D-Cy5 from normal eyes was almost complete by 72 hours after intravitreal injection and 24 hours after intravenous delivery. In eyes with activated microglia after I/R injury, D-Cy5 was retained by activated microglia/macrophage (Iba1+ cells) up to 21 days after intravitreal and intravenous administration. In I/R eyes, the relative retention of intravitreal and intravenous D-Cy5 was comparable, if a 30-fold higher intravenous dose was used.

CONCLUSIONS

Intravitreal and systemic dendrimers target activated microglia and show qualitatively similar retinal biodistribution when administered by either route. Results provide proof-of-concept insights for developing dendrimer drug formulations as treatment options for retinal diseases associated with microglia or macrophage activation such as age-related macular degeneration, diabetic retinopathy, and retinal degenerations.

Polyol pathway: A possible mechanism of diabetes complications in the eye

In complex diseases such as diabetes mellitus, the causative agents include various serum factors such as glucose, aldose reductase, oxygen-free radicals, advanced glycation end products, protein kinase-C and growth factors. The polyol pathway is a pathway of glucose metabolism and is regarded as an important element in the pathogenesis of refractive changes, cataract formation and diabetic retinopathy in individuals with diabetes mellitus. The focus of this review is on the role of the polyol pathway in the pathogenesis of diabetic complications in the eye. The first enzyme (aldose reductase) in the polyol pathway reduces glucose to sorbitol. The second enzyme (sorbitol dehydrogenase) converts sorbitol to fructose. The accumulation of sorbitol and fructose in the crystalline lens and retina leads to the generation of oxidative stress. Oxidative stress is the imbalance between levels of reactive oxygen species and the antioxidant defence in a biological system, and it results in tissue damage. How hyperglycaemia leads to oxidative stress is not clear but could be through a combination of increased levels of reactive oxygen species and decreased capacity of the cellular antioxidant system. Oxidative stress causes the development of diabetic complications that are seen clinically.

Printed educational messages aimed at family practitioners fail to increase retinal screening among their patients with diabetes: a pragmatic cluster randomized controlled trial [ISRCTN72772651]

Background

Evidence of the effectiveness of printed educational messages in narrowing the gap between guideline recommendations and practice is contradictory. Failure to screen for retinopathy exposes primary care patients with diabetes to risk of eye complications. Screening is initiated by referral from family practitioners but adherence to guidelines is suboptimal. We aimed to evaluate the ability of printed educational messages aimed at family doctors to increase retinal screening of primary care patients with diabetes.

Methods

Design: Pragmatic 2×3 factorial cluster trial randomized by physician practice, involving 5,048 general practitioners (with 179,833 patients with diabetes). Setting: Ontario family practitioners. Interventions: Reminders (that retinal screening helps prevent diabetes-related vision loss and is covered by provincial health insurance for patients with diabetes) with prompts to encourage screening were mailed to each physician in conjunction with a widely-read professional newsletter. Alternative printed materials formats were an ‘outsert’ (short, directive message stapled to the outside of the newsletter), and/or a two-page, evidence-based article (‘insert’) and a pre-printed sticky note reminder for patients. Main outcome measure: A successful outcome was an eye examination (which includes retinal screening) provided to a patient with diabetes, not screened in the previous 12 months, within 90 days after visiting a family practitioner. Analysis accounted for clustering of doctors within practice groups.

Results

No intervention effect was detected (eye exam rates were 31.6% for patients of control physicians, 31.3% for the insert, 32.8% for the outsert, 32.3% for those who received both, and 31.2% for those who received both plus the patient reminder with the largest 95% confidence interval around any effect extending from −1.3% to 1.1%).

Conclusions

This large trial conclusively failed to demonstrate any impact of printed educational messages on screening uptake. Despite their low cost, printed educational messages should not be routinely used in attempting to close evidence-practice gaps relating to diabetic retinopathy screening.

Trial registration

ISRCTN72772651

Electronic supplementary material

The online version of this article (doi:10.1186/1748-5908-9-87) contains supplementary material, which is available to authorized users.

Oxidants, antioxidants and mitochondrial function in non-proliferative diabetic retinopathy

BACKGROUND

Diabetic retinopathy (DR) is a preventable cause of visual disability. The aims of the present study were to investigate levels and behavior oxidative stress markers and mitochondrial function in non-proliferative DR (NPDR) and to establish the correlation between the severity of NPDR and markers of oxidative stress and mitochondrial function.

METHODS

In a transverse analysis, type 2 diabetes mellitus (T2DM) patients with mild, moderate and severe non-proliferative DR (NPDR) were evaluated for markers of oxidative stress (i.e. products of lipid peroxidation (LPO) and nitric oxide (NO) catabolites) and antioxidant activity (i.e. total antioxidant capacity (TAC), catalase, and glutathione peroxidase (GPx) activity of erythrocytes). Mitochondrial function was also determined as the fluidity of the submitochondrial particles of platelets and the hydrolytic activity of F0 /F1 -ATPase.

RESULTS

Levels of LPO and NO were significantly increased in T2DM patients with severe NPDR (3.19 ± 0.05 μmol/mL and 45.62 ± 1.27 pmol/mL, respectively; P < 0.007 and P < 0.0001 vs levels in health volunteers, respectively), suggesting the presence of oxidative stress. TAC had significant decrease levels with minimum peak in severe retinopathy with 7.98 ± 0.48 mEq/mL (P < 0.0001). In contrast with TAC, erythrocyte catalase and GPx activity was increased in patients with severe NPDR (139.4 ± 4.4 and 117.13 ± 14.84 U/mg, respectively; P < 0.0001 vs healthy volunteers for both), suggesting an imbalance between oxidants and antioxidants. The fluidity of membrane submitochondrial particles decreased significantly in T2DM patients with mild, moderate, or severe NPDR compared with that in healthy volunteers (P < 0.0001 for all). Furthermore, there was a significant increase in the hydrolytic activity of the F0 /F1 -ATPase in T2DM patients with mild NPDR (265.07 ± 29.55 nmol/PO4 ; P < 0.0001 vs healthy volunteers), suggesting increased catabolism.

CONCLUSIONS

Patients with NPDR exhibit oxidative deregulation with decreased membrane fluidity of submitochondrial particles and increased systemic catabolism (mitochondrial dysfunction) with the potential for generalized systemic damage in T2DM.

Arginase in retinopathy

Ischemic retinopathies, such as diabetic retinopathy (DR), retinopathy of prematurity and retinal vein occlusion are a major cause of blindness in developed nations worldwide. Each of these conditions is associated with early neurovascular dysfunction. However, conventional therapies target clinically significant macula edema or neovascularization, which occur much later. Intra-ocular injections of anti-VEGF show promise in reducing retinal edema, but the effects are usually transient and the need for repeated injections increases the risk of intraocular infection. Laser photocoagulation can control pathological neovascularization, but may impair vision and in some patients the retinopathy continues to progress. Moreover, neither treatment targets early stage disease or promotes repair. This review examines the potential role of the ureahydrolase enzyme arginase as a therapeutic target for the treatment of ischemic retinopathy. Arginase metabolizes l-arginine to form proline, polyamines and glutamate. Excessive arginase activity reduces the l-arginine supply for nitric oxide synthase (NOS), causing it to become uncoupled and produce superoxide and less NO. Superoxide and NO react and form the toxic oxidant peroxynitrite. The catabolic products of polyamine oxidation and glutamate can induce more oxidative stress and DNA damage, both of which can cause cellular injury. Studies indicate that neurovascular injury during retinopathy is associated with increased arginase expression/activity, decreased NO, polyamine oxidation, formation of superoxide and peroxynitrite and dysfunction and injury of both vascular and neural cells. Furthermore, data indicate that the cytosolic isoform arginase I (AI) is involved in hyperglycemia-induced dysfunction and injury of vascular endothelial cells whereas the mitochondrial isoform arginase II (AII) is involved in neurovascular dysfunction and death following hyperoxia exposure. Thus, we postulate that activation of the arginase pathway causes neurovascular injury by uncoupling NOS and inducing polyamine oxidation and glutamate formation, thereby reducing NO and increasing oxidative stress, all of which contribute to the retinopathic process.

Direct and indirect antioxidant properties of α-lipoic acid and therapeutic potential

Diabetes has emerged as a major threat to worldwide health. The exact mechanisms underlying the disease are unknown; however, there is growing evidence that the excess generation of reactive oxygen species (ROS) associated with hyperglycemia, causes oxidative stress in a variety of tissues. In this context, various natural compounds with pleiotropic actions like α-lipoic acid (LA) are of interest, especially in metabolic diseases such as diabetes. LA, either as a dietary supplement or a therapeutic agent, modulates redox potential because of its ability to match the redox status between different subcellular compartments as well as extracellularly. Both the oxidized (disulfide) and reduced (di-thiol: dihydro-lipoic acid, DHLA) forms of LA show antioxidant properties. LA exerts antioxidant effects in biological systems through ROS quenching but also via an action on transition metal chelation. Dietary supplementation with LA has been successfully employed in a variety of in vivo models of disease associated with an imbalance of redox status: diabetes and cardiovascular diseases. The complex and intimate association between increased oxidative stress and increased inflammation in related disorders such as diabetes, makes it difficult to establish the temporal sequence of the relationship.

Potential beneficial role of sevelamer hydrochloride in diabetic retinopathy

Patients with chronic kidney disease (CKD) experience co-morbid illnesses, including cardiovascular disease and retinopathy. Sevelamer hydrochloride (Renagel®); a non-calcium phosphate binder reduces coronary artery and aortic calcification as compared to calcium containing phosphate binders and additionally effects inflammatory biomarkers such as C-reactive protein (CRP), and lowers LDL cholesterol in patients with CKD. Since retinopathy is proven to be associated with increased coronary calcification, shared pathophysiological processes may contribute to both microvascular and macrovascular disease. We here suggest three different mechanisms of possible sevelamer's influence on the retinopathy: (1) by direct effect on the microvasculature through lowering CRP and LDL, involved in endothelial dysfunction and atherogenesis, (2) indirectly by attenuation of vascular calcification of aorta and carotid internal artery, it reduces ischaemia and improves circulation in the opthalmic artery and hence postponing retinopathy, (3) through hypertension by reducing atherosclerosis and calcification of carotid arteries, sevelamer decreases stiffness and intima-media wall thickness, therefore lowering blood pressure, which is well known to increase progression of diabetic retinopathy. So far no studies have yet been published on the direct influence of sevelamer on the retinopathy which we believe has good theoretical background. With its combined macrovascular and microvascular effect, sevelamer could potentially postpone and/or decrease retinopathy in diabetic patients with hypertension, and that are on hemodialysis or even predialysis patients.

Laser refractive surgery in diabetic patients: a review of the literature

BACKGROUND

The purpose of this study was to evaluate the current recommendations regarding laser refractive surgery in patients with diabetes mellitus and to assess whether these patients make appropriate candidates for laser vision correction.

METHODS

A literature search was conducted to identify current research on the ocular complications of diabetes and original publications on laser refractive surgery in diabetic patients.

RESULTS

Diabetes was associated with several ocular complications. Initially the US Food and Drug Administration listed these complications as justification to advise against refractive surgery in patients with diabetes. However, recent studies on laser in situ keratomileusis in diabetic patients indicate that this procedure may be safe in diabetic patients with very well controlled systemic disease and no ocular manifestations.

CONCLUSION

Laser refractive surgery may be performed safely in a very selected group of patients with diabetes.

The role of glia in retinal vascular disease

Retinal vascular diseases collectively represent a leading cause of blindness. Unsurprisingly, pathological characterisation and treatment of retinal 'vascular' diseases have primarily focused on the aetiology and consequences of vascular dysfunction. Far less research has addressed the contribution of neuronal and glial dysfunction to the disease process of retinal vascular disorders. Ample evidence now suggests that retinal vasculopathy only uncommonly occurs in isolation, usually existing in concert with neuropathy and gliopathy. Retinal glia (Müller cells, astrocytes and microglia) have been reported to exhibit morphological and functional changes in both early and advanced phases of almost every retinal vascular disease. It is anticipated that identifying the causes of glial activation and dysfunction, and their contribution to loss of vision in retinal vascular disease, will lead to a better understanding of retinal vascular diseases, which might ultimately be translated into novel clinical therapies.

Inflammation and diabetic retinal microvascular complications

Diabetic retinopathy (DR) is one of the most common complications of diabetes and is a leading cause of blindness in people of the working age in Western countries. A major pathology of DR is microvascular complications such as non-perfused vessels, microaneurysms, dot/blot hemorrhages, cotton-wool spots, venous beading, vascular loops, vascular leakage and neovascularization. Multiple mechanisms are involved in these alternations. This review will focus on the role of inflammation in diabetic retinal microvascular complications and discuss the potential therapies by targeting inflammation.

Anti-inflammatory therapy for diabetic retinopathy

Diabetic retinopathy (DR) is one of the most common complications of diabetes. This devastating disease is a leading cause of blindness in people of working age in industrialized countries and affects the daily lives of millions of people. Despite tight glycemic control, blood pressure control and lipid-lowering therapy, the number of DR patients keeps growing and therapeutic approaches are limited. Moreover, there are significant limitations and side effects associated with the current therapies. Thus, there is a great need for development of new strategies for prevention and treatment of DR. Studies have shown that DR has prominent features of chronic, subclinical inflammation. This article focuses on the role of inflammation in DR and summarizes the progress of studies of anti-inflammatory strategies for DR.

The potential of nanomedicine therapies to treat neovascular disease in the retina

Neovascular disease in the retina is the leading cause of blindness in all age groups. Thus, there is a great need to develop effective therapeutic agents to inhibit and prevent neovascularization in the retina. Over the past decade, anti-VEGF therapeutic agents have entered the clinic for the treatment of neovascular retinal disease, and these agents have been effective for slowing and preventing the progression of neovascularization. However, the therapeutic benefits of anti-VEGF therapy can be diminished by the need for prolonged treatment regimens of repeated intravitreal injections, which can lead to complications such as endophthalmitis, retinal tears, and retinal detachment. Recent advances in nanoparticle-based drug delivery systems offer the opportunity to improve bioactivity and prolong bioavailability of drugs in the retina to reduce the risks associated with treating neovascular disease. This article reviews recent advances in the development of nanoparticle-based drug delivery systems which could be utilized to improve the treatment of neovascular disease in the retina.

Diabetic cataract-pathogenesis, epidemiology and treatment

Cataract in diabetic patients is a major cause of blindness in developed and developing countries. The pathogenesis of diabetic cataract development is still not fully understood. Recent basic research studies have emphasized the role of the polyol pathway in the initiation of the disease process. Population-based studies have greatly increased our knowledge concerning the association between diabetes and cataract formation and have defined risk factors for the development of cataract. Diabetic patients also have a higher risk of complications after phacoemulsification cataract surgery compared to nondiabetics. Aldose-reductase inhibitors and antioxidants have been proven beneficial in the prevention or treatment of this sightthreatening condition in in vitro and in vivo experimental studies. This paper provides an overview of the pathogenesis of diabetic cataract, clinical studies investigating the association between diabetes and cataract development, and current treatment of cataract in diabetics.

Vascular endothelial growth factor in eye disease

Collectively, angiogenic ocular conditions represent the leading cause of irreversible vision loss in developed countries. In the US, for example, retinopathy of prematurity, diabetic retinopathy and age-related macular degeneration are the principal causes of blindness in the infant, working age and elderly populations, respectively. Evidence suggests that vascular endothelial growth factor (VEGF), a 40kDa dimeric glycoprotein, promotes angiogenesis in each of these conditions, making it a highly significant therapeutic target. However, VEGF is pleiotropic, affecting a broad spectrum of endothelial, neuronal and glial behaviors, and confounding the validity of anti-VEGF strategies, particularly under chronic disease conditions. In fact, among other functions VEGF can influence cell proliferation, cell migration, proteolysis, cell survival and vessel permeability in a wide variety of biological contexts. This article will describe the roles played by VEGF in the pathogenesis of retinopathy of prematurity, diabetic retinopathy and age-related macular degeneration. The potential disadvantages of inhibiting VEGF will be discussed, as will the rationales for targeting other VEGF-related modulators of angiogenesis.

The Ontario printed educational message (OPEM) trial to narrow the evidence-practice gap with respect to prescribing practices of general and family physicians: a cluster randomized controlled trial, targeting the care of individuals with diabetes and hypertension in Ontario, Canada

Background

There are gaps between what family practitioners do in clinical practice and the evidence-based ideal. The most commonly used strategy to narrow these gaps is the printed educational message (PEM); however, the attributes of successful printed educational messages and their overall effectiveness in changing physician practice are not clear. The current endeavor aims to determine whether such messages change prescribing quality in primary care practice, and whether these effects differ with the format of the message.

Methods/design

The design is a large, simple, factorial, unblinded cluster-randomized controlled trial. PEMs will be distributed with informed, a quarterly evidence-based synopsis of current clinical information produced by the Institute for Clinical Evaluative Sciences, Toronto, Canada, and will be sent to all eligible general and family practitioners in Ontario. There will be three replicates of the trial, with three different educational messages, each aimed at narrowing a specific evidence-practice gap as follows: 1) angiotensin-converting enzyme inhibitors, hypertension treatment, and cholesterol lowering agents for diabetes; 2) retinal screening for diabetes; and 3) diuretics for hypertension.

For each of the three replicates there will be three intervention groups. The first group will receive informed with an attached postcard-sized, short, directive "outsert." The second intervention group will receive informed with a two-page explanatory "insert" on the same topic. The third intervention group will receive informed, with both the above-mentioned outsert and insert. The control group will receive informed only, without either an outsert or insert.

Routinely collected physician billing, prescription, and hospital data found in Ontario's administrative databases will be used to monitor pre-defined prescribing changes relevant and specific to each replicate, following delivery of the educational messages. Multi-level modeling will be used to study patterns in physician-prescribing quality over four quarters, before and after each of the three interventions. Subgroup analyses will be performed to assess the association between the characteristics of the physician's place of practice and target behaviours.

A further analysis of the immediate and delayed impacts of the PEMs will be performed using time-series analysis and interventional, auto-regressive, integrated moving average modeling.

Trial registration number

Current controlled trial ISRCTN72772651.

Oxidative stress, glucose metabolism, and the prevention of type 2 diabetes: pathophysiological insights

With the rising epidemic of type 2 diabetes worldwide, including the United States, the death and disability due to the suboptimal control of cardiovascular disease associated with this epidemic has made prevention of type 2 diabetes emerge as a primary strategic intervention. Several modalities have been assessed in large randomized controlled trials for diabetes prevention such as lifestyle interventions and various pharmacologic agents. Included in these agents are metformin, thiazolidinediones, acarbose, angiotensin converting enzyme inhibitors, as well as angiotensin receptor blockers. Abrogation of oxidative stress appears to be a common soil hypothesis that explains the favorable effects of these agents on glucose metabolism, including the prevention of diabetes and its complications. This comprehensive review highlights the role of oxidative stress in the pathogenesis of diabetes, with emphasis on the major clinical trials conducted on prevention of type 2 diabetes.

A genome-wide linkage scan for diabetic retinopathy susceptibility genes in Mexican Americans with type 2 diabetes from Starr County, Texas

We conducted a genome-wide linkage scan for genes contributing to retinopathy risk using 794 diabetes case subjects from 393 Mexican-American families from Starr County, Texas, having at least two diabetic siblings. The sample included 567 retinopathy case subjects comprising 282 affected sibling pairs. Retinopathy was classified as none, early nonproliferative, moderate-to-severe nonproliferative, or proliferative. Using 360 polymorphic markers (average spacing 9.4 cM), we conducted nonparametric linkage analysis followed by ordered-subset analysis (OSA) ranking families by average age of diabetes diagnosis. For any retinopathy, the highest LOD scores including all families were on chromosomes 3 (2.41 at 117 cM) and 12 (2.47 at 15.5). OSA logarithm of odds (LOD) scores >2 for any retinopathy occurred on chromosomes 12 (4.47 at 13.2 cM), 15 (3.65 at 100.6), and 20 (2.67 at 54.1). Scores >2 for either moderate-to-severe nonproliferative or proliferative retinopathy occurred on chromosomes 5 (2.53 at 11.2 cM), 6 (2.28 at 30.6), and 19 (2.21 at 100.6). Thus, unconditional linkage analysis revealed suggestive evidence of linkage with retinopathy on two chromosomes, whereas OSA revealed strong evidence of linkage on two chromosomes, and suggestive evidence on four. Candidate genes were identified in most implicated regions.

Genetics of diabetic retinopathy

Diabetes is rapidly increasing in frequency with an attendant toll of complications, including diabetic retinopathy. Although the underlying mechanisms remain elusive, genetic susceptibility is key to both types 1 and 2 diabetes and is increasingly recognized for its contribution to diabetic complications. In this article we review the evidence connecting genetic susceptibility to diabetic retinopathy. Elucidating the susceptibility genes and pathways should permit strategies to slow and reverse the troubling trends for the population, families, and individuals.

EFFECTIVE TRANSSCLERAL DELIVERY OF TWO RETINAL ANTI-ANGIOGENIC MOLECULES

PURPOSE

To evaluate the human transscleral diffusion and intravitreal delivery of carboxyamido-triazole (CAI) and 2-Methoxyestradiol (2ME2).

METHODS

The transscleral diffusion of two retinal antiangiogenic molecules, CAI and 2ME2, was measured in vitro to assess their potential transscleral delivery. Varying concentrations and different solvents of CAI and 2ME2 were placed in the upper compartment of a two-chamber acrylic perfusion apparatus, on the episcleral side of the sclera obtained from human donor eyes. Samples were taken from the lower compartment (uveal side) for up to 24 hours and measured by high performance liquid chromatography.

RESULTS

All three solutions that contained CAI efficiently diffused through the sclera with permeability constants that ranged from 2.8 to 5.5 x 10 cm/s. The scleral permeability constant derived for 2ME2 was 9.96 x 10 cm/s. The permeability constants obtained for both CAI and 2ME2 are similar to each other as well as to permeability constants measured for other small molecules such as fluorescein and dexamethasone fluorescein.

CONCLUSION

Both CAI and 2ME2 traverse the sclera efficiently. These data combined with the reported inhibition of posterior segment neovascularization observed with these two molecules demonstrates that CAI and 2ME2 are good candidate molecules to treat posterior segment neovascularization by local delivery.

Familial aggregation of severity of diabetic retinopathy in Mexican Americans from Starr County, Texas

OBJECTIVE

Diabetic retinopathy is a major cause of blindness. To determine whether retinopathy itself or only its severity aggregates in families, we examined the occurrence and severity of diabetic retinopathy in Mexican-American siblings with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Using stereoscopic fundus photography of seven standard fields, we measured retinopathy in 656 type 2 diabetic patients from 282 Mexican-American families from Starr County, Texas. Retinopathy severity was scored using the Early Treatment of Diabetic Retinopathy Study system and classified as no retinopathy, early nonproliferative diabetic retinopathy (NPDR-E), moderate-to-severe nonproliferative diabetic retinopathy (NPDR-S), or proliferative diabetic retinopathy (PDR).

RESULTS

Of 249 siblings of randomly selected probands with retinopathy, 169 (67.9%) had retinopathy, compared with 95 of 125 siblings of unaffected probands (76.0%; P = 0.11). Proband retinopathy class was associated (P = 0.03) with sibling retinopathy class, with significant odds ratios (ORs) for NPDR-E versus no retinopathy (OR 0.57 [95% CI 0.35-0.93]) and PDR versus NPDR-E (2.02 [1.13-3.63]); the contrast of NPDR-S versus NPDR-E approached significance (1.78 [0.99-3.20]). With the more severe classes (PDR and NPDR-S) combined in one group and the less severe ones (none and NPDR-E) in another, more severe proband retinopathy was associated with more severe sibling retinopathy (1.72 [1.03-2.88]).

CONCLUSIONS

More severe diabetic retinopathy showed evidence of familial aggregation, but the occurrence of diabetic retinopathy per se did not. The factors involved in the onset of diabetic retinopathy may differ from those involved in its progression to more severe forms.

Vascular endothelial growth factor and diabetic retinopathy: pathophysiological mechanisms and treatment perspectives

Retinal neovascularization and macular edema are central features of diabetic retinopathy, the major cause of blindness in the developed world. Current treatments are limited in their efficacy and are associated with significant adverse effects. Characterization of the molecular and cellular processes involved in vascular growth and permeability has led to the recognition that the angiogenic growth factor and vascular permeability factor vascular endothelial growth factor (VEGF) plays a pivotal role in the retinal microvascular complications of diabetes. Therefore, VEGF represents an exciting target for therapeutic intervention in diabetic retinopathy. This review highlights the current understanding of the mechanisms that regulate VEGF gene expression and mediate its biological effects and how these processes may become altered during diabetes. The cellular and molecular alterations that characterize experimental models of diabetes are considered in relation to the influence of high glucose-mediated oxidative stress on VEGF expression and on the mechanisms of VEGF's actions under hyperglycemic induction. Finally, potential therapeutic strategies for preventing VEGF overexpression or blocking its pathological effects in the diabetic retina are considered.

Studies on semicarbazide-sensitive amine oxidase in patients with diabetes mellitus and in transgenic mice

Patients with diabetes mellitus and with vascular complications in particular, exhibit higher plasma activities of semicarbazide-sensitive amine oxidase (SSAO) compared to control subjects. It has been speculated that production of cytotoxic products of SSAO may cause endothelial damage and thus contribute to the development of diabetic vascular complications such as retino-, nephro-, and neuropathies as a result of SSAO activity.In order to explore the possibility that high SSAO activity contributes to the development of vascular complications in diabetes, we have performed two studies in patients with Type-2 diabetes quantifying plasma SSAO activity, HbA(1c), and urinary levels of the SSAO substrate, methylamine. We also examined the prevalence of retinopathy in these patients. Additionally, we have studied a model of transgenic mice expressing human SSAO in smooth muscle cells. The transgenic mice have an increased SSAO activity as well as mRNA expression. Histological studies revealed a specific aorta phenotype with a condensed and rigid vessel wall in some of the transgenic mice. No wild-type animals displayed this phenotype.In conclusion, we suggest that this transgenic mouse model may be of great value for increasing the knowledge about to what extent human SSAO contributes to vascular complications in diabetes, and also to which extent inhibition of SSAO can prevent the development of such complications.

Risk, causes, and outcomes of visual impairment after loss of vision in the non-amblyopic eye: a population-based study

BACKGROUND

Screening for amblyopia in early childhood is done in many countries to ensure that affected children are detected and treated within the critical period, and achieve a level of vision in their amblyopic eye that would be useful should they lose vision in their non-amblyopic eye later in life. We aimed to investigate the risk, causes, and outcomes of visual impairment attributable to loss of vision in the non-amblyopic eye.

METHODS

For 24 months from July, 1997, national surveillance was done to identify all individuals in the UK with unilateral amblyopia (acuity worse than 6/12) who had newly acquired vision loss in the non-amblyopic eye, resulting in acuity of worse than 6/12 or visual-field restriction precluding driving. Information about participants was obtained at presentation and 1 year later. Participants were categorised as having socially significant visual impairment, or visual impairment, severe visual impairment, or blindness, in accordance with WHO taxonomy.

FINDINGS

Of 370 eligible individuals, at presentation 104 (28%) had socially significant visual impairment, 180 (49%) visual impairment, and 86 (23%) severe visual impairment or blindness. The minimum risk of permanent visual impairment by age 95 years was 32.9 (95% CI 29.1-36.9) per 100,000 total population. The projected lifetime risk of vision loss for an individual with amblyopia was at least 1.2% (95% CI 1.1-1.4). Only 36 (35%) of 102 people previously in paid employment were able to continue.

INTERPRETATION

In the UK, where screening for amblyopia is under review, risk of serious vision loss affecting the non-amblyopic eye and its results are greater than that previously assumed. Thus, in addition to the benefits of improved vision in the amblyopic eye, treatment of amblyopia during childhood is a potentially valuable strategy to prevent incapacitating vision loss later in life.

The relation of atherosclerotic cardiovascular disease to retinopathy in people with diabetes in the Cardiovascular Health Study

AIMS

To describe the association of retinopathy with atherosclerosis and atherosclerotic risk factors in people with diabetes.

METHODS

296 of the 558 people classified as having diabetes by the American Diabetes Association criteria, from a population based cohort of adults (ranging in age from 69 to 102 years) living in four United States communities (Allegheny County, Pennsylvania; Forsyth County, North Carolina; Sacramento County, California; and Washington County, Maryland) were studied from 1997 to 1998. Lesions typical of diabetic retinopathy were determined by grading a 45 degrees colour fundus photograph of one eye of each participant, using a modification of the Airlie House classification system.

RESULTS

Retinopathy was present in 20% of the diabetic cohort, with the lowest prevalence (16%), in those 80 years of age or older. Retinopathy was detected in 20.3% of the 296 people with diabetes; 2.7% of the 296 had signs of proliferative retinopathy and 2.1% had signs of macular oedema. The prevalence of diabetic retinopathy was higher in black people (35.4%) than white (16.0%). Controlling for age, sex, and blood glucose, retinopathy was more frequent in black people than white (odds ratio (OR) 2.26, 95% confidence interval (CI) 1.01, 5.05), in those with longer duration of diabetes (OR (per 5 years of diabetes) 1.42, 95% CI 1.18, 1.70), in those with subclinical cardiovascular disease (OR 1.49, 95% CI 0.51, 4.31), or coronary heart disease or stroke (OR 3.23, 95% CI 1.09, 9.56) than those without those diseases, in those with higher plasma low density lipoprotein (LDL) cholesterol (OR (per 10 mg/dl of LDL cholesterol) 1.12, 95% CI 1.02, 1.23), and in those with gross proteinuria (OR 4.76, 95% CI 1.53, 14.86).

CONCLUSION

Data from this population based study suggest a higher prevalence of retinopathy in black people than white people with diabetes and the association of cardiovascular disease, elevated plasma LDL cholesterol, and gross proteinuria with diabetic retinopathy. However, any conclusions or explanations regarding associations described here must be made with caution because only about one half of those with diabetes mellitus were evaluated.

Columbia University's Informatics for Diabetes Education and Telemedicine (IDEATel) Project: rationale and design

The Columbia University Informatics for Diabetes Education and Telemedicine (IDEATel) Project is a four-year demonstration project funded by the Centers for Medicare and Medicaid Services with the overall goals of evaluating the feasibility, acceptability, effectiveness, and cost-effectiveness of telemedicine in the management of older patients with diabetes. The study is designed as a randomized controlled trial and is being conducted by a state-wide consortium in New York. Eligibility requires that participants have diabetes, are Medicare beneficiaries, and reside in federally designated medically underserved areas. A total of 1,500 participants will be randomized, half in New York City and half in other areas of the state. Intervention participants receive a home telemedicine unit that provides synchronous videoconferencing with a project-based nurse, electronic transmission of home fingerstick glucose and blood pressure data, and Web access to a project Web site. End points include glycosylated hemoglobin, blood pressure, and lipid levels; patient satisfaction; health care service utilization; and costs. The project is intended to provide data to help inform regulatory and reimbursement policies for electronically delivered health care services.

Heart rate elevation and diabetic retinopathy in patients with type 2 diabetes mellitus and normoalbuminuria

To investigate the role of heart rate (HR) and blood pressure (BP) for diabetic retinopathy, 24-h ambulatory HR and BP were monitored for 162 in patients with type 2 diabetes and normoalbuminuria. The fundus was assessed as no retinopathy, simple diabetic retinopathy (SDR) and proliferative retinopathy (PDR). Comparing the highest with the lowest quartile of diabetic duration, the relative risk for retinopathy was 9.3 and for nocturnal HR, it was 3.6. Comparison among three retinopathy groups (no retinopathy, group 1, n=122; SDR, group 2, n=24; Pre-PDR or PDR, group 3, n=16) showed that 24-h and nocturnal HR were significantly higher in group 3 (80+/-9 and 71+/-9 beats per min) than in group 2 (73+/-8 and 64+/-8) and group 1 (72+/-7 and 60+/-7). In multiple logistic analysis, the odds ratio of diabetic duration and nocturnal HR to the existence of retinopathy was 1.17 (95% CI, 1.10-1.25, P=0.00001) and 1.11 (95% CI, 1.05-1.17, P=0.0002). We concluded that diabetic retinopathy is related to diabetic duration and high heart rate in type 2 diabetes mellitus with normoalbuminuria. Heart rate elevation may be a predictor of advanced retinopathy.

Rheopheresis: rheologic, functional, and structural aspects

Rheopheresis is a specific application of membrane differential filtration, synonymous with double filtration plasmapheresis for extracorporeal hemorheotherapy, eliminating an exactly defined spectrum of high molecular weight proteins from human plasma (e.g.: fibrinogen, alpha-2-macroglobulin, low-density lipoprotein cholesterol, IgM). This results in the improvement of blood flow and microcirculation initiated by lowering blood and plasma viscosity, and erythrocyte aggregation. In this context, microcirculation stands not only for the patency of small blood vessels, but for the complete interactive network between plasma, blood cells, the vessel wall, and cellular and extracellular compartments of the surrounding tissue. Insufficient tissue oxygenation leads to tissue damage, e.g., a microcirculatory disorder develops, creating acute as well as chronic symptoms. Therefore, impaired microcirculation has a rheologic, functional, and structural dimension with respect to involved organs or tissues. Rheopheresis represents a specific therapeutic approach with an acute rheologic as well as chronic functional and structural effects, which was confirmed in pilot and controlled clinical studies for several organ systems. Data from 2 controlled clinical trials are available for the safe and effective treatment in patients with age-related macular degeneration.

The effect of health education on the rate of ophthalmic examinations among African Americans with diabetes mellitus

OBJECTIVES

This study evaluated a multicomponent educational intervention to increase ophthalmic examination rates among African Americans with diabetes.

METHODS

A randomized trial was conducted with 280 African Americans with diabetes, enrolled from outpatient departments of 5 medical centers in the New York City metropolitan area, who had not had a dilated retinal examination within 14 months of randomization (65.7% female, mean age = 54.7 years [SD = 12.8 years]).

RESULTS

After site differences were controlled, the odds ratio for receiving a retinal examination associated with the intervention was 4.3 (95% confidence interval = 2.4, 7.8). The examination rate pooled across sites was 54.7% in the intervention group and 27.3% in the control group.

CONCLUSIONS

The intervention was associated with a rate of ophthalmic examination double the rate achieved with routine medical care.