Diabetic Eye Disease

Laíns I, Talcott KE, Santos AR, Marques JH, Gil P, Gil J, Figueira J, Husain D, Kim IK, Miller JW, Silva R, Miller JB. CHOROIDAL THICKNESS IN DIABETIC RETINOPATHY ASSESSED WITH SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY. Retina 2018;38(1):173-182.Abstract
PURPOSE: To compare the choroidal thickness (CT) of diabetic eyes (different stages of disease) with controls, using swept-source optical coherence tomography. METHODS: A multicenter, prospective, cross-sectional study of diabetic and nondiabetic subjects using swept-source optical coherence tomography imaging. Choroidal thickness maps, according to the nine Early Treatment Diabetic Retinopathy Study (ETDRS) subfields, were obtained using automated software. Mean CT was calculated as the mean value within the ETDRS grid, and central CT as the mean in the central 1 mm. Diabetic eyes were divided into four groups: no diabetic retinopathy (No DR), nonproliferative DR (NPDR), NPDR with diabetic macular edema (NPDR + DME), and proliferative DR (PDR). Multilevel mixed linear models were performed for analyses. RESULTS: The authors included 50 control and 160 diabetic eyes (n = 27 No DR, n = 51 NPDR, n = 61 NPDR + DME, and n = 21 PDR). Mean CT (ß = -42.9, P = 0.022) and central CT (ß = -50.2, P = 0.013) were statistically significantly thinner in PDR eyes compared with controls, even after adjusting for confounding factors. Controlling for age, DR eyes presented a significantly decreased central CT than diabetic eyes without retinopathy (β = -36.2, P = 0.009). CONCLUSION: Swept-source optical coherence tomography demonstrates a significant reduction of CT in PDR compared with controls. In the foveal region, the choroid appears to be thinner in DR eyes than in diabetic eyes without retinopathy.
Yau GL, Silva PS, Arrigg PG, Sun JK. Postoperative Complications of Pars Plana Vitrectomy for Diabetic Retinal Disease. Semin Ophthalmol 2017;:1-8.Abstract
Despite recent advances in the medical management of diabetic retinal disease, there remain established indications for vitreoretinal surgery in the treatment of severe proliferative diabetic retinopathy. These include non-clearing vitreous hemorrhage and tractional retinal detachment. Advances in surgical instrumentation, technique, and experience have led to improved visual outcomes, as well as a corresponding decrease in the incidence of postoperative complications. However, the presence of systemic and ocular factors in diabetic patients increases the risk of adverse events compared to non-diabetic individuals. This review will focus on the most important postoperative complications following pars plana vitrectomy, with specific considerations for the diabetic patient.
Peterson SR, Silva PA, Murtha TJ, Sun JK. Cataract Surgery in Patients with Diabetes: Management Strategies. Semin Ophthalmol 2017;:1-8.Abstract
Diabetes is a chronic systemic disease that affects nearly one in eight adults worldwide. Ocular complications, such as cataract, can lead to significant visual impairment. Among the worldwide population, cataract is the leading cause of blindness, and patients with diabetes have an increased incidence of cataracts which mature earlier compared to the rest of the population. Cataract surgery is a common and safe procedure, but can be associated with vision-threatening complications in the diabetic population, such as diabetic macular edema, postoperative macular edema, diabetic retinopathy progression, and posterior capsular opacification. This article is a brief review of diabetic cataract and complications associated with cataract extraction in this population of patients.
Wang JC, Laíns I, Providência J, Armstrong GW, Santos AR, Gil P, Gil J, Talcott KE, Marques JH, Figueira J, Vavvas DG, Kim IK, Miller JW, Husain D, Silva R, Miller JB. Diabetic Choroidopathy: Choroidal Vascular Density and Volume in Diabetic Retinopathy With Swept-Source Optical Coherence Tomography. Am J Ophthalmol 2017;184:75-83.Abstract
PURPOSE: To compare choroidal vascular density (CVD) and volume (CVV) in diabetic eyes and controls, using en face swept-source optical coherence tomography (SS-OCT). DESIGN: Prospective cross-sectional study. METHODS: Setting: Multicenter. PATIENT POPULATION: Total of 143 diabetic eyes-27 with no diabetic retinopathy (DR), 47 with nonproliferative DR (NPDR), 51 with NPDR and diabetic macular edema (DME), and 18 with proliferative DR (PDR)-and 64 age-matched nondiabetic control eyes. OBSERVATION PROCEDURES: Complete ophthalmologic examination and SS-OCT imaging. En face SS-OCT images of the choroidal vasculature were binarized. MAIN OUTCOME MEASURES: CVD, calculated as the percent area occupied by choroidal vessels in the central macular region (6-mm-diameter circle centered on the fovea), and throughout the posterior pole (12 × 9 mm). The central macular CVV was calculated by multiplying the average CVD by macular area and choroidal thickness (obtained with SS-OCT automated software). Multilevel mixed linear models were performed for analyses. RESULTS: Compared to controls (0.31 ± 0.07), central macular CVD was significantly decreased by 9% in eyes with NPDR + DME (0.28 ± 0.06; ß = -0.03, P = .02) and by 15% in PDR (0.26 ± 0.05; ß = -0.04, P = .01). The central macular CVV was significantly decreased by 19% in eyes with PDR (0.020 ± 0.005 mm3, ß = -0.01, P = .01) compared to controls (0.025 ± 0.01 mm3). CONCLUSIONS: Choroidal vascular density and volume are significantly reduced in more advanced stages of diabetic retinopathy. New imaging modalities should allow further exploration of the contributions of choroidal vessel disease to diabetic eye disease pathogenesis, prognosis, and treatment response.
Sobrin L, Chong YH, Fan Q, Gan A, Stanwyck LK, Kaidonis G, Craig JE, Kim J, Liao W-L, Huang Y-C, Lee W-J, Hung Y-J, Guo X, Hai Y, Ipp E, Pollack S, Hancock H, Price A, Penman A, Mitchell P, Liew G, Smith AV, Gudnason V, Tan G, Klein BEK, Kuo J, Li X, Christiansen MW, Psaty BM, Sandow K, Sandow K, Jensen RA, Klein R, Cotch MF, Wang JJ, Jia Y, Chen CJ, Chen Y-DI, Rotter JI, Tsai F-J, Hanis CL, Burdon KP, Wong TY, Cheng C-Y. Genetically Determined Plasma Lipid Levels and Risk of Diabetic Retinopathy: A Mendelian Randomization Study. Diabetes 2017;66(12):3130-3141.Abstract
Results from observational studies examining dyslipidemia as a risk factor for diabetic retinopathy (DR) have been inconsistent. We evaluated the causal relationship between plasma lipids and DR using a Mendelian randomization approach. We pooled genome-wide association studies summary statistics from 18 studies for two DR phenotypes: any DR (N = 2,969 case and 4,096 control subjects) and severe DR (N = 1,277 case and 3,980 control subjects). Previously identified lipid-associated single nucleotide polymorphisms served as instrumental variables. Meta-analysis to combine the Mendelian randomization estimates from different cohorts was conducted. There was no statistically significant change in odds ratios of having any DR or severe DR for any of the lipid fractions in the primary analysis that used single nucleotide polymorphisms that did not have a pleiotropic effect on another lipid fraction. Similarly, there was no significant association in the Caucasian and Chinese subgroup analyses. This study did not show evidence of a causal role of the four lipid fractions on DR. However, the study had limited power to detect odds ratios less than 1.23 per SD in genetically induced increase in plasma lipid levels, thus we cannot exclude that causal relationships with more modest effect sizes exist.
Olivares AM, Althoff K, Chen GF, Wu S, Morrisson MA, Deangelis MM, Haider N. Animal Models of Diabetic Retinopathy. Curr Diab Rep 2017;17(10):93.Abstract
PURPOSE OF REVIEW: Diabetic retinopathy (DR) is one of the most common complications associated with chronic hyperglycemia seen in patients with diabetes mellitus. While many facets of DR are still not fully understood, animal studies have contributed significantly to understanding the etiology and progression of human DR. This review provides a comprehensive discussion of the induced and genetic DR models in different species and the advantages and disadvantages of each model. RECENT FINDINGS: Rodents are the most commonly used models, though dogs develop the most similar morphological retinal lesions as those seen in humans, and pigs and zebrafish have similar vasculature and retinal structures to humans. Nonhuman primates can also develop diabetes mellitus spontaneously or have focal lesions induced to simulate retinal neovascular disease observed in individuals with DR. DR results in vascular changes and dysfunction of the neural, glial, and pancreatic β cells. Currently, no model completely recapitulates the full pathophysiology of neuronal and vascular changes that occur at each stage of diabetic retinopathy; however, each model recapitulates many of the disease phenotypes.
Machuca-Parra AI, Bigger-Allen AA, Sanchez AV, Boutabla A, Cardona-Vélez J, Amarnani D, Saint-Geniez M, Siebel CW, Kim LA, D'Amore PA, Arboleda-Velasquez JF. Therapeutic antibody targeting of Notch3 signaling prevents mural cell loss in CADASIL. J Exp Med 2017;214(8):2271-2282.Abstract
Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a neurological syndrome characterized by small vessel disease (SVD), stroke, and vascular cognitive impairment and dementia caused by mutations in NOTCH3 No therapies are available for this condition. Loss of mural cells, which encompass pericytes and vascular smooth muscle cells, is a hallmark of CADASIL and other SVDs, including diabetic retinopathy, resulting in vascular instability. Here, we showed that Notch3 signaling is both necessary and sufficient to support mural cell coverage in arteries using genetic rescue in Notch3 knockout mice. Furthermore, we show that systemic administration of an agonist Notch3 antibody prevents mural cell loss and modifies plasma proteins associated with Notch3 activity, including endostatin/collagen 18α1 and Notch3 extracellular domain in mice with the C455R mutation, a CADASIL variant associated with Notch3 loss of function. These findings open opportunities for the treatment of CADASIL and other SVDs by modulating Notch3 signaling.
Ung C, Sanchez AV, Shen L, Davoudi S, Ahmadi T, Navarro-Gomez D, Chen CJ, Hancock H, Penman A, Hoadley S, Consugar M, Restrepo C, Shah VA, Arboleda-Velasquez JF, Sobrin L, Gai X, Kim LA. Whole exome sequencing identification of novel candidate genes in patients with proliferative diabetic retinopathy. Vision Res 2017;Abstract
Rare or novel gene variants in patients with proliferative diabetic retinopathy may contribute to disease development. We performed whole exome sequencing (WES) on patients at the phenotypic extremes of diabetic retinal complications: 57 patients diagnosed with proliferative diabetic retinopathy (PDR) as cases and 13 patients with no diabetic retinopathy despite at least 10years of type 2 diabetes as controls. Thirty-one out of the 57 cases and all 13 controls were from the African American Proliferative Diabetic Retinopathy Study (AA). The rest of the cases were of mixed ethnicities (ME). WES identified 721 candidate genes with rare or novel non-synonymous variants found in at least one case with PDR and not present in any controls. After filtering for genes with null alleles in greater than two cases, 28 candidate genes were identified in our ME cases and 16 genes were identified in our AA cases. Our analysis showed rare and novel variants within these genes that could contribute to the development of PDR, including rare non-synonymous variants in FAM132A, SLC5A9, ZNF600, and TMEM217. We also found previously unidentified variants in VEGFB and APOB. We found that VEGFB, VPS13B, PHF21A, NAT1, ZNF600, PKHD1L1 expression was reduced in human retinal endothelial cells (HRECs) cultured under high glucose conditions. In an exome sequence analysis of patients with PDR, we identified variants in genes that could contribute to pathogenesis. Six of these genes were further validated and found to have reduced expression in HRECs under high glucose conditions, suggestive of an important role in the development of PDR.
Silva PS, El-Rami H, Barham R, Gupta A, Fleming A, van Hemert J, Cavallerano JD, Sun JK, Aiello LP. Hemorrhage and/or Microaneurysm Severity and Count in Ultrawide Field Images and Early Treatment Diabetic Retinopathy Study Photography. Ophthalmology 2017;124(7):970-976.Abstract
OBJECTIVE: To evaluate detection of hemorrhage and/or microaneurysm (H/Ma) using ultrawide field (UWF) retinal imaging as compared with standard Early Treatment Diabetic Retinopathy Study (ETDRS) 7-field photographs (ETDRS photos). DESIGN: Single-site comparative study of UWF images and ETDRS photos. PARTICIPANTS: One hundred twenty-six eyes of 69 patients with no diabetic retinopathy (DR) or mild or moderate nonproliferative DR (NPDR). METHODS: Stereoscopic 200° UWF images and stereoscopic 35mm 30° 7-field color photographs were acquired on the same visit. Images were graded for severity and distribution of H/Ma. H/Mas were counted in ETDRS fields 2 to 7 in both ETDRS photos and UWF images. H/Mas in the UWF peripheral fields were also counted. MAIN OUTCOME MEASURES: Kappa (κ) and weighted κ statistics for agreement. Number of H/Ma within and outside ETDRS fields identified in UWF images and ETDRS photos. RESULTS: Distribution of DR severity by ETDRS photos was 24 (19.0%) no DR, 48 (38.1%) mild NPDR, and 54 (42.9%) moderate NPDR. A total of 748 of 756 fields (98.9%) were gradable for H/Mas on ETDRS photos and UWF images. Simple κ/weighted κ statistics for severity of H/Ma: all fields 0.61/0.69, field 2 0.70/0.77, field 3 0.62/0.73, field 4 0.50/0.62, field 5 0.54/0.65, field 6 0.64/0.70, and field 7 0.58/0.63 with overall exact agreement in 81.3% and within 1 step in 97.9% of fields. A greater proportion of fields was graded a more severe H/Ma level in UWF images than in the corresponding ETDRS photos (UWF: 12.7% vs. ETDRS: 6.5%). Evaluating comparable areas in UWF images and ETDRS photos (fields 2-7), a mean of 42.8 H/Mas were identified using ETDRS photos and 48.8 in UWF images (P = 0.10). An additional mean of 21.3 H/Mas (49.8% increase, P < 0.0001) were identified in the peripheral fields of the UWF images. CONCLUSIONS: There is good to excellent agreement between UWF images and ETDRS photos in determining H/Ma severity, with excellent correlation of H/Ma counts within ETDRS photo fields. UWF peripheral fields identified 49.8% more H/Ma, suggesting a more severe H/Ma in 12.7% of eyes. Given the additional lesions detected in peripheral fields and the known risks associated with H/Ma and peripheral lesions, quantification of H/Ma using UWF images may provide a more accurate representation of DR disease activity and potential greater accuracy in predicting DR progression.
Chen Q, Qiu F, Zhou K, Matlock GH, Takahashi Y, Rajala RVS, Yang Y, Moran E, Ma J-X. Pathogenic Role of MicroRNA-21 in Diabetic Retinopathy Through Down-Regulation of PPARα. Diabetes 2017;Abstract

Fenofibrate, a specific agonist of peroxisome proliferator-activated receptor alpha (PPARα), displays robust therapeutic effects on diabetic retinopathy (DR) in type 2 diabetic patients. Our recent studies have shown that PPARα is down-regulated in the diabetic retina, which contributes to the pathogenesis of DR. However, the mechanism for diabetes-induced down-regulation of PPARα remains unknown. We investigated the role of microRNA-21 (miR-21) in regulating PPARα in DR. MiR-21 was over-expressed, while PPARα levels were decreased in the retina of db/db mice, a type 2 diabetic model. Such alterations were also observed in palmitate-treated retinal endothelial cells. MiR-21 targeted PPARα by inhibiting its mRNA translation. Knockout of miR-21 prevented the decrease of PPARα, alleviated microvascular damage, ameliorated inflammation and reduced cell apoptosis in the retina of db/db mice. Intravitreal injection of miR-21 inhibitor attenuated PPARα down-regulation and ameliorated retinal inflammation in db/db mice. Further, retinal miR-21 levels were increased, while PPARα levels were decreased in oxygen-induced retinopathy (OIR). Knockout of miR-21 prevented PPARα down-regulation and ameliorated retinal neovascularization and inflammation in OIR retinas. In conclusion, diabetes-induced over-expression of miR-21 in the retina is responsible, at least in part, for PPARα down-regulation in DR. Targeting miR-21 may represent a novel therapeutic strategy for DR.

Dagher Z, Gerhardinger C, Vaz J, Goodridge M, Tecilazich F, Lorenzi M. The Increased Transforming Growth Factor-β Signaling Induced by Diabetes Protects Retinal Vessels. Am J Pathol 2017;187(3):627-638.Abstract

The roles of transforming growth factor (TGF)-β in extracellular matrix production and vascular remodeling, coupled with increased TGF-β expression and signaling in diabetes, suggest TGF-β as an important contributor to the microangiopathy of diabetic retinopathy and nephropathy. To investigate whether increased TGF-β signaling could be a therapeutic target for preventing retinopathy, we used a pharmacologic approach (SM16, a selective inhibitor of the type 1 TGF-β receptor activin receptor-like kinase 5, orally active) to inhibit the increased, but not the basal, Tgf-β signaling in retinal vessels of diabetic rats. At the level of vascular gene expression, 3.5 months' diabetes induced minimal changes. Diabetes + SM16 for 3 weeks caused widespread changes in gene expression poised to enhance vascular inflammation, thrombosis, leakage, and wall instability; these changes were not observed in control rats given SM16. The synergy of diabetes and SM16 in altering gene expression was not observed in the lung. At the level of vascular network morphology, 7 months' diabetes induced no detectable changes. Diabetes + SM16 for 3 weeks caused instead distorted morphology and decreased density. Thus, in diabetes, retinal vessels become dependent on a small increase in TGF-β signaling via activin receptor-like kinase 5 to maintain early integrity. The increased TGF-β signaling may protect against rapid retinopathy progression and should not be a target of inhibitory interventions.

Barham R, Rami HE, Sun JK, Silva PS. Evidence-Based Treatment of Diabetic Macular Edema. Semin Ophthalmol 2017;32(1):56-66.Abstract

Diabetes mellitus is a chronic disease that affects 415 million people worldwide. Despite treatment advances, diabetic eye disease remains a leading cause of vision loss worldwide. Diabetic macular edema (DME) is a common cause of vision loss in diabetic patients. The pathophysiology is complex and involves multiple pathways that ultimately lead to central retinal thickening and, if untreated, visual loss. First-line treatment of DME has evolved from focal/grid laser established by the Early Treatment of Diabetic Retinopathy Study (ETDRS) to intravitreous pharmacologic therapy. Landmark prospective clinical trials examining the effect of intravitreous injections of vascular endothelial growth factor (VEGF) inhibitors in the treatment of DME have demonstrated improved visual outcomes over focal grid laser. This review focuses on the scientific evidence treatment of DME, disease pathophysiology, clinical disease course, current treatment standards, and emerging novel therapeutic approaches.

Gupta A, Cavallerano J, Sun JK, Silva PS. Evidence for Telemedicine for Diabetic Retinal Disease. Semin Ophthalmol 2017;32(1):22-28.Abstract

According to current projections, the number of Americans with diabetes mellitus will increase from 27.8 million in 2007 to 60.7 million in 2030. With the increasing gap between demand for eye care and supply of ophthalmologists and optometrists, and the non-uniform distribution of eye care providers in US counties, barriers to eye examinations will likely increase. Telemedicine assessment of diabetic retinal disease through remote retinal imaging and diagnosis has the potential to meet these growing demands. To establish evidence for a telemedicine program as an effective modality for diabetic retinopathy (DR) assessment, the interpretation of teleretinal images should compare favorably with Early Treatment Diabetic Retinopathy Study film or digital photographs. We review the current evidence on the critical features and characteristics of ocular telehealth programs for DR in the following categories: image gradability, mydriasis, sensitivity and specificity, cost-effectiveness, long-term effectiveness, patient comfort and satisfaction, and improvement of patient related outcomes.

Rami HE, Barham R, Sun JK, Silva PS. Evidence-Based Treatment of Diabetic Retinopathy. Semin Ophthalmol 2017;32(1):67-74.Abstract

Diabetic retinopathy (DR) is the most frequent microvascular complication from diabetes and requires annual screening and at least annual follow-up. A systemic approach to optimize blood glucose and blood pressure may halt progression to severe stages of DR and obviate the need for ocular treatment. Although there is evidence of benefit from fenofibrate or intravitreous antiVEGF treatment for eyes with nonproliferative DR (NPDR), these therapies are not standard care for NPDR at this time. Some patients with severe NPDR, especially those with type 2 diabetes, benefit from early panretinal photocoagulation (PRP). Once DR progresses to proliferative DR (PDR), treatment is often necessary to prevent visual loss. PRP remains mainstay treatment for PDR with high-risk characteristics. However, intravitreous antiVEGF injections appear to be a safe and effective treatment alternative for PDR through at least two years. Vitreoretinal surgery is indicated for PDR cases with non-clearing vitreous hemorrhage and/or tractional retinal detachment.

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