首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
OBJECTIVE--To determine whether non-mydriatic Polaroid retinal photography was comparable to ophthalmoscopy with mydriasis in routine clinic screening for early, treatable diabetic retinopathy. DESIGN--Prospective study of ophthalmoscopic findings according to retinal camera screening and ophthalmoscopy and outcome of referral to ophthalmologist. SETTING--Outpatient diabetic clinics of three teaching hospitals and three district general hospitals. PATIENTS--2159 Adults selected randomly from the diabetic clinics, excluding only those registered as blind or those in wheelchairs and unable to enter the screening vehicle. MAIN OUTCOME MEASURES--Numbers of patients and eyes correctly identified by each technique as requiring referral with potentially treatable retinopathy (new vessel formation and maculopathy) and congruence in numbers of microaneurysms, haemorrhages, and exudates reported. RESULTS--Camera screening missed two cases of new vessel formation and did not identify a further 12 but indicated a need for referral. Ophthalmoscopy missed five cases of new vessel formation and indicated a need for referral in another four for other reasons. Maculopathy was reported in 147 eyes with camera screening alone and 95 eyes by ophthalmoscopy only (chi 2 = 11.2; p less than 0.001), in 66 and 29 of which respectively maculopathy was subsequently confirmed. Overall, 38 eyes received laser treatment for maculopathy after detection by camera screening compared with 17 after ophthalmoscopic detection (chi 2 = 8.0; p less than 0.01). Camera screening underestimated numbers of microaneurysms (chi 2 = 12.9; p less than 0.001) and haemorrhages (chi 2 = 7.4; p less than 0.01) and ophthalmoscopy underestimated hard exudates (chi 2 = 48.2; p less than 0.001). CONCLUSIONS--Non-mydriatic Polaroid retinal photography is at least as good as ophthalmoscopy with mydriasis in routine diabetic clinics in identifying new vessel formation and absence of retinopathy and is significantly better in detecting exudative maculopathy.  相似文献   

2.
OBJECTIVE--To evaluate whether adding retinal photography improved community screening for diabetic retinopathy. SETTING--Mobile screening unit at rural and urban general practices in south west England. SUBJECTS--1010 diabetic patients from primary care. DESIGN--Prospective study; patients were examined by ophthalmoscopy by general practitioners or opticians without fundal photographs and again with photographs, and assessments were compared to those of an ophthalmologist. MAIN OUTCOME MEASURES--Whether fundal photography improved the sensitivity of detection of retinopathy and referrable diabetic retinopathy, and whether this sensitivity could be improved by including a review of the films by the specialist. RESULTS--Diabetic retinopathy was detected by the ophthalmologist in 205 patients (20.5%) and referrable retinopathy in 49 (4.9%). The sensitivity of the general practitioners and opticians for referrable retinopathy with ophthalmoscopy was 65%, and improved to 84% with retinal photographs. General practitioners'' sensitivity in detecting background retinopathy improved with photographs from 22% to 65%; opticians'' sensitivity in detecting background retinopathy improved from 43% to 71%. The sensitivity of detecting referrable retinopathy by general practitioners improved from 56% to 80% with photographs; for opticians it improved from 75% to 88%. CONCLUSIONS--Combining modalities of screening by providing photography with specialist review of all films in addition to direct ophthalmoscopy through dilated pupils improves assessment and referral for diabetic retinopathy by general practitioners and opticians. With further training and experience, primary care screeners should be able to achieve a sensitivity that will achieve an effective, acceptable, and economical community based screening programme for this condition.  相似文献   

3.
R.D. Badgujar  P.J. Deore 《IRBM》2019,40(2):69-77
Background: The diabetic retinopathy can result in loss of vision if not detected in the earlier stages. Exudates are the lesions which play a crucial role in early diagnosis of diabetic retinopathy. The localization of exudates lesions with high values of performance metrics is complicated due to presence of blood vessels and other noisy artifacts. Method: We present computer aided system for classification of retinal fundus images using a novel nature inspired spider monkey optimization for parameter tuning of gradient boosting machines classifier. The image enhancement has been performed with histogram equalization and contourlet transform. The pixels belonging to optic disc region are detected and eliminated using circular Hough transform and Otsu's segmentation method. We have employed Kirsch's matrices for blood vessel detection. The GLCM based feature vector extraction has been employed for textural features. The classification has been performed with hybrid SMO-GBM classifier. Result: We have utilized the STARE database for validation of proposed technique. The proposed system can effectively classify entire image set from test data. The SMO-GBM classifier can further sub-segregate into sub classes with an average accuracy of 97.5%. Conclusion: The proposed approach provides detection and grading of diabetic retinopathy. The abnormality is further categories as soft, moderate and severe. The hybrid SMO-GBM classifier yields a better statistical metrics than the existing exudates classification approaches.  相似文献   

4.
A dual-channel optical coherence tomography system with wavelengths in the visible and near-infrared light ranges can provide both structural and functional information for retinal microvasculature simultaneously. We applied this integrated system in an ongoing clinical study of patients with various retinal pathologies. Here, we present case study results of patients with diabetic retinopathy, central retinal vein occlusion, and sickle cell retinopathy compared to a healthy subject. For the first time, this comparison validates the system’s ability to detect structural anomalies in both en face and B-scan images with simultaneous retinal optical coherence tomography angiography and measurement of sO2 in parafoveal vessels that are around 20–30 µm in diameter. This integrated system represents a powerful instrument with potentially far-reaching clinical implications for the early detection and diagnosis of retinal vascular diseases.  相似文献   

5.
The paper presents a new approach for medical image segmentation. Exudates are a visible sign of diabetic retinopathy that is the major reason of vision loss in patients with diabetes. If the exudates extend into the macular area, blindness may occur. Automated detection of exudates will assist ophthalmologists in early diagnosis. This segmentation process includes a new mechanism for clustering the elements of high-resolution images in order to improve precision and reduce computation time. The system applies K-means clustering to the image segmentation after getting optimized by Pillar algorithm; pillars are constructed in such a way that they can withstand the pressure. Improved pillar algorithm can optimize the K-means clustering for image segmentation in aspects of precision and computation time. This evaluates the proposed approach for image segmentation by comparing with Kmeans and Fuzzy C-means in a medical image. Using this method, identification of dark spot in the retina becomes easier and the proposed algorithm is applied on diabetic retinal images of all stages to identify hard and soft exudates, where the existing pillar K-means is more appropriate for brain MRI images. This proposed system help the doctors to identify the problem in the early stage and can suggest a better drug for preventing further retinal damage.  相似文献   

6.

Background

Non-proliferative diabetic retinopathy is the early stage of diabetic retinopathy. Automatic detection of non-proliferative diabetic retinopathy is significant for clinical diagnosis, early screening and course progression of patients.

Methods

This paper introduces the design and implementation of an automatic system for screening non-proliferative diabetic retinopathy based on color fundus images. Firstly, the fundus structures, including blood vessels, optic disc and macula, are extracted and located, respectively. In particular, a new optic disc localization method using parabolic fitting is proposed based on the physiological structure characteristics of optic disc and blood vessels. Then, early lesions, such as microaneurysms, hemorrhages and hard exudates, are detected based on their respective characteristics. An equivalent optical model simulating human eyes is designed based on the anatomical structure of retina. Main structures and early lesions are reconstructed in the 3D space for better visualization. Finally, the severity of each image is evaluated based on the international criteria of diabetic retinopathy.

Results

The system has been tested on public databases and images from hospitals. Experimental results demonstrate that the proposed system achieves high accuracy for main structures and early lesions detection. The results of severity classification for non-proliferative diabetic retinopathy are also accurate and suitable.

Conclusions

Our system can assist ophthalmologists for clinical diagnosis, automatic screening and course progression of patients.
  相似文献   

7.
BackgroundThe accumulation of advanced glycated end products (AGEs) in retinal blood vessels is one of the major etiological factors contributing to diabetic retinopathy. Aminoguanidine (AG) is one of the most extensively used inhibitors of AGEs formation. The aim of this study was to investigate whether AG could protect the development of diabetic retinopathy through inhibition of AGEs.MethodsRat diabetes was induced by intraperitoneal injection with streptozotocin (STZ). AG was given to rats in drinking water. Retina was extracted 3 and 6 months following STZ and AG administration. Immunochemistry and transmission electron microscope were used to detect the expression of AGEs and retina morphology.ResultsExtensive staining of AGEs was detected in retinal blood vessels of 3- and 6-month diabetic rats, while no significant staining was found in the control non-diabetic retina or AG treated groups. Pericyte loss, endothelial cell proliferation, increased ratio of endothelial cells/pericytes, acellular capillaries and capillary occlusion were observed in the retina of 6-month diabetic rats. The increased electron density of retinal capillary basement membrane, mitochondrial swelling in pericytes and endothelial cells were also found in 6-month diabetic rats. The 3-month diabetic rats and the AG-treated rats did not have similar morphological changes compared to control group. The AGEs staining in AG-treated rats was still weakly positive.ConclusionsAGEs plays pivotal roles in diabetic retinopathy. AGE deposition occurs prior to retinal microvasculature changes. AG could prevent the onset and development of diabetic retinopathy through inhibition of AGEs.  相似文献   

8.
This paper discusses the new national guidelines for a systematic screening programme to detect sight-threatening diabetic retinopathy in the population of people with diabetes in England. A review of the literature examines the evidence base to support screening interventions and effective management and treatments in diabetic retinopathy. The current evidence supports the establishment of a digital retinal photography system using pupil dilation. A Policy Advisory Group has been formulated by the National Screening Committee to guide the meeting of this target in England. A conclusion is made that with increased effort and organisation, health care professionals can ensure that the screening programme is successfully implemented and rates of visual impairment and blindness caused by diabetic retinopathy can be reduced significantly.  相似文献   

9.
Leukocytes and proteins that govern leukocyte adhesion to endothelial cells play a causal role in retinal abnormalities characteristic of the early stages of diabetic retinopathy, including diabetes-induced degeneration of retinal capillaries. Leukocyte integrin αmβ2 (CD11b/CD18, MAC1), a protein mediating adhesion, has been shown to mediate damage to endothelial cells by activated leukocytes in vitro. We hypothesized that Neutrophil Inhibitory Factor (NIF), a selective antagonist of integrin αmβ2, would inhibit the diabetes-induced degeneration of retinal capillaries by inhibiting the excessive interaction between leukocytes and retinal endothelial cells in diabetes. Wild type animals and transgenic animals expressing NIF were made diabetic with streptozotocin and assessed for diabetes-induced retinal vascular abnormalities and leukocyte activation. To assess if the leukocyte blocking therapy compromised the immune system, animals were challenged with bacteria. Retinal superoxide production, leukostasis and leukocyte superoxide production were increased in wild type mice diabetic for 10 weeks, as was the ability of leukocytes isolated from diabetic animals to kill retinal endothelial cells in vitro. Retinal capillary degeneration was significantly increased in wild type mice diabetic 40 weeks. In contrast, mice expressing NIF did not develop any of these abnormalities, with the exception that non-diabetic and diabetic mice expressing NIF generated greater amounts of superoxide than did similar mice not expressing NIF. Importantly, NIF did not significantly impair the ability of mice to clear an opportunistic bacterial challenge, suggesting that NIF did not compromise immune surveillance. We conclude that antagonism of CD11b (integrin αmβ2) by NIF is sufficient to inhibit early stages of diabetic retinopathy, while not compromising the basic immune response.  相似文献   

10.
目的:探讨糖尿病患者糖尿病性视网膜病变早期多焦视网膜电图(multifocal electroretinogram,mfERG)的特点。方法:应用德国ROLAND公司RETIscan系统对24例40眼糖尿病患者,同时对27例40眼正常对照眼记录mfERG。按机器的默认值一阶反应进行记录。整个记录过程中可以分为12个时段,每个时段记录为时间47秒。结果:mERG测得的糖尿病患者组1~5环所在位置的P1波的振幅密度随离心度的增加而降低,P1波和N1波幅值降低和潜伏时延迟。各象限的P1、N1波振幅密度、波幅值降低,潜伏时延迟。结论:糖尿病性视网膜病变受累的区域多发生在黄斑部,功能上的改变早于形态学的变化;病变的早期功能改变最先出现于视网膜的后极偏颞上方;糖尿病患者在未出现眼底改变时各个象限视网膜的外层已经严重受累。  相似文献   

11.

Background

The impact of retinal pathology detected by high-resolution imaging on vision remains largely unexplored. Therefore, the aim of the study was to achieve high-resolution structure-function correlation of the human macula in vivo.

Methodology/Principal Findings

To obtain high-resolution tomographic and topographic images of the macula spectral-domain optical coherence tomography (SD-OCT) and confocal scanning laser ophthalmoscopy (cSLO), respectively, were used. Functional mapping of the macula was obtained by using fundus-controlled microperimetry. Custom software allowed for co-registration of the fundus mapped microperimetry coordinates with both SD-OCT and cSLO datasets. The method was applied in a cross-sectional observational study of retinal diseases and in a clinical trial investigating the effectiveness of intravitreal ranibizumab in macular telangietasia type 2. There was a significant relationship between outer retinal thickness and retinal sensitivity (p<0.001) and neurodegeneration leaving less than about 50 µm of parafoveal outer retinal thickness completely abolished light sensitivity. In contrast, functional preservation was found if neurodegeneration spared the photoreceptors, but caused quite extensive disruption of the inner retina. Longitudinal data revealed that small lesions affecting the photoreceptor layer typically precede functional detection but later cause severe loss of light sensitivity. Ranibizumab was shown to be ineffective to prevent such functional loss in macular telangietasia type 2.

Conclusions/Significance

Since there is a general need for efficient monitoring of the effectiveness of therapy in neurodegenerative diseases of the retina and since SD-OCT imaging is becoming more widely available, surrogate endpoints derived from such structure-function correlation may become highly relevant in future clinical trials.  相似文献   

12.
Diabetes mellitus is a major cause of blindness in England and Wales in those aged between 30 and 64. Photocoagulation can frequently prevent blindness provided the retinopathy is detected at an appropriate stage but unfortunately the benefits are small if the changes are advanced. Early detection of diabetic retinopathy by regular examination is needed. We have shown that ophthalmic opticians have the skill to detect retinal changes at a treatable stage. Out of 844 eye checks, 80 were reported by ophthalmic opticians to justify referral to an ophthalmologist and 20 of these required photocoagulation treatment. Of a sample of 197 patients rechecked by an ophthalmologist reported by ophthalmic opticians not to justify referral, only one needed treatment. With local agreement this system of detecting retinopathy could be easily applied anywhere in the United Kingdom. No extra personnel or facilities are needed.  相似文献   

13.
Both the clinical diagnosis and fundamental investigation of major ocular diseases greatly benefit from various non-invasive ophthalmic imaging technologies. Existing retinal imaging modalities, such as fundus photography1, confocal scanning laser ophthalmoscopy (cSLO)2, and optical coherence tomography (OCT)3, have significant contributions in monitoring disease onsets and progressions, and developing new therapeutic strategies. However, they predominantly rely on the back-reflected photons from the retina. As a consequence, the optical absorption properties of the retina, which are usually strongly associated with retinal pathophysiology status, are inaccessible by the traditional imaging technologies.Photoacoustic ophthalmoscopy (PAOM) is an emerging retinal imaging modality that permits the detection of the optical absorption contrasts in the eye with a high sensitivity4-7 . In PAOM nanosecond laser pulses are delivered through the pupil and scanned across the posterior eye to induce photoacoustic (PA) signals, which are detected by an unfocused ultrasonic transducer attached to the eyelid. Because of the strong optical absorption of hemoglobin and melanin, PAOM is capable of non-invasively imaging the retinal and choroidal vasculatures, and the retinal pigment epithelium (RPE) melanin at high contrasts 6,7. More importantly, based on the well-developed spectroscopic photoacoustic imaging5,8 , PAOM has the potential to map the hemoglobin oxygen saturation in retinal vessels, which can be critical in studying the physiology and pathology of several blinding diseases 9 such as diabetic retinopathy and neovascular age-related macular degeneration.Moreover, being the only existing optical-absorption-based ophthalmic imaging modality, PAOM can be integrated with well-established clinical ophthalmic imaging techniques to achieve more comprehensive anatomic and functional evaluations of the eye based on multiple optical contrasts6,10 . In this work, we integrate PAOM and spectral-domain OCT (SD-OCT) for simultaneously in vivo retinal imaging of rat, where both optical absorption and scattering properties of the retina are revealed. The system configuration, system alignment and imaging acquisition are presented.  相似文献   

14.
The present study was designed to examine therapeutic efficacy of the root extract of Stephania Tetrandra S. Moore (STMS) (traditional Chinese medicine; Han Fang Ji) for treatment of neovascularization of the retinal capillary (retinopathy) in streptozotocin (STZ)-induced diabetic rats (STZ diabetic rats) in culture. Recently we have established the culture system in which fetal bovine serum (FBS) in Dulbecco modified Eagle medium (DMEM) induced neovascularization of the retinal capillary and choroidal capillary in normal rats in culture. STZ diabetic rats showed more neovascularization of the retinal capillary and choroidal capillary than did normal rats in culture. In this study, the retinal tissue was removed for the posterior ocular region and cultured in DMEM containing FBS. The choroidal tissue of the posterior ocular region was also removed and cultured as an internal reference. Administration of STSM (0.91, 9.1 and 91 microg/ml) significantly suppressed neovascularization of the retinal capillary in both STZ diabetic rats and normal rats in a dose-dependent manner. Similar results were obtained with the choroidal capillary; administration of STSM suppressed neovascularization of the choroidal capillary in both STZ diabetic rats and normal rats. In order to determine the component of STSM inhibiting neovascularization of the retinal capillary, tetrandrine (a major chemical constituent of STSM) was administered and neovascularization of the retinal capillary was examined in culture. The effect of tetrandrine on the choroidal capillary was also examined as an internal reference. Administration of tetrandrine (0.1, 1.0 and 10 microM) suppressed neovascularization of the retinal capillary in both STZ diabetic rats and normal rats in a dose-dependent manner. Similar results were obtained with the choroidal capillary of both STZ diabetic rats and normal rats. We infer, therefore, that STSM has a direct effect on the retinal capillary of posterior ocular region and suppresses neovascularization of retinal capillary in STZ diabetic rats through the activation of tetrandrine. These results suggest that STSM may prevent for delay the progression of retinopathy in diabetic patients.  相似文献   

15.
The changes in retinal thickness and visual function in type 2 diabetic patients without clinical evidence of diabetic retinopathy were evaluated. A total of 141 diabetic subjects without retinopathy and 158 healthy subjects were enrolled in this study. Superior macular ganglion cell complex thicknesses were significantly decreased in diabetic cases, and no significant peripapillary retinal nerve fiber layer thickness changes were observed. The contrast sensitivities at all space frequencies were significantly different between diabetic patients and controls. The mean P50 amplitude from pattern electroretinogram results was reduced significantly in the diabetic group. In the diabetic group, average superior ganglion cell complex thicknesses positively correlated with both contrast sensitivities at high spatial frequencies and P50 amplitudes. The results indicated that ganglion cell complex thickness and visual function changes could be observed in diabetic subjects before the onset of any significant diabetic retinopathy. Macular ganglion cell complex reduction occurred much earlier than peripapillary retinal nerve fiber layer thinning in diabetic patients without retinopathy.  相似文献   

16.
This paper discusses the new national guidelines for a systematic screening programme to detect sight-threatening diabetic retinopathy in the population of people with diabetes in England. A review of the literature examines the evidence base to support screening interventions and effective management and treatments in diabetic retinopathy. The current evidence supports the establishment of a digital retinal photography system using pupil dilation. A Policy Advisory Group has been formulated by the National Screening Committee to guide the meeting of this target in England. A conclusion is made that with increased effort and organisation, health care professionals can ensure that the screening programme is successfully implemented and rates of visual impairment and blindness caused by diabetic retinopathy can be reduced significantly. (Mol Cell Biochem 261: 183–185, 2004)  相似文献   

17.
OBJECTIVES--(a) To report on the basic parameters of retinal blood flow in a population of diabetic patients with and without retinopathy and non-diabetic controls; (b) to formulate a haemodynamic model for the pathogenesis of diabetic retinopathy from this and other studies. DESIGN--Laser-Doppler velocimetry and computerised image analysis to determine retinal blood flow in a large cross sectional study. SETTING--Diabetic retinopathy outpatient clinic. SUBJECTS--24 non-diabetic controls and 76 diabetic subjects were studied (63 patients with insulin dependent diabetes, 13 with non-insulin dependent diabetes). Of the diabetic subjects, 12 had no diabetic retinopathy, 27 had background retinopathy, 13 had pre-proliferative retinopathy, 12 had proliferative retinopathy, and 12 had had pan-retinal photocoagulation for proliferative retinopathy. MAIN OUTCOME MEASURES--Retinal blood flow (microliters/min) and conductance (rate of flow per unit of perfusion pressure). RESULTS--In comparison with non-diabetic controls (9.52 microliters/min) and diabetic patients with no diabetic retinopathy (9.12 microliters/min) retinal blood flow was significantly increased in all grades of untreated diabetic retinopathy (background 12.13 microliters/min, pre-proliferative 15.27 microliters/min, proliferative 13.88 microliters/min). There was a significant decrease in flow after pan-retinal photocoagulation in comparison with all the other groups studied (4.48 microliters/min). Conductance of the retinal circulation was higher in the untreated diabetic retinopathy groups. These results were independent of age, sex, type of diabetes, duration of diabetes, glycated haemoglobin concentration, blood glucose concentration, blood pressure, and intraocular pressure. CONCLUSIONS--Retinal blood flow is significantly increased in diabetic retinopathy in comparison with non-diabetic controls and diabetic subjects with no retinopathy. This has implications for controlling hypertension and hyperglycaemia as a strategy in reducing morbidity from diabetic retinopathy.  相似文献   

18.
Various electrophysiological tests have been employed to reveal functional abnormalities at different levels of the visual system in insulin-dependent diabetic (IDDM) patients. The aim of our work was to assess, with a comprehensive neurophysiological protocol evaluating the retinal, macular and visual pathways functions, whether and when such electrophysiological abnormalities do appear in IDDM patients free of any fluorangiographic sign of retinopathy with various disease duration. Flash-electroretinogram (ERG), oscillatory potentials (OPs), pattern-electroretinogram (PERG), and visual evoked potentials (VEPs) in basal condition and after photostress were assessed in 12 control subjects (C) and 42 aged-matched IDDM patients without clinical retinopathy (DR−) divided, on the basis of the disease duration, into 4 groups (1–5, 6–10, 11–15, 16–20 years). In addition another age-matched group of IDDM patients with a background retinopathy (DR+; n=12; duration of disease 18±49 years) was evaluated. In all IDDM DR− patients PERG and VEP were significantly impaired. In addition, groups 11–15 and 16–20 years displayed impaired OPs. All electrophysiological parameters were further impaired in DR+ patients. In conclusion, retinal, macular and visual pathways functions are differently impaired in IDDM (DR−) patients with different disease duration. Electrophysiological impairment starts in the nervous conduction of the visual pathways with an early involvement, goes on in the innermost retinal layers and in the macula and ends in the middle and outer retinal layers.  相似文献   

19.
20.
Diabetic Retinopathy (DR) is a disease that occurs in the eye which results in blindness as it passes to proliferative stage. Diabetes can significantly result in symptoms like blurring of vision, kidney failure, nervous damage. Hence it has become necessary to identify retinal damage that occurs in diabetic eye due to raised glucose level in its initial stage itself. Hence automated detection of anamoly has become very essential. The appearance of crimson and yellow lesions is considered as the earliest symptoms of DR which are called as hemorrhages and exudates. If DR is analysed at initial stage, blindness does not occur. The damage in retina can hinder the light that passes through nerves of the eye leading to visual loss. The motivation behind this research is to reduce the number of false positives by accurate detection which is possible using proposed fuzzy system based on ANN. Though several classifiers are available to detect the exudates this paper makes analysis of support vector machine using radial basis kernel function with proposed ANN technique. Also, adaptive neuro fuzzy inference system segmentation is performed after feature extraction technique, which makes classifer to outperform. The evaluation results showed that proposed artificial neural network based on fuzzy approach attained significant results compared to other classifiers. Moreover, the proposed algorithm has significant accuracy of 94% and minimum error rate has been observed.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号