IVAN软件测量视网膜管径的重复性和再现性评价

背景 视网膜血管管径的监测可以反映心血管疾病和糖尿病血管性并发症的病情进展,视网膜血管管径的定量测量对全身相关病变和视网膜血管性疾病的评估和治疗过程监测具有重要的临床意义,但关于视网膜血管管径检测的方法学研究少见. 目的 评价IVAN血管测量软件对视网膜血管管径测量的重复性和再现性.方法 采用前瞻性诊断性试验研究设计,收集2013年1月至2014年12月在内蒙古医科大学附属医院进行体检的健康志愿者96人192眼的以视盘为中心的数字化眼底照片,采用双盲法利用IVAN血管测量软件对眼底照片进行分析,分别得到视网膜中央动脉当量(CRAE)、视网膜中央静脉当量(CRVE)和动/静脉比值(AVR),评价患者双眼相关测量指标的对称性.分别由测量者1和测量者2对85名志愿者的85眼右眼视网膜血管管径进行测量,采用组内相关系数(ICC)评价IVAN血管测量软件测量结果的再现性;由同一测量者采用盲法对受检者的视网膜血管管径进行测量,采用组内相关系数(ICC)评价IVAN血管测量软件测量结果的重复性.采用Pearson线性相关分析法分析观察者间或观察者内测量结果的相关性;采用Bland-Altman一致性分析评价观察者内或观察者间测量结果的一致性. 结果 IVAN血管测量软件测量结果显示,受检者不同眼别间CRAE、CRVE和AVR值的差异均无统计学意义(t=-1.009、1.090、-1.259,均P＞0.05);测量者1测量的CRAE、CRVE和AVR值分别为(145.02±12.94) μm、(400.72±9.12)μm和0.36±0.03,测量者2测量值分别为(145.10±11.86) μm、(401.17±9.85) μm和0.36±0.03,差异均无统计学意义(t=-0.074、-0.913、0.116,均P＞0.05);同一测量者第1次测量的CRAE、CRVE和AVR值分别为(145.02±12.94) μm、(400.72±9.12) μm和0.36±0.03,第2次测量值分别为(145.78± 13.08) μm、(400.75±9.96) μm和0.36±0.03,差异均无统计学意义(t=-0.777、-0.048、-0.745,均P＞0.05).观察者内2次测量结果重复性较好(均ICC≥0.738),2次测量值均呈明显正相关(均r≥0.739);观察者间2次测量结果再现性较好(均ICC≥0.657),2次测量值均呈明显正相关(均r≥0.662).Bland-Altman一致性分析显示,观察者内CRAE和CRVE测量均有5个点位于95％一致性界限(LoA)外(CRAE:95％ LoA为-18.5-17.3 μm;CRVE:95％ LoA为-9.8 ～ 9.6μm).观察者间CRAE和CRVE中均有6个点位于95％ LoA外(CRAE:95％LoA为-19.3-20.0 μm;CRVE:95％ LoA为-10.2-9.0μm).结论 IVAN血管测量软件用于数字化彩色眼底照片中视网膜血管管径测量的重复性和再现性均较好.     

ARIA软件测量视网膜血管管径及迂曲度的重复性和再现性

目的：评价不同操作者使用视网膜自动图像分析(automated retinal image analyzer,ARIA)软件测量糖尿病患者视网膜血管管径和迂曲度的重复性和再现性。方法：采用前瞻性诊断性试验研究设计，由2名熟练操作者应用ARIA软件对49名糖尿病患者以视盘为中心的45°数码眼底彩照进行视网膜血管半自动分析。通过测量距离视盘0.5～1.0个视盘直径内的视网膜动静脉血管参数，各选取6条最粗的动静脉综合计算得到中央动脉管径当量(central retinal artery equivalent,CRAE)、视网膜中央静脉管径当量(central retinal vein equivalent,CRVE)、视网膜动静脉比值(arteriole-tovenuleratio,AVR)、平均视网膜动脉迂曲度(meanretinalar teriolartor tuosity,MR AT)、平均视网膜静脉迂曲度(mean retinal venular tortuosity,MRVT)。在此基础上，评价同一操作者与不同操作者间测量结果的重复性和再现性，并绘制Bland-Altman图进行...     

视网膜分支静脉阻塞视网膜微血管改变的定量研究

【摘要】 目的 研究视网膜分支静脉阻塞（BRVO）患者视网膜微血管改变的特点。设计 病例对照研究。研究对象 河北省邯郸市眼科医院连续的BRVO患者58例,对照组为“邯郸眼病研究”中按匹配原则抽取的非BRVO者200例。方法 对被研究者的眼底彩色照片定性判读视网膜微血管局部改变;利用计算机辅助软件（IVAN software, Australia）定量测量视网膜微血管管径,比较两组间的差异。主要指标 视网膜微血管局部改变包括局部视网膜动脉缩窄（FAN）、视网膜动静脉交叉压迫征（AVN）和动脉反光增强（OPAC）。定量测量指标为视网膜中央动脉直径（CRAE）、视网膜中央静脉直径（CRVE）和视网膜动静脉比值（AVR）。结果 CRAE、CRVE、AVR在BRVO组和非BRVO组分别为（136.0±20.7） μm Vs. （152.0±19.3） μm（P=0.000）;（207.2±23.1） μm Vs. （235.3±29.7） μm（P=0.000）;（0.66±0.13） Vs. （0.65±0.06）（P=0.019）。经多因素校正后视网膜血管局部改变FAN、AVN和OPAC在两组间比较的相对危险度分别为5.65（95%CI=1.77~18.03）、3.42（95%CI=1.48~7.89）和3.44（95%CI=1.44~8.24）（P均<0.05）。结论 视网膜动、静脉直径在BRVO者比非BRVO者均变窄,视网膜血管的局部改变在BRVO者比非BRVO者显著,因此视网膜血管的定量、定性分析可作为BRVO的观察指标。（眼科,2012,21：239-243）     

2型糖尿病患者血清类胡萝卜素与视网膜血管管径的相关性研究

目的 探讨2型糖尿病患者血清类胡萝卜素水平与视网膜血管管径之间的相关性。设计横断面研究。研究对象北京“德胜社区糖尿病眼病研究”的462例2型糖尿病(T2DM)受试者。方法按照纳入排除标准,排除21例受试者后,纳入189例糖尿病无视网膜病变(DWR)患者和252例轻中度非增生性糖尿病视网膜病变(NPDR)患者。通过问卷调查收集人口学和生活方式特征。所有受试者都进行一般身体和眼科检查。使用高效液相色谱法检测血清类胡萝卜素水平。通过半自动软件测定眼底像上视网膜血管管径,包括视网膜中央小动脉当量(CRAE)、视网膜中央小静脉当量(CRVE)和动静脉比值(AVR)。比较两组间各个变量的差异。通过多元Logistic回归分析血清类胡萝卜素水平与视网膜血管管径之间的相关性。主要指标CRAE、CRVE、AVR、血清类胡萝卜素水平。结果DWR组和轻中度NPDR组CRAE分别为(150.8±16.0)μm和(149.9±14.4)μm(t=0.58,P=0.56);CRVE分别为(220.9±22.2)μm和(230.3±25.1)μm(t=3.97,P<0.001);AVR分别为0.68±0.06...     

健康人视网膜血管参数变化研究

目的　测量健康人群视网膜血管形态学几何参数（弯曲度、管径、分形维数）,并探讨这些参数随年龄、性别、体质量指数（body mass index,BMI）的变化特征。方法　观察性横断面研究。纳入147名健康人,拍摄眼底彩照,测量血管分形维数,测量距离视盘中心1.5~3.0个视盘直径的视网膜动脉、静脉血管弯曲度和血管管径。按眼别、视网膜象限、性别、年龄、BMI分组,比较各组视网膜血管的分形维数、弯曲度、管径值。结果　左右眼视网膜血管几何参数比较差异均无统计学意义（均为P＞0.05）。颞侧与鼻侧象限视网膜动脉弯曲度、动静脉管径比较差异均有统计学意义（均为P＜0.05）。男性与女性视网膜动静脉弯曲度、动静脉管径比较差异均无统计学意义（均为P>0.05）,分形维数比较差异有统计学意义（P＜0.05）。不同年龄亚组视网膜血管几何参数比较差异均有统计学意义（均为P＜0.05）,随年龄增大,视网膜动静脉弯曲度增加,视网膜动静脉管径、血管分形维数变小。不同BMI亚组视网膜动静脉管径比较差异有统计学意义（P＜0.05）;视网膜动静脉弯曲度、分形维数比较差异均无统计学意义（均为P>0.05）;动静脉管径随BMI增高而减小。结论　正常人群视网膜血管几何参数是微循环状态的潜在新生物标记,其随性别、年龄、BMI的不同而变化,且具有象限差异。     

应用激光扫描眼底镜录像血管造影测量眼血流指标

目的：建立和评价应用激光扫描眼底镜录像血管造影和计算机视频图像处理技术定量了解眼血流动力状况的方法。方法：对青光眼病人进行激光扫描眼底镜荧光素、吲哚青绿视网膜脉络膜血管造影;利用计算机视频图像处理技术和相应的测量软件,测量视网膜脉络膜血管造影的系列数字化图像,得到相应的时间－荧光强度曲线,并计算该曲线得到反映血流动力学状况的指标。结果：该方法可测量脉络膜分区的充盈时间及速率、视乳头分区的充盈时间及速率、视网膜动静脉充盈时间及速率、动静脉通过时间及动静脉血管直径。该方法的观察者间及观察者内的重复性良好。结论：计算机视频图像处理技术可以有助于定量了解视网膜脉络膜血流动力学状况。     

芪明颗粒对非增生期糖尿病视网膜病变患者视网膜微循环状态影响的临床研究

目的探讨芪明颗粒对非增生期糖尿病视网膜病变患者视网膜微循环状态的影响。 方法纳入2016年10月至2017年5月于成都中医药大学附属医院眼科确诊为非增生期糖尿病视网膜病变(DR)的16例(31只眼)患者。其中,男性12例(23只眼),女性4例(8只眼);年龄49~75岁,平均年龄(62.5±8.3)岁。观察并记录芪明颗粒治疗前、治疗后4周、治疗后8周及治疗后12周患者的视力、眼底出血面积、糖化血红蛋白(HbA1c)、视网膜血氧饱和度、视网膜血管管径、眼平均灌注压的变化情况。治疗前后患者的视力、眼底出血面积、HbAlc、视网膜血氧饱和度、视网膜血管管径及眼平均灌注压等定量数据,以均数±标准差表示。采用单因素重复测量方差分析比较患者治疗前后视力的变化情况;采用配对样本t检验比较组内治疗前后HbAlc、视网膜血氧饱和度、视网膜血管管径及眼平均灌注压的变化。 结果受试者糖尿病病程1~30年,平均(13.75±9.31)年。在治疗前、治疗后4周、治疗后8周及治疗后12周患者的视力分别为(73.81±7.90)、(73.97±8.53)、(74.74±7.29)及(76.26±6.80)。经单因素重复测量方差分析,治疗前后患者视力的比较,差异无统计学意义(F＝2.162,P>0.05)。治疗前患者的收缩压、舒张压、眼压及眼平均灌注压分别为(129.13±8.36)mmHg(1 mmHg＝0.133 kPa)、(74.44±6.92)mmHg、(15.58±2.90)mmHg及(46.06±4.90)mmHg。治疗后12周分别为(126.94±10.11)mmHg、(70.81±8.83)mmHg、(14.54±1.84)mmHg及(45.43±4.80)mmHg。经t检验,治疗前后患者收缩压、舒张压、眼压及眼平均灌注压的比较,差异无统计学意义(t＝0.797,1.383,1.853,0.538;P>0.05)。治疗前患者的HbAlc、视网膜静脉血氧饱和度平均值及视网膜动静脉血氧饱和度差值的平均值分别为(7.68±1.17)%、(63.18±7.07)%及(37.93±6.50)%。治疗后12周分别为(6.73±1.49)%、(60.16±5.21)%及(39.93±4.04)%。经t检验,治疗前后患者HbAlc、视网膜静脉血氧饱和度平均值及视网膜动静脉血氧饱和度差值平均值的比较,差异有统计学意义(t＝2.611,2.482,-2.259;P<0.05)。治疗前患者的眼底出血面积和视网膜动脉血氧饱和度平均值分别为(4713.70±8082.42)像素和(101.12±6.54)%。治疗后12周分别为(3776.66±6553.91)像素和(100.09±5.95)%。经t检验,治疗前后患者眼底出血面积和视网膜动脉血氧饱和度平均值的比较,差异无统计学意义(t＝1.571,1.047;P>0.05)。 结论芪明颗粒可以降低非增生期糖尿病视网膜病变患者视网膜静脉血氧饱和度,增大视网膜动静脉血氧饱和度差值。     

血脂比值与视网膜血管管径的相关性

目的：探讨血脂比值与视网膜血管管径间的相关关系。方法：横断面研究。收集2010 年1-12 月在广州市第十一人民医院体检的无严重心脑血管疾病史且年龄在40岁及以上的广州市公务员4 882名,对该群体进行血脂蛋白浓度的监测,并采集研究对象同时期的眼底彩照。采用科学有效的眼底血管分析软件（IVAN软件）测定视网膜动静脉管径。采用多重线性回归模型分析低密度脂蛋白/高密度脂蛋白（LDL/HDL）、载脂蛋白B/高密度脂蛋白（ApoB/HDL）、载脂蛋白B/载脂蛋白A1（ApoB/ApoA1）、总胆固醇/高密度脂蛋白（TC/HDL）、甘油三酯/高密度脂蛋白（TG/HDL）和低密度脂蛋白/载脂蛋白B（LDL/ApoB）等6 种血脂比值与视网膜血管管径的相关关系。结果：最终纳入研究对象4 715 名。在矫正年龄、性别等传统心脑血管危险因素后,多重线性回归分析发现LDL/HDL、ApoB/HDL、ApoB/ApoA1比值与视网膜动脉管径呈负相关性（β=-0.61,P=0.046;β=-1.91,P=0.020;β=-2.58,P=0.010）,与视网膜静脉管径呈正相关性（β=2.01、4.63、5.99,均P < 0.001）。而TC/HDL、TG/HDL、LDL/ApoB比值与视网膜动静脉管径均无相关性。结论：LDL/HDL、ApoB/HDL、ApoB/ApoA1比值为视网膜血管管径的危险因素,TC/HDL、TG/HDL、LDL/ApoB比值对视网膜血管管径无明显影响。     

基于光学微血流成像技术的相干光断层扫描血流成像对视网膜血流定量分析的可重复性评价

目的 评价基于光学微血流成像技术（OMAG）的相干光断层扫描血流成像（OCTA）在正常眼视网膜血流定量分析的可重复性。设计 诊断试验。研究对象 40名（40眼）健康志愿者，年龄22~55岁，平均（33.0±8.8）岁。方法 使用ZeissCirrus HD-OCT 5000扫描，以基于OMAG技术的AngioPlexTM软件对视网膜浅层3 mm×3 mm OCTA图像的血流长度密度（VLD）、灌注密度（PD）及黄斑中心凹无血流信号区（FAZ）面积、周长、圆形度进行自动定量分析。采用变异系数（CV）评价观察日内及观察日间重复性，组内相关系数（ICC）评价观察者间再现性。主要指标 变异系数（CV）和组内相关系数（ICC）。结果 各血流参数观察日内CV（1.2±1.0)%~(4.2±5.5)%，均≤4.2％，观察日间CV（1.4±0.8)%~(4.6±4.9)%，均≤4.6％，观察日间CV高于观察日内CV，而中心凹、FAZ各参数CV高于旁中心凹CV；各血流参数观察者间ICC（0.923~0.994），均≥0.923，中心凹、FAZ各参数ICC高于旁中心凹。结论 基于OMAG技术的OCTA对正常眼视网膜浅层血流各参数测量均具有较好的重复性和再现性。（眼科，2018, 27：107-110）     

正常视网膜血管直径的非对称性研究

目的:利用IMAGEnet软件对眼底血管造影数字图像进行视网膜血管直径测量以探讨正常眼视网膜血管直径是否存在差异。方法:利用IMAGEnet软件对眼底血管造影数字图像进行放大和对比度调整,测量4个象限近视盘周围1PD范围内的视网膜动脉直径(RAD)和静脉直径(RVD),计算视网膜动静脉比值(A/V)并检验该测量方法的可重复性。结果:左右眼对应象限之间的RAD,RVD和A/V比值差异无统计学意义,但对单眼而言,颞侧与鼻侧象限的RAD和RVD以及A/V比值有着显著性差异。可重复性检验以类内相关系数(intraclass correlation coefficient,ICC)来表示,RAD的者内信度为0.97(P<0.01),RVD为0.986(P<0.01);RAD的者间信度为0.976(P<0.01),RVD为0.975(P<0.01)。结论:正常双眼对应象限的视网膜血管直径没有差异,但单眼不同象限的视网膜血管直径存在差异,利用IMAGEnet软件对视网膜荧光造影血管直径进行测量是可行和可靠的。     

Ethnic variability in retinal vessel caliber: a potential source of measurement error from ocular pigmentation?--the Sydney Childhood Eye Study

PURPOSE: To describe the effects of ethnicity and iris color on measurement of retinal vascular caliber. METHODS: The Sydney Childhood Eye Study (SCES) examined 1740 6-year-old children from 34 randomly selected Sydney schools during 2003 and 2004. Retinal arteriolar and venular calibers (central retinal arteriolar [CRAE] and central retinal venular [CRVE] equivalents) were measured from retinal photographs by a standardized computer-assisted METHOD: Associations of retinal vascular caliber with ethnicity and iris color were analyzed. RESULTS: Of the total participants, 1612 (92.6%) had gradable retinal photographs. CRAE and CRVE were normally distributed, with means (SD) of 163.2 (14.0) and 227.3 (18.3) microm, respectively. Both arteriolar and venular calibers were substantially wider in the East Asian than in the Caucasian children (CRAE, 171.5 mum vs. 160.5 mum; and CRVE, 240.5 microm vs. 222.4 microm; P < 0.0001 for both comparisons). Among the Caucasian children, darker iris color was associated with wider arteriolar and venular caliber: CRAE increased from 157.5 microm in blue eyes to 169.2 microm in dark brown eyes (P for trend < 0.0001), and CRVE increased from 218.4 microm in blue eyes to 230.0 microm in dark brown eyes (P for trend < 0.0001). Among the children with dark brown eyes, there was no significant difference in CRAE between the Caucasian and the East Asian children, although mean CRVE was still approximately 10 mum wider in the East Asian than in the Caucasian children. CONCLUSIONS: Retinal vessel caliber was wider in the children of East Asian ethnicity. This difference was explained principally by darker iris color. Retinal pigmentation, as approximated by iris color, could be an important source of error in the measurement of retinal vessel caliber. If confirmed, this may affect comparisons of retinal vessel caliber between subjects with different ethnic backgrounds.     

Effect of capsular tension ring implantation on predicted refractive error after cataract surgery in patients with pseudoexfoliation syndrome

AIM: To investigate the effect of capsular tension ring(CTR) implantation on predicted refractive error after cataract surgery in patients with pseudoexfoliation(PEX) syndrome.METHODS: This double-blind randomized clinical trial was conducted on 60 patients with PEX syndrome referring to Imam Khomeini Hospital affiliated to Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran, for undergoing cataract surgery. The study population was divided into two groups, namely CTR group(n=30) and non-CTR group(control group;n=30). The refractive error and anterior chamber depth(ACD) were measured 1 wk, 1 mo, and 3 mo after phacoemulsification(PE) surgery.RESULTS: The results indicated no statistically significant difference between the two groups in terms of predicted refractive error(obtained by subtracting preoperative predicted refractive error from actual postoperative refractive error) 1 wk(P=0.47), 1 mo(P=0.30), and 3 mo(P=0.06) after the PE surgery. Regarding the CTR group, the changes of ACD was statistically significant 1 and 3 mo after the PE surgery, compared to those obtained 1 wk post-surgery(P=0.005).CONCLUSION: The CTR implantation in PEX cataractous patients without zonulysis has no statistically significant effect on the predicted refraction and ACD changes after PE. The predicted refraction error has a hyperopic shift in both groups. The results reveal the unnecessary of calculating modified IOL in CTR implantation.     

Correlation and Reproducibility of Retinal Vascular Geometric Measurements for Stereoscopic Retinal Images of the Same Eyes

Purpose: To assess the correlation and reproducibility of retinal vascular geometric measurements obtained from two stereo-paired fundus images.

Methods: Thirty stereoscopic pairs of color optic disc-centered photographs from the Blue Mountains Eye Study were analyzed. Side-by-side grading was performed by a single grader, using semi-automated computer software to quantify the following retinal geometric parameters: (1) retinal arteriolar/venular caliber (CRAE/CRVE); (2) arteriole-to-venule ratio (AVR); (3) branching angle; and (4) tortuosity. We used Pearson correlation (r), intra-class correlation coefficient (ICC), and Bland-Altman plots to assess within-pair correlation and reproducibility for each parameter measured.

Results: Inter- and intra-grader r and ICC were high (all r > 0.90 and ICC > 0.90), except for branching angle (ICCs between 0.69–0.83). There was no significant difference between within-pair means of all retinal vascular geometric parameters, before and after excluding poor quality images. CRAE, CRVE, AVR, and arteriolar and venular tortuosity showed very high within-pair correlation and agreement (all r > 0.80 and all ICC > 0.90 respectively). Arteriolar and venular branching angles demonstrated moderate within-pair correlation (r = 0.65 and r = 0.62, respectively) and within-pair agreement (ICC = 0.76 and ICC = 0.77, respectively).

Conclusions: Use of computer-assisted software to measure retinal vascular geometric parameters from paired fundus images was highly repeatable and is robust to differences in photographic angles of paired stereo images. Such measurements can be applied to evaluate temporal changes in longitudinal studies.     

Right and left correlation of retinal vessel caliber measurements in anisometropic children: effect of refractive error

Purpose. Previous studies have reported high right-left eye correlation in retinal vessel caliber. We test the hypothesis that right-left correlation in retinal vessel caliber would be reduced in anisometropic compared with emmetropic children. Methods. Retinal arteriolar and venular calibers were measured in 12-year-old children. Three groups were selected: group 1, both eyes emmetropic (n = 214); group 2, right-left spherical equivalent refraction (SER) difference ≥1.00 but <2.00 diopter (D) (n = 35); and group 3, right-left SER difference ≥2.00 D (n = 32). Pearson's correlations between the two eyes were compared between group 1 and group 2 or 3. Associations between right-left difference in refractive error and right-left difference in caliber measurements were assessed using linear regression models. Results. Right-left correlation in group 1 was 0.57 for central retinal arteriolar equivalent (CRAE) and 0.70 for central retinal venular equivalent (CRVE) compared with 0.60 and 0.82 for CRAE and CRVE, respectively, in group 2 (P = 0.42 and P = 0.08), and 0.36 and 0.52, respectively, in group 3 (P = 0.08 and P = 0.07, referenced to group 1). Each 1.00-D increase in right-left SER difference was associated with a 0.74-μm increase in mean CRAE difference (P = 0.02) and a 1.23-μm increase in mean CRVE difference between the two eyes (P = 0.002). Each 0.1-mm increase in right-left difference in axial length was associated with a 0.21-μm increase in the mean difference in CRAE (P = 0.01) and a 0.42-μm increase in the mean difference in CRVE (P < 0.0001) between the two eyes. Conclusions. Refractive error ≥2.00 D may contribute to variation in measurements of retinal vessel caliber.     

Does retinal vascular geometry vary with cardiac cycle?

Purpose. Changes in retinal vascular parameters have been shown to be associated with systemic vascular diseases. In this study, we assessed the physiologic variations in retinal vascular measurements during the cardiac cycle. Methods. Fundus images were taken using electrocardiogram-synchronized retinal camera at nine distinct cardiac points from 15 healthy volunteers (135 images). Analyses of retinal vessel geometric measures, including retinal vessel caliber (individual and summary), tortuosity, branching angle, length-diameter ratio (LDR), and optimality deviation, were performed using semiautomated computer software. Repeated-measures ANOVAs were used to obtain the means and to estimate the variation of each cardiac point compared with cardiac point 1. Results. There was a significant variation of the caliber of the individual arteriolar and venular vessels. However, there was no significant variation found for vessel caliber summary, represented by the central retinal arteriolar equivalent (CRAE) and the central retinal venular equivalent (CRVE). There was also no significant variation found for tortuosity and branching angle, and LDR showed none or very little variations at different cardiac points: variations in caliber ranges between 0 and 4.1%, tortuosity 0 and 1.5%, branching angle 0 and 3.5%, and LDR 0 and 2%; all values for variations, P > 0.1; linear trend, P > 0.5; and nonlinear trend, P > 0.8. Conclusions. This study showed that there were minimal variations in the CRAE, CRVE, tortuosity, and branching angle that are clinically used for two-dimensional measures of retinal vascular geometry during cardiac cycles. However, there was significant variation in the caliber of the individual vessels over the cardiac cycle.     

Relationships between age,blood pressure,and retinal vessel diameters in an older population

PURPOSE: To describe the cross-sectional relationships between age, blood pressure (BP), and quantitative measures of retinal vessel diameters in an older Australian population. METHODS: Retinal photographs from right eyes of participants (n = 3654, aged 49+ years) in the Blue Mountains Eye study taken during baseline examinations (1992-1994) were digitized. The width of all retinal vessels located 0.5 to 1.0 disc diameters from the disc margin was measured by a computer-assisted method. Summarized estimates for central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) represent average retinal vessel diameters. The arteriole-to-venule ratio (AVR) was calculated. Associations between age and BP and CRAE, CRVE, and AVR were assessed with generalized linear models. RESULTS: Retinal vessel diameters decreased with increasing age in both men and women. CRAE and CRVE decreased by 4.8 microm and 4.1 microm, respectively, per decade increase in age, after adjusting for sex and mean arterial blood pressure. Mean AVR declined by 0.01 for each increasing decade of age, until 79 years. After adjustment for age, sex, smoking, and body mass index, CRAE, CRVE and AVR were all significantly and inversely associated with BP. For every 10-mm Hg increase in mean arterial blood pressure, AVR decreased by 0.012 and CRAE and CRVE decreased by 3.5 microm and 0.96 microm, respectively. CONCLUSIONS: Retinal arteriolar and venular diameters narrow with increasing age, and these parameters are inversely related to BP, independent of age, gender, and smoking. The findings are consistent with those from the Atherosclerosis Risk in Communities Study suggesting that decreased retinal vessel diameters may reflect microvascular damage from elevated blood pressure.     

Retinal vascular caliber, blood pressure, and cardiovascular risk factors in an Asian population: the Singapore Malay Eye Study

PURPOSE: To describe the relationship of retinal vascular caliber with cardiovascular risk factors in an Asian population. METHODS: The Singapore Malay Eye Study is a population-based, cross-sectional survey that included 3280 (78.7% response) persons aged 40 to 80 years. Retinal vascular caliber was measured from digital retinal photographs using a validated standardized protocol. Data on major cardiovascular risk factors were collected from all participants. RESULTS: Of the 3019 participants with retinal vascular caliber data available, the mean retinal arteriolar caliber (CRAE) was 139.5 +/- 15.7 microm (SD), and mean venular caliber (CRVE) was 219.3 +/- 22.2 microm (SD). Smaller retinal arteriolar caliber was associated with higher current mean blood pressure and male sex (P < 0.001 for both). Larger retinal venular caliber was associated with younger age, current cigarette smoking, greater body mass index, higher glycosylated hemoglobin level, and lower HDL cholesterol (P = 0.012 for glycosylated hemoglobin level and P < 0.001 for other risk factors). The association of retinal arteriolar narrowing and blood pressure was stronger in younger people than in older people and in men than in women (P for interaction < 0.001 for both). CONCLUSIONS: In this Asian population, smaller retinal arteriolar caliber was associated with hypertension and larger retinal venular caliber with cigarette smoking, dyslipidemia, hyperglycemia, and higher body mass index. The pattern of these associations is similar to that in white populations.     

Pupil Dilation May Affect Retinal Vessel Caliber Measures

Purpose: To assess the effect of pupil dilation on measures of retinal vessel caliber.

Design: Observational study with self-comparisons

Methods: Retinal photographs were taken for both eyes of 25 subjects before and after pupil dilation. Three photographic graders, masked to pupil dilation status, measured the same set of images using a computer-assisted, semi-automatic method. We compared means (standard deviations) of retinal arteriolar caliber equivalent (CRAE) and retinal venular caliber equivalent (CRVE) of the same eyes between pre- and post-dilation images. We assessed concordance correlation coefficients (CC), Bland Altman limits-of-agreements, and used linear mixed models to assess CRAE and CRVE measures associated with pupil dilation (influencing image quality), graders (observers) and right-left eye variation.

Results: We found high CCs for CRAE (0.82-0.94) and CRVE (0.87-0.94) between pre- and post-dilation images of the same eyes across the graders. Bland Altman plots showed that mean differences ranged from 0.55-3.42μm for CRAE and 1.56-2.29μm for CRVE. After adjusting for right-left eye random variation, a significant fixed effect of dilation was evident in mean CRAE in two of the three graders. There was no significant fixed effect of dilation in mean CRVE across all graders. In models including data of both eyes’ measures from pre- and post-dilation images by three graders, the fixed effect for dilation status contributed significantly to CRAE and CRVE variances whereas random effects for graders and dilation status contributed minimally.

Conclusions: Contrary to our hypothesis, we found a systematic effect of pupil dilation on retinal vessel caliber measures.