Retinal Vascular Caliber Measurements Research Articles

Retinal vessel caliber and cognitive performance: the multi-ethnic study of atherosclerosis (MESA).

Retinal vessel calibers share anatomic and physiologic characteristics with the cerebral vasculature and can be visualized noninvasively. In light of the known microvascular contributions to brain health and cognitive function, we aimed to determine if, in a community based-study, retinal vessel calibers and change in caliber over 8years are associated with cognitive function or trajectory. Participants in the Multi-Ethnic Study of Atherosclerosis (MESA) cohort who completed cognitive testing at Exam 5 (2010-2012) and had retinal vascular caliber measurements (Central Retinal Artery and Vein Equivalents; CRAE and CRVE) at Exam 2 (2002-2004) and Exam 5 were included. Using multivariable linear regression, we evaluated the association of CRAE and CRVE from Exam 2 and Exam 5 and their change between the two exams with scores on tests of global cognitive function (Cognitive Abilities Screening Instrument; CASI), processing speed (Digit Symbol Coding; DSC) and working memory (Digit Span; DS) at Exam 5 and with subsequent change in cognitive scores between Exam 5 and Exam 6 (2016-2018).The main effects are reported as the difference in cognitive test score per SD increment in retinal vascular caliber with 95% confidence intervals (CI). A total of 4334 participants (aged 61.6 ± 9.2years; 53% female; 41% White) completed cognitive testing and at least one retinal assessment. On multivariable analysis, a 1 SD larger CRAE at exam 5 was associated with a lower concomitant CASI score (-0.24, 95% CI -0.46, -0.02). A 1 SD larger CRVE at exam 2 was associated with a lower subsequent CASI score (-0.23, 95%CI -0.45, -0.01). A 1 SD larger CRVE at exam 2 or 5 was associated with a lower DSC score [(-0.56, 95% CI -1.02, -0.09) and -0.55 (95% CI -1.03, -0.07) respectively]. The magnitude of the associations was relatively small (2.8-3.1% of SD). No significant associations were found between retinal vessel calibers at Exam 2 and 5 with the subsequent score trajectory of cognitive tests performance over an average of 6years. Wider retinal venular caliber was associated with concomitant and future measures of slower processing speed but not with later cognitive trajectory. Future studies should evaluate the utility of these measures in risk stratification models from a clinical perspective as well as for screening on a population level.

Normative data of retinal arteriolar and venular calibre measurements determined using confocal scanning laser ophthalmoscopy system - Importance and implications for study of cardiometabolic disorders.

Purpose:To determine and validate retinal vascular caliber measurements by using the confocal scanning laser ophthalmoscopy system. Retinal vasculature changes are often regarded as clinical markers for systemic disease.Methods:It was a prospective observational study conducted on 600 eyes of 300 normal subjects with no systemic or ocular illness from January 1, 2016 to June 30, 2017 in a tertiary referral eye center. Non-mydriatic infrared reflectance, blue reflectance, and blue peak blue autofluorescence fundus imaging were done on the confocal scanning laser ophthalmoscopy system. The dimensions of the retinal vessels were measured using inbuilt calipers at 1800 mm from the center of the optic disc. Internal and external dimensions were measured. Observer variation and its comparison using Image J software were assessed.Results:The median age was 29 years (18–50 years). Mean internal and external diameters for arterioles were 85.1 ± 12.4 mm and 105.0 ± 12.0 mm, and for venules were 133.8 ± 16.6 mm and 145.4 ± 16.1 mm, respectively. The mean internal and external wall thicknesses were 19.7 ± 8.0 mm and 11.0 ± 5.6 mm, and wall thickness-to-lumen ratios were 0.3 ± 0.1 and 0.1 ± 0.1, respectively. Arteriolar-to-venular ratio for lumen and vessel was 0.66 ± 0.1 and 0.74 ± 0.1, respectively. There was no statistically significant difference between age groups. Both inter- and intra-observer reproducibility was >95%. The Bland–Altman plot showed that the difference between measurements using both confocal scanning laser ophthalmoscopy and Image J software lies within the limits of agreement approximately 95% of the time.Conclusion:This is the first effort to develop a normative database by using a simple non-invasive confocal scanning laser ophthalmoscopy system with high observer reproducibility.

Correlation between retinal vascular parameters and cystatin C in patients with type 2 diabetes.

To investigate the relationship between retinal vascular parameters and cystatin C in patients with type 2 diabetes in northwestern China. This was a cross-sectional study of 1689 patients with type 2 diabetes. A validated fully automated computer program was used to extract retinal vascular parameters from the entire vascular tree. Multiple logistic regression analyses were conducted to investigate the relationship between these vascular measurements and cystatin C. For retinal vascular geometrical measurements, smaller arteriolar fractal dimension was related to high cystatin C after adjusting for multiple variables (odds ratio [OR] 0.149, 95% CI 0.042-0.532). For retinal vascular caliber measurements, narrower central and middle arteriolar calibers were related to high cystatin C after adjusting for multiple variables (central: OR 0.922, 95% CI 0.886-0.960; middle: OR 0.940, 95% CI 0.901-0.981). Wider central, middle and peripheral venular calibers were associated with high cystatin C after adjusting for multiple variables (central: OR 1.058, 95% CI 1.003-1.117; middle: OR 1.094, 95% CI 1.040-1.150; peripheral: OR 1.075, 95% CI 1.023-1.130). Multiple retinal vascular geometrical and caliber measurements are associated with cystatin C in type 2 diabetic patients. Further studies are needed to explore whether these retinal vascular changes can predict the incidence and progress of diabetic nephropathy.

Repeatability and reproducibility of IVAN software measuring retinal vascular caliber

Background Retinal vascular caliber changes can reflect the development status of cardiovascular disease and diabetes-associated vascular diseases, so it is very important to quantitatively measure retinal vascular caliber in the study of systemic diseases and retinal vascular disease.However, the methodology study is rately seen in China within our knowledge. Objective The present study was to investigate the repeatability and reproducibility of IVAN software in measuring retinal vascular caliber. Methods This study was approved by Ethic Committee of Affiliated Hospital of Inner Mongolia Medical University, and written informed consent was obtained from each subject prior to medical examination.A prospectively diagnostic trail was performed.The digitized fundus color photograph centered on the disc from 192 eyes of 96 healthy volunteers were collected in Affiliated Hospital of Inner Mongolia Medical University from January, 2013 to December, 2014, and central retinal arteriolar equivalent (CRAE), central retinal venular equivalent (CRVE) and arteriovenous ratio (AVR) were analyzed by IVAN measurement software.The repeatability and reproducibility of IVAN software for random repeat measurement of retinal vessel caliber from consecutive 85 right eyes of 85 volunteers were evaluation by interobserver and intraobserver measurement with interclass correlation coefficient (ICC). The correlations of measuring results between two observers or two-time measuring were analyzed with Pearson linear correlation analysis.Bland-Altman agreeement analysis was employed to assess the agreeement of the outcomes. Results No significant differences were found in CRAE, CRVE and AVR between the right eyes and the left eyes (t=-1.009, 1.090, -1.259, all at P>0.05). The CRAE, CRVE and AVR values from observer 1 were (145.02±12.94)μm, (400.72±9.12)μm and 0.36±0.03, and those from observer 2 were (145.10±11.86)μm, (401.17±9.85)μm and 0.36±0.03, with no significant differences between observer 1 and observer 2 (t=-0.074, -0.913, 0.116, all at P>0.05). The repeat CRAE, CRVE and AVR values from observer 1 were (145.02±12.94)μm, (400.72±9.12)μm and 0.36±0.03, which were significantly different from the initial values (t=-0.777, -0.048, -0.745, all at P>0.05). In two-time measurements of intra-observer, all ICC were ≥0.738 and showed good correlations (all at r≥0.739). The two measurements of inter-observer, showed good correlations (r≥0.662), with all ICC ≥0.657.Bland-Altman plots showed good agreements in CRAE and CRVE measurement with 95% limits of agreement(LoA) ranged from -18.5 μm to 17.3 μm and -9.8 μm to 9.6 μm in intraobserver, and from -19.3 μm to 20.0 μm and -10.2 μm to 9.0 μm in interobserver, respectively. Conclusions IVAN measurement software yields good repeatability and reproducibility in the quantitative measurement of retinal vascular caliber. Key words: Vascular caliber, retinal; Biometry; Repeatability; Reproducibility; IVAN software

Retinopathy Signs Improved Prediction and Reclassification of Cardiovascular Disease Risk in Diabetes: A prospective cohort study

CVD risk prediction in diabetics is imperfect, as risk models are derived mainly from the general population. We investigate whether the addition of retinopathy and retinal vascular caliber improve CVD prediction beyond established risk factors in persons with diabetes. We recruited participants from the Singapore Malay Eye Study (SiMES, 2004–2006) and Singapore Prospective Study Program (SP2, 2004–2007), diagnosed with diabetes but no known history of CVD at baseline. Retinopathy and retinal vascular (arteriolar and venular) caliber measurements were added to risk prediction models derived from Cox regression model that included established CVD risk factors and serum biomarkers in SiMES, and validated this internally and externally in SP2. We found that the addition of retinal parameters improved discrimination compared to the addition of biochemical markers of estimated glomerular filtration rate (eGFR) and high-sensitivity C-reactive protein (hsCRP). This was even better when the retinal parameters and biomarkers were used in combination (C statistic 0.721 to 0.774, p = 0.013), showing improved discrimination, and overall reclassification (NRI = 17.0%, p = 0.004). External validation was consistent (C-statistics from 0.763 to 0.813, p = 0.045; NRI = 19.11%, p = 0.036). Our findings show that in persons with diabetes, retinopathy and retinal microvascular parameters add significant incremental value in reclassifying CVD risk, beyond established risk factors.

Abstract 11652: Sex-Specific Association of Retinal Microvascular Signs With Atrial Fibrillation: The Multi-Ethnic Study of Atherosclerosis

Background: Atrial fibrillation (AF) affects men more frequently than women in elderly individuals. Several risk factors have been identified; however the relationship of microvascular characteristics with AF is unclear. Assessment of the relationship of retinal microvascular signs with AF in men and women may provide insights into such a relationship. Methods: We prospectively examined the sex-specific association of retinal microvascular signs with incident AF events in 2,394 men and 2,618 women ages 47-86 years, who were free of prior AF, underwent fundus photography at the second exam (2002-2004) of the Multi-Ethnic Study of Atherosclerosis (MESA), and were followed through 2012. Retinal microvascular signs evaluated include retinal vascular caliber measurements from computer software (defined as the central retinal arteriolar equivalents (CRAE) and venular equivalents (CRVE)), and presence of retinopathy signs. AF events were identified using hospital discharge records, Medicare claims data, and electrocardiographic findings at visit. Results: Over an 8.8-year average follow-up period, 255 and 202 AF events were identified in men and women respectively. In Cox regression analyses, we adjusted for age, race, body mass index, smoking status, diabetes status, systolic blood pressure, lipid profile, HbA1c, C-reactive protein, anti-hypertensive therapy, lipid-lowering therapy, cardiovascular disease, and heart failure. In men, wider CRVE (wider venular diameter) was associated with lower risk of incident AF (hazard ratio [HR] and 95% confidence interval per 10-μm increase in CRVE: 0.92 [0.86-0.99]), whereas in women, wider CRVE was associated with higher risk of incident AF (HR: 1.09 [1.01-1.18], p-value for interaction of sex = 0.0023). There were no associations of CRAE or of any retinopathy with AF in men or women. Conclusions: We found associations of narrower retinal venular diameters in men and wider retinal venular diameters in women at baseline with the incidence of AF but with no evidence of relationships of retinal arteriolar diameters or the presence of any retinopathy at baseline to the incidence of AF in either men or women. The reasons for the interaction are not understood and its clinical relevance remains to be determined.

Comparison of Common Retinal Vessel Caliber Measurement Software and a Conversion Algorithm.

PurposeTo compare three commonly used retinal vessel caliber measurement software systems, and propose an algorithm for conversion between measurement systems.MethodsWe used 120 retinal photographs to evaluate the agreement between three commonly used software (Retinal Analysis [RA], Integrative Vessel Analysis [IVAN], and Singapore I Vessel Assessment [SIVA]). Bland-Altman plots were used to evaluate agreement of retinal arteriolar (central retinal artery equivalent, CRAE) and venular (central retinal vein equivalent, CRVE) calibers. Pearson's correlation was used to assess the associations between systemic factors and retinal vessel calibers, and Z-test was used to compare the strength of the correlation coefficients across the three software systems. An algorithm was created to convert measurements, with paired t-test performed to evaluate the differences between SIVA-measured retinal calibers and SIVA-approximates converted from RA- and IVAN-measurements using the algorithm.ResultsDifferences between SIVA- and RA-measured calibers (CRAE: mean difference [MD] = −21.8 μm, 95% limits of agreement [LOA], −47.3 to 3.7 μm; CRVE: MD = −7.7 μm, 95% LOA, −28.0 to 12.6 μm), SIVA- and IVAN-measured calibers (CRAE: MD = −6.7 μm, 95% LOA, −23.8 to 10.4 μm; CRVE: MD = −18.2 μm 95% LOA, −36.7 to 0.4 μm) were large. However, the strength of correlations between systemic factors with SIVA-measured retinal calibers was not significantly different to that measured using RA and IVAN (P ≥ 0.332). SIVA-approximates converted from RA and IVAN measurements using the proposed algorithm was not significantly different from SIVA-measured calibers (P ≥ 0.20).ConclusionAbsolute measurements of retinal vessel calibers vary between three common software systems but associations with systemic factors were similar.Translational RelevanceThe proposed algorithm allowed conversions of RA and IVAN measurements to SIVA-approximates. This conversion is important for future data pooling and establishment of normative values for retinal vascular caliber measurements.

Relation between retinal vessel diameters and carotid artery stenosis patients with cerebral infarction

Objective To investigate the relationship between retinal vessel diameters and cerebral infarction of carotid artery stenosis patients. Methods Eighty-seven patients (174 eyes) with carotid stenosis were included in this study. There were 49 males and 38 females, with an average age of (65.25±7.85) years. Thirty-four patients were suffered from cerebral infarction (cerebral infarction group), and the other 53 patients had no cerebral infarction (control group). There was no significant difference in age (t=1.916), male rate (χ2=0.142) and carotid stenosis extent (χ2=0.785) between the two groups (P=0.059, 0.706, 0.675). All patients underwent color fundus photography after mydriasis. Retinal vascular caliber measurements were performed using IVAN software. The main parameters were central retinal artery diameter (central retinal artery equivalent, CRAE), the diameter of the central retinal vein (central retinal vein equivalent, CRVE) and the retinal arteriole to venular ratio (AVR). The relationship between retinal vessel diameter and cerebral vascular disease were analyzed with logistic regression analysis. Results In cerebral infarction group, CRVE, CRAE and AVR ratios were (132.90±20.67) μm, (243.47±43.92) μm and 0.56±0.10, while the control group was (145.26±21.59) μm, (224.99±32.35) μm and 0.68±0.13 respectively. There were significant differences between the two groups (t=-2.648, 2.257, -4.631; P<0.05). After correction for risk factors, such as age, smoking history, CRAE reduction and CRVE increases were significantly correlated with cerebral infarction. Conclusion CRAE reduction and CRVE increases are risk factors of cerebral infarction in patients with carotid stenosis, and it is useful in the prediction. Key words: Retinal vessels/physiopathology; Carotid stenosis/complications; Brain infarction/ etiology

Ocular blood flow assessment in vascular pathology of the eye

The review discusses some of the most common methods of ocular microcirculation assessment in vascular lesions of the eye: color and power Doppler imaging, laser Doppler flowmetry, fluorescent and indocyanine green angiography, digital retinal photographs and measurement of retinal vascular caliber, pulsative ocular blood flow analyzer, OCT-angiography. These methods are used in diagnostic of impairment of blood flow in vessels of optic nerve and retina, which also are full informative in early diagnostic of vascular pathology of eye.

Late Postoperative Evaluation of Retinal and Choroidal Thickness and Retinal Vessel Caliber after Surgical Repair of Corneal Perforation.

Objectives:To examine the late period retinal and choroidal alterations in the posterior pole of eyes that underwent primary suturing due to traumatic corneal perforation.Materials and Methods:This cross-sectional case series included 21 eyes of 21 patients. The fellow eyes served as the control group. Macular thickness, peripapillary retinal nerve fiber layer (RNFL) thickness, choroidal thickness, and retinal vessel caliber measurements were performed by spectral-domain optical coherence tomography (SD-OCT).Results:The mean RNFL thickness was 102.1±10.9 µm in the perforated eyes and 99.5±8.5 µm in the fellow eyes (p=0.29). The mean central macular thickness was 300.1±25.6 µm in the perforated eyes and 295.6±23.2 µm in the fellow eyes (p=0.62). The choroidal thickness and retinal vascular caliber measurements were also similar between the groups (p>0.05).Conclusion:Operated traumatic corneal perforations do not cause significant posterior pole retinal and choroidal SD-OCT thickness changes in the late postoperative period.

Choroidal thickness and retinal vascular caliber correlations with internal carotid artery Doppler variables.

Decreased retinal arteriolar caliber and increased retinal venular caliber have been associated with increased cardiovascular mortality. This study aimed to evaluate correlations of choroidal thickness and retinal vascular caliber measurements with internal carotid artery (ICA) Doppler ultrasound variables. In this cross-sectional and observational study, 43 eyes and ICAs of 43 healthy volunteers were examined. Spectral domain optical coherence tomography was used to measure subfoveal choroidal thickness (SFCT) and retinal vascular caliber. The ICA Doppler ultrasonographic parameters were diameter, flow volume, peak-systolic velocity, end-diastolic velocity, resistance index (RI), and pulsatility index (PI). Negative correlations emerged between ICA RI and SFCT (p = 0.017, r = -0.36) as well as between ICA PI and retinal arteriolar caliber (p = 0.015, r = -0.37). A negative linear correlation appeared between ICA diameter and SFCT (p = 0.005, r = -0.42), although ICA diameter and flow volume showed no association with retinal vessel caliber (p > 0.05). Choroidal thickness is negatively correlated with ICA diameter and ICA RI, while retinal arteriolar caliber is inversely related with ICA PI in normal volunteers.

Retinal Vascular Caliber and Age-related Macular Degeneration in an Indian Population from Singapore

Purpose: To examine the association between retinal vascular caliber and early age-related macular degeneration (AMD) in an Indian population.Methods: A total of 3112 Indian participants aged ≥40 years from the population-based Singapore Indian Eye Study who had data available on retinal vascular caliber measurements and AMD status were included. Retinal arteriolar and venular calibers were measured from digital photographs using computer-assisted software according to a standardized protocol. Images of the macular region were graded according to the modified Wisconsin age-related maculopathy grading system. Right eyes were selected for analyses. Binary logistic regression models were used to assess the association, adjusting for age, sex, systolic blood pressure, total cholesterol, random blood glucose, body mass index, and the companion retinal vascular caliber.Results: A total of 107 participants (3.4%) were diagnosed with early AMD. Neither arteriolar nor venular caliber was related to AMD. For early AMD, the age-, sex-, and companion retinal vascular caliber-adjusted odds ratio (OR) per standard deviation (SD) decrease in arteriolar caliber was 0.95 (95% CI 0.84–1.31; p = 0.671), and per SD increase in venular caliber was OR: 0.96 (95% CI: 0.77–1.20); p = 0.714. No trend was found after categorizing retinal vascular calibers into quartiles. Multivariate adjustment and stratified analyses did not alter these results.Conclusion: Retinal vascular calibers were not related to early AMD among Indian participants. These findings differ from those of several previous studies performed in Caucasian and Asian populations.

The Association between Ocular Biometry and Retinal Vascular Caliber Is Comparable from Early Childhood to Adolescence

We aimed to establish whether the change in retinal microvascular structure observed cross-sectionally with axial elongation and larger corneal curvature is comparable from early childhood to adolescence. In all, 1077 Sydney Paediatric Eye Study participants (36 to <72 months of age) and 1740, 2353, and 1216 from the Sydney Childhood Eye Study (6, 12, and 17 years of age), respectively, were examined. Quantifiable retinal vascular caliber measurements were obtained using validated computer-based methods. Ocular biometry measurements were performed according to standardized protocols. After multivariable adjustment, in children 36 to <72 months of age, each 1.0-mm increase in axial length was associated with a 3.67- and 6.53-μm narrowing of mean retinal arteriolar caliber (P = 0.005) and venular caliber (P < 0.0001), respectively. Each 1.0-mm increase in axial length in children 6, 12, and 17 years of age was associated with a 5.30-, 3.96-, and 4.03-μm decrease in mean retinal arteriolar caliber, respectively. Each 1.0-mm increase in axial length in children 6, 12, and 17 years of age was associated with a 7.12-, 6.72-, and 6.85-μm decrease in retinal venular caliber, respectively. Corneal curvature was inversely associated with retinal vascular caliber among all age groups (P < 0.001). Among those without significant refractive error (>0.00 and <2.00 diopters), significant inverse associations were observed between axial length and corneal curvature with retinal vessel caliber among all age groups. We demonstrate a similar magnitude of retinal vessel narrowing with axial length elongation and increasing corneal curvature from childhood through to adolescence. These data confirm the robustness of the associations between ocular biometric traits and retinal microvascular structural changes during childhood development.

Phenotypic and Genetic Correlation of Blood Pressure and Body Mass Index with Retinal Vascular Caliber in Children and Adolescents: The Guangzhou Twin Eye Study

To examine the phenotypic and genetic associations of blood pressure and body mass index (BMI) with retinal vascular caliber. A total of 657 monozygotic and 378 dizygotic twin pairs aged 7 to 19 years were recruited from the Guangzhou Twin Registry. All twins underwent digital retinal photography and measurement of retinal vascular caliber. The genetic correlations between the traits were estimated by applying a multivariate Cholesky model. In traditional regression analyses, participants with a higher mean arterial pressure (MAP) and a higher BMI were significantly more likely to have narrower retinal arterioles, whereas participants with a higher BMI level were more likely to have a wider retinal venule (all P < 0.001). In multivariate Cholesky models, only 1% to 2% of the phenotypic variation in retinal arteriole was shared with those in MAP and BMI, although the majority of these phenotypic variations were explained by shared genetic components. The phenotypic variation in retinal venule was not shared with those in MAP and BMI. Retinal vascular caliber is significantly but weakly associated with MAP and BMI in children and young adolescents. These phenotypic correlations are mainly attributable to genetic components.

Automated measurement of retinal vascular caliber and arteriovenous ratio in type 2 diabetic patients without retinopathy

AbstractPurpose To determine the retinal vascular caliber and arteriovenous ratio (AVR) in type 2 diabetic patients without retinopathy.Methods We retrospectively reviewed the medical records of 70 patients diagnosed as type 2 diabetes without retinopathy. Digital fundus photographs of the right eye were selected for measurement. The caliber of all retinal vessels passing through an area 0.5 to 1 disc diameter around the optic disc was measured using automated computer software (Zeiss AV ratio). Seventy seven age‐ and sex‐matched healthy subjects were included in the study as a control.Results The mean AVR was 0.801 ± 0.068 in the diabetic patients compared to 0.762 ± 0.054 in the control group (P &lt; 0.001). Higher AVR was significantly associated with increasing blood HbA1c levels (r2 = 0.106, P = 0.006). However, there was no significant correlation between AVR and body mass index (P = 0.478).Conclusion The rise in AVR seems to be an early feature of retinal vascular caliber in type 2 diabetes and correlates with an elevated blood HbA1c level.

Retinal Vessel Caliber and Risk Factors for Branch Retinal Vein Occlusion

Purpose: To describe the association between retinal vessel caliber and risk factors for branch retinal vein occlusion (BRVO).Materials and Methods: We included 10,890 participants who underwent a health checkup at Kangbuk Samsung Hospital between January 2006 and December 2006. BRVO was diagnosed from retinal photographs taken for both eyes. Retinal vascular caliber measurements were performed using a computer-assisted program. Risk factors were assessed based on a patient-answered questionnaire and laboratory investigations. Logistic regression analyses were performed to identify potential risk factors for BRVO.Results: The overall prevalence of BRVO was 0.8%. Among all BRVO patients, the mean central retinal artery equivalent (CRAE) was 142.59 µm (±14.63 µm), and the mean central retinal vein equivalent (CRVE) was 203.46 µm (±18.84 µm). The mean CRAE and CRVE of the control eyes were 148.15 µm (± 15.89 µm) and 211.12 µm (±18.54 µm), respectively. There were significant differences in mean CRAE and CRVE between the control group and the BRVO group (P < 0.05). Arterial hypertension was an important risk factor for BRVO (OR: 1.02 (1.01–1.03).Conclusions: Eyes with BRVO had narrow CRAE and CRVE when compared with age- and gender-matched normal eyes. Generalized attenuation of retinal vessel caliber may be characteristic of eyes with BRVO. Emphasis on blood pressure control is needed for the prevention of BRVO.

Retinal Vascular Calibers and Risk of Late-Life Depression: The Rotterdam Study

To test the "vascular depression" hypothesis, the authors investigated whether smaller retinal arteriolar or larger venular calibers, which are markers of cerebral microvascular disease, were associated with incident late-life depression. The authors included 3,605 participants (age > or =55 years) from the population-based Rotterdam Study with no depression at baseline (1993-1995) and fundus photographs gradable for retinal vascular caliber measurements. The authors identified persons with incident depressive symptoms and syndromes using psychiatric interviews during follow-up visits and continuous monitoring. The follow-up was complete until October 2005. After a mean follow-up of 9.0 years, 555 participants developed incident depression, including 312 with depressive syndrome. Neither smaller arteriolar (age- and sex-adjusted hazard ratio: 1.01; 95% confidence interval: 0.93-1.10), nor larger venular calibers (hazard ratio: 1.02; 95% confidence interval: 0.94-1.12) were associated with incident depressive syndromes. Our data showed no evidence of an association between retinal vascular calibers and incident late-life depression.

Correlation between Retinal Oscillatory Potentials and Retinal Vascular Caliber in Type 2 Diabetes

To assess retinal function in individuals with type 2 diabetes with no retinopathy or nonproliferative diabetic retinopathy (NPDR) and determine the relationship between retinal function and retinal vascular caliber. A full-field electroretinogram (ERG) and retinal vascular caliber measurements were performed in subjects with nonproliferative diabetic retinopathy (NPDR, n = 10), diabetic subjects without retinopathy (no-DR, n = 18), and normal control subjects (n = 18). The response amplitudes and implicit times of scotopic and photopic ERG and the retinal arteriolar and venular calibers were compared among the study groups. The relationships between ERG parameters and retinal vascular calibers were determined. There were statistically significant differences between diabetic (no-DR and NPDR groups) and control subjects in the amplitudes and implicit times of rod-derived ERG responses, but not in the cone-derived ERG responses. All the oscillatory potential (OP) components (OP1-OP4) were significantly reduced in amplitude and increased in implicit time in the no-DR and NPDR groups. No significant difference was found in any of the ERG parameters between the no-DR and NPDR groups. Of all the ERG parameters examined, only OP4 amplitude correlated significantly with the retinal arteriolar caliber (r = -0.556, P = 0.006). None of the OP components correlated significantly with retinal venular caliber. Significant retinal dysfunction was demonstrated in all diabetic patients, even in those without clinically detectable retinopathy, with the rod system being predominantly affected. OP4 amplitude correlates with retinal arteriolar caliber in diabetic patients, suggesting a correlation between retinal neuronal dysfunction and microvasculature changes.

Correlation of Light-Flicker–Induced Retinal Vasodilation and Retinal Vascular Caliber Measurements in Diabetes

Subtle changes in retinal vascular caliber have been shown to predict diabetic retinopathy and other diabetic complications. This study was undertaken to investigate whether retinal vascular caliber correlates with light-flicker-induced retinal vasodilation, a measure of endothelial function. The participants were 224 persons with diabetes (85 type 1 and 139 type 2) and 103 persons without diabetes (controls). Flicker-induced retinal vasodilation (percentage increase over baseline diameter) was measured with a vessel analyzer. Retinal vascular caliber was measured from digital retinal photographs according to a standardized, validated protocol. Data from both right and left eyes were used and modeled with generalized estimating equations to account for correlation between eyes. In persons with diabetes, after adjustment for age and sex, reduced flicker-induced vasodilation was associated with wider retinal vascular caliber. Eyes with the lowest tertiles of flicker-induced arteriolar dilation had wider arteriolar caliber (5.40 mum; 95% confidence interval [CI], 1.76-9.05) and eyes with the lowest tertiles of flicker-induced venular dilation had corresponding wider venular caliber (12.4 mum; 95% CI, 6.48-18.2), respectively, than eyes with the highest tertile of vasodilation. These associations persisted after further adjusting for diabetes duration, systolic blood pressure, fasting glucose, lipids, body mass index, current smoking, and presence of diabetic retinopathy. No associations were evident in persons without diabetes. Changes in retinal vascular caliber (wider arterioles and venules) are associated with impaired flicker-induced vasodilation in persons with diabetes. Determining whether endothelial dysfunction explains the link between retinal vascular caliber and risks of diabetic microvascular complications calls for further study.

Retinal vascular changes and diabetic retinopathy

Recent studies support the concept that the retinal vasculature may provide a summary measure of lifetime exposure to the effects of hyperglycemia. Advances in retinal photographic techniques and in image analysis have allowed objective and precise in vivo measurement of retinal vascular changes. In particular, quantitative assessment of retinopathy signs and measurement of retinal vascular caliber have greatly increased our knowledge of early microcirculatory alterations in prediabetes, diabetes, and diabetic micro- and macrovascular complications. Data from recent population-based studies suggest that retinal arteriolar and venular caliber changes reflect different pathophysiologic processes. Retinal arteriolar narrowing, for example, is associated with risk of diabetes and coronary artery disease, whereas retinal venular widening is associated with development and progression of diabetic retinopathy and risk of stroke. Studying these changes offers the potential to improve our understanding of the early pathophysiologic pathways of diabetes development and its complications. Future research will assess the ability of retinal vascular imaging to provide clinically useful prognostic information for patients with diabetes.