Diabetes mellitus represents a growing international public health issue with a near quadrupling in its worldwide prevalence since 1980. Though it has many known microvascular complications, vision loss from diabetic retinopathy is one of the most devastating for affected individuals. In addition, there is increasing evidence to suggest that diabetic patients have a greater risk for glaucoma as well. Though the pathophysiology of glaucoma is not completely understood, both diabetes and glaucoma appear to share some common risk factors and pathophysiologic similarities with studies also reporting that the presence of diabetes and elevated fasting glucose levels are associated with elevated intraocular pressure-the primary risk factor for glaucomatous optic neuropathy. While no study has completely addressed the possibility of detection bias, most recent epidemiologic evidence suggests that diabetic populations are likely enriched with glaucoma patients. As the association between diabetes and glaucoma becomes better defined, routine evaluation for glaucoma in diabetic patients, particularly in the telemedicine setting, may become a reasonable consideration to reduce the risk of vision loss in these patients.
Diabetic retinopathy (DR) is the leading cause of blindness in the working-age population in developed countries, and its prevalence will increase as the global incidence of diabetes grows exponentially. DR begins with an early nonproliferative stage in which retinal blood vessels and neurons degenerate as a consequence of chronic hyperglycemia, resulting in vasoregression and persistent retinal ischemia, metabolic disequilibrium, and inflammation. This is conducive to overcompensatory pathological neovascularization associated with advanced proliferative DR. Although DR is considered a microvascular complication, the retinal microvasculature is intimately associated with and governed by neurons and glia; neurodegeneration, neuroinflammation, and dysregulation of neurovascular cross talk are responsible in part for vascular abnormalities in both early nonproliferative DR and advanced proliferative DR. Neuronal activity directly regulates microvascular dilation and blood flow in the process of neurovascular coupling. Retinal neurons also secrete guidance cues in response to injury, ischemia, or metabolic stress that may either promote or suppress vascular outgrowth, either alleviating or exacerbating DR, contingent on the stage of disease and retinal microenvironment. Neurodegeneration, impaired neurovascular coupling, and dysregulation of neuronal guidance cues are key events in the pathogenesis of DR, and correcting these events may prevent or delay development of advanced DR. The review discusses the mechanisms of neurovascular cross talk and its dysregulation in DR, and their potential therapeutic implications.
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.
Abnormal blood vessel growth in the retina is a hallmark of many retinal diseases, such as retinopathy of prematurity (ROP), proliferative diabetic retinopathy, and the wet form of age-related macular degeneration. In particular, ROP has been an important health concern for physicians since the advent of routine supplemental oxygen therapy for premature neonates more than 70 years ago. Since then, researchers have explored several animal models to better understand ROP and retinal vascular development. Of these models, the mouse model of oxygen-induced retinopathy (OIR) has become the most widely used, and has played a pivotal role in our understanding of retinal angiogenesis and ocular immunology, as well as in the development of groundbreaking therapeutics such as anti-vascular endothelial growth factor injections for wet age-related macular degeneration. Numerous refinements to the model have been made since its inception in the 1950s, and technological advancements have expanded the use of the model across multiple scientific fields. In this review, we explore the historical developments that have led to the mouse OIR model utilized today, essential concepts of OIR, limitations of the model, and a representative selection of key findings from OIR, with particular emphasis on current research progress.
PURPOSE: The risk of vision loss from proliferative diabetic retinopathy (PDR) can be reduced with timely detection and treatment. We aimed to identify serum molecular signatures that might help in the early detection of PDR in patients with diabetes. METHODS: A total of 40 patients with diabetes were recruited at King Khaled Eye Specialist Hospital in Riyadh, Saudi Arabia, 20 with extensive PDR and 20 with mild non-proliferative diabetic retinopathy (NPDR). The two groups were matched in age, gender, and known duration of diabetes. We examined the whole genome transcriptome of blood samples from the patients using RNA sequencing. We built a model using a support vector machine (SVM) approach to identify gene combinations that can classify the two groups. RESULTS: Differentially expressed genes were calculated from a total of 25,500 genes. Six genes (CCDC144NL, DYX1C1, KCNH3, LOC100506476, LOC285847, and ZNF80) were selected from the top 26 differentially expressed genes, and a combinatorial molecular signature was built based on the expression of the six genes. The mean area under receiver operating characteristic (ROC) curve was 0.978 in the cross validation. The corresponding sensitivity and specificity were 91.7% and 91.5%, respectively. CONCLUSIONS: Our preliminary study defined a combinatorial molecular signature that may be useful as a potential biomarker for early detection of proliferative diabetic retinopathy in patients with diabetes. A larger-scale study with an independent cohort of samples is necessary to validate and expand these findings.
PURPOSE: We seek to identify pathogenic mechanisms for diabetic retinopathy that can become therapeutic targets beyond hyperglycemia and hypertension. We investigated if a defective myogenic response of retinal arteries to increased perfusion pressure, which exposes capillaries to increased pressure and flow, is associated with the onset of clinical retinopathy. METHODS: We examined prospectively the incidence of retinopathy in type 1 diabetic individuals tested 4 years earlier for the retinal arterial myogenic response, and in a cross-sectional study the prevalence of defective myogenic response in type 1 patients who had diabetic retinopathy. Among these, we contrasted early-onset (after 15 ± 2 years of diabetes, E-DR; n = 5) to late-onset (after 26 ± 3 years of diabetes, L-DR; n = 7) retinopathy. We measured the myogenic response using a laser Doppler blood flowmeter after a change in posture from sitting to reclining, which increases retinal perfusion pressure. RESULTS: Five of seven participants who 4 years prior had a defective myogenic response had now developed clinical retinopathy; as compared with only one of six participants who 4 years prior had a normal response (P = 0.10). In the cross-sectional study, all participants had normal retinal hemodynamics at steady state. In response to the postural change, only the E-DR group showed defective myogenic response (P = 0.005 versus controls, P = 0.02 versus L-DR) and abnormally high retinal blood flow (P = 0.016 versus controls). CONCLUSIONS: In type 1 diabetic patients, a defective myogenic response of retinal arteries to pressure is not required for the development of clinical retinopathy, but is prominently associated with an accelerated onset of retinopathy.
PURPOSE: To determine whether hyperglycemic levels as determined from high hemoglobin A1c (HbA1c) levels influence intraocular pressure (IOP) in patients with non-proliferative diabetic retinopathy (NPDR). METHODS: A retrospective chart review was performed on subjects with a diagnosis of NPDR and a corresponding HbA1c level measured within 90 days before or after an IOP measurement over a two-year period. Exclusion criteria included a diagnosis of glaucoma or treatment with IOP lowering medications or oral or topical steroids. RESULTS: Using 14.5mmHg as a baseline mean value for IOP, 42 subjects had an IOP < 14.5mmHg and mean HbA1c of 8.1±1.1, while 72 subjects had an IOP ≥ 14.5mmHg and a mean HbA1c of 9.0±2.1. Although there was an overlap in the confidence intervals, a significant difference (P = 0.01) in the mean HbA1c level was observed in regression analysis between the two groups. Importantly, diabetic subjects with elevated HbA1c levels rarely (<1%) exhibited reduced IOP levels. CONCLUSIONS: Diabetic subjects with elevated HbA1c levels exhibited significantly higher IOPs compared to those with lower HbA1c levels. Findings from this study indicate an association between hyperglycemia and elevated IOP and that poor glycemic control may contribute to increased IOP levels in long-term diabetic patients.
PURPOSE: To assess personal and demographic risk factors for proliferative diabetic retinopathy in African Americans with type 2 diabetes. METHODS: In this prospective, non-interventional, cross-sectional case-control study, 380 African Americans with type 2 diabetes were enrolled. Participants were recruited prospectively and had to have either: (1) absence of diabetic retinopathy after ≥10 years of type 2 diabetes, or (2) presence of proliferative diabetic retinopathy when enrolled. Dilated, 7-field fundus photographs were graded using the Early Treatment Diabetic Retinopathy Study scale. Covariates including hemoglobin A1C (HbA1C), blood pressure, height, weight and waist circumference were collected prospectively. Multivariate regression models adjusted for age, sex and site were constructed to assess associations between risk factors and proliferative diabetic retinopathy. RESULTS: Proliferative diabetic retinopathy was associated with longer duration of diabetes (odds ratio, OR, 1.62, p < 0.001), higher systolic blood pressure (OR 1.65, p < 0.001) and insulin use (OR 6.65, p < 0.001) in the multivariate regression analysis. HbA1C was associated with proliferative diabetic retinopathy in the univariate analysis (OR 1.31, p = 0.002) but was no longer significant in the multivariate analysis. CONCLUSIONS: In this case-control study of African Americans with type 2 diabetes, duration of diabetes, systolic hypertension and insulin use were strong risk factors for the development of proliferative diabetic retinopathy. Interestingly, HbA1C did not confer additional risk in this cohort.
PURPOSE: To compare diabetic retinopathy (DR) identification and ungradable image rates between nonmydriatic ultrawide field (UWF) imaging and nonmydriatic multifield fundus photography (NMFP) in a large multistate population-based DR teleophthalmology program. DESIGN: Multiple-site, nonrandomized, consecutive, cross-sectional, retrospective, uncontrolled imaging device evaluation. PARTICIPANTS: Thirty-five thousand fifty-two eyes (17 526 patients) imaged using NMFP and 16 218 eyes (8109 patients) imaged using UWF imaging. METHODS: All patients undergoing Joslin Vision Network (JVN) imaging with either NMFP or UWF imaging from May 1, 2014, through August 30, 2015, within the Indian Health Service-JVN program, which serves American Indian and Alaska Native communities at 97 sites across 25 states, were evaluated. All retinal images were graded using a standardized validated protocol in a centralized reading center. MAIN OUTCOME MEASURES: Ungradable rate for DR and diabetic macular edema (DME). RESULTS: The ungradable rate per patient for DR and DME was significantly lower with UWF imaging compared with NMFP (DR, 2.8% vs. 26.9% [P < 0.0001]; DME, 3.8% vs. 26.2% [P < 0.0001]). Identification of eyes with either DR or referable DR (moderate nonproliferative DR or DME or worse) was increased using UWF imaging from 11.7% to 24.2% (P < 0.0001) and from 6.2% to 13.6% (P < 0.0001), respectively. In eyes with DR imaged with UWF imaging (n = 3926 eyes of 2402 patients), the presence of predominantly peripheral lesions suggested a more severe level of DR in 7.2% of eyes (9.6% of patients). CONCLUSIONS: In a large, widely distributed DR ocular telehealth program, as compared with NMFP, nonmydriatic UWF imaging reduced the number of ungradable eyes by 81%, increased the identification of DR nearly 2-fold, and identified peripheral lesions suggesting more severe DR in almost 10% of patients, thus demonstrating significant benefits of this imaging method for large DR teleophthalmology programs.
PURPOSE: Diabetes mellitus is an increasingly common systemic disease. Many diabetic patients seek cataract surgery for a better visual acuity. Unlike in the general population, the influence of cataract surgery on tear film function in diabetic patients remains elusive. The aim of this study was to evaluate the tear function in diabetic and nondiabetic patients following cataract surgery. METHODS: In this prospective, interventional case series, 174 diabetic patients without dry eye syndrome (DES) and 474 age-matched nondiabetic patients as control who underwent phacoemulsification were enrolled at two different eye centers between January 2011 and January 2013. Patients were followed up at baseline and at 7 days, 1 month, and 3 months postoperatively. Ocular symptom scores (Ocular Surface Disease Index, OSDI) and tear film function including tear film stability (tear film break-up time, TBUT), corneal epithelium integrity (corneal fluorescein staining, CFS), and tear secretion (Schirmer's I test, SIT) were evaluated. RESULTS: In total, 83.9% of the diabetic patients (146 cases with 185 eyes) and 89.0% of the nondiabetic patients (422 cases with 463 eyes) completed all check-ups after the interventions (P = 0.095). The incidence of DES was 17.1% in the diabetic patients and 8.1% in the nondiabetic patients at 7 days after cataract surgery. In the diabetic patients, the incidence of DES remained 4.8% at 1 month postoperatively and decreased to zero at 3 months after surgery. No DES was diagnosed in nondiabetic patients at either the 1-month or 3-month follow-up. Compared with the baseline, the diabetic patients had worse symptom scores and lower TBUT values at 7 days and 1 month but not at 3 months postoperatively. In the nondiabetic patients, symptom scores and TBUT values had returned to preoperative levels at 1-month check-up. CFS scores and SIT values did not change significantly postoperatively in either group (P = 0.916 and P = 0.964, respectively). CONCLUSIONS: Diabetic patients undergoing cataract surgery are prone to DES. Ocular symptoms and tear film stability are transiently worsened in diabetic patients and are restored more slowly than those in nondiabetic patients.
Importance: Comparisons of the relative effect of 3 anti-vascular endothelial growth factor agents to treat diabetic macular edema warrant further assessment. Objective: To provide additional outcomes from a randomized trial evaluating 3 anti-vascular endothelial growth factor agents for diabetic macular edema within subgroups based on baseline visual acuity (VA) and central subfield thickness (CST) as evaluated on optical coherence tomography. Design, Setting, and Participants: Post hoc exploratory analyses were conducted of randomized trial data on 660 adults with diabetic macular edema and decreased VA (Snellen equivalent, approximately 20/32 to 20/320). The original study was conducted between August 22, 2012, and August 28, 2013. Analysis was conducted from January 7 to June 2, 2015. Interventions: Repeated 0.05-mL intravitreous injections of 2.0 mg of aflibercept (224 eyes), 1.25 mg of bevacizumab (218 eyes), or 0.3 mg of ranibizumab (218 eyes) as needed per protocol. Main Outcomes and Measures: One-year VA and CST outcomes within prespecified subgroups based on both baseline VA and CST thresholds, defined as worse (20/50 or worse) or better (20/32 to 20/40) VA and thicker (≥400 µm) or thinner (250 to 399 µm) CST. Results: In the subgroup with worse baseline VA (n = 305), irrespective of baseline CST, aflibercept showed greater improvement than bevacizumab or ranibizumab for several VA outcomes. In the subgroup with better VA and thinner CST at baseline (61-73 eyes across 3 treatment groups), VA outcomes showed little difference between groups; mean change was +7.2, +8.4, and +7.6 letters in the aflibercept, bevacizumab, and ranibizumab groups, respectively. However, in the subgroup with better VA and thicker CST at baseline (31-43 eyes), there was a suggestion of worse VA outcomes in the bevacizumab group; mean change from baseline to 1 year was +9.5, +5.4, and +9.5 letters in the aflibercept, bevacizumab, and ranibizumab groups, respectively, and VA letter score was greater than 84 (approximately 20/20) in 21 of 33 (64%), 7 of 31 (23%), and 21 of 43 (49%) eyes, respectively. The adjusted differences and 95% CIs were 39% (17% to 60%) for aflibercept vs bevacizumab, 25% (5% to 46%) for ranibizumab vs bevacizumab, and 13% (-8% to 35%) for aflibercept vs ranibizumab. Conclusions and Relevance: These post hoc secondary findings suggest that for eyes with better initial VA and thicker CST, some VA outcomes may be worse in the bevacizumab group than in the aflibercept and ranibizumab groups. Given the exploratory nature of these analyses and the small sample size within subgroups, caution is suggested when using the data to guide treatment considerations for patients. Trial Registration: clinicaltrials.gov Identifier: NCT01627249.
BACKGROUND/AIMS: Digital retinal imaging using store-and-forward technology is used to screen for diabetic retinopathy (DR). Its usefulness in detecting non-diabetic eye diseases is uncertain. We determined the level of agreement between teleretinal imaging supplemented with visual acuity and intraocular pressure (IOP) measurements (ie, technology-assisted eye (TAE) exam) and a comprehensive eye exam in evaluation for DR and non-diabetic ocular conditions. METHODS: We conducted a prospective, observational study with two parallel evaluations. Patients with diabetes (n=317) had a TAE exam and a comprehensive eye exam on the same day. A subset of participants with normal baseline exams (n=72) had follow-up exams 1 year later. We measured the level of agreement for referable ocular findings. RESULTS: Agreement for referable ocular findings was moderate (n=389, agreement: 77%; κ: 0.55), due in part to ungradable exams (22%). However, about half of the ungradable exams had findings that warranted referral. There was substantial agreement for follow-up exams (n=72, agreement: 93%; κ: 0.63). Among all gradable exams (n=303), the TAE exam had 86% sensitivity and 84% specificity for referable ocular findings, with high agreement (≥94%) for DR and other major ocular diagnoses. CONCLUSIONS: There was moderate-to-substantial agreement between a TAE exam and a comprehensive eye exam for referable ocular findings in patients with diabetes. Ungradable exams were a frequent marker of ocular pathology. Teleretinal imaging may be a useful evaluation for both diabetic and non-diabetic ocular conditions.
Importance: Preservation of vision in patients with diabetes mellitus is critical. Interventions to improve glycemic control through early intensive treatment of diabetes reduce rates of severe retinopathy and preserve visual acuity. Objective: To assess the effects of prior intensive insulin treatment and risk factors on patient-reported visual function in the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) cohort. Design, Setting, and Participants: Cohort study of 1184 participants with type 1 diabetes from the DCCT/EDIC study (randomized clinical trial followed by an observational follow-up study) who completed the 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-25) during EDIC years 17 through 20 (September 1, 2009, through April 30, 2014) in 28 institutions across the United States and Canada. Main Outcomes and Measures: The primary outcome was the composite NEI-VFQ-25 score. Secondary outcomes were visual acuity (measured by the Early Treatment Diabetic Retinopathy Study protocol), retinopathy level (determined by masked grading of stereoscopic color fundus photographs), and NEI-VFQ-25 subscale scores. The composite NEI-VFQ-25 scale and its subscales were scored 0 to 100, corresponding to poor to excellent function, respectively. Results: The overall average NEI-VFQ-25 score for 1184 DCCT/EDIC participants (mean [SD] age, 52.3 [6.9] years; 48% female) with a 30-year duration of diabetes was high (all participants: median, 91.7; interquartile range [IQR], 89.7-96.9; intensive treatment [n = 605]: median, 94.7; IQR, 91.0-97.2; conventional treatment [n = 579]: median, 94.0; IQR, 88.4-96.1; P = .006 for intensive vs conventional). After adjustment for sex, age, hemoglobin A1c level, and retinopathy level at DCCT baseline, the former intensive treatment group had a significant, albeit modest, improvement in overall NEI-VFQ-25 score compared with the former conventional diabetes treatment group (median difference, -1.0; 95% CI, -1.7 to -0.3; P = .006). This beneficial treatment effect was fully attributed to the prior glycemic control in DCCT (explained treatment effect: 100%). Those with visual acuity worse than 20/100 reported the largest decline in visual function (median difference, -21.0; 95% CI, -40.5 to -1.6; P = .03). Conclusions and Relevance: In the DCCT/EDIC cohort, patient-reported visual function remains high in both treatment groups, comparable to previous reports of overall health-related quality of life. Intensive diabetes therapy modestly improved NEI-VFQ-25 score 30 years after the start of the DCCT, the benefit underestimated owing to more nonparticipants from the conventional treatment group. Visual acuity had the greatest effect on patient-reported visual function from among all risk factors. Trial Registration: clinicaltrials.gov Identifiers: NCT00360815 and NCT00360893.
PURPOSE: The proteomic profile of vitreous from second-trimester human embryos and young adults was characterized using mass spectrometry and analyzed for changes in protein levels that may relate to structural changes occurring during this time. This vitreous proteome was compared to previous reports to confirm proteins already identified and reveal novel ones. METHODS: Vitreous from 17 human embryos aged 14 to 20 weeks gestation (WG) and from a 12-, a 14-, a 15-, and a 28-year-old was individually analyzed using tandem mass spectrometry-based proteomics. Peptide spectral count associations with embryonic age were assessed using a general linear model of fold changes and Spearman's rank correlation. Differences between embryonic and young adult vitreous proteomes were also compared. Immunohistochemistry was used to evaluate three proteins in five additional fetal (10-18 WG) human eyes. RESULTS: There were 1217 proteins identified in fetal and young adult human vitreous, 206 after quantile normalization and variance filtering. In embryos, the peptide counts of 37 proteins changed significantly from 14 to 20 WG: 75.7% increased, 24.3% decreased. Immunohistochemistry confirmed the absence of clusterin and cadherin in 10 and 14 WG eyes and their presence at 18 WG. Comparing embryonic to young adult vitreous, 47 proteins were significantly higher or lower. A total of 768 proteins not previously identified in the literature are presented. CONCLUSIONS: Proteins previously unreported in the human vitreous were identified. The human vitreous proteome undergoes significant changes during embryogenesis and young adulthood. A number of protein levels change considerably during the second trimester, with the majority decreasing.