婴幼儿视力检查视光班

Infant Vision,婴幼儿视力检查,钱学翰 医学博士 副主任医师 Q天津医科大学眼科中心 天津医科大学视光学院斜视与小儿眼科18920395031Depts. of Pediatric Ophthalmology & Strabismus,What do children see and how do we know?孩子看的好吗？如何知道？,The optics of vision 屈光系统,正视化 Emmetropization,眼轴变长角膜曲率变小晶状体屈光力变小,The Neurology of vision 视觉神经学,我们并非生来即拥有1.0的视力光学系统发育成熟 Optics of the eye matures -眼球增大 Globe enlarges -调节更精准 Accommodation becomes more precise,The Neurology of vision 视觉神经学,我们并非生来即拥有1.0的视力视网膜发育成熟 Retina matures -视锥细胞向中心凹移行 Cones migrate centrally -视锥细胞变长&感光效能提高 Cones elongate and become more efficient,The Neurology of vision 视觉神经学,我们并非生来即拥有1.0的视力视神经发育成熟(髓鞘化)Optic nerve matures (myelination)视放射形成(髓鞘化)The optic radiations mature (myelination),The Neurology of vision 视觉神经学,我们并非生来即拥有1.0的视力 1视皮质形成(新的连接建立)1 Visual cortex matures-new connections -依赖于视觉经验和有效刺激 This requires experience & quality stimulation视皮层联合区发育成熟(建立新的连接)Association visual cortex matures (new connections),Vision is a complex task,精细视觉中央视力Detail vision-visual acuity -优质的光学系统 (优质镜头) High optical quality (“good camera”)-视网膜敏感性 (优质底片） Retinal sensitivity (“high quality film”) “高密度胶片”-许多光感受器 “Fine grain film” =lots of photoreceptors “高感光度胶片”-光感受器对光敏感 “Sensitive film” = sensitive photoreceptors,视觉的形成是一项复杂的过程,对比敏感度 Contrast sensitivity色觉 Color vision运动知觉 Motion perception,视觉的形成是一项复杂的过程,Vision is a complex task,Pelli-Robson Contrast Sensitivity Chart,双眼视觉/深度觉 Binocular vision/Depth perception更高级的视功能 Higher visual function -空间感知觉 Spatial perception -面部识别 Facial discrimination -视觉记忆 Visual memory,Vision is a complex task,视觉的形成是一项复杂的过程,Assessment of the infant visual system,感觉功能检查 Sensory exam -这个孩子的视觉正常吗？ Is this childs vision normal? 运动功能检查 Motor exam -这个孩子的眼球运动系统正常吗？ Is this childs oculomotor system normal?,婴儿视觉系统评估,A pediatric vision conundrum:,对视觉感觉系统的检查依赖于眼运动系统功能 Testing the visual sensory system depends upon the integrity of the oculomotor system.反之亦然 Testing the oculomotor system depends upon the integrity of the visual system.,儿童视觉检查的一个难点：,我们如何知道一个孩子的视觉是否正常？,知道正常眼视觉功能&运动功能发育 的几个重要阶段 Know the normal “stages” of visual sensory & oculomotor development. 儿童并非小大人！ Children are not miniature adults ! - 解剖和生理学的改变 Anatomic and physiologic changes - 不同年龄的特征性视觉行为改变 Age-related behavioral milestones,Monocular acuity-from birth to 1 year,中心凹结构的变化 Changes in foveal structure. 中心凹锥细胞发育成熟 Maturation of the foveal cones. 更致密 (图像精细化) Denser (finer grain image)更高 (捕获光子更高效) Higher (higher % of photon capture),出生至一岁龄婴幼儿单眼视锐度,Monocular acuity-from birth to 1 year,出生至一岁龄婴幼儿单眼视锐度,眼球 Globe 轴长由16mm增至23mm length 16mm-23mm 更大的图像会刺激诱导网膜产生更多的光感受器 Larger image stimulates more photoreceptors视神经髓鞘化 Myelination of optic nerves颅内视觉传导通路的髓鞘化 (髓鞘化1岁后10岁以前继续发生) Myelination of intracranial visual pathways (continues through 1st decade),Is this the whole story ?,成人眼 Adult eye视力接近由以下因素决定的理论极限值 VA is close to the theoretical limit imposed by 光感受细胞的密度 density of photoreceptors 眼的光学性能 optical properties of the eye. 婴幼儿眼 Infant eye视力小于理论极限值 VA theoretical limit612个月视网膜, 外侧膝状体, 视皮质的神经回路的进一步精细化视神经,视交叉,视束髓鞘化后段(视放射),Visual Milestones 视觉里程碑,胎儿期Gestational age 25 周29-31 周,视觉行为特征对光照有瞬目反应Blinks to light瞳孔对光反射已形成Pupillary reflex to light,Visual Milestones 视觉里程碑,出生后 Post-natal age出生时(40周) 23月龄,视觉行为特征 视力 20/400-500 (双眼)20/100-200 (视觉电生理检查) 获得全视野 (视动性眼球震颤OKN)再注视,扫视 Refixation saccades追随人脸移动 Follows faces注视静止目标 Fixes still objects3月时达到正视 Orthotropic by 3 mos,Visual Milestones 视觉里程碑,出生后23月龄6个月 双眼视,视觉行为特征扫视性追随 Saccadic tracking部分婴儿3月时获得此种能力辐辏运动 Convergence融合 Fusion立体视 Stereopsis视力 20/80-100 (选择性观看FPL) 20/25 (视觉诱发电位VEP)拿够小物体 Reaches small objects识别人脸 Recognizes faces,新生儿眼中的世界 Newborn,4周龄婴儿眼中的世界,8周龄婴儿眼中的世界,3月龄婴儿眼中的世界,6月龄婴儿眼中的世界,成人眼中的世界,What can children see ?,注视和追随的能力 Quality of fixation-Fix & Follow,行为检查 Behavioral testing,What can children see ?,注视偏好检查 Fixation preference,行为检查 Behavioral testing,What can children see ?,视动性眼球震颤OKN,行为检查 Behavioral testing,What can children see ?,强制性选择性观看Forced preferential looking (Teller acuity),行为检查 Behavioral testing,What can children see ?,视力表 Optotypes 图案 字母,行为检查 Behavioral testing,What can children see ?,视觉诱发电位 VEP acuity 快速记录多振幅线条轨迹Rapid display of stripes of multiple widths ERG振幅波峰与条带宽度成比例Amplitude of EEG “spike” is proportional to stripe width,电生理检查 Electrophysiologic testing,固视和追随 Quality of Fixation Fix & follow (F & F),中心注视，稳定注视，维持注视Central, steady, & maintained (CSM),斜视儿童注视偏好检查,Fixation Preference Test (FPT) in children with strabismus注视偏好检查主要用于探查: 无法获得可信视锐度的儿童(除外患有微小斜视以及有显斜视的儿童)是否患有弱视.Fixation-preference testing has been useful in detecting amblyopia in children unable to give reliable visual acuities, except for children with small-angle tropias and those without manifest deviations.,斜视儿童注视偏好检查,SFPT 检查方法:将14度垂直三棱镜置于一眼前,从而诱导出垂直斜视.当双眼被分离后, 可以检测出患儿的注视偏好,并用于推测弱视是否存在.By placing a 14-diopter vertical prism over one eye, we induce a vertical deviation. Once the eyes are dissociated, fixation preference is evaluated and used to predict the presence of amblyopia.,垂直棱镜诱导斜视试验,Vertical induced tropia test (VITT, 14 prism test),正常反应:注视眼应该是没带棱镜的眼Fix pref should be eye without prism,垂直棱镜诱导斜视试验,Vertical induced tropia test (VITT, 14 prism test),如一眼存在弱视，当另一眼前置棱镜时，未戴棱镜的这一眼不能很好的注视目标。,斜视儿童注视偏好检查,FPT 结果通过测试两眼可以自然的交替注视 ( Alternates ) 能持续注视一段时间(5秒)直到眨眼 ( Holds well-5 sec pursuit or thru a blink)未通过测试坚持看很短的时间(3秒)即眨眼 (Holds briefly-up to a blink 3 sec)只能坚持看一瞬间(12秒) (Holds momentarily 1-2 sec)不能注视 (Will not hold),PFT检查是否好用?, 敏感性1 Sensitivity当弱视被定义为2 行 15% 当弱视被定义为3 行 25%对年龄更小的婴幼儿敏感性更差特异性1-2 Specificity75-95%* (5-25% false +)如果外斜或内斜 10 40%微小斜视，单眼固视者(microtropia, monofixators)阳性预测值 Positive predictive value (PPV) 当弱视被定义为2 行 47% 当弱视被定义为3 行 55%,两种方法测得随年龄增长视力变化曲线对比,How good is FPL?,强制性选择性观看V.S.临床判断,在伴有斜视的病人中强制性选择性观看与临床判断相比容易低估弱视程度In patients with strabismus-FPL underestimates amblyopia compared to clinical judgement.,Acuity in verbal pre-literate children,会说话但不识字的儿童视力的检查,LEA,ALLEN,Acuity in verbal pre-literate children,会说话但不识字的儿童视力的检查,HOTV,视觉诱发电位 VEP acuity,快速记录多振幅线条轨迹Rapid display of stripes of multiple widths ERG振幅波峰与条带宽度成比