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Cone Photoreceptor Dysfunction in Early-Stage Diabetic Retinopathy: Association Between the Activation Phase of Cone Phototransduction and the Flicker Electroretinogram
摘要： PURPOSE. To define the nature and extent of cone photoreceptor abnormalities in diabetic individuals who have mild or no retinopathy by assessing the activation phase of cone phototransduction and the flicker ERG in these individuals. METHODS. Light-adapted single-flash and flicker ERGs were recorded from 20 diabetic individuals who have no clinically apparent retinopathy (NDR), 20 diabetic individuals who have mild nonproliferative diabetic retinopathy (NPDR), and 20 nondiabetic, age-equivalent controls. A-waves elicited by flashes of different retinal illuminance were fit with a delayed Gaussian model to derive Rmp3 (maximum amplitude of the massed photoreceptor response) and S (phototransduction sensitivity). Fundamental amplitude and phase of ERGs elicited by full-field sinusoidal flicker were obtained across a frequency range of 6 to 100 Hz. RESULTS. ANVOA indicated that both diabetic groups had significant S losses compared with the controls, whereas mean Rmp3 did not differ significantly among the groups. ANOVA also indicated significantly reduced flicker ERG amplitude for frequencies ≥56 Hz for both diabetic groups compared with the controls. Flicker ERG timing (phase) did not differ significantly among the groups. Log Rmp3 + log S was significantly correlated with the patients’ high-frequency (62.5 Hz) flicker ERG amplitude loss (r = 0.69, P < 0.001). CONCLUSIONS. The delayed Gaussian a-wave model is useful for characterizing abnormalities in the activation phase of cone phototransduction and can help explain flicker ERG abnormalities in early-stage diabetic retinopathy. Reduced cone sensitivity and attenuated high-frequency flicker ERGs provide evidence for impaired cone function in these individuals.
关键词： electroretinogram,diabetic retinopathy,flicker electroretinogram,photoreceptors,a-wave
更新于2025-09-23 15:22:29
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[Lecture Notes in Computational Vision and Biomechanics] Computer Aided Intervention and Diagnostics in Clinical and Medical Images Volume 31 || Segmentation of Type II Diabetic Patient’s Retinal Blood Vessel to Diagnose Diabetic Retinopathy
摘要： Diabetic Retinopathy is one of the ophthalmic reasons for visual deficiency. The favored fixate of consideration is on the estimation of deviation in the breadth of the retinal veins and the new vessel development. To witness the progressions, segmentation has to be made primarily. A framework to improve the quality of the segmentation result over pathological retinal images is proposed. The proposed method uses adaptive histogram equalizer for preprocessing, pulse coupled neural Network model for automatic feature vector generation and extraction of the retinal blood vessels. The test result represents that the proposed method is enhanced than other retinal competitive methods. The evaluation of the proposed approach is executed over standard public DRIVE, STARE, REVIEW, HRF, and DRIONS fundus image datasets. The proposed technique improves the segmentation results in terms of sensitivity, specificity, and accuracy.
关键词： Fundus image,Feature extraction,Diabetic Retinopathy,Retinal blood vessel,Medical imaging
更新于2025-09-23 15:22:29
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MicroRNA-9 inhibits retinal neovascularization in rats with diabetic retinopathy by targeting vascular endothelial growth factor A
摘要： Diabetic retinopathy (DR) is a leading cause of adult visual impairment and loss. This study aims to explore the effects of microRNA‐9 (miR‐9) on retinal neovascularization during DR by targeting the vascular endothelial growth factor A (VEGFA). DR rat models were successfully established. Retinal microvascular endothelial cells (RMECs) of DR rats were isolated and treated with miR‐9 mimic, miR‐9 inhibitor or small interfering RNA (siRNA)‐VEGFA. The expressions of miR‐9, VEGFA, and cluster of differentiation 31 (CD31) of the rats’ tissues and cells were examined. The targeting relationship between miR‐9 and VEGFA was testified. The tubule formation, the cell proliferation and the periodic distribution and apoptosis were evaluated after transfection. In the retinal tissues of DR rats, miR‐9 expression decreased while the expression of VEGFA and CD31 increased. Notably, miR‐9 targeted and inhibited VEGFA expression. In response to the treatment of miR‐9 mimic and siRNA‐VEGFA, a reduction was identified in CD31 expression, tubule formation, and proliferation of RMECs and cell ratio in the S phase, but an increase was observed in apoptosis rate of RMECs. The treatment of miR‐9 inhibitor reversed the manifestations. Our study demonstrated that miR‐9 could inhibit retinal neovascularization of DR and tubule formation, and promote apoptosis in RMECs by targeting VEGFA.
关键词： retinal microvascular endothelial cells,diabetic retinopathy,vascular endothelial growth factor A,microRNA‐9,retinal neovascularization
更新于2025-09-23 15:21:21
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Medicine in ophthalmology
摘要： Ophthalmology is often a branch of medicine that is viewed as minor in relation to other specialities. However, there are numerous ophthalmic manifestations of neurological, rheumatological and general medical conditions. Some of these are considered emergencies (see pages xx of this chapter), but often signs are found within the eye that lead to systemic diagnoses requiring further intervention.
关键词： papilloedema,optic neuropathy,Diabetic retinopathy,thyroid eye disease,uveitis,MRCP
更新于2025-09-23 15:21:21
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Gradation of diabetic retinopathy on reconstructed image using compressed sensing
摘要： This study explores neovascularisation and lesion detection in an integrated framework for gradation in diabetic retinopathy (DR). Imaging is assumed to be done from sub-sample measurements following compressed sensing. Blind estimation of the scale of the matched filter (MF) followed by fuzzy entropy maximisation is done for extraction and classification of the thick and the thin vessels. Mutual information (MI) between vessel density and tortuosity of the thin vessel class is maximised in two dimensions (2D) for neovascularisation detection. For lesion detection, MI between the maximum MF response and the maximum Laplacian of Gaussian filter response is jointly maximised in 2D. The outcomes are then combined in a common platform for gradation in DR. Simulation results demonstrate that 95% images of each of DRIVE, STARE and DIARETDB1 databases and 94% images of MESSIDOR database are correctly graded by the proposed method when 80% measurement space is considered.
关键词： compressed sensing,lesion detection,diabetic retinopathy,fuzzy entropy,mutual information,neovascularisation
更新于2025-09-23 15:21:21
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Deep Learning-based Algorithms in Screening of Diabetic Retinopathy: A Systematic Review of Diagnostic Performance.
摘要： Topic: Diagnostic performance of deep learning-based algorithms in screening patients with diabetes for diabetic retinopathy (DR). The algorithms were compared to the current gold standard of classification by human specialists. Clinical relevance: As DR is a common cause of visual impairment, screening is indicated to avoid irreversible vision loss. Automated DR-classification using deep learning may be a suitable new screening tool that could improve diagnostic performance and reduce manpower. Methods: For this systematic review, we aimed to identify studies that incorporated the use of deep learning in classifying full-scale DR in retinal fundus images of patients with diabetes. The studies had to provide a DR-grading scale, a human grader as a reference standard and a deep learning performance score. A systematic search on April 5, 2018 through Medline and Embase yielded 304 publications. To identify potentially missed publications, the reference lists of the final included studies were manually screened, yielding no additional publications. The Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool was used for risk of bias and applicability assessment. Results: Based on objective selection, we included 11 diagnostic accuracy studies that validated the performance of their deep learning method using either a new group of patients or retrospective datasets. Eight studies reported sensitivity and specificity of 80.28%–100.0% and 84.0%–99.0%, respectively. Two studies report accuracies of 78.7% and 81.0%. One study provides an area under the receiver operating curve (AUC) of 0.955. In addition to diagnostic performance, one study also reported on patient satisfaction, showing that 78% of patients preferred an automated deep learning model over manual human grading. Conclusion: Advantages of implementing deep learning-based algorithms in DR-screening include reduction in manpower, cost of screening and issues relating to intra- and intergrader variability. However, limitations which may hinder such an implementation particularly revolves around ethical concerns regarding lack of trust in the diagnostic accuracy of computers. Considering both strengths and limitations as well as the high performance of deep learning-based algorithms, automated DR classification using deep learning could be feasible in a real-world screening scenario.
关键词： Diagnostic performance,Diabetic retinopathy,Automated classification,Neural network,Deep learning,Screening
更新于2025-09-23 15:21:01
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Nonmydriatic widefield retinal imaging with an automatic white LED confocal imaging system compared with dilated ophthalmoscopy in screening for diabetic retinopathy
摘要： Purpose To compare nonmydriatic montage widefield images with dilated fundus ophthalmoscopy for determining diabetic retinopathy (DR) severity. Materials and methods In this prospective, observational, cross-sectional study, patients with a previous diagnosis of diabetes and without history of diabetes-associated ocular disease were screened for DR. Montage widefield imaging was obtained with a system that combines confocal technology with white-light emitting diode (LED) illumination (DRSplus, Centervue, Padua, Italy). Dilated fundus examination was performed by a retina specialist. Results Thirty-seven eyes (20 patients, 8 females) were finally included in the analysis. Mean age of the patients enrolled was 58.0 ± 11.6?years [range 31–80?years]. The level of DR identified on montage widefield images agreed exactly with indirect ophthalmoscopy in 97.3% (36) of eyes and was within 1 step in 100% (37) of eyes. Cohen’s kappa coefficient (κ) was 0.96, this suggesting an almost perfect agreement between the two modalities in DR screening. Nonmydriatic montage widefield imaging acquisition time was significantly shorter than that of dilated clinical examination (p = 0.010). Conclusion Nonmydriatic montage widefield images were compared favorably with dilated fundus examination in defining DR severity; however, they are acquired more rapidly.
关键词： Diabetic retinopathy,Screening,Widefield retinal imaging
更新于2025-09-23 15:21:01
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Validating a low-cost laser speckle contrast imaging system as a quantitative tool for assessing retinal vascular function
摘要： The ability to monitor progression of retinal vascular diseases like diabetic retinopathy in small animal models is often complicated by their failure to develop the end-stage complications which characterize the human phenotypes in disease. Interestingly, as micro-vascular dysfunction typically precedes the onset of retinal vascular and even some neurodegenerative diseases, the ability to visualize and quantify hemodynamic changes (e.g. decreased flow or occlusion) in retinal vessels may serve as a useful diagnostic indicator of disease progression and as a therapeutic outcome measure in response to treatment. Nevertheless, the ability to precisely and accurately quantify retinal hemodynamics remains an unmet challenge in ophthalmic research. Herein we demonstrate the ability to modify a commercial fundus camera into a low-cost laser speckle contrast imaging (LSCI) system for contrast-free and non-invasive quantification of relative changes to retinal hemodynamics over a wide field-of-view in a rodent model.
关键词： ophthalmic research,laser speckle contrast imaging,retinal hemodynamics,retinal vascular diseases,diabetic retinopathy
更新于2025-09-23 15:21:01
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Value of optical coherence tomography in the detection of macular pathology before the removal of silicone oil
摘要： Purpose: To assess the pathological macular changes with optical coherence tomography (OCT) before the removal of silicone oil (SiO) in eyes that had undergone pars plana vitrectomy for complicated forms of retinal detachment (RD). Patients and methods: Subjects included 48 patients (51 eyes) with complicated RD including proliferative vitreoretinopathy, proliferative diabetic retinopathy, recurrent RD, penetrating trauma, uveitis, giant retinal tears, and macular holes. All the eyes had undergone SiO injection. Furthermore, all eyes had been planned for the removal of SiO 6–12 months after the primary surgery. Finally, all eyes had a fundus examination and OCT examination before the silicone oil removal. Results: OCT findings indicated epiretinal membrane in 41% of the eyes, macular edema in 17%, macular detachment in 13.5%, macular thinning in 13.5%, macular holes in 10%, and subretinal membranes in 2%. Preoperative OCT was normal in only 12% of the eyes, while a clinical fundus examination was normal in 43% (P0.001). Eyes with normal OCT had significantly better mean logMAR (0.35) than eyes with pathological changes detected through OCT (1.28; P0.001). Surgical modifications were made during the removal of SiO in 74.5% of the eyes. Conclusion: OCT detected significantly more pathological changes than a clinical fundus examination. This had an impact on both surgical step modification during the removal of SiO and predictability of visual outcome after the removal of SiO.
关键词： optical coherence tomography,pars plana vitrectomy,silicone oil,proliferative diabetic retinopathy,proliferative vitreoretinopathy
更新于2025-09-23 15:21:01
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Use of Telehealth Screening to Detect Diabetic Retinopathy and Other Ocular Findings in Primary Care Settings
摘要： Purpose: To determine the incidence of diabetic retinopathy (DR) and other ocular findings in previously diagnosed diabetes using telehealth retinal screening with nonmydriatic fundus photography (nFP) in primary care physicians’ offices. Methods: A retrospective study based on electronic chart review was performed. All diabetic patients who participated in the Wills Eye Hospital (WEH) telehealth retinal screening program from July 1, 2012 to February 20, 2017 were included. In addition to evaluation of DR, other eye pathologies of the retina were detected using nFP. Results: Overall, 9,946 diabetics participated in the WEH telehealth screening system. After exclusion of missing or unreadable images, 15,180 eyes of 7,624 (76.7%) patients were eligible for final analysis. A total of 1,269 (16.6%) patients were noted to have DR changes in at least one eye. Of those, 475 (37.4%) had mild nonproliferative DR (NPDR) in the more severely affected eye, 712 (56.1%) had moderate NPDR, 33 (2.6%) had severe NPDR, 19 (1.5%) had proliferative DR, and 30 (2.4%) have received pan-retinal photocoagulation previously. In addition, there was evidence of diabetic macular edema detectable on nFP in 34 eyes of 29 patients. Other ocular findings included hypertensive retinopathy (709, 9.3%), increased or asymmetric cup-to-disc ratio (562, 7.4%), age-related cataract (379, 5.0%), cotton-wool spots (221, 2.9%), choroidal nevus (74, 1.0%), age-related macular degeneration (AMD) (66, 0.9%), and epiretinal membrane (48, 0.6%). Patients with hypertensive retinopathy, glaucomatous findings, cataract, or AMD were significantly older (p < 0.001) than those without these ocular pathologies. Conclusion: The WEH Telehealth Screening Program identified DR in approximately one out of six patients and other ocular pathologies in over 25% of the diabetic population that received screenings in Philadelphia area primary care offices. Given the importance of early detection and routine eye care to prevent vision loss for DR patients, these findings have a significant impact.
关键词： ocular pathology,diabetic retinopathy,telehealth,screening
更新于2025-09-23 15:21:01