Retinal vessel diameters and incident open-angle glaucoma and optic disc changes: the Rotterdam study

PURPOSE: It remains unclear whether reduced retinal blood flow and smaller arterioles, reported to exist in patients with open-angle glaucoma (OAG), are a cause or a consequence of ganglion cell loss. We examined whether baseline retinal vessel diameters were related to incident (i)OAG or incident optic disc changes in a population-based sample. METHODS: In the prospective population-based Rotterdam Study, baseline diameters of retinal arterioles and venules (1990-1993) were measured in digitized images of 3469 persons (aged 55 years and older) at risk for OAG. The follow-up examinations took place from 1997 to 1999. iOAG was based on the presence of incident glaucomatous visual field loss and/or incident glaucomatous optic neuropathy. Changes in neuroretinal rim, cup area, or vertical cup-to-disc ratio were calculated with a semiautomated image analyzer in 2782 persons. RESULTS: After a mean follow-up time of 6.5 years, 74 participants had iOAG. At baseline, the mean arteriolar diameter was 147.5 +/- 14.2 microm (SD) and the venular, 222.9 +/- 20.0 microm. Neither arteriolar diameters (odds ratio [OR] per SD decrease: 0.82; 95% confidence interval [CI]: 0.66-1.03) nor venular ones (OR per SD increase: 1.20; 95% CI: 0.95-1.53) were significantly related to iOAG. Baseline retinal vessel diameters did not predict changes in the optic disc. Additional adjustment for cardiovascular risk factors did not alter these results. CONCLUSIONS: The data show that baseline retinal vessel diameters did not influence the risk of iOAG or incident optic disc changes. These data provide no evidence for a retinal vascular role in the pathogenesis of OAG.     

正常眼及三种视网膜疾病血管直径测量

目的 探讨正常眼、年龄相关性黄斑变性(age-related maculardegeneration,AMD)、糖尿病性视网膜病变(diabetic retinopathy,DR)和视网膜静脉阻塞(retinal vein occlusion,RVO)视网膜血管直径的变化规律.方法 将328只正常眼按年龄分成5组,应用计算机程序分别测量距离视盘边缘0.5～1.0视盘直径范围内六条最粗的视网膜动脉和静脉直径,比较其平均值.然后,以同样方法 测量AMD、DR和RVO三种视网膜疾病动静脉直径,并与同年龄正常人比较动静脉平均直径.结果 正常视网膜动静脉平均直径50岁以上较50岁以下减小.与同年龄正常人相比AMD、DR和RVO视网膜动脉平均直径减小,AMD和RVO视网膜静脉平均直径与同年龄正常人相比也减小,而DR视网膜静脉平均直径不变.结论 正常眼视网膜动静脉平均直径50岁以上变细.AMD、DR和RVO动脉平均直径也变细,AMD和RVO静脉平均直径变细,DR静脉平均直径不变.     

Retinal vessel diameters and their associations with age and blood pressure

PURPOSE: To describe the cross-sectional relationship between retinal arteriolar and venular diameters with age and blood pressure. METHODS: A population-based study was conducted in Beaver Dam, Wisconsin (n=4926, age range, 43-84 years). Retinal photographs of right eyes taken at the baseline examination (1988-90) were digitized. All arterioles and venules located in the area between one-half and one disc diameter from the optic disc margin were measured with a computer-based program. These measurements were combined to provide the average diameters of retinal arterioles and venules of each eye, and the association with age and blood pressure (BP) was analyzed. RESULTS: After controlling for gender, hypertension, diabetes, serum glucose and lipids, cigarette smoking, and body mass index, retinal arteriolar diameters were found to be decreased by 2.1 microm (95% confidence interval [CI], 1.5-2.7) for each decade increase in age, and by 4.4 microm (95% CI, 3.8-5.0) for each 10-mm Hg increase in mean arterial BP. The association of narrowed retinal arterioles and higher BP was stronger in younger persons. For each 10-mm Hg increase in mean arterial BP, arteriolar diameters decreased by 7.0 microm in persons aged 43 to 54 years but by only 2.5 microm in persons aged 75 to 84 years. In contrast, retinal venular diameters narrowed with increasing age but not with increasing BP. CONCLUSIONS: Retinal arteriolar diameters are narrower in older persons and in persons with higher BP, independent of other factors. The weaker association of retinal arteriolar diameters and BP in older people may reflect greater sclerosis of the retinal arterioles, preventing a degree of narrowing with higher BP similar to that seen in younger persons.     

Medication use and retinal vessel diameters

PURPOSE: To study the influence of different medications on retinal vessel diameters. DESIGN: Cross-sectional study. METHODS: Retinal photographs in the Beaver Dam Eye Study (n = 4926, aged 43 to 84 years) were digitized, and the diameters of retinal vessels were measured. Participants' current medications were recorded at the examination. RESULTS: There were few significant associations between medication use and retinal vessel diameters. After adjusting for age, blood pressure, and other factors, participants who were using topical beta-blocker eyedrops had narrower retinal arteriolar (P = .05) and venular (P = .006) diameters than nonusers. Systemic beta-blocker was not associated with retinal vessel diameter size. CONCLUSION: We found few associations between current medication use and retinal vessel diameter. Retinal vessels were narrowed in those taking antiglaucoma medications, most strikingly in those prescribed topical beta-blockers, although such a relationship could not be established among those using systemic beta-blockers.     

Retinal vessel diameters and their correlation with retinal nerve fiber layer thickness in patients with pseudoexfoliation syndrome

AIM: To compare retinal artery-vein diameters (RAVDs) of patients with pseudoexfoliation (PSX) syndrome with healthy controls and investigate the correlations between retinal nerve fiber layer (RNFL) thickness parameters and RAVDs. METHODS: Seventeen eyes with PSX and 17 eyes of age-matched controls were included in the study. All participants underwent routine ophthalmological examination, Humphrey visual field and RNFL examination by using Stratus OCT. Retinal images were obtained by using a retinal camera (Topcon 501X). RAVDs were measured from inferior nasal, inferior temporal, superior nasal and superior temporal arcuates by using IMAGEnet software. Superior, inferior, nasal, temporal and average RNFL thicknesses were recorded. RAVDs and RNFL parameters in groups and correlations were analyzed by Mann-Whitney U and Spearmann correlation tests. RESULTS: Only inferior quadrant and average RNFL thickness were detected thinner in the PSX group compared with control group (P=0.009, P=0.038, respectively). No statistically significant difference regarding RAVDs was found between two groups. CONCLUSION: RAVDs seems to be comparable in the PSX and control group. RNFL is thinner in the inferior quadrant in the PSX group. RNFL thickness and RAVDs show significant correlations in both groups. This correlation doesn’t seem to be specific to PSX.     

糖尿病性视网膜血管径改变

目的 量化糖尿病视网膜动静脉血流与血管横径的改变。方法 糖尿病患者和非糖尿病对照组跟底彩色照相和荧光血管造影检查，比较检查结果，并统计分析。结果 跟底荧光造影的血管横径显著大于彩照的血流横径；糖尿病组的血管横径大于对照组；颞侧的血管横径大于鼻侧；用彩色照片计算的第4分支动静脉比值大于用荧光造影结果计算。结论 颞侧分支血管横径和其轴流宽度相对大于鼻侧。与颞侧视网膜面积较大，颞侧视网膜起丰要的感光功能，新陈代谢较旺盛，需氧量增加，血流量增多有关。视网膜血管湍流表现为彩照的血流宽度等于甚至大于荧光造影的血管横径。在视网膜动脉第4分支可见血流以湍流方式流动，表明分支血管血流速度加快，或血管阻力增加。荧光造影动静脉期，静脉外周血浆层最早呈现荧光，说明在微小静脉腔内，越靠近管壁流速不是越慢，反而是最快。这种血流逆反轴流现象可解释血管口径变小反而血流阻力降低的原因。糖尿病组的静脉分支血管横径大于非糖尿病组的同级血管径，与糖尿病视刚膜组织缺血，高血糖使视网膜血管径自我调节力受损有关。对疑似高血压或动脉粥样硬化，特别是伴糖尿病者，最好应用荧光造影结果来测量动静脉血管比值，避免眼底镜检查方法判定血管动脉硬化的高假阴性率，防止漏诊。     

Determination of retinal blood vessel diameters and arteriovenous ratios in systemic hypertension: comparison of different calculation formulae

Background Generalized arteriolar narrowing is one of the retinal changes influenced by systemic hypertension. The ratio of retinal arteriolar to venular diameters is often used as a marker of generalized arteriolar narrowing. There are several ways to determine the retinal arteriovenous ratio (A/V ratio). However, no comparison of retinal vascular measurements and A/V ratios determined by different formulae has been presented.Methods Eighty-seven men participating in the Tampere Ambulatory Hypertension Study returned for a 10-year follow-up examination in which fundus photographs were taken of both eyes. The diameters of retinal arterioles and venules were measured 1 and 2 disc diameters from the optic disc edge. The A/V ratio was determined using mean arteriole and venule width, the sum of widths of arterioles and venules, the sum of squares of widths of arterioles and venules, the central retinal artery equivalent (CRAE) and the central retinal venous equivalent (CRVE). The repeatability of measurements and A/V ratios was determined. Comparison was made between A/V ratios determined by different calculation formulas.Results In general, determination of A/V ratios yielded lower deviation than that of diameters of arterioles and venules separately. Calculation of A/V ratios using different formulas gave different ratio levels. According to linear regression analysis, the A/V ratio calculated using the sum of squares of widths of arterioles and venules correlated best with CRAE/CRVE (R ² 0.92) and A/V ratios calculated using the mean arteriole and venule widths or the sum of widths of arterioles and venules resulted in clearly lower associations (R ² 0.38–0.40 and R² 0.41–0.48, respectively). Of all A/V ratios, CRAE/CRVE had the best repeatability. No statistically significant differences were found between measurements from right and left eyes.Conclusions The high repeatability of CRAE/CRVE and sum of squares of widths of arterioles/sum of squares of widths of venules, as well as the good association of the two formulae, favor the use of these in evaluation of retinal vascular changes in systemic diseases. Our results also showed that if only one eye can be examined, it seems to suffice if fundus vascular alterations associated with systemic hypertension are evaluated.     

Effects of atropine and propranolol on retinal vessel diameters during isometric exercise.

PURPOSE: There is controversy regarding the nervous control of retinal blood vessels in humans. Most in vitro studies indicate that the intraocular part of the central retinal artery lacks autonomic innervation. We investigated the response of retinal vessels to isometric exercise during blockade of beta-receptors (propranolol) or muscarinic receptors (atropine). METHODS: Twelve healthy subjects performed squatting for 6 min during infusion of either propranolol atropine or placebo. Blood pressure and pulse rate were measured non-invasively. Retinal vessel diameters were measured continuously using the Zeiss Retinal Vessel Analyser. RESULTS: Squatting induced a significant increase in blood pressure and pulse rate, which was paralleled by a decrease in retinal vein and artery diameters. Atropine did not change the retinal vessel response to isometric exercise. Propranolol significantly blunted the exercise-induced vasoconstriction in retinal arteries. CONCLUSION: This result likely indicates propranolol-evoked vasoconstriction in the extraocular parts of the central retinal artery during isometric exercise.