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1.
近视眼是影响我国儿童青少年眼健康的焦点问题。远视储备是眼球发生近视前的屈光状态, 是眼轴长度与角膜及晶状体等参数之间动态匹配的结果, 对于近视眼防控意义重大。我国一直缺乏儿童眼球发育参数的指导依据以及遗传因素影响的参考资料, 尤其针对上述参数在儿童眼球正视化过程中变化规律的总结。为了促进儿童青少年近视眼防控工作的标准化, 规范人群筛查和临床治疗, 使社会各界对近视眼的预防干预和评价有据可依, 中华预防医学会公共卫生眼科分会基于我国不同地区儿童青少年的屈光不正调查数据, 针对我国学龄儿童正视眼在不同年龄段眼球远视储备、眼轴长度和角膜曲率的参考区间及相关遗传因素达成共识性意见。  相似文献   
2.
The distribution of cone photoreceptor subtypes (important for color vision and vision quality) varies widely in different carnivore species, but there have been limited studies on bear (ursid) cone distribution. A previous behavioral study suggests that American black bears (Ursus americanus) are dichromatic, indicating that they possess two cone subtypes, although the retinal distribution of cones is unknown. The purpose of this study was to examine the subtype and topography of cones in American black bear retinas to further predict the nature of their color vision and image resolution. We studied 10 eyes from seven individual legally hunted black bears in northeastern North Carolina. Cryosections and retinal wholemounts were labeled using antibodies targeting two cone opsin subtypes: long/medium (L/M) wavelength sensitive and short (S) wavelength sensitive. Cones in fluorescent microscopy images were counted and density maps were created for retinal wholemounts. The black bear retina contains both cone subtypes and L/M cones outnumber S cones by at least 3:1, a finding confirmed in retinal frozen sections. There are higher concentrations of S cones present than typically seen in other carnivores with some evidence for co-expression of L/M and S cones. A cone-dense area centralis is present dorsotemporal to the optic nerve, similar to other carnivores. These results confirm that American black bears are predicted to have a dichromatic vision with high acuity indicated by the presence of a dorsotemporally located area centralis.  相似文献   
3.
廖珊  刘可 《国际眼科杂志》2022,22(7):1123-1126

随着人们生活水平的不断提高和生活方式的多样化发展,获得更好的视觉质量已成为现阶段手术治疗白内障的新目标。角膜散光直接影响白内障手术功能性人工晶状体(IOL)种类的选择和患者术后视功能的恢复,角膜散光检查的种类不再局限于单一的散光数值,而是细分成角膜前表面散光、后表面散光、全角膜散光以及高阶角膜散光等,相应的检查设备及技术也有较多更新。临床医生可根据不同设备特点及应用范围,选择适合的检查设备评估术前角膜散光情况,为制定更精准的屈光性白内障手术规划提供参考,对散光型IOL的定位、度数计算以及多焦点类IOL的选择有重要意义。本文将对白内障术前角膜散光检查种类和检查设备新进展进行综述。  相似文献   

4.
Objectives:To report the corneal elevation and thickness values for Saudi myopes and to evaluate the differences between these parameters in subgroups of this target population.Methods:Pentacam corneal topographic maps of the right eyes of patients visiting Al-Hokama Eye Clinic, Riyadh, Saudi Arabia, a tertiary eye center between January 2009 and December 2015 were retrospectively analyzed in this cross-sectional study. The patients were grouped into 3 categories based on their spherical readings: mild (-0.25 to -2.75D), moderate (-3.00 to -5.75D), and severe (≥-6.00D). Furthermore, patients with cylindrical readings of ≥-1.00 diopter were categorized as having myopic astigmatism, whereas those with less than -1.00 cylindrical diopter were categorized as having simple myopia.Results:Our sample was comprised of 1,276 patients; 838 (65.7%) had simple myopia and 438 (34.3%) had myopic astigmatism. The values for the whole myopic group were as follows: anterior corneal elevation (AE) at the apex= 2.60±1.48 (standard deviation), thinnest AE= 2.56±1.68, posterior elevation (PE) at the apex= 3.67±3.58, thinnest PE= 4.92±3.81, central pachymetry= 550.09±34.29, apical pachymetry=550.73±34.64, and thinnest pachymetry= 546.30±34.61. All of the measurements, except the apical PE and thinnest PE, were statistically significant across the simple and myopic astigmatism groups (p<0.05). Comparing the mild to moderate myopia groups revealed a significant difference in the apical AE (p=0.037). Moreover, the comparison between the mild and severe myopia groups revealed that the apical PE and the thinnest PE, as well as the central, apical, and thinnest pachymetry values were statistically significantly different (p<0.05).Conclusion:The corneal elevation indices and thicknesses specific to the Saudi myopes were found to be comparable to the international databases in terms of the elevation and thickness in some of the parameters.  相似文献   
5.
BackgroundSurface topography can be used for the evaluation of spinal deformities without any radiation. However, so far this technique is limited to posterior trunk measurements due to the use of a single posterior camera.Research questionPurpose of this study was to introduce a new multi camera surface topography system and to test its reliability and validity.MethodsThe surface topograph uses a two-camera system for imaging and evaluating the subjects front and back simultaneously. Inter- and intra-rater reliability was tested on 40 human subjects by two observers. For validation human, subjects were scanned by MRI and surface-topography. For additional validation we used a phantom with an anthropomorphic body which was scanned by CT and surface topography.ResultsInter- (0.97−0.99) and intra-rater reliability (0.81−0.98) testing revealed good and excellent results in the detection of the body surface structures and measurement of areas and volumes. CT based validation revealed good correspondence between systems in the imaging and evaluation of the phantom model (0.61–10.52 %). Results on validation of human subjects revealed good to moderate results in the detection and measurements of almost all body surface structures (1.36–13.34 %). Only measurements using jugular notch as a reference showed moderate results in validity (0.62–27.5%) testing.SignificanceWe have introduced a novel and innovative surface topography system that allows for simultaneous anterior and posterior trunk measurements. The results of our reliability and validity tests are satisfactory. However, in particular around the jugular notch region further improvements in the surface topography reconstruction are needed.  相似文献   
6.
目的探讨角膜形态学和生物力学参数对近视眼人群角膜后表面高度异常的影响及其辅助诊断角膜后表面高度异常的可行性。方法病例对照研究。选取2017年12月至2018年10月在青岛眼科医院拟行角膜屈光手术的屈光不正患者144例(227只眼),其中男性90例(139只眼),女性54例(88只眼);年龄(22.8±5.6)岁。所有患者检查最佳矫正视力下的球镜和柱镜度数,并行Pentacam眼前节分析系统和Corvis ST角膜生物力学检查。根据Pentacam参数角膜后表面高度变化值(BD)进行分组,将BD<12μm定为对照组(59例,118只眼);将BD≥12μm定为高BD组(85例,109只眼),其中BD≤16μm者为可疑组(44例,53只眼),>16μm者为异常组(41例,56只眼)。选取Pentacam眼前节分析系统中BD、前表面曲率(ASK)、后表面曲率(PSK)、前表面散光(AAstig)、后表面散光(PAstig)、中央角膜厚度(CCT)、角膜直径(W-W)7个参数及Corvis ST角膜生物力学检测系统中第1次压平时间(AT1)、第1次压平长度(AL1)、第1次压平速度(AV1)、第2次压平时间(AT2)、第2次压平长度(AL2)、第2次压平速度(AV2)、最大压陷时间(HCT)、最大压陷峰距(HC-PD)、最大压陷形变幅度(HC-DA)、最大压陷曲率半径(HC-R)、形变幅度比值(DA Ratio)、综合半径、最薄点厚度/厚度变化率(ARTH)、硬度参数(SPA1)、Corvis生物力学指数(CBI)15个参数纳入研究。采用独立样本t检验、Kruskal-Wallis H检验及Bonferroni法进行组间差异性比较,利用Spearman秩相关分析探讨BD的相关影响因素,并建立多元线性回归模型寻找影响BD的主要因素。结果对照组和高BD组在年龄、球镜度数、柱镜度数差异无统计学意义(t=-3.311,-1.808,-2.359;P=0.071,0.072,0.121);Pentacam测量发现在对照组、可疑组和异常组中,ASK、PSK、PAstig、W-W组间差异有统计学意义(Z=18.492,31.547,10.773,70.167;P<0.05),AAstig、CCT组间差异无统计学意义(Z=2.204,1.108;P>0.05)。其中异常组[43.40(42.20,44.40)]较对照组[42.80(41.98,44.00)]ASK增大(t=-4.292;P<0.05),可疑组[-6.50(-6.60,-6.35)]与异常组[-6.50(-6.70,-6.33)]较对照组[-6.30(-6.50,-6.20)]PSK均增大(t=4.492,4.618;P<0.05);可疑组[0.40(0.30,0.40)]与异常组[0.40(0.30,0.40]较对照组[0.40(0.30,0.50)]PAsting均增大(t=2.796,2.515;P=0.016,0.036);可疑组[11.40(11.00,11.60)]和异常组[11.10(10.90,11.30)]较对照组[11.50(11.40,11.80)]W-W减小,同时异常组较可疑组W-W也明显减小(t=3.235,8.353,4.282;P<0.05);Corvis ST参数在3个组间差异无统计学意义(P>0.05)。将每组患者BD与Pentacam参数进行相关性分析发现,在对照组、可疑组、异常组以及所有患者中,BD与W-W呈低至中度负相关(r=-0.614,-0.304,-0.396,-0.661;P<0.05),BD与其他参数相关性较低或未见明显相关性;将患者BD与Corvis ST参数进行相关性分析发现,仅在可疑组中,BD与AV1、HCT、HC-DA间存在低度正相关(r=0.332,0.361,0.382;P<0.05),BD与Corvis ST其他参数在各组中未见明显相关性。以BD为因变量,选取Pentacam参数与Corvis ST参数建立多元线性回归分析模型:变量W-W、ASK、PSK、HC-PD、SPA1、CCT间不存在共线性(容忍度<0.100),方程检验结果F=37.221,P<0.001,调整r^2=0.504,拟合较好。结论角膜形态学参数中角膜直径、前表面曲率、后表面曲率是影响BD的主要因素,角膜生物力学参数中HC-PD和SPA1也可能对BD产生一定程度影响。角膜形态学和生物力学参数的联合评估有助于角膜后表面高度异常的鉴别诊断。  相似文献   
7.
8.
The paper solves the problem of the nonexistence of a new method for calculation of dynamics of stress-deformation states of deformation tool-material systems including the construction of stress-strain diagrams. The presented solution focuses on explaining the mechanical behavior of materials after cutting by abrasive waterjet technology (AWJ), especially from the point of view of generated surface topography. AWJ is a flexible tool accurately responding to the mechanical resistance of the material according to the accurately determined shape and roughness of machined surfaces. From the surface topography, it is possible to resolve the transition from ideally elastic to quasi-elastic and plastic stress-strain states. For detecting the surface structure, an optical profilometer was used. Based on the analysis of experimental measurements and the results of analytical studies, a mathematical-physical model was created and an exact method of acquiring the equivalents of mechanical parameters from the topography of surfaces generated by abrasive waterjet cutting and external stress in general was determined. The results of the new approach to the construction of stress-strain diagrams are presented. The calculated values agreed very well with those obtained by a certified laboratory VÚHŽ.  相似文献   
9.
背景 角膜屈光参数的准确测量对于眼表疾病的诊治、屈光手术的设计、人工晶状体屈光度的计算等至关重要,Ophtha TOP是一种用于临床的新型角膜人工晶状体测量仪,但验证其测量角膜屈光参数稳定性及准确性的研究尚少见. 目的 评估Ophtha TOP测量正常人群角膜屈光参数的稳定性,并评价白内障术前患者用Ophtha TOP测量的角膜屈光参数与Pentacam测量结果的一致性. 方法 采用诊断试验可靠性评价方法,2013年9月至2014年10月在天津市眼科医院选取健康志愿者30人60眼行Ophtha TOP检查,评价Ophtha TOP测量角膜屈光参数的稳定性;另选取拟行白内障手术的白内障患者30例30眼进行OphthaTOP检查,以评估Ophtha TOP测量角膜屈光参数与Pentacam测量结果的一致性.记录角膜曲率最平坦曲率径线(Kf)、最陡峭曲率径线(Ks)、平均角膜曲率(Km),并记录轴位J0和J45的散光度.正常眼使用OphthaTOP连续测量5次以上,采用组内相关系数(ICC)、变异系数(CoYs)和重复度(2.77Sw)评价Ophtha TOP测量上述参数的稳定性;白内障患者用Ophtha TOP和Pentacam连续测量2次以上,采用Bland-Altman一致性分析法评估Ophtha TOP测量的角膜屈光参数和散光参数与Pentacam测量结果的一致性. 结果 Ophtha TOP测量的正常眼Kf、Ks、Km、J0和J45的ICC均≥0.90,重复度2.77Sw均≤0.36,Kf、Ks、Km的CoVs均≤0.30.Ophtha TOP与Pentacam测量的白内障眼的角膜屈光参数Kf、Ks和Km的平均差值分别为(0.18±0.28)、(0.24±0.29)和(0.21±0.26)D,Ophtha TOP测量值均略高于Pentacam测量值,差异均有统计学意义(t=3.48、4.50、4.49,均P=0.00);而2种测量仪器测量的散光参数J0、J45的平均差值分别为(0.07±0.21)D和(-0.02±0.18)D,差异均无统计学意义(均P>0.05).Bland-Altman一致性检验显示,2种测定方法测量的Kf、Ks和Km的95%一致性区间(LoA)分别为-0.37 ~0.73、-0.33~0.81和-0.30 ~0.72 D,J0和J45的95%LoA分别为-0.34~0.48和-0.37~0.33D. 结论 Ophtha TOP对正常人眼角膜屈光参数测量结果的稳定性较好.在白内障术前患者中,Ophtha TOP测量的角膜曲率和角膜散光结果与Pentacam测量值一致性好.  相似文献   
10.
How the human brain represents distinct motor features into a unique finalized action still remains undefined. Previous models proposed the distinct features of a motor act to be hierarchically organized in separated, but functionally interconnected, cortical areas. Here, we hypothesized that distinct patterns across a wide expanse of cortex may actually subserve a topographically organized coding of different categories of actions that represents, at a higher cognitive level and independently from the distinct motor features, the action and its final aim as a whole. Using functional magnetic resonance imaging and pattern classification approaches on the neural responses of 14 right‐handed individuals passively watching short movies of hand‐performed tool‐mediated, transitive, and meaningful intransitive actions, we were able to discriminate with a high accuracy and characterize the category‐specific response patterns. Actions are distinctively coded in distributed and overlapping neural responses within an action‐selective network, comprising frontal, parietal, lateral occipital and ventrotemporal regions. This functional organization, that we named action topography, subserves a higher‐level and more abstract representation of finalized actions and has the capacity to provide unique representations for multiple categories of actions. Hum Brain Mapp 36:3832–3844, 2015. © 2015 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.  相似文献   
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