Histopathology and regression of retinal hard exudates in diabetic retinopathy after reduction of elevated serum lipid levels

Effectiveness of dexamethasone implants in treating diabetic macular edema with hard exudates: a clinical observation

OBJECTIVE

This study seeks to explain the relationship between systemic conditions and hard exudate formations in diabetic macular edema patients. Besides, the study aimed to quantitatively examine changes in the area, location, and impact on visual function of hard exudates following intravitreal dexamethasone implant injections.

METHODS

A retrospective analysis was conducted, including 40 patients (40 eyes) diagnosed with non-proliferative diabetic retinopathy and concurrent macular edema between January 1, 2022, and January 1, 2024. Preoperative evaluations included glycated hemoglobin, lipid profile, and renal function examinations. Based on the location of HE, patients were divided into two groups: Group A, with HE in 1 mm of the central fovea, and Group B, with HE outside 1 mm of the central fovea. Selected eyes were subject to pre- and postoperative examinations, including best-corrected visual acuity (BCVA), intraocular pressure, slit-lamp biomicroscopy, scanning laser ophthalmoscopy (SLO), optical coherence tomography, and multifocal electroretinography. Following screening and examination, patients received an immediate intravitreal injection of the DEX implant, with an injection administered at the four-month mark. Hard exudate (HE) areas were measured utilizing SLO fundus imaging.

RESULTS

Total cholesterol, low-density lipoprotein, and triglyceride levels were found to be positively correlated with the presence of HE. Following surgical intervention, all patients demonstrated an improvement in BCVA. The mean BCVA increased from a preoperative measurement of 0.79 ± 0.04 to 0.39 ± 0.02 at the 6 month follow-up, indicating a statistically significant difference (p < 0.001). The baseline HE area for the entire patient cohort was 2.28 ± 0.22. One month post-operation, the HE area exhibited a slight increase to 2.27 ± 0.22. However, by the 6 month follow-up, the HE area had significantly decreased to 0.8 ± 0.87, representing a 35.09% reduction from the baseline measurement (p < 0.001). It is worth noting that Patient P1 did not exhibit a statistically significant difference between preoperative and six-month postoperative HE area (p = 0.032). Preoperative BCVA measurements for Group A and Group B were 0.81 ± 0.03 and 0.77 ± 0.03, respectively, with no statistically significant intergroup difference (p = 0.333). The baseline HE area for Group A was 2.61 ± 0.16, which decreased to 0.38 ± 0.20 at the six-month follow-up, representing a 14.60% reduction from the baseline total area. For Group B, the baseline HE area was measured at 1.95 ± 0.09, then decreasing to 1.21 ± 0.13 at the six-month follow-up, indicating a 62.05% reduction from the baseline total area. A statistically significant difference in the postoperative 6 month HE area was observed between Group A and Group B (p < 0.001). In Group A, the reduction in HE area (initial HE area-final HE area) was positively correlated with the improvement in P1 (initial P1-final P1) (r = 0.610, p = 0.004). In Group B, a similar positive correlation was found (initial HE area-final HE area with initial P1-final P1) (r = 0.488, p = 0.029). In Group B, the reduction in HE area (initial HE area-final HE area) correlated positively with the improvement in BCVA (initial BCVA-final BCVA) (r = 0.615, p = 0.004). Additionally, in Group B, the reduction in HE area (initial HE area-final HE area) was positively correlated with the improvement in CMT (initial CMT-final CMT) (r = -0.725, p< 0.001). Aggravated cataracts were observed in thirteen eyes during a follow-up examination 6 months later.

CONCLUSION

HE formation is associated with lipid levels. Dexamethasone implants demonstrate effectiveness in reducing HE areas in the short term, reducing macular edema, improving retinal structure, and enhancing visual function. The incidence of postoperative complications such as cataracts and glaucoma remains low.

A deep learning approach to hard exudates detection and disorganization of retinal inner layers identification on OCT images

The purpose of the study was to detect Hard Exudates (HE) and classify Disorganization of Retinal Inner Layers (DRIL) implementing a Deep Learning (DL) system on optical coherence tomography (OCT) images of eyes with diabetic macular edema (DME). We collected a dataset composed of 442 OCT images on which we annotated 6847 HE and the presence of DRIL. A complex operational pipeline was defined to implement data cleaning and image transformations, and train two DL models. The state-of-the-art neural network architectures (Yolov7, ConvNeXt, RegNetX) and advanced techniques were exploited to aggregate the results (Ensemble learning, Edge detection) and obtain a final model. The DL approach reached good performance in detecting HE and classifying DRIL. Regarding HE detection the model got an AP@0.5 score equal to 34.4% with Precision of 48.7% and Recall of 43.1%; while for DRIL classification an Accuracy of 91.1% with Sensitivity and Specificity both of 91.1% and AUC and AUPR values equal to 91% were obtained. The P-value was lower than 0.05 and the Kappa coefficient was 0.82. The DL models proved to be able to identify HE and DRIL in eyes with DME with a very good accuracy and all the metrics calculated confirmed the system performance. Our DL approach demonstrated to be a good candidate as a supporting tool for ophthalmologists in OCT images analysis.

Efficacy and safety of intravitreal injection of conbercept for moderate to severe nonproliferative diabetic retinopathy

Purpose

This study aimed to assess the effectiveness and safety of intravitreal injection of conbercept (IVC) in treating moderate to severe nonproliferative diabetic retinopathy (NPDR), with or without accompanying diabetic macular edema.

Methods

In this longitudinal retrospective study, 35 patients (50 eyes) with moderate to severe NPDR and Diabetic Retinopathy Severity Scale (DRSS) scores between 43 and 53 were treated at the Department of Ophthalmology, First Affiliated Hospital of Kunming Medical University, from October 2018 to January 2023. Treatment protocol included three monthly IVC injections followed by a pro re nata (PRN) regimen over a two-year follow-up period. Outcome measures were best-corrected visual acuity (BCVA), intraocular pressure, central macular thickness (CMT), extent of hard exudate (HE), and changes in DRSS scores. DRSS scores before and after treatment were analyzed using the Wilcoxon rank-sum test. Both systemic and ocular adverse events were meticulously documented to ascertain safety.

Results

From baseline to the final follow-up, the mean BCVA improved from 0.41 ± 0.39 to 0.23 ± 0.20 logMAR (p<0.05). The mean CMT decreased from 306.22 ± 77.40 to 297.97 ± 88.15 μm (p = 0.385). At 24 months, DRSS scores improved by ≥1 stage in 40 eyes (80%), ≥ 2 stages in 28 eyes (56%), ≥3 stages in 10 eyes (20%), and remained stable in 6 eyes (12%). The DRSS scores at each follow-up interval demonstrated statistically significant improvement from baseline (p<0.05). In 15 of 27 eyes (55.56%) with diabetic macular edema (DME), there was a significant reduction in the mean area of HE from baseline (p<0.05). No serious systemic adverse events were observed.

Conclusion

IVC is an effective and safe treatment for moderate to severe NPDR, demonstrating significant improvements in DRSS scores.

Imaging Histology Correlations of Intraretinal Fluid in Neovascular Age-Related Macular Degeneration

Purpose

Fluid presence and dynamism is central to the diagnosis and management of neovascular age-related macular degeneration. On optical coherence tomography (OCT), some hyporeflective spaces arise through vascular permeability (exudation) and others arise through degeneration (transudation). Herein we determined whether the histological appearance of fluid manifested this heterogeneity.

Methods

Two eyes of a White woman in her 90s with anti-vascular endothelial growth factor treated bilateral type 3 neovascularization secondary to age-related macular degeneration were osmicated, prepared for submicrometer epoxy resin sections, and correlated to eye-tracked spectral domain OCT. Examples of intraretinal tissue fluid were sought among similarly prepared donor eyes with fibrovascular scars, in a web-based age-related macular degeneration histopathology resource. Fluid stain intensity was quantified in reference to Bruch's membrane and the empty glass slide.

Results

Exudative fluid by OCT was slightly reflective and dynamically responded to anti-vascular endothelial growth factor. On histology, this fluid stained moderately, possessed a smooth and homogenous texture, and contained blood cells and fibrin. Nonexudative fluid in degenerative cysts and in outer retinal tubulation was minimally reflective on OCT and did not respond to anti-vascular endothelial growth factor. By histology, this fluid stained lightly, possessed a finely granular texture, and contained mainly tissue debris. Quantification supported the qualitative impressions of fluid stain density. Cells containing retinal pigment epithelium organelles localized to both fluid types.

Conclusions

High-resolution histology of osmicated tissue can distinguish between exudative and nonexudative fluid, some of which is transudative.

Translational Relevance

OCT and histological features of different fluid types can inform clinical decision-making and assist in the interpretation of newly available automated fluid detection algorithms.

Perilipin 2-positive mononuclear phagocytes accumulate in the diabetic retina and promote PPARγ-dependent vasodegeneration

Type 2 diabetes mellitus (T2DM), characterized by hyperglycemia and dyslipidemia, leads to nonproliferative diabetic retinopathy (NPDR). NPDR is associated with blood-retina barrier disruption, plasma exudates, microvascular degeneration, elevated inflammatory cytokine levels, and monocyte (Mo) infiltration. Whether and how the diabetes-associated changes in plasma lipid and carbohydrate levels modify Mo differentiation remains unknown. Here, we show that mononuclear phagocytes (MPs) in areas of vascular leakage in DR donor retinas expressed perilipin 2 (PLIN2), a marker of intracellular lipid load. Strong upregulation of PLIN2 was also observed when healthy donor Mos were treated with plasma from patients with T2DM or with palmitate concentrations typical of those found in T2DM plasma, but not under high-glucose conditions. PLIN2 expression correlated with the expression of other key genes involved in lipid metabolism (ACADVL, PDK4) and the DR biomarkers ANGPTL4 and CXCL8. Mechanistically, we show that lipid-exposed MPs induced capillary degeneration in ex vivo explants that was inhibited by pharmaceutical inhibition of PPARγ signaling. Our study reveals a mechanism linking dyslipidemia-induced MP polarization to the increased inflammatory cytokine levels and microvascular degeneration that characterize NPDR. This study provides comprehensive insights into the glycemia-independent activation of Mos in T2DM and identifies MP PPARγ as a target for inhibition of lipid-activated MPs in DR.

Onion ring sign on spectral domain optical coherence tomography in diabetic macular edema: Its evolution and outcomes

PURPOSE

To report evolution and outcomes of hyperreflective crystalline deposit (HCD) on optical coherence tomography (OCT) in diabetic maculopathy (DM).

METHODS

Patients with DM showing HCD on OCT for the first time between June 2017 and May 2021 were included in the study. Demographic, ophthalmic and OCT features were documented and analysed. Factors leading to the development of HCD and its effect on the functional outcome were analysed and described in this study.

RESULTS

Sixty cases of HCD were identified in 45 (males -33; females - 12) patients for the first-time during the defined study period. Mean age of the eligible patients was 61.53 ± 8.19 years. Average duration of diabetes was 13.82 ± 7.38 years. Mean visual acuity of these patients was 0.902 ± 0.438 logMAR units (Snellen equivalent = 20/160). Patients with HCD showed subretinal hard exudates, were on anti-cholesterol medications (n = 36, 80%) and showed reduced visual acuity (20/160) if the HCD involved the fovea. The median time taken for the development of HCD was 28 months. Mean follow-up duration of the study was 26.19 ± 27.98 months. Persistence of HCD in all cases (n = 42, 100%) was noted at the last follow-up visit.

CONCLUSION

Horizontal, single or multi-layered HCDs on OCT in DM represent intraretinal or subretinal cholesterol crystal precipitates evolving from the hard exudates identical to the "onion ring sign" seen in neovascular AMD. HCDs or CCs depict deranged lipid metabolism, chronic vascular leakage and can lead to substantial visual impairment if the fovea gets involved.

Pathological Neurovascular Unit Mapping onto Multimodal Imaging in Diabetic Macular Edema

Diabetic retinopathy is a form of diabetic microangiopathy, and vascular hyperpermeability in the macula leads to retinal thickening and concomitant reduction of visual acuity in diabetic macular edema (DME). In this review, we discuss multimodal fundus imaging, comparing the pathogenesis and interventions. Clinicians diagnose DME using two major criteria, clinically significant macular edema by fundus examination and center-involving diabetic macular edema using optical coherence tomography (OCT), to determine the appropriate treatment. In addition to fundus photography, fluorescein angiography (FA) is a classical modality to evaluate morphological and functional changes in retinal capillaries, e.g., microaneurysms, capillary nonperfusion, and fluorescein leakage. Recently, optical coherence tomography angiography (OCTA) has allowed us to evaluate the three-dimensional structure of the retinal vasculature and newly demonstrated that lamellar capillary nonperfusion in the deep layer is associated with retinal edema. The clinical application of OCT has accelerated our understanding of various neuronal damages in DME. Retinal thickness measured by OCT enables us to quantitatively assess therapeutic effects. Sectional OCT images depict the deformation of neural tissues, e.g., cystoid macular edema, serous retinal detachment, and sponge-like retinal swelling. The disorganization of retinal inner layers (DRIL) and foveal photoreceptor damage, biomarkers of neurodegeneration, are associated with visual impairment. Fundus autofluorescence derives from the retinal pigment epithelium (RPE) and its qualitative and quantitative changes suggest that the RPE damage contributes to the neuronal changes in DME. These clinical findings on multimodal imaging help to elucidate the pathology in the neurovascular units and lead to the next generation of clinical and translational research in DME.

Role of acyl-coenzyme A: cholesterol transferase 1 (ACAT1) in retinal neovascularization

BACKGROUND

We have investigated the efficacy of a new strategy to limit pathological retinal neovascularization (RNV) during ischemic retinopathy by targeting the cholesterol metabolizing enzyme acyl-coenzyme A: cholesterol transferase 1 (ACAT1). Dyslipidemia and cholesterol accumulation have been strongly implicated in promoting subretinal NV. However, little is known about the role of cholesterol metabolism in RNV. Here, we tested the effects of inhibiting ACAT1 on pathological RNV in the mouse model of oxygen-induced retinopathy (OIR).

METHODS

In vivo studies used knockout mice that lack the receptor for LDL cholesterol (LDLR^-/-) and wild-type mice. The wild-type mice were treated with a specific inhibitor of ACAT1, K604 (10 mg/kg, i.p) or vehicle (PBS) during OIR. In vitro studies used human microglia exposed to oxygen-glucose deprivation (OGD) and treated with the ACAT1 inhibitor (1 μM) or PBS.

RESULTS

Analysis of OIR retinas showed that increased expression of inflammatory mediators and pathological RNV were associated with significant increases in expression of the LDLR, increased accumulation of neutral lipids, and formation of toxic levels of cholesterol ester (CE). Deletion of the LDLR completely blocked OIR-induced RNV and significantly reduced the AVA. The OIR-induced increase in CE formation was accompanied by significant increases in expression of ACAT1, VEGF and inflammatory factors (TREM1 and MCSF) (p < 0.05). ACAT1 was co-localized with TREM1, MCSF, and macrophage/microglia makers (F4/80 and Iba1) in areas of RNV. Treatment with K604 prevented retinal accumulation of neutral lipids and CE formation, inhibited RNV, and decreased the AVA as compared to controls (p < 0.05). The treatment also blocked upregulation of LDLR, ACAT1, TREM1, MCSF, and inflammatory cytokines but did not alter VEGF expression. K604 treatment of microglia cells also blocked the effects of OGD in increasing expression of ACAT1, TREM1, and MCSF without altering VEGF expression.

CONCLUSIONS

OIR-induced RNV is closely associated with increases in lipid accumulation and CE formation along with increased expression of LDLR, ACAT1, TREM1, and MCSF. Inhibiting ACAT1 blocked these effects and limited RNV independently of alterations in VEGF expression. This pathway offers a novel strategy to limit vascular injury during ischemic retinopathy.

Potential Roles of Anti-Inflammatory Plant-Derived Bioactive Compounds Targeting Inflammation in Microvascular Complications of Diabetes

Diabetes mellitus (DM) is a group of metabolic disorders, the characteristics of which include chronic hyperglycemia owing to defects in insulin function, insulin secretion, or both. Inflammation plays a crucial role in DM pathogenesis and innate immunity in the development of microvascular complications of diabetes. In addition, hyperglycemia and DM mediate a proinflammatory microenvironment that can result in various microvascular complications, including diabetic nephropathy (DNP), diabetic neuropathy (DN), and diabetic retinopathy (DR). DNP is a major cause of end-stage renal disease. DNP can lead to albuminuria, decreased filtration, mesangium expansion, thickening of the basement membrane, and eventually renal failure. Furthermore, inflammatory cells can accumulate in the interstitium and glomeruli to deteriorate DNP. DN is another most prevalent microvascular complication of DM and the main cause of high mortality, disability, and a poor quality of life. DNs have a wide range of clinical manifestations because of the types of fiber dysfunctions and complex structures of the peripheral nervous system. DR is also a microvascular and multifactorial disease, as well as a major cause of visual impairment globally. Pathogenesis of DR is yet to be fully revealed, however, numerous studies have already confirmed the role of inflammation in the onset and advancement of DR. Despite evidence, and better knowledge regarding the pathogenesis of these microvascular complications of diabetes, there is still a deficiency of effective therapies. Bioactive compounds are mainly derived from plants, and these molecules have promising therapeutic potential. In this review, evidence and molecular mechanisms regarding the role of inflammation in various microvascular complications of diabetes including DNP, DN, and DR, have been summarized. The therapeutic potential of several bioactive compounds derived from plants in the treatment of these microvascular complications of diabetes has also been discussed.

The Effect of Hyperlipidemia on the Course of Diabetic Retinopathy—Literature Review

Diabetes mellitus is a very important social issue, and its retinal complications continue to be one of the major causes of blindness worldwide. The effect of glucose level on the development of retinal retinopathy has been the subject of numerous studies and is well understood. Hypertension and hyperlipidemia have been known to be important risk factors in the development of diabetes complications. However, the mechanisms of this effect have not been fully explained and raise a good deal of controversy. The latest research results suggest that some lipoproteins are closely correlated with the incidence of diabetic retinopathy and that by exerting an impact on their level the disease course can be modulated. Moreover, pharmacotherapy which reduces the level of lipids, particularly by means of statins and fibrate, has been shown to alleviate diabetic retinopathy. Therefore, we have decided to review the latest literature on diabetic retinopathy with respect to the impact of hyperlipidemia and possible preventive measures

Intravitreal Injection for Diabetic Macular Edema as Adjunctive Therapy for Proliferative Diabetic Retinopathy: A Retrospective Study

Purpose

To detect the impact of intravitreal injection (IVI) therapy with sole anti-vascular-endothelial-growth-factor (VEGF) or combined with steroids treating diabetic macular edema (DME) on activity of proliferative diabetic retinopathy (PDR) based on total number of panretinal photocoagulation (PRP) spots needed within 2 years.

Patients and Methods

A retrospective study of 102 eyes with primary-onset PDR and minimum follow-up of 24 months divided into 2 groups: Group 1 (G1) 40 eyes received only PRP and did not develop DME. Group 2 (G2) 62 eyes received additional IVI-therapy due to concomitant DME, with anti-VEGF only (subgroup 2a, G2a) or in combination with steroids (subgroup 2b, G2b). Main outcomes: central macular thickness (CMT, µm), best-corrected visual acuity (BCVA, LogMAR) and total number of needed PRP spots and IVI after 24 months.

Results

CMT was significantly higher in G2 compared to G1, initially (p < 0.01) and after 24 months (p = 0.01). CMT was significantly higher in G2b compared to G2a, both initially (p = 0.01) and after 24 months (p < 0.01). BCVA was significantly higher in G1 compared to G2, initially and after 24 months (p = 0.01). BCVA was not significantly different between the two subgroups, initially (p = 0.54) and after 24 months (p = 0.29). The total number of PRP spots was significantly higher in G1 compared to G2 (p < 0.01) but not significantly different between the subgroups (p = 0.8).

Conclusion

Regardless of severity of concomitant DME, IVI with sole anti-VEGF or combined with steroids reduced the total number of PRP spots needed within 2 years significantly indicating a favorable effect on activity of PDR.

Behavior of hyperreflective spots noted on optical coherence tomography following intravitreal therapy in diabetic macular edema: A systematic review and meta-analysis

Purpose:

Hyperreflective spots (HRS) are considered as spectral domain optical coherence tomography biomarkers in predicting response to intravitreal therapy (IVT) in diabetic macular edema (DME). We aimed to determine if there was a quantitative reduction in HRS following IVT in DME, if the response to antivascular endothelial growth factor (anti-VEGF) drugs was different from steroids, and if HRS-response was associated with improvement in visual acuity (VA) or reduction in central macular thickness (CMT).

Methods:

PubMed/MEDLINE, Scopus, ProQuest, CINAHL, Wiley online, and Web of Science were searched (between January 1, 2011 and July 1, 2020). Publication bias and heterogeneity were assessed. Meta-analysis was done using the random-effects model.

Results:

Totally, 1168 eyes from 19 studies were eligible for inclusion. IVT was associated with a reduction in quantitative HRS (z = -6.3, P < 0.0001). Studies, however, showed heterogeneity (I² = 93.2%). There was no difference between anti-VEGF and steroid therapies (P = 0.23). The evidence on predicting VA and CMT outcomes were limited by the number of analyzable studies, owing to the wide variation in individual study designs, and lack of randomized controlled trials.

Conclusion:

We could conclude that there is a definite reduction in quantitative HRS following either form of IVT. We highlight the lacunae in the existing literature on HRS in DME and propose goals for future studies to harness the advantage of this promising biomarker.

Detection of the Microvascular Changes of Diabetic Retinopathy Progression Using Optical Coherence Tomography Angiography

Purpose

To investigate microvascular parameters that are related to the severity of diabetic retinopathy (DR) with optical coherence tomography angiography (OCTA).

Methods

In total, 105 eyes from 105 diabetic patients were recruited in this prospective cross-sectional study, including 37 eyes with no clinical signs of DR (NoDR), 43 eyes with nonproliferative diabetic retinopathy (NPDR), and 25 eyes with proliferative diabetic retinopathy (PDR). Angiogram images from the parafoveal superficial capillary plexus (SCP), the deep capillary plexus (DCP), and the radial peripapillary capillary plexus were analyzed, and metrics were compared among groups. Multivariate regression analysis was used to identify the best OCTA parameters that could distinguish DR severity among groups.

Results

Parafoveal vessel diameter index in the SCP and vessel density (VD) in the DCP showed the strongest correlation with the severity of DR (P < 0.01). Extrafoveal avascular area in the SCP was the parameter that could most distinguish NoDR from NPDR (P < 0.01) with sensitivity and specificity of 83.72% and 78.38%, respectively. VD in the DCP also was the most sensitive biomarker to distinguish NPDR from PDR (P < 0.01) with sensitivity and specificity of 84.00% and 79.07%, respectively.

Conclusions

The microvascular changes in the SCP and DCP in DR may have different characteristics that could be identified with specific OCTA parameters. OCTA serves as a promising technology to discriminate eyes with different severity of DR.

Translational Relevance

Our study investigated OCTA metrics and severity of DR. At different stages of DR, ophthalmologists may focus on specific OCTA parameters to predict the progression of retinopathy in individual patients.

Atorvastatin-Eluting Contact Lenses: Effects of Molecular Imprinting and Sterilization on Drug Loading and Release

Statins are receiving increasing attention in the ophthalmic field. Their activity as 3-hydroxy-3-methylglutaryl–CoA (HMG–CoA) reductase inhibitors is clinically used to regulate cholesterol levels and leads to pleiotropic effects, which may help in the management of diabetes-related ocular pathologies. This work aims to design bioinspired contact lenses (CLs) with an affinity for atorvastatin by mimicking the active site of HMG–CoA reductase. Sets of imprinted and nonimprinted 2-hydroxyethyl methacrylate (HEMA) hydrogels were synthesized, varying the contents in functional monomers that bear chemical groups that resemble those present in HMG–CoA reductase, namely, ethylene glycol phenyl ether methacrylate (EGPEM), 2-aminoethyl methacrylate hydrochloride (AEMA), and N-(3-aminopropyl) methacrylamide hydrochloride (APMA). The hydrogels were characterized in terms of suitability as CLs (solvent uptake, light transmission, mechanical properties, and biocompatibility) and capability to load and release atorvastatin. Three sterilization protocols (steam heat, gamma radiation, and high hydrostatic pressure) were implemented and their effects on hydrogel properties were evaluated. Copolymerization of AEMA and, particularly, APMA endowed the hydrogels with a high affinity for atorvastatin (up to 11 mg/g; K_N/W > 200). Only high hydrostatic pressure sterilization preserved atorvastatin stability and hydrogel performance. Permeability studies through the porcine cornea and sclera tissues revealed that the amount of atorvastatin accumulated in the cornea and sclera could be effective to treat ocular surface diseases.

The Safety of Pharmacological and Surgical Treatment of Diabetes in Patients with Diabetic Retinopathy-A Review

BACKGROUND

Diabetes mellitus (DM) is a non-infectious pandemic of the modern world; it is estimated that in 2045 it will affect 10% of the world's population. As the prevalence of diabetes increases, the problem of its complications, including diabetic retinopathy (DR), grows. DR is a highly specific neurovascular complication of diabetes that occurs in more than one third of DM patients and accounts for 80% of complete vision loss cases in the diabetic population. We are currently witnessing many groundbreaking studies on new pharmacological and surgical methods of treating diabetes.

AIM

The aim of the study is to assess the safety of pharmacological and surgical treatment of DM in patients with DR.

MATERIAL AND METHODS

An analysis of the data on diabetes treatment methods currently available in the world literature and their impact on the occurrence and progression of DR.

RESULTS

A rapid decrease in glycaemia leads to an increased occurrence and progression of DR. Its greatest risk accompanies insulin therapy and sulfonylurea therapy. The lowest risk of DR occurs with the use of SGLT2 inhibitors; the use of DPP-4 inhibitors and GLP-1 analogues is also safe. Patients undergoing pancreatic islet transplants or bariatric surgeries require intensive monitoring of the state of the eye, both in the perioperative and postoperative period.

CONCLUSIONS

It is of utmost importance to individualize therapy in diabetic patients, in order to gradually achieve treatment goals with the use of safe methods and minimize the risk of development and progression of DR.

Hyperreflective cystoid spaces in diabetic macular oedema: prevalence and clinical implications

AIMS

To analyse the prevalence and evolution of hyper-reflective cystoid spaces with decorrelation signal detected using optical coherence tomography angiography (OCTA) in diabetic macular oedema (DMO).

METHODS

A retrospective study of consecutive eyes with DMO imaged using OCTA over a 1-year period was conducted. All eyes with hyper-reflective cystoid spaces at baseline and at least 3 months of follow-up were included in a longitudinal analysis.

RESULTS

The prevalence of hyperreflective cystoid spaces with decorrelation signal was of 37% (61/165) in DMO eyes. Hyperreflective foci within hyperreflective cystoid spaces were observed in 85% of eyes. The longitudinal study included 33 eyes (10 observed and 23 treated with intravitreal anti-vascular endothelial growth factor), with a median follow-up of 15 months. The hyperreflective cystoid spaces resolved in 85% of eyes. The mean best-corrected visual acuity remained stable during the follow-up, even in the eyes achieving a resolution of the hyperreflective cystoid spaces. Hard exudates appeared in the area of resolved hyperreflective cystoid spaces in 33% of eyes.

CONCLUSION

Hyperreflective cystoid spaces detected by OCTA affected more than one-third of the DMO eyes. Their disappearance was not associated with any functional improvement and led to the formation of new hard exudate deposits in about one-third of the eyes.

Intensive treat-to-target statin therapy and severity of diabetic retinopathy complicated by hypercholesterolaemia

OBJECTIVES

To compare the effects of intensive and standard statin therapy on severity of diabetic retinopathy (DR) complicated by hypercholesterolaemia in a prespecified substudy of the standard vs. intEnsive statin therapy for hypercholesteroleMic Patients with diAbetic retinopaTHY (EMPATHY) study.

METHODS

Among 5144 patients in the multicentre, prospective, randomized EMPATHY study, this substudy considered 157 patients with seven-field fundus photographs of sufficient quality taken during study enrolment and at the 3-year visit. Eighty-five and seventy-two patients received intensive and standard statin treatments, respectively, in a treat-to-target manner. The primary endpoint was a two-step change in the Early Treatment Diabetic Retinopathy Study (ETDRS) DR severity scale at 36 months. Surrogate markers included changes in hard exudates, changes in visual acuity, and additional ocular treatments during study follow-up.

RESULTS

Intensive and standard treatment groups did not differ significantly in terms of changing two or more steps on the DR severity scale (P = 0.4380). In patients with severe DR, defined as ≥47 on the severity scale, exploratory analysis showed more frequent improvement of DR, by at least one step, with intensive vs. standard treatment (83.3% vs. 40.0%; P = 0.0346). The intensive and standard groups did not differ in changes on the hard exudates severity scale (P = 0.3460), logarithm of minimum angle of resolution visual acuity (P = 0.5500), or additional ocular treatment during follow-up.

CONCLUSIONS

Intensive and standard statin treatment may have similar effects on DR in the population of all patients with DR and hypercholesterolaemia, but intensive therapy may be more beneficial in patients with severe DR.

Effects of intravitreal conbercept before panretinal photocoagulation on lipid exudates in diabetic macular documented by optical coherence tomography

AIM

To evaluate the effects of intravitreal conbercept (IVC) as adjunctive treatments before panretinal photocoagulation (PRP) to decrease hyperreflective dots (HRDs) in Chinese proliferative diabetic retinopathy (PDR) patients.

METHODS

Fifty-nine enrolled patients were categorized into 2 groups: single dose IVC (0.5 mg/0.05 mL) 1wk before PRP (Plus group) or PRP only (PRP group). Six months later, we measured the best corrected visual acuity (BCVA), central macula thickness (CMT) by optical coherence tomography and counted the number of HRDs in different retina layers.

RESULTS

The average CMT significantly decreased in Plus group but increased in PRP group. The average BCVA in the Plus group was also significantly better than that in the PRP group. Total HRDs decreased in the Plus group but increased in PRP group significantly. IVC pre-treatment has beneficial effects on reducing HRDs forming in the inner retina layer while the PRP alone increased the HRDs in the outer retina layer.

CONCLUSION

IVC is a promising adjunctive treatment to PRP in the treatment of PDR. Single dose IVC one week before PRP is suggested to improve retina blood-retina barrier, decrease lipid exudate and inhibit HRDs development in PDR.

Differences in Risk Factors for Diabetic Retinopathy in Type 1 and Type 2 Diabetes Mellitus Patients in North-East Poland

Background and objective: Nowadays, diabetes is one of the main causes of blindness in the world. Identification and differentiation of risk factors for diabetic retinopathy depending on the type of diabetes gives us the opportunity to fight and prevent this complication. Aim of the research: To assess differences in the risk factors for diabetic retinopathy in type 1 and type 2 diabetes mellitus patients in Warmia and Mazury Region, Poland. Materials and Methods: Risk factors for diabetic retinopathy (DR) were assessed on the basis of an original questionnaire, which included: personal data, clinical history of diabetes and eye disease. Elements of clinical examination: blood pressure, BMI, waist circumference. Indicators of diabetes metabolic control: mean glycemia, glycated hemoglobin (HbA1c), total cholesterol and triglycerides, creatinine, glomerular filtration rate (GFR), albumin-creatinine ratio in urine. Results: The study group included 315 (26%) patients with DM1 and 894 (74%) patients with DM2. Risk factors were estimated on the basis of logistic regression and verified with Student's t-test. Statistically significant dependencies were found in both groups between the occurrence of diabetic retinopathy and diabetes duration, HbA1c, triglyceride concentrations, indicators of kidney function and cigarette smoking status. In the DM2 group, the development of DR was significantly influenced by the implemented models of diabetic treatment. Conclusions: In the whole study group, the risk of DR was associated with the duration of diabetes, HbA1c, triglyceride concentrations and smoking. In DM1 patients, the risk of DR was associated with diabetic kidney disease in the G1A1/A2 stage of chronic kidney disease, and in DM2 patients with the G2 stage of chronic kidney disease. An important risk factor for DR in DM2 patients was associated with late introduction of insulin therapy.

Fast and Automated Hyperreflective Foci Segmentation Based on Image Enhancement and Improved 3D U-Net in SD-OCT Volumes with Diabetic Retinopathy

Purpose

To design a robust and automated hyperreflective foci (HRF) segmentation framework for spectral-domain optical coherence tomography (SD-OCT) volumes, especially volumes with low HRF-background contrast.

Methods

HRF in retinal SD-OCT volumes appear with low-contrast characteristics that results in the difficulty of HRF segmentation. Therefore to effectively segment the HRF we proposed a fully automated method for HRF segmentation in SD-OCT volumes with diabetic retinopathy (DR). First, we generated the enhanced SD-OCT images from the denoised SD-OCT images with an enhancement method. Then the enhanced images were cascaded with the denoised images as the two-channel input to the network against the low-contrast HRF. Finally, we replaced the standard convolution with slice-wise dilated convolution in the last layer of the encoder path of 3D U-Net to obtain long-range information.

Results

We evaluated our method using two-fold cross-validation on 33 SD-OCT volumes from 27 patients. The average dice similarity coefficient was 70.73%, which was higher than that of the existing methods with significant difference (P < 0.01).

Conclusions

Experimental results demonstrated that the proposed method is faster and achieves more reliable segmentation results than the current HRF segmentation algorithms. We expect that this method will contribute to clinical diagnosis and disease surveillance.

Translational Relevance

Our framework for the automated HRF segmentation of SD-OCT volumes may improve the clinical diagnosis of DR.

Innate immune response in retinal homeostasis and inflammatory disorders

Innate immune cells such as neutrophils, monocyte-macrophages and microglial cells are pivotal for the health and disease of the retina. For the maintenance of retinal homeostasis, these cells and immunosuppressive molecules in the eye actively regulate the induction and the expression of inflammation in order to prevent excessive activation and subsequent tissue damage. In the disease context, these regulatory mechanisms are modulated genetically and/or by environmental stimuli such as damage-associated molecular patterns (DAMPs), and a chronic innate immune response regulates or contributes to the formation of diverse retinal disorders such as uveitis, retinitis pigmentosa, retinal vascular diseases and retinal fibrosis. Here we summarize the recent knowledge regarding the innate immune response in both ocular immune regulation and inflammatory retinal diseases, and we describe the potential of the innate immune response as a biomarker and therapeutic target.

HYPERREFLECTIVE DEPOSITION IN THE BACKGROUND OF ADVANCED STARGARDT DISEASE

PURPOSE

To describe an unusual manifestation of hyperreflective deposits in the subretinal space in a group of patients with clinically and genetically confirmed Stargardt disease.

METHODS

Retrospective review of color fundus, autofluorescence, infrared reflectance, red-free images, and spectral domain optical coherence tomography in 296 clinically diagnosed and genetically confirmed (2 expected disease-causing mutations in ABCA4) patients with Stargardt disease. Full-field electroretinogram (ffERG), medical history, and genotype data (in silico predictions) were further analyzed from the selected cohort.

RESULTS

Eight of 296 patients (2.7%) were found to exhibit small crystalline deposits that were detectable on certain imaging modalities, such as color, infrared reflectance and red-free images, but not autofluorescence. The deposits were most prevalent in the superior region of the macula, and spectral domain optical coherence tomography revealed their presence in the subretinal space. All patients presented with these findings at a notably advanced disease stage with abnormal ffERG and a high proportion of highly deleterious ABCA4 alleles.

CONCLUSION

Hyperreflective subretinal deposits may be a manifestation of advanced ABCA4 disease, particularly in regions susceptible to disease-related changes, such as lipofuscin accumulation.

"For Mass Eye and Ear Special Issue" Adaptive Optics in the Evaluation of Diabetic Retinopathy

Retinal imaging is a fundamental tool for clinical and research efforts in the evaluation and management of diabetic retinopathy. Adaptive optics (AO) is an imaging technique that enables correction of over 90% of the optical aberrations of an individual eye induced primarily by the tear film, cornea and lens. The two major tasks of any AO system are to measure the optical imperfections of the eye and to then compensate for these aberrations to generate a corrected wavefront of reflected light from the eye. AO scanning laser ophthalmoscopy (AOSLO) provides a theoretical lateral resolution limit of 1.4 μm, allowing the study of microscopic features of the retinal vascular and neural tissue. AOSLO studies have revealed irregularities of the photoreceptor mosaic, vascular loss, and details of vascular lesions in diabetic eyes that may provide new insight into development, regression, and response to therapy of diabetic eye disease.

Statins in ophthalmology

Statins, 3-hydroxy-3-methyl-gutaryl coenzyme A reductase inhibitors, are a class of lipid-lowering drugs with anti-inflammatory, immunomodulatory, and vascular effects. Statins are increasingly being used in the treatment of a variety of medical conditions. We examine the actions of statins on the eye and its associated ophthalmic disorders. Statins can be synthetic or nonsynthetic, and their differentiating derivations may contribute to their varying cholesterol-lowering and pleiotropic effects. There is conflicting evidence on the ocular therapeutic and adverse effects of the statins. Statins may play a role in reducing the burden of dry eye, corneal ulcer scarring, thyroid-associated orbitopathy, glaucoma, uveitis and other associated ocular inflammatory states, cataract, proliferative vitreoretinopathy, diabetic retinopathy, macular degeneration, and choroidal melanoma. Topical preparations of statins can be formulated, thereby extending the range of ocular diseases that may be amenable to treatment. Statins have a relatively safe side effect profile, but rare and serious adverse reactions have been reported with their usage in ophthalmology, including myopathies and rhabdomyolysis with acute renal failure.

Short-Term Progression of Diabetic Hard Exudates Monitored with High-Resolution Camera

PURPOSE

To assess the progression of diabetic hard exudates over an 8-week period, using a high-resolution adaptive optics camera.

DESIGN

Prospective observational study.

METHODS

Five eyes of three patients presenting diabetic maculopathy with hard exudates were studied. An area of clinically visible exudates was imaged sequentially using SD-OCT and high-resolution flood illumination adaptive optics for 2 months, on a weekly basis. A time-lapse video was obtained for each eye studied. Changes in terms of surface, number of free elements (foci), and central macular thickness were recorded.

RESULTS

Short-term modifications in terms of disposition, size, and number of exudates were observed. Two patterns of progression were identified: two eyes showed exudate dislocation concomitant with the regression of the underlying macular edema, with hard exudates being progressively replaced by a multitude of smaller foci. These exudates were labeled resorption exudates. In three other eyes with persistent diabetic macular edema, foci aggregated into larger exudates.

CONCLUSION

Diabetic hard exudate changes occurred over a short period of time but were not assessable clinically. Adaptive optics was able to document these subtle changes precisely. Further studies using this imaging modality may improve our understanding of the natural history of exudates and eventually help assess the efficacy of the various treatments available such as lipid-lowering drugs and anti-VEGFs injections.

Suspended Scattering Particles in Motion: A Novel Feature of OCT Angiography in Exudative Maculopathies

OBJECTIVE

To characterize features of extra-vascular optical coherence tomography angiography (OCTA) signals corresponding to hyperreflective intraretinal fluid across various exudative maculopathies.

DESIGN

Multicenter, retrospective, observational study.

PARTICIPANTS

Eyes with various forms of exudative maculopathy including diabetic retinopathy (DR), retinal vein occlusion (RVO), and neovascular-age related macular degeneration (nvAMD).

METHODS

Patients with extra-vascular OCTA signal identified on en face OCTA images were included in this study. This signal was readily distinguishable from projection artifacts. The regions with the extra-vascular motion signal on OCTA were named "Suspended Scattering Particles in Motion (SSPiM)." Depth-encoded, color, en face OCTA images (3mm × 3mm) centered on the fovea and their corresponding structural OCT scans were used to quantify features of SSPiM and its corresponding hyperreflective fluid. Longitudinal data were collected when available.

MAIN OUTCOME MEASURES

Anatomic location, the association with hyperreflective material, changes in location and appearance of SSPiM over time, and replication of SSPiM OCTA signal in an in vitro phantom.

RESULTS

Seventy-six eyes in 62 patients with various forms of exudative maculopathy were evaluated; 60 eyes with DR, 9 eyes with RVO, and 5 eyes nvAMD, 1 eye with macroaneurysm, and 1 eye with radiation retinopathy. Intraretinal accumulations of fluid with increased OCT signal intensity corresponded to regions of SSPiM in several exudative maculopathies. An in vitro phantom model demonstrates that particulate matter in suspension can generate similar OCTA signal. SSPiM showed an anatomic preference for vascular-avascular junctions. The hyperreflective fluid corresponding to SSPiM appeared more frequently in Henle's fiber layer (HFL) than the inner nuclear layer (INL) and was highly associated with hyperreflective material (HRM) found bordering the fluid. In five of eight longitudinal cases, the resolution of SSPiM resulted in the formation of confluent HRM. Clinically, this appeared as hard exudate on funduscopic images.

CONCLUSIONS

Clinical data suggest that SSPiM is a novel imaging feature of retinal vascular diseases that was not appreciated prior to the use of OCTA. We characterized several novel features of SSPiM and demonstrated that at least in some cases it resolves with residual hard exudate.

Decorrelation Signal of Diabetic Hyperreflective Foci on Optical Coherence Tomography Angiography

Diabetic hyperreflective foci in the outer retinal layers are a clinically relevant finding on optical coherence tomography (OCT) images, although their characteristics remain to be elucidated. Here we investigated the decorrelation signal around hyperreflective foci on OCT angiography (OCTA) images in diabetic retinopathy (DR). We retrospectively reviewed sufficient quality OCTA images from 102 eyes of 66 patients that were obtained using split-spectrum amplitude-decorrelation angiography algorithm. Most confluent hyperreflective foci were randomly deposited or appeared in a radiating array on the en-face structural OCT images in the inner nuclear layer (INL) or Henle’s fiber layer (HFL), respectively. Within the INL, hyperreflective foci were not accompanied by decorrelation signals and attached to capillaries on OCTA images. Decorrelation signals were sometimes delineated in hyperreflective foci in the HFL and other times appeared to be pseudopod-like or wrapping around hyperreflective foci, referred to as reflectance-decorrelated foci. The decorrelation signal intensity of hyperreflective foci in the HFL was associated with logMAR VA (R = 0.553, P < 0.001) and central subfield thickness (R = 0.408, P < 0.001) but not with DR severity. These data suggest that reflectance-decorrelated foci on OCTA images are clinically relevant as well as shed lights on the properties in diabetic hyperreflective foci.

The prevalence and systemic risk factors of diabetic macular edema: a cross-sectional study from Turkey

Background

The aim of this study was to evaluate the prevalence of diabetic macular edema (DME) utilizing optical coherence tomography (OCT), and to clarify the effects of the systemic findings and risk factors on the development of DME.

Methods

This cross-sectional study was conducted in the departments of ophthalmology and endocrinology at the Dokuz Eylul University School of Medicine in Izmir, Turkey. The demographics, type and duration of diabetes mellitus, treatment modality, smoking and alcohol consumption habits, as well as the systemic blood pressure, renal functional tests, hemoglobulin A1c level, serum lipid profile, and 24-h urine albumin level were noted and statistically analyzed. The relationships between the systemic findings and DME were studied.

Results

Four-hundred and thirteen eyes of 413 diabetic patients who were examined between January 2011 and July 2012 were enrolled in this study. The prevalence of DME was 15.3% among the patients. The males exhibited DME significantly more frequently than the females (p = 0.031), and the duration of diabetes was significantly longer in those patients with DME (p < 0.001). Those patients without DME frequently used antihyperlipidemic drugs and had a higher level of high density lipoprotein cholesterol (p = 0.040 and p = 0.046, respectively). The patient’s alcohol consumption, nephropathy, neuropathy, previous cataract surgery, severity of diabetic retinopathy, and insulin usage were statistically significant factors with regard to the DME prevalence.

Conclusions

This study demonstrated the prevalence of DME in Turkey by utilizing OCT. The development of DME can be avoided or limited and the response to treatment may be improved by the regulation of the DME risk factors.

Role of Inflammation in Diabetic Retinopathy

Diabetic retinopathy is a common complication of diabetes and remains the leading cause of blindness among the working-age population. For decades, diabetic retinopathy was considered only a microvascular complication, but the retinal microvasculature is intimately associated with and governed by neurons and glia, which are affected even prior to clinically detectable vascular lesions. While progress has been made to improve the vascular alterations, there is still no treatment to counteract the early neuro-glial perturbations in diabetic retinopathy. Diabetes is a complex metabolic disorder, characterized by chronic hyperglycemia along with dyslipidemia, hypoinsulinemia and hypertension. Increasing evidence points to inflammation as one key player in diabetes-associated retinal perturbations, however, the exact underlying molecular mechanisms are not yet fully understood. Interlinked molecular pathways, such as oxidative stress, formation of advanced glycation end-products and increased expression of vascular endothelial growth factor have received a lot of attention as they all contribute to the inflammatory response. In the current review, we focus on the involvement of inflammation in the pathophysiology of diabetic retinopathy with special emphasis on the functional relationships between glial cells and neurons. Finally, we summarize recent advances using novel targets to inhibit inflammation in diabetic retinopathy.

'Statins in retinal disease'

Statins are known for their blood cholesterol-lowering effect and are widely used in patients with cardiovascular and metabolic diseases. Research over the past three decades shows that statins have diverse effects on different pathophysiological pathways involved in angiogenesis, inflammation, apoptosis, and anti-oxidation, leading to new therapeutic options. Recently, statins have attracted considerable attention for their immunomodulatory effect. Since immune reactivity has been implicated in a number of retinal diseases, such as uveitis, age-related macular degeneration (AMD) and diabetic retinopathy, there is now a growing body of evidence supporting the beneficial effects of statins in these retinopathies. This review evaluates the relationship between statins and the pathophysiological basis of these diseases, focusing on their potential role in treatment. A PubMed database search and literature review was conducted. Among AMD patients, there is inconsistent evidence regarding protection against development of early AMD or delaying disease progression; though they have been found to reduce the risk of developing choroidal neovascular membranes (CNV). In patients with retinal vein occlusion, there was no evidence to support a therapeutic benefit or a protective role with statins. In patients with diabetic retinopathy, statins demonstrate a reduction in disease progression and improved resolution of diabetic macular oedema (DMO). Among patients with uveitis, statins have a protective effect by reducing the likelihood of uveitis development.

Quantitative evaluation of hard exudates in diabetic macular edema after short-term intravitreal triamcinolone, dexamethasone implant or bevacizumab injections

Background

To quantitatively compare short-term hard exudates (HEs) alteration in patients with diabetic macular edema (DME) after intravitreal triamcinolone, dexamethasone implant or bevacizumab injections.

Methods

This retrospective study enrolled DME eyes with HEs that underwent a single-dose intravitreal injection of triamcinolone (25 eyes), dexamethasone implant (20 eyes), or three monthly injections of bevacizumab (25 eyes) and completed at least three months of follow-up. All patients were examined before and after 1, 2 and 3 months of injections. Using color fundus photographs, the amount of HEs was quantified by two masked graders. The difference in HEs area between baseline and each follow-up visit was compared among the three groups.

Results

After three months, HEs area was reduced to 52.9 ± 4.21% (P < 0.001) in the triamcinolone group, 63.6 ± 6.08% (P = 0.002) in the dexamethasone implant group, and 85.2 ± 5.07% (P = 0.198) in the bevacizumab group. A significant reduction in HEs appeared at one month in the triamcinolone group (53.5 ± 4.91%, P < 0.001) and at two months in the dexamethasone implant group (70.1 ± 5.21%, P = 0.039).

Conclusions

Our study suggests intravitreal steroids (triamcinolone, dexamethasone implants) significantly reduce HEs in DME patients on short-term follow-up, whereas intravitreal bevacizumab does not. Therefore, intravitreal steroids may be useful in DME with HEs in the fovea.

Semi-automated quantification of hard exudates in colour fundus photographs diagnosed with diabetic retinopathy

Background

Hard exudates (HEs) are the classical sign of diabetic retinopathy (DR) which is one of the leading causes of blindness, especially in developing countries. Accordingly, disease screening involves examining HEs qualitatively using fundus camera. However, for monitoring the treatment response, quantification of HEs becomes crucial and hence clinicians now seek to measure the area of HEs in the digital colour fundus (CF) photographs. Against this backdrop, we proposed an algorithm to quantify HEs using CF images and compare with previously reported technique using ImageJ.

Methods

CF photographs of 30 eyes (20 patients) with diabetic macular edema were obtained. A robust semi-automated algorithm was developed to quantify area covered by HEs. In particular, the proposed algorithm, a two pronged methodology, involved performing top-hat filtering, second order statistical filtering, and thresholding of the colour fundus images. Subsequently, two masked observers performed HEs measurements using previously reported ImageJ-based protocol and compared with those obtained through proposed method. Intra and inter-observer grading was performed for determining percentage area of HEs identified by the individual algorithm.

Results

Of the 30 subjects, 21 were males and 9 were females with a mean age of the 50.25 ± 7.80 years (range 33–66 years). The correlation between the two measurements of semi-automated and ImageJ were 0.99 and 0.99 respectively. Previously reported method detected only 0–30% of the HEs area in 9 images, 30–60% in 12 images and 60–90% in remaining images, and more than 90% in none. In contrast, proposed method, detected 60–90% of the HEs area in 13 images and 90–100% in remaining 17 images.

Conclusion

Proposed method semi-automated algorithm achieved acceptable accuracy, qualitatively and quantitatively, on a heterogeneous dataset. Further, quantitative analysis performed based on intra- and inter-observer grading showed that proposed methodology detects HEs more accurately than previously reported ImageJ-based technique. In particular, we proposed algorithm detect faint HEs also as opposed to the earlier method.

Automatic detection of Hyperreflective Foci in optical coherence tomography B-scans using Morphological Component Analysis

Hyperreflective Foci (HF) is one of the most common complications distributed in cross-sectional images of patients with Diabetic Macular Edema (DME). Scanning Laser Ophthalmoscope (SLO) images usually consists of several B-scans that represent a cross-sectional reconstruction of a plane through the anterior or posterior regions of retina. In each B-scan, HFs are geometrically distinct constituents in different retinal layers. Since the intensity levels of HFs and many other subjects in B-scans are the same, in this paper we try to separate HFs from other objects by detection of the point and curve singularities in each B-scan. The decomposition algorithm presented in this paper is based on sparse image representation of B-scans using Morphological Component Analysis (MCA) technique. By using curvelet transform and Daubechies wavelet basis, two different over-complete dictionaries are constructed which represent two various aspects of B-scans. The HFs are more distinguished in reconstructed image with wavelet dictionary and other objects are mostly detectable by curvelet dictionary. So, HFs can be detected by applying an optimum threshold criterion on reconstructed image by wavelet atoms. Finally, the false positive points are reduced by removing the candidate points in RNFL and RPE layers, which are automatically segmented based on ridgelet transform. Our simulation results on 1924 HFs show that sensitivity and specificity for HF detection is 91.0% and 100%, respectively.

Multimodality analysis of Hyper-reflective Foci and Hard Exudates in Patients with Diabetic Retinopathy

To investigate the correlations between hyper-reflective foci and hard exudates in patients with non-proliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR) by spectral-domain optical coherence tomography (SD OCT) images. Hyper-reflective foci in retinal SD OCT images were automatically detected by the developed algorithm. Then, the cropped CFP images generated by the semi-automatic registration method were automatically segmented for the hard exudates and corrected by the experienced clinical ophthalmologist. Finally, a set of 5 quantitative imaging features were automatically extracted from SD OCT images, which were used for investigating the correlations of hyper-reflective foci and hard exudates and predicting the severity of diabetic retinopathy. Experimental results demonstrated the positive correlations in area and amount between hard exudates and hyper-reflective foci at different stages of diabetic retinopathy, with statistical significance (all p < 0.05). In addition, the area and amount can be taken as potential discriminant indicators of the severity of diabetic retinopathy.

OPTICAL COHERENCE TOMOGRAPHY CHARACTERISTICS OF MACULAR EDEMA AND HARD EXUDATES AND THEIR ASSOCIATION WITH LIPID SERUM LEVELS IN TYPE 2 DIABETES

PURPOSE

To determine whether hyperreflective foci (HF) and macular thickness on spectral domain ocular coherence tomography are associated with lipid levels in patients with Type 2 diabetes.

METHODS

Two hundred and thirty-eight participants from four sites had fundus photographs and spectral domain ocular coherence tomography images graded for hard exudates and HF, respectively. Regression models were used to determine the association between serum lipid levels and 1) presence of HF and hard exudates and 2) central subfield macular thickness, central subfield macular volume, and total macular volume.

RESULTS

All patients with hard exudates on fundus photographs had corresponding HF on spectral domain ocular coherence tomography, but 57% of patients with HF on optical coherence tomography did not have hard exudates detected in their fundus photographs. Presence of HF was associated with higher total cholesterol (odds ratio = 1.13, 95% confidence interval = 1.01-1.27, P = 0.03) and higher low-density lipoprotein levels (odds ratio = 1.17, 95% confidence interval = 1.02-1.35, P = 0.02) in models adjusting for other risk factors. The total macular volume was also associated with higher total cholesterol (P = 0.009) and triglyceride (P = 0.02) levels after adjusting for other risk factors.

CONCLUSION

Higher total and low-density lipoprotein cholesterol were associated with presence of HF on spectral domain ocular coherence tomography. Total macular volume was associated with higher total cholesterol and triglyceride levels.

Role of lipid-lowering agents in the management of diabetic retinopathy

Diabetic retinopathy affects a substantial proportion of patients with diabetes mellitus (DM) and is the leading cause of blindness in working-aged adults. Even though the incidence of diabetic retinopathy has declined in the last decades, its prevalence increased and is expected to rise further as a result of the increasing incidence of type 2 DM (T2DM) and the longer life expectancy of patients with DM. The pathogenesis of diabetic retinopathy is multifactorial. Some observational studies suggested an association between dyslipidemia and the development and progression of retinopathy in patients with DM but others did not confirm this association. Regarding lipid-lowering agents, studies that evaluated the role of statins in the management of these patients are mostly small and yielded discrepant results. Large randomized studies with statins in patients with T2DM showed no benefit of these agents on diabetic retinopathy but were not designed to address this effect. In contrast, both preclinical data and two large randomized controlled studies, the FIELD and the ACCORD trial, showed that fenofibrate delays the progression of diabetic retinopathy. Even though the mechanisms underpinning this favorable effect are not entirely clear, these findings suggest that fenofibrate might represent a useful tool for the management of diabetic retinopathy.

Effect of focal laser photocoagulation in eyes with mild to moderate non-proliferative diabetic retinopathy

AIM

To report the effect of focal laser photocoagulation on both the severity of hard exudates (HEs) and the rate of disease progression in eyes with mild to moderate non-proliferative diabetic retinopathy (NPDR).

METHODS

We retrospectively reviewed the medical records of 33 patients (60 eyes) who had been diagnosed with mild to moderate NPDR between January 2006 and December 2012. The patients were divided into 2 groups: Group A (38 eyes in 20 patients treated using focal laser photocoagulation) and Group B (treated without laser photocoagulation). We also reviewed the best corrected visual acuity measurements, and the fundus photographs taken at both baseline and follow-up visits.

RESULTS

In Group A, HE severity grade had decreased significantly from baseline to the final visit (P<0.05), but this was not the case in Group B (P=0.662). The cumulative probabilities of retinopathy progression at 5y were 26% in Group A and 30% in Group B. Kaplan-Meier survival curves showed no significant difference between the groups with regard to retinopathy progression (P=0.805).

CONCLUSION

Focal laser photocoagulation reduced the levels of HEs in eyes with mild to moderate NPDR. However, the treatment was not able to decelerate the progression of DR.

Diabetic Retinopathy Clinical Practice Guidelines: Customized for Iranian Population

PURPOSE

To customize clinical practice guidelines (CPGs) for management of diabetic retinopathy (DR) in the Iranian population.

METHODS

Three DR CPGs (The Royal College of Ophthalmologists 2013, American Academy of Ophthalmology [Preferred Practice Pattern 2012], and Australian Diabetes Society 2008) were selected from the literature using the AGREE tool. Clinical questions were designed and summarized into four tables by the customization team. The components of the clinical questions along with pertinent recommendations extracted from the above-mentioned CPGs; details of the supporting articles and their levels of evidence; clinical recommendations considering clinical benefits, cost and side effects; and revised recommendations based on customization capability (applicability, acceptability, external validity) were recorded in 4 tables, respectively. Customized recommendations were sent to the faculty members of all universities across the country to score the recommendations from 1 to 9.

RESULTS

Agreed recommendations were accepted as the final recommendations while the non-agreed ones were approved after revision. Eventually, 29 customized recommendations under three major categories consisting of screening, diagnosis and treatment of DR were developed along with their sources and levels of evidence.

CONCLUSION

This customized CPGs for management of DR can be used to standardize the referral pathway, diagnosis and treatment of patients with diabetic retinopathy.

High-Resolution Imaging by Adaptive Optics Scanning Laser Ophthalmoscopy Reveals Two Morphologically Distinct Types of Retinal Hard Exudates

Histological studies from autopsy specimens have characterized hard exudates as a composition of lipid-laden macrophages or noncellular materials including lipid and proteinaceous substances (hyaline substances). However, the characteristics of hard exudates in living patients have not been examined due to insufficient resolution of existing equipment. In this study, we used adaptive optics scanning laser ophthalmoscopy (AO-SLO) to examine the characteristics of hard exudates in patients with retinal vascular diseases. High resolution imaging using AO-SLO enables morphological classification of retinal hard exudates into two types, which could not be distinguished either on fundus examination or by spectral domain optical coherence tomography (SD-OCT). One, termed a round type, consisted of an accumulation of spherical particles (average diameter of particles: 26.9 ± 4.4 μm). The other, termed an irregular type, comprised an irregularly shaped hyper-reflective deposition. The retinal thickness in regions with round hard exudates was significantly greater than the thickness in regions with irregular hard exudates (P = 0.01 →0.02). This differentiation of retinal hard exudates in patients by AO-SLO may help in understanding the pathogenesis and clinical prognosis of retinal vascular diseases.

Quantifying changes in retinal anatomy after interventions for diabetic maculopathy

Introduction

Diabetic maculopathy remains the major cause of loss of vision in diabetes. There is evidence to show that control of lipid levels reduces the amount of exudate in diabetic maculopathy, but to date there is no information on the effect of lipid reduction on diabetic macular oedema.

Purpose

The purpose of this case series was to compare retinal thickness using optical coherence tomography (OCT) of patients with exudative diabetic maculopathy whose only change in management was starting statins or increasing the current dose.

MethodsV"

Four patients with exudative diabetic maculopathy had serial OCT measurements to assess retinal thickness M before and after commencing or increasing their statin dose. Results

Analysis showed a reduction of macula thickness in all cases. Visual acuity also improved during the time course of the measurements.

Conclusion

Statins may aid management of diabetic maculopathy by reducing macular oedema. This case series gives the first quantified evidence of the effect of statins on reduction of diabetic macular oedema.

Efficacy of dexamethasone versus bevacizumab on regression of hard exudates in diabetic maculopathy: data from the BEVORDEX randomised clinical trial

OBJECTIVE

To report the effect of bevacizumab versus dexamethasone on hard exudates (HEX) in diabetic macular oedema (DME).

DESIGN

Post hoc analysis of 24-month data from the Randomised clinical trial of BEVacizumab OR DEXamethasone for diabetic macular oedema (BEVORDEX) phase 2 multicentre randomised clinical trial. Eyes with centre-involving DME resistant to or unlikely to benefit from macular laser therapy were included. Eyes were randomly assigned to bevacizumab every 4 weeks or Ozurdex dexamethasone implant (DEX) every 16 weeks, both as required. The 68 eyes from 48 patients that completed 24-month follow-up were analysed. Two masked graders assessed extent and location of HEX on baseline, 12-month and 24-month foveal-centred colour fundus photographs using validated grading software.

RESULTS

Macular HEX was present in 60% of study eyes. Of these, 21 eyes were treated with DEX and 20 eyes with bevacizumab. Both treatments led to reduction in area of macular HEX at 12 months and 24 months. There was greater regression of HEX from the foveal centre in DEX-treated eyes (median change +890 µm, IQR=1040 µm) than bevacizumab-treated eyes (median change +7.0 µm, IQR=590 µm) at 12 months (p=0.04) but the difference was no longer statistically significant (p=0.10) by 24 months (DEX +1400 µm, IQR=1590 µm; bevacizumab +20 µm, IQR=2680 µm). Reassuringly, no study eye developed HEX at the foveal centre, a visually devastating consequence of diabetic maculopathy.

CONCLUSIONS

Bevacizumab and DEX were effective in reducing area of HEX in eyes with DME. DEX provided more rapid regression of HEX from the foveal centre although bevacizumab-treated eyes started to catch up by 24 months. Distance from the foveal centre as well as total area of macular HEX should be assessed when evaluating treatments for foveal-threatening HEX.

TRIAL REGISTRATION NUMBER

NCT01298076; Post-results.

Quantitative Proteomics Analysis of Vitreous Humor from Diabetic Retinopathy Patients

Initial triggers for diabetic retinopathy (DR) are hyperglycemia-induced oxidative stress and advanced glycation end-products. The most pathological structural changes occur in retinal microvasculature, but the overall development of DR is multifactorial, with a complex interplay of microvascular, neurodegenerative, genetic/epigenetic, immunological, and secondary inflammation-related factors. Although several individual factors and pathways have been associated with retinopathy, a systems level understanding of the disease is lacking. To address this, we performed mass spectrometry based label-free quantitative proteomics analysis of 138 vitreous humor samples from patients with nonproliferative DR or the more severe proliferative form of the disease. Additionally, we analyzed samples from anti-VEGF (vascular endothelial growth factor) (bevacizumab)-treated patients from both groups. In our study, we identified 2482 and quantified the abundancy of 1351 vitreous proteins. Of these, the abundancy of 230 proteins was significantly higher in proliferative retinopathy compared with nonproliferative retinopathy. This specific subset of proteins was linked to inflammation, complement, and coagulation cascade proteins, protease inhibitors, apolipoproteins, immunoglobulins, and cellular adhesion molecules, reflecting the multifactorial nature of the disease. The identification of the key molecules of the disease is critical for the development of new therapeutic molecules and for the new use of existing drugs.

Oxidative stress-associated neuroretinal dysfunction and nitrosative stress in diabetic retinopathy

OBJECTIVE

The present study was intended to investigate whether oxidative stress is the key regulator to alter neuroretinal biochemical homeostasis and in turn aggravate the process of diabetic retinopathy by inducing nitrosative stress in the retinal neurovascular unit.

METHODS

Peripheral blood mononuclear cell reactive oxygen species level was measured by flow cytometry along with spectrophotometric detection of malondialdehyde (MDA) and glutamate from serum or plasma and a vitreous sample of study groups (i.e. subjects with proliferative diabetic retinopathy [PDR], type 2 diabetes without retinopathy [DNR] and healthy controls [HCs]). Further, nitrosative stress assessment was performed by spectrophotometric and enzyme-linked immunosorbent assay-based detection of serum and vitreous nitrite and nitrotyrosine concentrations, respectively.

RESULTS

The plasma glutamate level remains insignificant between subjects with PDR and DNR (p=0.505) or in HC (p=0.1344) individuals. However, serum MDA (p=0.0004), nitrite (p=0.0147) and nitrotyrosine (p=0.0129) were found to be strikingly higher among PDR subjects compared with the DNR group. Significantly increased levels of peripheral blood mononuclear cell reactive oxygen species (p<0.0001), vitreous glutamate (p=0.0009, p<0.0001), MDA (p=0.0058, p=0.0003), nitrite (p=0.0014, p<0.0001) and nitrotyrosine (p=0.0008, p<0.0001) were found in PDR subjects compared with DNR and HC subjects, respectively.

CONCLUSIONS

Our observation suggests that oxidative stress is associated with impairment in neuroretinal biochemical homeostasis among PDR subjects, which further augments retinal nitrosative stress and thus worsens the pathogenic process of retinopathy among PDR subjects.

Increased Serum Chemerin Levels in Diabetic Retinopathy of Type 2 Diabetic Patients

PURPOSE

To compare serum levels of chemerin in type 2 diabetes mellitus (T2DM) with or without retinopathy, and to investigate the relationship between serum chemerin levels and diabetes retinopathy.

MATERIALS AND METHODS

A total of 60 T2DM patients and 20 healthy subjects (control group) were enrolled in this study. Of the T2DM patients, 15 had proliferative diabetic retinopathy (PDR group), 20 had non-proliferative retinopathy (NPDR group) and 25 had no retinopathy (T2DM group). Their serum samples were collected for testing the levels of chemerin, vascular endothelial growth factor (VEGF), C-reactive protein (CRP) and so on. The values were analyzed to compare the differences among the groups. Simple linear regression analysis and multiple stepwise linear regression analysis were used to determine the correlations between variables and chemerin. Trend chi-square was used to determine the correlations between chemerin and the severity of diabetic retinopathy (DR).

RESULTS

Chemerin levels in group PDR, NPDR and no DR were 147.56 ± 35.98 μg/l, 128.09 ± 16.33 μg/l and 113.19 ± 19.89 μg/l, with the significant difference across the three groups (p < 0.05). But there was no difference between control group (109.55 ± 20.98 μg/l) and T2DM group. Simple linear regression show that serum chemerin was correlated with duration of diabetes, body mass index (BMI), serum triglycerides, total-cholesterol, CRP and VEGF, and not correlated with age, systolic and diastolic blood pressure in T2DM patients. Stepwise regression analysis showed that BMI, CRP and VEGF were significantly associated with serum chemerin (p = 0.006, p = 0.011 and p = 0.036, respectively). In addition, the more severity of DR as the chemerin levels increased (χ(2) = 16.07, p < 0.001).

CONCLUSIONS

Serum levels of chemerin were significantly increased in the NPDR and PDR group. Elevated serum level of chemerin and its positive correlation with BMI, CRP and VEGF suggested that chemerin was associated with obesity, inflammation and neovascularization and might be involved in the development of DR.

Effects of intravitreal ranibizumab on retinal hard exudate in diabetic macular edema: findings from the RIDE and RISE phase III clinical trials

PURPOSE

To evaluate the effect of monthly intravitreal ranibizumab on hard exudate (HE) area and the impact of HE on visual acuity (VA) outcomes in diabetic macular edema (DME) patients using data from 2 phase III clinical trials.

DESIGN

Exploratory analyses of phase III, randomized, double-masked, sham-controlled, multicenter clinical trials.

PARTICIPANTS

Adults with DME, baseline best-corrected VA 20/40 to 20/320 Snellen equivalent, and central foveal thickness of ≥275 μm.

METHODS

Between the 2 studies, 759 patients with DME were randomized to receive monthly 0.3 or 0.5 mg intravitreal ranibizumab (Lucentis; Genentech, Inc., South San Francisco, CA) or sham injections.

MAIN OUTCOME MEASURES

Hard exudate area was assessed from color fundus stereophotographs both on an ordinal scale and using continuous estimates of areas within the Early Treatment Diabetic Retinopathy Study grid.

RESULTS

Data from 739 eyes were available for analysis. Mean baseline HE area was similar across treatment groups, ranging from 0.65 to 0.82 mm(2). Through month 24, the percentage of eyes without HE increased from 20.9% to 36.3% in the sham group and from 22.1% to 61.3% and 23.6% to 62.0% in the ranibizumab 0.3-mg and 0.5-mg groups, respectively. Resolution of HE became apparent sometime after month 6 in ranibizumab-treated eyes. At baseline, there was no meaningful correlation between VA and presence or absence of HE. After baseline, there also was no consistent correlation between presence or absence of HE and change in VA over time.

CONCLUSIONS

In this exploratory analysis, monthly intravitreal ranibizumab resulted in significantly greater reduction of HE area compared with sham (P < 0.0001). In contrast to the rapid effects of ranibizumab on macular edema, changes in HE area were more gradual. Contrary to prior expectations, the presence and area of HE did not increase as DME resolved (either in the ranibizumab or sham groups). Importantly, baseline VA was not correlated with presence of HE, nor was the therapeutic benefit of ranibizumab on VA affected negatively by the presence of HE. These data suggest that in the context of intravitreal anti-vascular endothelial growth factor therapy, the presence of HE is not a prognostic indicator of poor visual outcomes.

A cross talk between class A scavenger receptor and receptor for advanced glycation end-products contributes to diabetic retinopathy

In response to hyperglycemia in patients with diabetes, many signaling pathways contribute to the pathogenesis of diabetic complications, including diabetic retinopathy (DR). Excessive production of inflammatory mediators plays an important role in this process. Amadori-glycated albumin, one of the major forms of advanced glycated end-products, has been implicated in DR by inducing inflammatory responses in microglia/macrophages. Our goal was to delineate the potential cross talk between class A scavenger receptor (SR-A) and the receptor for advanced glycated end-product (RAGE) in the context of DR. We show here that SR-A ablation caused an exacerbated form of DR in streptozotocin-injected C57BL/6J mice as evidenced by fundus imaging and electroretinography. Immunohistochemical staining and RT-PCR assay indicated that there was augmented activation of proinflammatory macrophages with upregulated synthesis of proinflammatory mediators in the retina in Sr-a(-/-) mice. Overexpression of SR-A suppressed RAGE-induced mitogen-activated protein kinase (MAPK) signaling, whereas RAGE activation in macrophages favored a proinflammatory (M1) phenotype in the absence of SR-A. Mechanistic analysis on bone marrow-derived macrophages and HEK293 cell line revealed that SR-A interacted with and inhibited the phosphorylation of mitogen-activated protein kinase kinase 7, the major kinase in the RAGE-MAPK-NF-κB signaling, thereby leading to diminished secretion of proinflammatory cytokines. Our findings suggest that the antagonism between SR-A and RAGE contributes to the pathogenesis of DR by nurturing a disease-prone macrophage phenotype. Therefore, specific agonist that boosts SR-A signaling could potentially provide benefits in the prevention and/or intervention of DR.