年龄及瞳孔直径对成人正视眼调制传递函数的影响

目的 探讨年龄及瞳孔直径对成人正视眼调制传递函数(modulation transfer function,MTF)的影响.方法 前瞻性临床研究.将102例正视眼按年龄分为3组:A组40眼(20～30岁)、B组30眼(31～40岁)、C组32眼(41～50岁),使用iTrace视觉功能分析仪测量所有正视眼在3.0、4.0、5.0mm瞳孔直径,5、10、15、20、25、30周/度(cpd)六个空间频率状态下的全眼总MTF曲线以及去除低阶像差的MTF曲线.对年龄与两种MTF作相关性分析,用单因素方差分析对不同年龄组、不同瞳孔的两种MTF分别进行比较.结果 在不同瞳孔直径所有空间频率下,年龄与总MTF及去除低阶像差的MTF均呈负相关,空间频率5c/d下3组5.0 mm瞳孔直径时的总MTF值分别为0.629±0.147、0.440±0.160、0.415±0.184,差异有统计学意义(F=18.773,P=0.000).其他空间频率及瞳孔直径下,3组的总MTF及去除低阶像差的MTF值差异也均有统计学意义.在所有空间频率下两种MTF均随瞳孔直径的增大而降低.结论 成人正视眼的总MTF及去除低阶像差的MTF均随年龄的增长、瞳孔的增大而下降,因此用它们来评价人眼视觉质量时,应当对不同年龄、不同瞳孔大小的人眼采用不同的评价标准.     

蓝光滤过型非球面人工晶状体植入术后高阶像差及MTF值临床对比观察

目的 对比观察白内障超声乳化联合植入蓝光滤过型非球面人工晶状体(intraocular lens,IOL)术后3个月的高阶像差及MTF值.方法 单纯年龄相关性白内障92例,依照患者意愿植入PY-60AD,AcrysofIQ,YA-60BB分为Ⅰ组Ⅱ组Ⅲ组,进行白内障超声乳化联合人工晶状体植入术.术后三个月利用波前像差仪i-Trace比较3mm,4mm,5mm,6mm瞳孔直径下各组球差(Z40),慧差(coma),总高阶像差(HOAs)的均方根 (the root meansquare,RMS)及3mm,5mm瞳孔直径下调制解调函数(modulation transferfunction,MTF).结果 ①波前像差检查,在各瞳孔直径下,两组非球面IOLZ40＜球面IOL,且差异具有统计学意义(P＜0.05).两组非球面IOL之间Z40差异无统计学意义(P＞0.05).②各瞳孔直径下三组IOL间coma差异无统计学意义(P＞0.05).③在各瞳孔直径下,两组非球面IOL高阶像差均方根(RMSh)＜球面IOL,但瞳孔直径在＜5mm下,差异无统计学意义(P＞0.05);瞳孔直径5mm下,差异有统计学意义(P＜0.05).在各瞳孔直径下,两组非球面IOL之间RMSh差异无统计学意义(P＞0.05).④3mm瞳孔直径下,去除低阶像差的MTF值每周5,10,15,20,25,30度(cyclesperdegree,cpd)六个空间频率下,两组非球面IOLMTF值＞球面IOL,三组间差异无统计学意义(P＞0.05).5mm瞳孔直径下,去除低阶像差的MTF值在5,10,15,20,25,30cpd六个空间频率下两组非球面IOL＞球面IOL,除30cpd外差异均有统计学意义(P＜0.05);两组非球面IOL间MTF值Ⅱ组＞Ⅰ组,差异无统计学意义(P＞0.05).结论 蓝光滤过型非球面人工晶状体在3mm瞳孔直径下可以明显降低球差,在5mm瞳孔直径下可以明显降低总高阶像差,从而使患者获得更好的视觉质量.且HOYAPY-60AD为预装式具有使用方便,减少人工晶状体装载过程中污染机会等优点,适于临床广泛应用.     

人眼高阶像差对正常近视眼调制传递函数影响的初步分析

目的 借助光学手段,分析不同高阶像差影响下近视患者调制传递函数（MTF）的变化,找出影响人眼光学质量的主要像差因素.方法 应用Hartmann-Shack原理的波阵面像差仪对255例（255眼）近视散光患者在不同直径瞳孔和不同空间频率下进行波阵面像差测量,应用光学常规数理统计方法分别进行MTF值计算和分析.应用配对t检验分析正常近视眼去除不同Zernike主要项C3^-3～C3^3和C40及不同阶S3、S4、S5、S6等之后的MTF值与总高阶像差MTF值的差异.结果 无论是3 mm还是6 mm直径瞳孔,分别去除上述各Zernike项后各空间频率（5～60 c/d）下的MTF值均有相应提高,差异均具有统计学意义（P均＜0.01）.其中,3 mm瞳孔下,C3^-1和C3^-3的影响最大,C31和C3^3次之,C40的影响最小;6mm瞳孔下,C40的影响最大,C3^-1和C3^-3次之,G3^1和C3^3影响最小.3 mm瞳孔下,除了去除S5、S6对MTF值影响不明显外,去除S3、S4后各空间频率下的MTF值均有相应提高（P均＜0.01）;其中,S3对MTF值的影响最大.6 mm瞳孔下,去除各阶像差后MTF值均有提高（P均＜0.01）;其中,在20 c/d及以下空间频率,S3的影响最大,从25 c/d开始,其与S4的差异无统计学意义（P＞0.05）.随着空间频率的增加,3 mm瞳孔下的MTF值呈匀速降低;6 mm瞳孔下,空间频率为30 c/d及以下时,MTF值急剧下降,空间频率大于30 c/d时,MTF值变化趋于平稳.结论 ①不论大、小瞳孔下,C3^-3～C3^3和C40等高阶像差均可降低各空间频率下的MTF值.②小瞳孔下G3^-1、C3^1及S3对各个空间频率的MTF值影响较大;大瞳孔下C40对各空间频率的MTF值影响较明显;S3对20 c/d及以下空间频率的 MTF值影响较大,从25 c/d空间频率开始,S3和S4对MTF值的影响基本一致.即不同直径瞳孔下和不同空间频率下,高阶像差对人眼光学质量的影响不同.     

配戴RGPCL后水平彗差的变化及其与瞳孔中心位移的关系

目的分析RGPCL配戴前后,全眼球和角膜像差的变化情况以及与瞳孔中心位移之间的关系。方法前瞻性病例自身对照研究。21例志愿者（42眼）,平均年龄（26.7±4.1）岁,平均屈光度（-3.59±1.36）D,散光度（-0.67±0.24）D;用鹰视角膜地形图测量瞳孔中心相对于角膜中心的偏移量、瞳孔直径以及角膜像差,鹰视波前像差仪测量裸眼的全眼球像差。然后由同一名视光师给予验配美尼康RGPCL,在配戴RGPCL 1个月后回访,用相同仪器分别测量戴镜时的瞳孔中心偏移、瞳孔直径、角膜像差和全眼球像差。统计分析6 mm直径下的前4阶14项波前像差。采用配对t检验和相关分析对数据进行分析。结果配戴RGPCL 1个月后,双眼瞳孔中心向颞侧水平偏移,瞳孔直径轻微增大,其变化量如下：?譹?訛水平位移：右眼戴前为（-0.067±0.141）mm,戴后（-0.103±0.129）mm（t=2.240,P＜0.05）;左眼戴前为（0.059±0.159）mm,戴后（0.114±0.132）mm（t=-3.371,P＜0.01）。?譺?訛瞳孔直径：戴前为（3.69±0.61）mm,戴后为（3.91±0.49）mm（t=-2.865,P＜0.01）。角膜和全眼球的水平彗差变化均有统计学意义：?譹?訛角膜水平彗差减少,右眼戴前为（-0.104±0.075）μm,戴后（0.019±0.050）μm（t=-5.697,P<0.01）,左眼戴前为（0.127±0.074）μm,戴后（-0.001±0.079）μm（t=5.113,P<0.01）;?譺?訛全眼球水平彗差增加,右眼戴前为（0.012±0.072）μm,戴后（0.097±0.054）μm（t=-5.291,P<0.01）;左眼戴前为（-0.038±0.071）μm,戴后（-0.099±0.051）μm（t=4.378,P<0.01）。在这些有变化的参数中瞳孔中心水平位移分别与角膜和全眼球水平彗差差值呈负相关（r=-0.583、-0.534,P<0.01）;并且瞳孔中心水平位移与瞳孔直径的改变有较大相关性（r=0.501,P<0.01）。结论配戴RGPCL后,瞳孔中心发生颞侧向的水平位移,从而角膜和全眼球水平彗差也相应改变,原来的角膜和眼内彗差的互补平衡被打破。瞳孔直径的轻微增加可能是造成此种改变的原因之一。     

优良视力正视眼不同对比度下视力与高阶像差的关系

目的 分析优良视力正视眼低、中、高对比度视力与高阶像差的关系。方法 描述性研究。选择优良视力正视眼,在流明值为260背景亮度下,测量对比度为100%、25%、10%和5% 4种状态下的视力;同时采集瞳孔直径为3.11 mm和5.96 mm眼高阶像差。分析3.11、5.96 mm瞳孔直径眼高阶像差与不同对比度视力之间的相关性。采用线性回归分析,拟合出回归方程。结果 低对比度状态下视力的个体差异性更大。瞳孔直径为3.11 mm时,高阶像差均方根值（RMS）与不同对比度视力之间存在着线性相关关系（mini R2＝0.1129）。结论 高阶像差对于对比度视力的影响特点是全频率。     

Prise en charge de la violence et du décrochage scolaire à l’école II. Résultats d’une recherche–action sur le modèle triangulaire au sein d’un collège à Grenoble

Background

Violence at school and school dropout constitute a big concern as well for the teachers, for the parents as for the clinicians. Several explanatory factors are proposed: individual, familial, school climate or factors in connection with the group of peers. These factors impact on the psychic, school and social health of the child. Coverages are proposed at the national and international level and seem to give convincing results. Each of these initiatives implied in a differentiated way parents, pupils and teachers. None put in the work a project integrating the educational triangle that is at the same time the parents, the children and the teachers within the school. The objective of this work is to report results of a research–action which took place during 5 years within a college of the academy of Grenoble and which put in the work on this lapse of time, in this college, the pupils, the parents and the teachers.

The accommodative pupil responses of children and young adults at low and intermediate levels of ambient illumination

Accommodative pupil constrictions were compared between 27 children (9-10 years) and 13 young adults (22-26 years) in order to clarify the issue whether or not children have such a response. Accommodative stimuli of 4 and 7 diopters were used to elicit the response and experiments were performed at 5 and 100 lux in order to investigate whether the level of ambient light has different effects on developing and mature visual systems. The accommodative pupil response is present in children, but weaker than in adults. Different levels of ambient light lead to only minor additional differences between children and adults. The weaker accommodative pupil response of children may be a consequence of their superior accommodative ranges, which make it unnecessary to close the pupil to increase depth of field. Adults, in contrast, may do better with smaller pupils that reduce accommodative demand because of increased depth of field. A mature human visual system may furthermore be better tuned to handle dimmer and thus noisier images in the photopic range than the developing visual system of a child.     

Variation in pupil diameter in North American Gartersnakes (Thamnophis) is regulated by immersion in water, not by light intensity

A variable pupil generally regulates the amount of incoming light available for image formation on the retina. However, some of the semi-aquatic snakes (North American Gartersnakes, Thamnophis) that forage in relatively low light conditions reduce the pupil aperture in response to submergence underwater at the expense incoming light. Given that these snakes have all-cone retinas, reduction of incoming light because of pupillary constriction upon immersion seems counterintuitive. To test the effect of light and water on pupil aperture, three species of North American Gartersnakes (T. atratus, T. hammondii, and T. sirtalis) were exposed to nine light intensities in air and water. There was no effect of light on relative pupil aperture for any species. However, all three species showed a significant reduction in pupil aperture upon submergence underwater. The lack of a light response is surprising, and may be related to the method of accommodation in snakes. Snakes lack a ciliary muscle, and move the lens by constricting the pupil, which increases pressure in the posterior chamber and pushes the lens forward. Upon submergence, the snakes may be attempting to overcome the change in refractive index and defocus imposed by the water, by constricting the pupil. Thus, having the iris muscle involved in accommodation may preclude it from much of a light regulating function.     

Spectral sensitivity of the photointrinsic iris in the red-eared slider turtle (Trachemys scripta elegans)

Our goal in this study was to examine the red-eared slider turtle for a photomechanical response (PMR) and define its spectral sensitivity. Pupils of enucleated eyes constricted to light by ∼11%, which was one-third the response measured in alert behaving turtles at ∼33%. Rates of constriction in enucleated eyes that were measured by time constants (1.44-3.70 min) were similar to those measured in turtles at 1.97 min. Dilation recovery rates during dark adaptation for enucleated eyes were predicted using line equations and computed times for reaching maximum sizes between 26 and 44 min. Times were comparable to the measures in turtles where maximum pupil size occurred within 40 min and possessed a time constant of 12.78 min. Hill equations were used to derive irradiance threshold values from enucleated hemisected eyes and then plot a spectral sensitivity curve. The analysis of the slopes and maximum responses revealed contribution from at least two different photopigments, one with a peak at 410 nm and another with a peak at 480 nm. Fits by template equations suggest that contractions are triggered by multiple photopigments in the iris including an opsin-based visual pigment and some other novel photopigment, or a cryptochrome with an absorbance spectrum significantly different from that used in our model. In addition to being regulated by retinal feedback via parasympathetic nervous pathways, the results support that the iris musculature is photointrinsically responsive. In the turtle, the control of its direct pupillary light response (dPLR) includes photoreceptive mechanisms occurring both in its iris and in its retina.