眼科医学—视光学与视觉科学

1、视光学与视觉科学视光学与视觉科学Optometry and Vision Optometry and Vision Science Science 第一节 概述 （一）视光学的概述和发展 视光学研究光与视的哲学。是确定正常人眼视觉状态或通过眼镜来矫正异常状况的一门艺术。 Optometry is an independent profession in Optometry is an independent profession in eye care. Its practice includes a complete eye care. Its practice includes a com

2、plete examination of the visual system required examination of the visual system required for the estimation of refractive errors. for the estimation of refractive errors. It also covers the fitting, manufacturing It also covers the fitting, manufacturing and supplying of spectacles, contact and sup

3、plying of spectacles, contact lenses and all other optical aids lenses and all other optical aids WCOs concept of Optometry:WCOs concept of Optometry: Optometry is a healthcare profession that is autonomous, educated and regulated (licensed/registered), and optometrists are the primary healthcare pr

4、actitioners of the eye and visual system who provide comprehensive eye and vision care, which includes refraction and dispensing, detection/diagnosis and management of disease in the eye, and the rehabilitation of conditions of the visual system. WCO: World Council of WCO: World Council of Optometry

5、 Optometry 1625年，Christopher首先描述近视眼的视觉功能状态，被公认为“视光学之父”。 1275-1285年，眼镜出现于欧洲。 1611年，Kepler第一个用光学仪器来解释眼成像系统19世纪初，英国Thomas Young 发现了散光。 1901年，美国明尼苏达州首先颁发了有关视光学的法律。 1919年，成立美国视光学学会。我国 1982年成立中华眼科学会屈光学组及上世纪末国内相继成立的大学光学系，视光学学院及中美联合开展的视光学教育计划（CORD），中法视光学培训课程（GIFO）等对推动我国视光学事业向前发展都起到了积极的作用 （二）视觉科学概念 广义的视觉科学（v

6、ision science）是指有关视觉形成过程中一切正常和病理状况警醒的研究，它包涵了现代眼科学和视光学的大部分内容，此外，还包括神经科学的运动觉、认知、知觉、色觉心理物理学与行为学和视网膜及视皮层的视觉机制等部分领域。第三节 眼球光学一 光与眼的屈光u屈光（refraction) 当光从一种介质进入另一种不同的折射率的介质时，光线在界面发生偏折现象，该现象为屈光。光线在界面偏折的程度可用屈光力（refraction power)表示。u眼的屈光系统包括角膜、房水、晶体和玻璃体。 u屈光系统相当于一组复合透镜，外界光线经过屈光系统将发生折射，在视网膜上形成倒立、缩小的实像，这种生理功能，称为

7、眼的屈光。 We see images of the world around us, by receiving light reflected off objects with our eyes. To see images clearly, the light must be refracted and brought to a focus precisely on our light sensing surfaces. The front part of eye refracts light and focuses it on the light-receptors of the ret

8、ina which is in the back of the eye. The light is refracted by both the cornea and the lens of the eye, although the cornea is the most important refracting structure in that it carries about 75% of the refractive power of the eye. 屈光力的大小可以用焦距（f）来表达，即平行光线经某透镜后聚焦为一点 ，该点离透镜中心的距离为焦距。在眼球光学中，应用屈光度（Diopte

9、r,D)作为屈光力的单位。屈光度为焦距（以m为单位）的倒数，即：D=1/f.如一透镜的焦距为0.5m，则该镜的屈光力为：1/0.5=2.00D。 眼的屈光力与眼轴长度（ocular axis ）匹配与否是决定屈光状态的关键。 The refractive power is measured in terms of diopter. The refractive power in diopters of a convex lens is equal to 1 meter divided by its focal length.Eyecamera refractive systemlens pup

10、il-aperture accommodation of the lens-adjust the distance retina-film眼球构造像照相机，屈光系统可以比作镜头，瞳孔好比自动光圈，晶体的调节作用犹如调整照相距离，而视网膜则是最理想的彩色底片 。眼的屈光状态与各屈光面（角膜、晶状体前后面）的曲率半径、房水、晶状体和玻璃体的折射率以及各屈光间质彼此的位置有关。为更好的理解屈光特性，将测量所得的曲率半径、前房深度、晶状体厚度和曲率半径、眼轴长度等的平均值来模拟人眼的屈光模型，称为模型眼（schematic eye),以Gullstrand的数据最精确。 按照Gullstrand测定，

11、 眼球的光学常数如下： 角膜前面曲率半径7.8mm 角膜后面曲率半径6.8mm 角膜屈光指数1.376 角膜系统屈光力43.05 晶体前面曲率半径10mm 晶体后面曲率半径6.0mm 晶体皮质屈光指数1.386 晶体核屈光指数1.406 晶体系统屈光力19.11D 房水、玻璃体的屈光指数1.336 眼球总屈光力58.64D 将眼球复杂的光学系统简化为单一界面，成为简约眼（reduced eye). If all the refractive surfaces of the eye are algebraically added together and then considered to b

12、e one single lens, the optics of the normal eye may be simplified and represented schematically as a reduced eye.Emsley简约眼的光学常数 折射球面的曲率半径为50/9mm, 折射率为4/3， 眼轴长为200/9mm， 其屈光力为+90D。 简化眼上：FF:前后主焦点,EE两主点,NN两节点 下:简化眼的基点,包括两个主焦点FF,一个节点N及代表EE的平均数的角膜的屈光面 简化眼的视 网膜成像 AB:目标 ab:视网膜上的像N：节点 cd:简化眼的屈光二 眼的调节与集合 In n

13、ormal vision, the light reflected off In normal vision, the light reflected off the image is refracted by the cornea and the image is refracted by the cornea and lens and is precisely focused on the lens and is precisely focused on the retina. Notice that the image projected retina. Notice that the

14、image projected on to the retina is upsidedown.on to the retina is upsidedown. 1.调节作用（accommodation） 一个正视眼，看远距离物体清楚。但如果屈光力不改变，自近距离（5米以内）物体发出的散开光线经眼屈折后，其焦点势必落在视网膜之后，此时视网膜上的影像即变模糊。因此一个正视眼如欲看清近距离物体，就必须增加眼的屈光力，缩短焦距，使落在视网膜之后的焦点前移到视网膜上。这种为了适应看近距离，而增加眼的屈光力的现象，成为调节作用。 经典的Helmholtz理论认为 调节作用是由睫状肌收缩，晶体悬韧带放松，晶体

15、凭借其本身的弹性使形状加厚，前囊变凸，屈光力增加（晶体前面凸较多，后面很少，前后囊曲率半径缩短）而完成的。 使用调节力的大小，须视目标的远近而定，目标距眼愈近则所需调节力愈大 晶体的调节情况 伴随调节出现的眼部改变： 瞳孔缩小 虹膜的瞳孔边缘和晶状体的前表面向前移 晶状体的前表面的弯曲度增加 晶状体后表面轻度变弯 由于重力作用，晶状体向下轻微移位 脉络膜前移2.调节幅度 眼所能产生的最大调节力 ，与年龄密切相关 最小调节幅度=15-0.25x年龄（Hoffstetter最小调节幅度)3.调节范围 能在视网膜上形成清晰影像的外界最远处的物体所在位置称为眼的远点，此时睫状肌完全松弛，其屈光状态为静

16、态屈光（static refraction).当眼处于最大调节时，能在视网膜上形成清晰像的外界最近的物体所在位置称为眼的近点，其屈光状态为动态屈光（dynamic refraction).近点和远点的距离称为调节范围。4.集合（辐辏，convergence)当眼调节在松弛状态下注视远处物体时，两眼的视轴是平行的，但要看清近处物体时，眼不但要调节，且两眼的视轴也要转向被注视物体，这样才能使双眼物象落在视网膜黄斑中心凹，经过视中枢合二为一，形成双眼单视，这种运动成为集合。物体慢慢移近，集合的程度也逐渐增加，最后集合达到极限时，两眼就放弃集合，向外转动。在放弃集合之前，两眼能保持集合的最近点，称为集

17、合近点（near point of convergence) When you look at objects that are very far away your two eyes point very nearly straight ahead. As objects come closer (less than about 6 meters or so) your eyes will noticeably turn in (converge). The nearer objects are to you the more your eyes will turn towards your

18、 nose. This eye position is called convergence. Look at a friends eyes as you hold your finger in front of him or her and move it towards the nose. You will see the eyes converge. 双眼的调节与集合是互相协同联合运动的，视近时，双眼眼轴内集、调节增加和瞳孔缩小，这种反射性视功能的三联运动称为近反射。第四节 正视、屈光不正和老视 emmetropia， ametropia & Presbyopia 正视眼（emm

19、etropia) 在调节松弛的情况下，平行光线经过眼的屈光间质后，聚集成一个焦点并准确地落在黄斑中心凹，这种状态称正视眼。 Normal eye ， an eye with a far point of distinct vision at infinity is called emmetropia eye It has appropriate range of accommodation. 屈光不正：当眼在调节松弛的状态下，来自5米以外的平行光线经过眼的屈光系统的屈光作用，不能在黄斑中心凹形成焦点。 屈光不正可分为近视、远视和散光。 Vision is blurred or distorte

20、dVision is blurred or distorted when the image of the objects isis not brought into proper focus on not brought into proper focus on the retinathe retina. This is evidence of a visual impairment known as ametropiaametropia, a term that covers myopia, hyperopia and astigmatism 一、近视myopia 近视：眼在调节松弛的状态

21、下，平行光线经过眼的屈光系统后，在视网膜前形成焦点。 The axis of the eye is too long, and even with full relaxation, images of objects at infinity are focused in front of the retina. This abnormality is called myopia. In In myopiamyopia the light reflected off the the light reflected off the image is refracted by the cornea

22、and image is refracted by the cornea and lens and is precisely focused on a lens and is precisely focused on a space space in frontin front of the retina. The of the retina. The image that reaches the retina is image that reaches the retina is blurry.blurry.分类 1、根据功能分类 单纯性近视眼 病理性近视眼 2、根据屈光成分分类 轴性近视，

23、由于眼轴延长 (be too long for its power) 屈光性近视，由于眼屈光成分异常 (be too powerful for its length) ,可分为 曲率性近视 角膜、晶状体的弯曲度过大 指数性近视 房水、晶状体屈光指数增加所致3、根据近视眼程度分类轻度近视眼：-3.00D 中度近视眼：-3.00D-6.00D 高度近视眼：-6.00D4、根据调节作用参与分类 假性近视眼 由于调节痉挛，正视眼或远视眼表现出一时的近视现象。 真性近视眼 用药后近视度未降低或降低度数0.5D 混合性近视眼 用药后屈光度降低0.50D，但未恢复正视 病因 1、遗传因素 2、发育因素 3、

24、外因临床研究：持续视近动物实验研究：形觉剥夺性近视、离焦性近视体外研究： 临床表现 1、视功能 远视力降低，光敏感度多降低。 2、视疲劳 畏光、眼干、异物感、伴眼皮沉重、眼痛、头痛。 3、眼位偏斜 视近时调节与集合不协调，易发生眼位的变化，表现为外隐斜或外斜视。 4、眼球改变 眼球前后径变长，眼球向前突出，眼轴长度的变化仅在赤道部以后。 5、眼底改变 随眼轴的延长，眼底病变范围扩大、程度加重，主要影响后极部。眼底主要的病理变化为视网膜和脉络膜的萎缩和变薄及视乳头的变形。 豹纹状眼底 由于眼球向后延长，视网膜血管变细，脉络膜血管也变直、变细，同时色素上皮层营养障碍，浅层色素消失，暴露脉络膜血管，

25、呈现豹纹状眼底。 近视弧形斑 视神经乳头周围的脉络膜，在后极部巩膜张力的牵引下，从视乳头旁脱开，后面的巩膜暴露形成弧形斑，多居颞侧。若眼球继续延长，可扩张到视乳头四周，形成环形斑。 黄斑部病变 色素紊乱、变形、萎缩、出血、新生血管、Fuchs斑、浆液性病变、裂孔等。 后巩膜葡萄肿 眼球后极部局限性扩张，形成后巩膜葡萄肿。 周边眼底改变 早期不易发现，发生率较高，破坏性较大，可致视网膜脱离。常见的有色素变性、铺路石样变性、格子样变性、无压力白斑 、囊样变性等。 Common symptoms include reduced visual acuity, blurred vision, visua

26、l distortion (metamorphosia, macropsia and micropsia), discrete scotoma, and reading difficulty. Patients with unilateral involvement may not be aware of the problem until the good eye is being covered. High myopic eyes, where the basic abnormality is excessive axial elongation, are associated with

27、more chances of having degenerative changes in the sclera, choroid, retinal pigment epithelium and retina. There is also an increased risk of choroidal neovascularization (CNV), which is estimated to be in the range of 5% to 10% of eyes with high myopia. The axial elongation has a familial tendency

28、and is present commonly with refractive errors greater than -6.0D. 高度近视Fuchs斑 高度近视性脉络膜视网膜 萎缩 高度近视性脉络膜视网膜萎缩合并黄斑出血 Fundus photo showing bleeding and edema over the macular region of a highly myopic eye Fluorescein angiography showing subretinal blood clot and accumulation of fluid over the macular reg

29、ion并发症 1、玻璃体异常 玻璃体液化、混浊及后脱离，导致明显的飞蚊症。 2、视网膜脱离 3、青光眼 4、白内障High myopia with secondary High myopia with secondary neovascularization. A) OCT C-scan taken at neovascularization. A) OCT C-scan taken at level of RPE, arrow (right) = neovascular level of RPE, arrow (right) = neovascular membrane surrounded

30、 by a hyporeflective membrane surrounded by a hyporeflective halo (left: patchy central white area in halo (left: patchy central white area in confocal part = corneal reflection); B) confocal part = corneal reflection); B) en-face OCT B-scan through neovascular en-face OCT B-scan through neovascular

31、 membrane, arrowheads indicate disruption membrane, arrowheads indicate disruption of the double highly reflective layer at of the double highly reflective layer at the level of RPE caused by the changed the level of RPE caused by the changed orientation of the photoreceptor layer; C) orientation of

32、 the photoreceptor layer; C) FA mid-phase image showing inside-out a FA mid-phase image showing inside-out a central hyperfluorescence, a central hyperfluorescence, a hypofluorescent halo (hyperpigmentation) hypofluorescent halo (hyperpigmentation) and a halo of hyperfluorescence (window and a halo

33、of hyperfluorescence (window defect) in the area of the defect) in the area of the neovascularization; D) transformed FA neovascularization; D) transformed FA image; E) overlay image showing that the image; E) overlay image showing that the central hyperfluorescence on FA is central hyperfluorescenc

34、e on FA is enclosed by the RPE detachment on OCT, and enclosed by the RPE detachment on OCT, and that the hyperfluorescent halo corresponds that the hyperfluorescent halo corresponds to the hyporeflective halo in the OCTto the hyporeflective halo in the OCT.矫正 Description: The eyeball is longer than

35、 usual, making the eye too powerful. The image is focused at a point in front of the retina. The higher the degree of myopia, the shorter the distance at which the nearsighted can see clearly Solution: Myopia can be corrected using a concave lens that is thin in the center and thick at the edge. Thi

36、s type of lens pushes the focus back onto the retina and restores good vision at any distance. 假性近视不需戴眼镜，可用睫状肌麻痹剂如1%阿托品及0.5%托品酰胺或雾视疗法，以松弛睫状肌。 真性近视：验光确诊，及时矫正。 1、普通眼镜 选择适当的凹透镜，平行光线被凹透镜分散后 ，焦点后移，正好落在视网膜上。 2、角膜接触镜 与框架眼镜相比，接触镜对成像的大小影响较小，而且不影响外观，特别适用于高度近视、屈光参差较大及某些特殊职业者，但要严格按照接触配戴规则和注意用眼卫生。 3、其他 渐进镜、角膜矫形镜

37、、屈光手术。预防 1、减少视力负荷 用电脑时间不应太长，用眼一小时后应休息10min左右并远看，使调解松弛。生活规律正常，姿势端正，眼与读物距离保持2530cm左右，乘车走路或卧床不看书。 2、改善视觉环境 保持环境中适宜的光亮度和对比度，勿在阳光照射或暗光下阅读或写字。 3、减少遗传因素影响 4、对进行性加深的恶性近视眼，应考虑作巩膜加固手术以预防近视进一步加重。 5、定期检查视力，注意营养，加强锻炼，增强体质。二、远视 hyperopia 眼在调节松弛的状况下，平行光线经过眼的屈光系统折射后，在视网膜之后形成焦点。 In some individuals, the eyeball is s

38、horter than normal and the paralled rays of light are brought to focus behind the retina. This abnormality is called hyperopia or far sightedness. Hyperopia Hyperopia or farsightedness occurs or farsightedness occurs when the light refracted by the cornea when the light refracted by the cornea and l

39、ens of the eye is brought to a and lens of the eye is brought to a sharp focus behind the retina.sharp focus behind the retina. 分类 1、按屈光成分分类 轴性近视) (be too short for its power) 新生儿眼球小，眼轴短，几乎都是远视眼，故婴幼儿的远视眼可认为是生理性的。随着发育，眼轴逐渐延长，到成年多变为正视，这种变化过程称为正视化。如果发育受到影响，正视化过程不充分时，眼轴不能达到正常长度，即成为轴性远视眼。 屈光性远视 (be too w

40、eak for its length) 可分为 曲率性远视 由于眼球任何屈光面的弯曲度较小所形 成，常由角膜引起。 屈光指数性远视 由于晶状体引起，如老年生理性变化 晶状体后脱位或无晶体眼 表现为高度远视2、按远视程度分类 轻度远视眼：+3.00D 中度远视眼：+3.00+5.00D 高度远视眼：+5.00D临床表现 1、视力 （远视的轻重与裸视力的好坏相关） 轻度远视眼 青少年 眼调节力的代偿，远近视力可正常 中年人 眼调节力减弱，远视力尚佳，或远视力与近视 力均下降 中度远视眼 年龄小时，远视力可能尚好，近视力多障碍 年龄增大，眼调节力不足，远近视力均减退 高度远视眼 远视力差，近视力也明

41、显障碍，模糊的物像将影响视网膜的发育，儿童时期应及时矫正 年轻患者由于长时间过度使用调节，可产生调节痉挛，不能完全放松，是远视或近视的状态，后者称为假性近视。 2、视疲劳 往往在视近时首先出现视疲劳症状，表现为视物模糊、眼球沉重、酸胀感、眼眶和眉弓部胀痛，甚至恶心呕吐，稍休息后症状减轻或消失。 3、内斜视 调节与集合联动关系失调，常发生调节性内斜视。 4、远视眼的病理变化 度数较高的远视眼，眼球较小，晶状体大小基本正常，前房变浅，易发青光眼。 远视眼调节紧张，结膜充血，时引起慢性结膜炎，睑缘炎，睑腺炎。 眼底：常见假性视神经炎,表现为视乳头较小、色红、边远不清、稍隆起，血管充盈、迂曲，但矫正视

42、力尚好，视野无改变。 Signs and SymptomsSigns and Symptoms Difficulty seeing up close Difficulty seeing up close Blurred distance vision (occurs Blurred distance vision (occurs with higher amounts of hyperopia) with higher amounts of hyperopia) Eye fatigue when reading Eye fatigue when reading Eye strain (head

43、aches, pulling Eye strain (headaches, pulling sensation, burning) sensation, burning) Crossed eyes in childrenCrossed eyes in children 矫正 Description: The eyeball is shorter than normal which means the eye is not powerful enough. The eye is said to be too short and the image is focused behind the re

44、tina. Solution: Hyperopia is corrected using a convex lens that is thin at the edge and thick in the center. This type of lens brings the focus forward to the retina. 远视眼用凸透镜矫正，使平行光线变为集合光线，焦点落在视网膜上。 1、幼儿及青少年 使用睫状肌麻痹剂验光，确定远视度数。 矫正原则 6岁以下，轻度远视是生理性的，不必配镜；如远视较明显，视力减退、视疲劳，及内斜倾向，应配镜，必要时进行弱视训练。 616岁的学生正处于视

45、近用眼较多阶段，轻度远视也考虑配镜。 处方时，从散瞳验光的度数中减去1.0D，以适应睫状肌的张力。但对于调节性内斜的患者，应给予全校正。 2、成年人 验光一般可在小瞳下进行。 处方根据具体情况而定。 显性远视的基础上通过矫正镜片取得最佳视力，且感到舒适。 年龄越轻，校正度数可少；视疲劳应给于足够度数；如有内斜视应全矫正。三、散光astigmatism 由于眼球屈光系统各径线的屈光力不同，平行光线进入眼内不能形成焦点的一种屈光状态。 Astigmatism is a refractive error of the eye that causes the visual image in plane

46、 to focus at a different distant Causes of astigmatism:Causes of astigmatism: Heredity Heredity Lid swellings such as chalazion Lid swellings such as chalazion Corneal scars Corneal scars KeratoconusKeratoconus 分类 1、规则散光 角膜和晶状体表面的曲率不等，但有一定规律，存在最强、最弱的互相垂直的两条主径线，形成互相垂直的前后两条焦线，这种散光称为规则散光。可用柱镜矫正。 顺规散光(a

47、stigmatism with the rule，WR) 最大屈光力主子午线90030 逆规散光(astigmatism against the rule，AR) 最大屈光力主子午线180030 规则散光根据主径线的屈光状态分为： 单纯近视散光 一条主径线的焦线落在视网膜上，另一条主径线的焦线落在视网膜之前。 单纯远视散光 一条主径线的焦线落在视网膜上，另一条主径线的焦线落在视网膜之后。 复性近视散光 两条主径线的焦线均落在 视网膜之前。 复性远视散光 两条主径线的焦线均落在 视网膜之后。 混合散光 一条主径线的焦线落在视网 膜上，另一条主径线的焦 线落在视网膜之后。 2、不规则散光 眼球的屈光系统的屈光面不光滑，各条径线的屈光力不相同，同一径线上各部分的屈光力也不同，没有规律可循，不能形成前后两条焦线，也不能用柱镜矫正。 单纯近视散光 单纯远视散光 复性近视散光复性远视散光 混合性散光 临床表现： 1.视力减退 其程度由于散光性质、屈光度高低及轴的方向等因素有较大差异，属于生理范围的散光通常对远近视力无任何影响，高度数散光，多由于合并径线性弱视或其他异常，视力减退明显，并难以获得良好的矫正视力。 2.视疲劳 较轻度散光眼患者为了提高视力，往往利用改变调节、眯眼、斜颈等方法进行自我矫正，持续的调节紧张和努力易引起视疲劳。高度散光眼由于主观