扫描翻转图像视觉诱发电位视力与对数视力表视力的比较

目的 对扫描图像视觉诱发电位视力(SPVER视力)与对数视力表视力进行比较。方法比较50例受试者的视力表和SPVER视力。在SPVER视力的测定中用了8个不同空间频率的光栅条纹连续扫描,所得数据经离散傅立叶分析后,获得振幅一空间频率曲线,并由外推法估计其视力。结果SPVER视力与视力表视力的总体相关系数r=0．699,在视力表视力大于0．5时,SPVER视力有低估现象,而在视力表视力小于0．5时SPVER视力有高估现象。结论SPVER视力与视力表视力有良好的相关性。由于视力表视力和SPVER视力所用于评估视力的指标不同,使两者结果不完全相同。     

随机点立体视图点大小和密度对弱视儿童立体视的影响

目的 比较不同间距视力表对经治疗后的弱视儿童视力的影响,应用计算机立体视检查系统研究随机点大小和密度对经治疗后的弱视儿童立体视的影响.方法 本研究分两部分,研究对象为13例弱视儿童患者.用单个视标、1/4倍、1/2倍、1倍、2倍间距拥挤视力表分别检查13例弱视儿童的视力,比较使用5种视标间距视力表所得检查差异.应用计算机立体视检查系统对13例儿童进行立体视检查,分别按3种不同密度和4种不同随机点大小的检查并比较其差异.结果 不同间距视力表检查弱视儿童平均视力分别为(0.577±0.039)、(0.412±0.033)、(0.469±0.033)、(0.515±0.039)、(0.554 +0.045),成对比较显示不同组别间差异存在统计学意义.当随机点的大小固定时,密度不同随机点对儿童立体视锐度影响差异无统计学意义;当随机点密度相同时,大小不同随机点对儿童立体视锐度影响差异亦无统计学意义.结论 弱视儿童有拥挤现象,拥挤现象没有影响其随机点立体视锐度的检查,提示随机点立体视图视差信息的机制和视觉对精细视标的分辨机制不同.(中国眼耳鼻喉科杂志,2011,11:224-227)     

影响屈光性调节性内斜视立体视锐度发育因素分析

目的分析影响屈光性调节性内斜视患者立体视锐度发育的因素。方法对100例屈光性调节性内斜视按斜、弱视常规戴镜的原则进行治疗;采用同视机测量斜视度数;用颜少明的立体视觉检查图测量近立体视锐度。结果屈光性调节性内斜视患者发病年龄越小、戴镜前斜视度越大、两眼视力差距越大,立体视锐度的发育越差。结论屈光性调节性内斜视患者的立体视锐度发育与发病年龄、戴镜前斜视度、两眼视力有关。     

啮齿类动物的行为学视力测试方法

啮齿类动物(大鼠、小鼠、豚鼠等)被广泛应用于视觉研究领域,动物视觉疾病模型的研究离不开视功能的检测。目前国际上认可的动物视力测试方法包括电生理学视锐度测试和行为学视锐度测试,这两类方法都有其优点和局限性。电生理学视力测试方法(视觉诱发电位)具有侵入性,电极植入后需要恢复时间,并且所测得的视锐度值仅反映单细胞的电活动或神经核团的场电位,不能从整体水平反映动物的视觉功能,而行为学视力测试方法可弥补上述缺陷,故广泛运用于啮齿类动物的视锐度测量中。本文就啮齿类动物行为学视力测试方法进行综述。     

Lea Symbols电子视力表与灯箱视力表在儿童视力检查中的对比研究

目的 比较类纸屏承载的电子视力表与灯箱视力表在儿童视力检查中的准确性、一致性及差异。方法前瞻性自身对照交叉设计临床试验研究。以分层整群抽样方法选取拉萨市7所小学共1506名二年级儿童,其中男生802名,女生704名,平均年龄8.5±0.5岁。在相同测试环境下,由经过培训的专业人员使用以Lea symbols为视标的灯箱视力表和类纸屏电子视力表进行检查,两种视力表的检查顺序随机决定,并以LogMAR计数进行分析。采用组内相关系数计算两种视力表测量值的相关性,使用散点图及Bland-Altman检验图观察两种视力表测量的分布情况。结果 灯箱视力表测得平均LogMAR视力为右眼0.13±0.19,左眼0.14±0.20,电子视力表测得平均LogMAR视力为右眼0.08±0.20,左眼0.09±0.20。两种视力表测得总体视力值一致性较好且呈明显正相关趋势(ICC_OD=0.91,ICC_OS=0.89,P<0.001)。灯箱视力表和类纸屏电子视力表测量的总体平均差值为右眼0.05±0.11,左眼0.05±0.12,在各个视力范围内电子视力表测量的...     

三种视力表视力测量差异研究

目的:探讨mc-3投影式视力表(A)、普通箱式视力表(B)以及综合验光仪(C)对不同年龄段人的裸眼视力及校正视力的测量结果是否有差异.方法:志愿者206人(395眼),根据患者年龄分为3组:青年组:25～45岁,共116眼;中年组:46～70岁,共102眼;老年组:71～90岁,共177眼.用视力表投影仪、普通箱式视力表以及综合验光仪分别测量各志愿者的裸眼视力及矫正视力.结果:矫正视力:3组中均无差别.裸眼视力:青年组、中年组中无差别.老年组中综合验光仪的视力测量结果要好于视力表投影仪和视力了表箱,差别具有显著性意义(秩和检验P＜0.05).结论:在老年组的裸眼视力测量结果中,综合验光仪好于视力表投影仪和视力表箱,这种视力测量的差异可能足由于不同背景亮度及视标照度下视标的对比度不同所引起.     

煤矿工人立体视锐度的测定分析

为了解从事井下暗光环境工作的煤矿工人的立体视锐度,我院从1991年7月起对我局煤矿工人进行矽肺拍片的同时进行了此项检查。一、对象和方法为我局从事煤矿工作的井下1687人。均为男性。由一位眼科医生和一名护士进行立体视锐度的测定和视力的检查。使用的为颜一郑氏立体视觉检查图和标准对数视力表,并按测定项目表逐项填写。检查是在自然光线较好的条件下,用秒表计算看图     

斜视和弱视患儿立体视锐度的临床检测及评价

目的　探讨斜视及弱视对立体视觉的影响。对L型立体视觉检测板和国内其它常用立体视觉检测图的临床应用进行评价。方法　采用中科院生物物理研究所研制的L型立体视觉检测板和Lang、Titmus立体视检测图对 2 0 4例斜视及弱视患儿立体视锐度进行检测。 结果　 (1 )斜视组患儿立体视锐度最差 ,其中内斜视组立体视锐度低于外斜视组。弱视组患儿中双眼视力不平衡组立体视锐度低于平衡组。 (2 )三种方法检测斜视及弱视患儿立体视觉无明显差别。结论　斜视、弱视严重地妨碍立体视觉的形成。L型立体视觉检测板可以用于儿童立体视觉的检测     

斜视术后立体视锐度的测定

目的：探讨斜视矫正术后立体视恢复情况。方法：采用颜氏《立体视觉检查图》和《随机点同视机立体图》,进行远、近立体视锐度测定。结果：远、近立体视锐度无明显差异。立体视的恢复随发病年龄增长和视力的增加而上升,外斜视高于其他类型斜视。结论：斜视矫正术后,立体视锐度的恢复与斜视类型、发病年龄和视力有密切关系。发病早、视力低则立体视恢复差。     

近视眼LASIK术后立体图形的辨认时间

目的:观察近视眼准分子激光原位角膜磨镶术(excmier laser in situ keratomileusis,LASIK)后立体视功能的变化,从视觉最高形式的角度评价LASIK手术的疗效。方法:2006-08/2006-12间观察在我院行LASIK手术的4例中、高度近视患者,于术前,术后1wk,术后1mo检查远体视锐度(包括交叉视差和非交叉视差)及测量远立体视锐度最小辨别阈值的辨认时间。结果:所有观察病例术后裸眼视力均在0.8以上,远立体视锐度正常。术后1mo时中、高度近视患者的远立体视锐度最小辨别阈值的辨认时间较术前的缩短。结论:LASIK手术使双眼屈光状态变为正视,远立体视锐度恢复正常,远立体视锐度图片辨认时间缩短;双眼视力相等,调节性辐辏与调节相平衡,有利于形成双眼单视和立体感知。     

视力表的标准化

回顾了我国多年来视力表在设计、制作和使用中存在的问题,着重分析了目前使用最普遍的两种视力表《国际标准视力表》和《标准对数视力表》存在的问题。认为视力表视力检查是评价人眼主觉视力简便而实用的方法,它只对视觉功能做粗略的评估,简便和实用是其最大的特点。因此今后在设计和使用视力表时应考虑:①设计合理、简便实用、兼顾习惯、国际接轨、全国统一;②除有通用表外,另设计出供3岁左右儿童使用的视力表。建议国家标准局在业务主管部门(卫生部及中华医学会)协助下,组织视力表问题研究专题组,广泛征求意见与建议,提出规范统一的方案。     

Changing from Snellen to LogMAR: debate or delay?

Visual acuity is the most commonly used test to assess visual function. The Snellen chart is the universally accepted tool for testing visual acuity despite its poor reliability and reproducibility. Newer logMAR charts are now available that have negated the disadvantages of the Snellen chart. However, these charts are not being used regularly in daily practice. This article discusses the reasons for the delayed acceptance of the logMAR chart.     

Preschool visual acuity tests: A comparison between two prototype charts and two visual acuity charts in current use

The lack of standardised visual acuity charts with established norms for preschool children has resulted in a diverse variety of visual acuity tests in use for the paediatric patient. All available tests appear to have some limitations, including inadequate norms, long test times, poor reliability, and frequently use test parameters and stimuli which are different from those used with adults. This study compares results for four visual acuity test charts. A Bailey-Lovie Illiterate E chart and an abbreviated Sheridan-Gardiner test were compared with two prototype acuity charts; a modified Bailey-Lovie letter chart and an Arrow chart. A novel symbol such as an arrow constructed as a Snellen optotype incorporated into a chart on the Bailey-Lovie principle, was the test of choice. This test was interesting to preschool children and results showed significant correlation with those obtained using charts based on adult standards.     

视觉噪声双视力表在弱视检查中的临床应用

目的 探讨视觉噪声双视力表在弱视视觉敏感度检测中的临床应用价值.方法 弱视门诊随机选择100例弱视患者作为弱视组,同时随机抽取100例屈光不正患者作为对照组,使用视觉噪声双视力表分别检测2组患者在有、无视觉噪声条件下视力.然后分别将2组中有、无视觉噪声条件下的视力求差后进行对比研究,以明确视觉噪声双视力表在弱视检查中的应用价值.结果 2组中所有患者在有视觉噪声下的视力均低于无视觉噪声条件下的视力,其中弱视组有、无视觉噪声条件下测得的视力相差(1.62±1.11)行,对照组的视力相差(0.97±0.61)行,2组之间差异有统计学意义(t=5.355,P<0.05).结论 视觉噪声双视力表能够提示弱视者的视觉噪声加工缺陷,借此将弱视者和其他视觉异常者区分开来;可作为常规枧力检查的有益补充,用于弱视的临床检测和诊断.     

学龄前儿童常用视力表的研究进展

学龄前期(3-6岁)是视觉发育的关键时期，及早发现并治疗学龄前儿童视觉问题至关重要。视力表是筛查儿童视觉问题的重要工具，国内常采用标准对数视力表和儿童图形视力表，而国外则常用Lea、HOTV和ETDRS视力表。已经有很多研究报道了这三种视力表在儿童视力检查中的可测性、可重复性及诊断视觉相关问题的敏感性。然而，在国内这三种视力表的应用较为有限，本文就这三种视力表的设计原理、临床中的应用及各自的特点进行综述，以便更好地了解它们在学龄前儿童中的适用性和局限性，从而为未来视力检查方法的选择和改进提供参考。     

Task Complexity and Visual Acuity in Senile Macular Degeneration

ABSTRACT The effects of choice of test object and inter-symbol spacing (contour interaction) on the measurement of low visual acuities was investigated. Visual acuities of sixteen subjects with senile macular degeneration and five age-matched normal subjects were measured using different test targets of varying complexities. Visual acuity of both groups of subjects decreased with increasing task complexity but the trend was more marked for the low vision subjects. However, within the low vision group, the complexity effect was not dependent on the level of visual acuity. This study showed that visual acuity of persons with senile macular degeneration can be measured equally well with single letters, constant contour interaction Landolt rings, or the Bailey-Lovie letter chart but the test used should be specified. Grating targets and word charts measure different visual functions from standard visual acuity tests.     

灯箱视力表与Freiburg电子视力表应用对比研究

目的 比较灯箱视力表与Freiburg电子视力表结果的一致性与可重复性,评价Freiburg电子视力表的临床应用价值。设计 诊断性技术评价。研究对象 空军杭州航空医学鉴定训练中心的工作人员86例,平均年龄（26.3±2.1）岁。方法 所有入选者均随机由2位固定检查者分别使用灯箱视力表和Freiburg电子视力表进行检查,两种视力表检查的顺序随机决定。所有检查均在同一房间内完成,房间内亮度小于3 lux。检查距离均为3 m。对不同视力表间与检查者间测量重复性采用配对t检验比较结果的差别并计算相关系数r值。主要指标 使用两种视力表获得的logMAR视力。结果 在检查者一,用灯箱视力表查,被检者logMAR视力为0.19±0.23,Freiburg电子视力表0.20±0.15,两者差值为-0.011±0.141,差异无统计学意义（t=-0.741, P=0.461）,但有显著相关性（r=0.808,P=0.000）。在检查者二,用灯箱视力表查,被检者logMAR视力为0.32±0.25,Freiburg电子视力表为0.20±0.15,两者差值为-0.118±0.151,差异有统计学意义（t=7.191, P=0.000）及显著相关性（r=0.810,P=0.000）。均用灯箱视力表,检查者一、二的差异有统计学意义（F=11.872,P=0.001）,两者显著相关（r=0.938,P=0.000）。而均用Freiburg电子视力表,检查者一、二的差异无统计学意义（F=0.019,P=0.890）,两者显著相关（r=0.986,P=0.000）。结论 Freiburg电子视力表受检查者因素的影响小于灯箱视力表,其在不同测量者间的可重复性优于灯箱视力表。（眼科, 2013, 22: 117-120）     

Comparison of visual acuity estimates using three different letter charts under two ambient room illuminations

Background:

Visual acuity is an essential estimate to assess ability of the visual system and is used as an indicator of ocular health status.

Aim:

The aim of this study is to investigate the consistency of acuity estimates from three different clinical visual acuity charts under two levels of ambient room illumination.

Materials and Methods:

This study involved thirty Malay university students aged between 19 and 23 years old (7 males, 23 females), with their spherical refractive error ranging between plano and –7.75D, astigmatism ranging from plano to –1.75D, anisometropia less than 1.00D and with no history of ocular injury or pathology. Right eye visual acuity (recorded in logMAR unit) was measured with Snellen letter chart (Snellen), wall mounted letter chart (WM) and projected letter chart (PC) under two ambient room illuminations, room light on and room light off.

Results:

Visual acuity estimates showed no statistically significant difference when measured with the room light on and with the room light off (F_1,372 = 0.26, P = 0.61). Post-hoc analysis with Tukey showed that visual acuity estimates were significantly different between the Snellen and PC (P = 0.009) and between Snellen and WM (P = 0.002).

Conclusions:

Different levels of ambient room illumination had no significant effect on visual acuity estimates. However, the discrepancies in estimates of visual acuity noted in this study were purely due to the type of letter chart used.     

A new Gujarati language logMAR visual acuity chart: Development and validation

Aims:

Gujarati is the main spoken language of a large proportion of the population of India. The aim of this study was to develop and validate a new Minimum Angle of Resolution (logMAR) visual acuity chart in the Gujarati language.

Materials and Methods:

A new Gujarati visual acuity chart was designed to logMAR specifications using Gujarati optotypes experimentally selected to have similar relative letter legibility under spherical and cylindrical defocus. The chart validation study was carried out using 153 adult subjects in a large clinical setting in India. Subjects who were literate in English and Gujarati participated in the study. Visual acuity was measured with the new Gujarati logMAR chart and a modified Early Treatment of Diabetic Retinopathy Study-(m-ETDRS) logMAR chart. The method of presentation was randomized between the charts. Repeat visual acuity was measured on a subsequent day with a second version of the Gujarati logMAR chart.

Results:

The Gujarati chart correlated highly with the m-ETDRS logMAR chart (r² = 0.974). The mean visual acuity difference (Gujarati – m-ETDRS logMAR) was equal to three letters (–0.06 logMAR). The Gujarati logMAR chart also proved to be highly repeatable (r² = 0.994, test-retest) with 95% CI of ± 0.04 logMAR.

Conclusions:

The new Gujarati logMAR visual acuity chart provides a valid and repeatable tool for the measurement of visual acuity in native Gujarati language speakers.     

Visual acuity testing. From the laboratory to the clinic

The need for precision in visual acuity assessment for low vision research led to the design of the Bailey–Lovie letter chart. This paper describes the decisions behind the design principles used and how the logarithmic progression of sizes led to the development of the logMAR designation of visual acuity and the improved sensitivity gained from letter-by-letter scoring. While the principles have since been adopted by most major clinical research studies and for use in most low vision clinics, use of charts of this design and application of letter-by-letter scoring are also important for the accurate assessment of visual acuity in any clinical setting. We discuss the test protocols that should be applied to visual acuity testing and the use of other tests for assessing profound low vision when the limits of visual acuity measurement by letter charts are reached.