Clinical correlation of diabetic retinopathy with nephropathy and neuropathy

Purpose:To evaluate the presence of nephropathy and neuropathy in patients with diabetic retinopathy (DR) and to correlate the severity of DR to that of diabetic nephropathy and diabetic neuropathy.Methods:This prospective noninterventional hospital-based study included 57 consecutive cases of DR of either sex, presenting to the eye OPD between January 2019 and November 2020 with minimum 5-year duration of Type 1 and 2 DM. Complete ophthalmic examination was done and DR was classified according to early treatment diabetic retinopathy study classification. Severity of diabetic nephropathy was based on urine albumin creatinine ratio and estimated glomerular filtration rate. Severity of diabetic neuropathy was based on nerve conduction velocity.Results:The study was conducted on 57 patients of whom patients 45 were males and 12 were females. Mild nonproliferative diabetic retinopathy was present in 22 patients, moderate in 14 patients, severe in 18 patients, and proliferative diabetic retinopathy in 3 patients. In our study, group 30 patients of DR presented without clinically significant macular edema (CSME) and 27 patients presented with CSME. The distribution of severity of DR according to CSME was observed to be statistically significant (P<<0.05). The association of severity of DR with severity of diabetic nephropathy was observed to be statistically significant (P<<0.05). The association of severity of DR with that of diabetic neuropathy was inconclusive.Conclusion:The association of severity of DR with severity of diabetic nephropathy and diabetic neuropathy can be used as a marker for future chronic kidney diseases progression and also to prognosticate neurological outcomes in diabetic patients.     

糖尿病视网膜病变激光术后视野的改变

目的报告增殖性糖尿病视网膜病变(proliferative diabetic retinopathy PDR)、严重非增殖性糖尿病视网膜病变(severe nonproliferative diabetic retinopathy severe NPDR)、糖尿病性黄斑水肿患者激光治疗后视野的改变.方法52眼分A、B、C三组.A组为无黄斑水肿的PDR及严重NPDR,行全视网膜光凝术(panretinal photocoagulation PRP).B组为PDR合并黄斑水肿者,行PRP联合黄斑区光凝.C组为单纯黄斑水肿者,行黄斑区光凝.结果A组光凝后,30°内视野平均光阈值敏感度下降(P＜0.01),周边视野暗点增多或增大.B组光凝后,30°视野平均光阈值敏感度下降(P＜0.01),周边视野暗点增大增多,10°内光阈值敏感度下降(P＜0.05).C组10°内视野平均光阈值敏感度下降(P＜0.05).三组激光治疗前后视力无显著区别,新生血管明显消退,黄斑水肿消退.结论全视网膜光凝可有效阻止PDR的进一步发展,防止病人视力进一步下降,但降低了视网膜光敏感度,且周边部视野暗点增多.黄斑区光凝不损伤黄斑中心视功能,对糖尿病黄斑部病变局部代谢的改善,促进组织修复有一定临床意义.     

糖尿病视网膜病变合并视神经病变的临床分析

目的探讨糖尿病视网膜病变合并糖尿病性视乳头病变和缺血性视神经病变两类疾病的发病特点及其发生与DR分期的相关性。方法回顾性分析诊断为DR的1126例患者2034只眼的眼底彩照、FFA与视野等资料,筛选出糖尿病性视乳头病变11例15眼,糖尿病缺血性视神经病变24例27眼,分析两组患者的年龄、眼别、视力、糖尿病病程、主诉等临床资料,并分析两类疾病的发生与DR分期的相关性。结果(1)DR合并DP发病率为0.74%,合并ION的发病率为1.33%,两类疾病在视力下降程度、糖尿病病程等方面都有不同。(2)背景期DR合并DP和ION的发病率高于增殖期DR。结论DR合并视神经病变并不少见,对于DR患者不明原因的视力下降,应考虑合并视神经病变的发生,以免延误患者病情。     

糖尿病视网膜病变患者视网膜光凝术后近期调节力的变化

目的 观察视网膜光凝术后糖尿病视网膜病变（DR）患者眼近期调节力的变化。设计 前瞻性病例系列。研究对象 15例（30眼）确诊须行眼底激光治疗的DR患者,平均年龄（57.4±13.4）岁。方法 由同一操作者进行视网膜光凝术,观察患者同一只眼激光前、激光后第1、3、7、14天的调节功能指标和视力。主要指标 调节幅度、正相对调节、负相对调节、最佳矫正远视力、近视力。结果 激光后各时间点的单眼调节幅度、正相对调节均较激光前有所下降（F=34.19,P=0.00; F=23.68,P=0.00）,差异有统计学意义。下降规律是从激光后第1天开始,第3天幅度最大,第7天稍有恢复,第14天的观察时间内未恢复到激光前。负相对调节在激光前后的比较差异无统计学意义（F=0.569,P=0.686）。激光后的近视力较激光前有所下降（F=5.54,P=0.00）,且变化规律与单眼调节幅度、正相对调节相似。结论 在激光后14天的观察时间内,视网膜光凝术会导致DR患眼近期调节力下降。（眼科,2014, 23： 322-325）     

Automated detection of diabetic retinopathy in retinal images

Diabetic retinopathy (DR) is a disease with an increasing prevalence and the main cause of blindness among working-age population. The risk of severe vision loss can be significantly reduced by timely diagnosis and treatment. Systematic screening for DR has been identified as a cost-effective way to save health services resources. Automatic retinal image analysis is emerging as an important screening tool for early DR detection, which can reduce the workload associated to manual grading as well as save diagnosis costs and time. Many research efforts in the last years have been devoted to developing automatic tools to help in the detection and evaluation of DR lesions. However, there is a large variability in the databases and evaluation criteria used in the literature, which hampers a direct comparison of the different studies. This work is aimed at summarizing the results of the available algorithms for the detection and classification of DR pathology. A detailed literature search was conducted using PubMed. Selected relevant studies in the last 10 years were scrutinized and included in the review. Furthermore, we will try to give an overview of the available commercial software for automatic retinal image analysis.     

Advances in retinal imaging for diabetic retinopathy and diabetic macular edema

Diabetic retinopathy and diabetic macular edema (DME) are leading causes of blindness throughout the world, and cause significant visual morbidity. Ocular imaging has played a significant role in the management of diabetic eye disease, and the advent of advanced imaging modalities will be of great value as our understanding of diabetic eye diseases increase, and the management options become increasingly varied and complex. Color fundus photography has established roles in screening for diabetic eye disease, early detection of progression, and monitoring of treatment response. Fluorescein angiography (FA) detects areas of capillary nonperfusion, as well as leakage from both microaneurysms and neovascularization. Recent advances in retinal imaging modalities complement traditional fundus photography and provide invaluable new information for clinicians. Ultra-widefield imaging, which can be used to produce both color fundus photographs and FAs, now allows unprecedented views of the posterior pole. The pathologies that are detected in the periphery of the retina have the potential to change the grading of disease severity, and may be of prognostic significance to disease progression. Studies have shown that peripheral ischemia may be related to the presence and severity of DME. Optical coherence tomography (OCT) provides structural detail of the retina, and the quantitative and qualitative features are useful in the monitoring of diabetic eye disease. A relatively recent innovation, OCT angiography, produces images of the fine blood vessels at the macula and optic disc, without the need for contrast agents. This paper will review the roles of each of these imaging modalities for diabetic eye disease.     

早期糖尿病视网膜病变视网膜血管管径变化的初步研究

目的 探讨2型糖尿病患者早期糖尿病视网膜病变(diabetic retinopathy,DR)视网膜血管管径的变化及其相关因素。设计病例对照研究。研究对象北京德胜社区糖尿病眼病随访研究的85例2型糖尿病患者(51～80岁)及年龄性别匹配的26例无糖尿病者(51～78岁)作为对照。方法 85例2型糖尿病患者根据DR情况分成两组:无DR(NDR)组(51例)、轻中度非增生性糖尿病视网膜病变(Nonproliferative diabetic retinopathy,NPDR)组(34例),26例无糖尿病者为对照组。使用计算机软件测量视网膜中央动脉管径当量(CRAE)和视网膜中央静脉管径当量(CRVE)。使用光学断层成像技术测量黄斑中心凹视网膜厚度。同时记录最佳矫正视力(BCVA)、糖尿病病程、身高、体重、糖化血红蛋白等数据。比较三组间CRAE、CRVE的差异,并分析可能的相关因素。主要指标CRAE、CRVE。结果 无糖尿病对照组右眼、NDR组右眼和NPDR组病变严重眼的CRAE分别为(151.91±13.65)μm、(156.73±11.53)μm、(154.08±9.82)μm(F=1....     

Correlation of leaking microaneurysms with retinal thickening in diabetic retinopathy

AIM: To investigate the contribution of fluorescein angiographic leaking microaneurysms (leak-MA) versus non-leaking microaneurysms (non-leak-MA) to retinal thickening in diabetic retinopathy. METHODS: A consecutive series of 38 eyes from 24 patients with diabetic retinopathy was included. Leak-MA and non-leak-MA in each eye were selected in pairs at corresponding topographic location. Leaking was defined by late phase fluorescein angiograms compared to early phase. Retinal thickness was measured with Heidelberg Spectralis OCT topographically aligned on early phase angiograms at the MA site and within a 1 mm circle. RESULTS: In all eyes, significant retinal thickening at the site of leaking compared to non-leaking microaneurysms was observed (356±69μm vs 318±56μm, P <0.001), showing a mean increase in thickness in the areas of leak-MA vs non-leak-MA of 38±39μm (95% confidence interval 25-51μm, P<0.001). All 1mm area measurements also showed significant (P<0.001) thickening of the leak-MA with average thickness of leak-MA vs non-leak-MA as 351±67μm vs 319±59μm; minimum thickness 311±62μm vs 284±60μm; maximum thickness 389±78μm vs 352±66μm; and retina volume 26.4±6.0mm vs 23.6±3.7mm3, respectively. CONCLUSION: Leaking of microaneurysms on fluorescein angiography appears to cause focal thickening of retina, which can be measured with high-resolution OCT. Therefore, targeting leaking microaneursyms in diabetic retinopathy has the potential to reduce retinal thickening.     

糖尿病性视网膜病变与其他眼底血管性疾病的玻璃体视网膜手术治疗研究

目的　探讨增生性糖尿病视网膜病变 (proliferative diabetic retinopathy,PDR)及眼底血管性疾病的玻璃体视网膜手术 (vitreous retinal surgery,VRS)效果。方法　统计 1999年 1月至 2 0 0 3年 7月我院 6 9例 (73只眼 ) PDR组和非 PDR组视网膜静脉阻塞 (retinal vein occlusion,RVO)及视网膜静脉周围炎 (retinal periphlebitis,又名 Eales病 ) VRS后的视力、视网膜复位情况及术后并发症 ,研究组分为 PDR组 30例 (33只眼 ) ,非 PDR组 39例 (40只眼 ) (包括 RVO2 6例 2 6只眼和 Eales病 13例 14只眼 )。手术方法主要包括玻璃体切除、膜剥离、过氟萘烷液体使用 ,眼内激光、气体或硅油填充。结果　 PDR组术后视网膜复位 31只眼 ,非 PDR组术后全部解剖复位 ,PDR组解剖复位率低于非 PDR组 ,但统计学差异无显著性 (P >0 .0 5 ) ;PDR组术后视力提高 11只眼 ,非 PDR组术后视力提高 31只眼 ,两组比较 ,差异有非常显著性 (χ2 =14 .4 37,P =0 .0 0 0 ) ;PDR组术后并发性白内障 14只眼 ,非 PDR组并发性白内障 2只眼 ,两组比较 ,差异有非常显著性 (χ2 =14 .798,P =0 .0 0 0 ) ;PDR组继发青光眼 5只眼 ,非 PDR组继发青光眼 1只眼 ,两组比较 ,差异有显著性 (χ2 =4 .0 15 ,P <0 .0 5 )。PDR组中术中高血压者发生缺血性     

Relationship between diabetic retinopathy and diabetic peripheral neuropathy - Neurodegenerative and microvascular changes

Purpose:To determine the relationship between diabetic retinopathy (DR) and diabetic peripheral neuropathy (DPN), and their associated risk factors.Methods:We conducted a cross-sectional analysis on 500 patients who attended the Endocrinology department at a quaternary health care center in Kerala between November 2017 and April 2018. Patients above the age of 30 years with type 2 diabetes mellitus (DM) were included. They underwent a detailed medical history, dilated fundus examination for DR, assessment and grading of DPN, and blood investigations. Among these, 49 randomly selected patients without DR had peripapillary retinal nerve fiber layer (RNFL) and ganglion cell inner plexiform layer (GCIPL) assessed by optical coherence tomogram. RNFL and GCIPL changes in different grades of neuropathy were evaluated.Results:Out of 500 patients, 303 (60.6%) were males and 197 (39.4%) were females. Prevalence of DR was 48% and DPN 71.8%. Risk factors for the development of DR included duration of DM >15 years, HbA1c (glycated hemoglobin) greater than 6.5%, serum creatinine more than 1.5 mg/dl, and the presence of DPN. There was a statistically significant association between DR and DPN. There was significant thinning of GCIPL in patients with moderate to severe neuropathy without DR.Conclusion:There is a significant association between DR and DPN and their severities. There are early changes in inner retinal layers of diabetic patients without microvascular changes of DR. These neurodegenerative changes parallel DPN in the course of DM. Our study stresses the importance of multidisciplinary approach in the management of diabetes and its complications.     

2型糖尿病视网膜病变与糖尿病其他并发症的相关性

目的：探讨2型糖尿病视网膜病变（ diabetic retinopathy, DR）与糖尿病的全身并发症的相关性。方法：分析2型糖尿病住院患者702例,将其分为NDR组、DR组两组,DR组又分为非增生性糖尿病视网膜病变（non－proliferative diabetic retinopathy,NPDR）组和增生性糖尿病视网膜病变（ proliferative diabetic retinopathy, PDR）组,分析DR与糖尿病大血管并发症、糖尿病肾病（ diabetic nephropathy, DN ）、糖尿病周围神经病变（ diabetic peripheral neuropathy,DPN）,糖尿病周围血管性疾病（ peripheral vascular disease of diabetes mellitus, PVD）、糖尿病足（ diabetic foot,DF）、糖尿病酮症酸中毒（ diabetic ketoacidosis,DKA）等糖尿病并发症的相关性。结果：DR的发生、发展与高血压、高血脂、颈部血管硬化、斑块,下肢动脉硬化、斑块, DN、DPN、DF及PVD等并发症有关。 PDR与高血压、DPN关系密切。结论：血管内皮损伤、微循环障碍是DR及糖尿病的全身大、小血管并发症的共同病理基础。糖尿病患者出现全身并发症时,DR的患病率增加,尤其是合并高血压、DPN时,PDR的患病率增加。所以糖尿病患者尤其是出现全身并发症者必需定期行眼底检查,以早期发现、早期治疗DR,降低致盲率。     

糖尿病视网膜病变的分级标准初探

本文参考国际糖尿病视网膜病变（DR）严重程度分级、“DR早期治疗研究组”（ETDRS）的分级标准及我国DR的严重程度分级，将DR分为非增生性和增生性两型。根据视网膜出血斑多少（出血斑〈10个、10～19个、≥20个）、丝棉斑、视网膜内微血管异常（IRMA）及静脉串珠在各象限的分布将非增生性DR分为轻、中、重度，并将纤维增生、牵拉性视网膜脱离、虹膜红变、新生血管性青光眼、缺血性视神经病变作为DR并发症。     

视网膜病变筛查中无症状视网膜血管阻塞患者发生颈动脉狭窄的评估与治疗

目的　评估糖尿病患者无症状视网膜动脉阻塞与颈动脉狭窄的相关性。方法　收集２０１３年至２０１５年我院内分泌科确诊的糖尿病患者,经过糖尿病视网膜病变筛查发现的视网膜栓塞患者资料,根据标准化方案,进行颈动脉多普勒超声及超声心动图等一系列检查确诊,并记录评估结果、用药变化和接受相关外科手术干预的患者数量。结果　糖尿病视网膜病变筛查患者中有６２例（１．０％）存在视网膜动脉阻塞。病例资料齐全的患者５３例,其中３３例（６２．３％）患者相关用药发生变化。５３例患者中１３例（２４．５％）存在明显的颈动脉狭窄,其中２例患者行颈动脉内膜切除术。１３例患者接受了最大剂量的药物治疗。结论　明显的颈动脉狭窄在经视网膜病变筛查发现的视网膜动脉阻塞患者中较为常见。而将视网膜动脉阻塞患者转诊到指定医院科室,并对其进一步调查可确定患者发生脑血管事件的风险,进而可优化其治疗措施。     

Risk factors associated with retinal neovasculari-zation of diabetic retinopathy in type 2 diabetes mellitus

AIM: To evaluate the risk factors associated with retinal neovascularization of diabetic retinopathy in northern Chinese Han patients with type 2 diabetes mellitus (T2DM). METHODS: The clinical characteristics of 200 patients with proliferative diabetic retinopathy (PDR) and 100 age-matched healthy individuals were compared. The univariate and multivariate logistic regression analysis were performed in the patients with PDR. RESULTS: Fasting blood glucose (FBG), triglyceride (TG), total cholesterol (TC), blood urea nitrogen (BUN), uric acid (UA), white blood cell count (WBC), absolute neutrophil count, hematocrit (HCT) and mean platelet volume (MPV) and mean platelet volume (MPV) were all significantly higher in patients with PDR than in the control group (P<0.05). The univariate and multivariate logistic regression analysis showed that risk factors independently associated with retinal neovascularization of DR were duration of diabetes mellitus (OR=1.112; P =0.000), BUN (OR=1.277; P=0.000), smoking (OR=3.967; P=0.000) and MPV(OR=2.472; P=0.000). On the other hand, panretinal photocoagulation was associated with reduced risk of retinal neovascularization (OR=0.983; P=0.000). CONCLUSION: Preventing and controlling T2DM in terms of risk factors, including duration of diabetes, BUN, smoking and MPV, might offer novel approaches to prevent or delay the onset of retinal neovascularization in patients with PDR.     

Screening for diabetic retinopathy using a non-mydriatic retinal camera in rural Victoria

Purpose: To develop a screening programme for the early detection of diabetic retinopathy using non-mydriatic retinal photography.
Methods: A community based screening service was offered to all people with known diabetes mellitus in selected townships in the LaTrobe and Goulburn Valleys in Victoria. At the local examination centre, basic sociodemographic information was collected as well as details of previous use of eye care services for the early detection of diabetic retinopathy. The examination included visual acuity (VA), glycosylated haemoglobin level and Polaroid photographs of each fundus using a Canon CR5-45NM non-mydriatic retinal camera (Canon, Tochigiken, Japan). Dilating drops were not used. Photographs were subsequently reviewed and letters were sent to all participants (with copies to their general practitioners) with recommendations for appropriate follow up.
Results: A total of I 177 people with diabetes attended the screening service, which is estimated to be 40% of the total population with known diabetes in the study area. The mean age was 65 years (range 20–94 years); 559 (48%) people reported not having a dilated fundus examination within the past 2 years; 345 (29%) people had never had a dilated fundus examination. Of the 2354 eyes, 2126 (90%) of the photographs were gradable. A total of 704 people (60%) had normal VA and no evidence of diabetic retinopathy, 209 people (18%) had diabetic retinopathy, 101 people (9%) had evidence of other fundus pathology, 42 people (3%) had reduced acuity (< 6/18) in one or both eyes (with no fundus pathology evident) and 121 people (10%) had ungradable photographs in one or both eyes.
Conclusions: The present study demonstrates the usefulness of a screening programme with non-mydriatic retinal photography as an adjunct to current eye care services for the early detection of diabetic retinopathy.     

Automated static perimetry as a screening method for evaluation of retinal perfusion in diabetic retinopathy

The aim of our study was firstly to assess whether areas of capillary non-perfusion in diabetic retinopathy are associated with reduction of retinal light sensitivity and secondly to assess whether automated perimetry can serve as a screening method for evaluation of retinal perfusion. 32 eyes with diabetic retinopathy and 30 eyes of controls underwent visual field testing on the 30-2program of the Humphrey field analyser and fluorescein angiography. The results are compared with the‘superimposition technique’. In 93.4% of our diabetic eyes (30 from 32) areas of capillary non-perfusion demonstrated by fluorescein angiography were associated with areas of reduced retinal sensitivity. The correlation between visual field defects and areas of reduced retinal perfusion was significant with probability more than 99% (P<0.01). In view of our findings we recommend automated static perimetry as a very sensitive method for evaluation of retinal perfusion in diabetic patients. This revised version was published online in August 2006 with corrections to the Cover Date.     

非增殖期糖尿病视网膜病变微血管直径的变化

目的：探讨不同分期下的非增殖期糖尿病视网膜病变微血管直径的变化。

方法：前瞻性病例对照研究。选取2020-09/2021-03于本院内分泌科室住院的2型糖尿病并糖尿病视网膜病变患者,据我国中华医学会于1985年制定的“糖尿病视网膜病变分期标准”将其分为糖尿病无视网膜病变组(50例50眼)、糖尿病视网膜病变Ⅰ期组(50例50眼)、糖尿病视网膜病变Ⅱ期组(50例50眼)、糖尿病视网膜病变Ⅲ期组(50例50眼),另取体检正常的对照组50例50眼,共计250例250眼。摄取眼底彩照图,录入ARIA1.0自动分析软件,记录不同范围内动静脉与毛细血管直径,每个范围取值4段,每组为200段,进行统计学分析。

结果：不同分期的非增殖期糖尿病视网膜病变的视网膜动脉直径均无差异(P>0.05),不同分期的非增殖期糖尿病视网膜病变的视网膜静脉直径、黄斑周围毛细血管直径均有差异(P<0.05),视网膜静脉直径与黄斑周围毛细血管直径的不同组别事后多重比较均有差异(P<0.01),0～<0.5PD和0.5～1.0PD范围的视网膜静脉直径组别平均值得分对比结果为“视网膜病变Ⅲ期组>视网膜病变Ⅱ期组>视网膜病变I期组>糖尿病无视网膜病变组>正常对照组”,黄斑周围毛细血管直径组别平均值得分对比结果为“视网膜病变Ⅲ期组>视网膜病变Ⅰ期组>正常对照组; 视网膜病变Ⅲ期组>糖尿病无视网膜病变组; 视网膜病变Ⅱ期组>视网膜病变Ⅰ期组>正常对照组; 视网膜病变Ⅱ期组>糖尿病无视网膜病变组; 糖尿病无视网膜病变组>正常对照组”,而视网膜病变Ⅲ期组与视网膜病变Ⅱ期组,视网膜病变Ⅰ期组与糖尿病无视网膜病变组均无显著差异(P>0.05)。

结论：视网膜动脉直径在非增殖期糖尿病视网膜病变不同分期中无明显变化; 糖尿病患者视网膜静脉及黄斑周围毛细血管扩张,在非增殖期糖尿病视网膜病变不同分期中,静脉与黄斑周围毛细血管的直径呈逐渐增宽的趋势。     

小胶质细胞在糖尿病视网膜病变视网膜神经血管单元中的作用

糖尿病视网膜病变(DR)是工作年龄人群主要致盲眼病,血-视网膜屏障破坏是关键环节。近年研究显示,DR不再是单纯微血管病变,而是视网膜胶质细胞与神经退行性变、微血管病变的共同发展结果。DR病程早期视网膜神经血管单元(RNVU)中神经元的损伤可能早于血管内皮的变化,胶质细胞的激活加重血管屏障功能障碍。视网膜小胶质细胞是常驻视网膜的局部免疫细胞,参与长期高糖诱导的慢性炎症反应、高糖诱导其分泌多种炎症因子,破坏血-视网膜屏障结构、增加神经元凋亡、改变Müller细胞胶质化等,影响视网膜局部稳态平衡。RNVU作为一个单元结构研究,近年来受到越来越多的关注,本文将针对小胶质细胞在RNVU中的作用机制、研究进展进行综述。     

糖尿病视网膜病变合并视网膜静脉阻塞的临床分析

目的: 分析糖尿病视网膜病变(DR)合并视网膜静脉阻塞(RVO)的眼底特征及荧光素眼底血管造影(FFA)的图像特征。方法: 回顾性分析118例129眼DR合并RVO患者的视力、眼底、荧光素眼底血管造影(FFA)的图像特征及相关临床资料。结果: DR合并RVO的患者118例中,双眼同时发病有11例22眼,其余皆为单眼,其中66眼表现为视网膜中央静脉阻塞(CRVO),占51.2%,58眼表现为颞上分支静脉阻塞,占45.0%,其它分支静脉阻塞有5眼,占3.9%。FFA表现为:静脉阻塞区视网膜有大量神经纤维层出血,相应黄斑区荧光渗漏,掩盖了此眼DR的改变,对侧眼均可见DR不同级别的改变。结论: 糖尿病视网膜病变合并视网膜静脉阻塞眼底表现复杂,应与单一的糖尿病视网膜病变和视网膜静脉阻塞甄别。