弱视视功能损害特点

目的：弱视是一种视觉异常,表现为没有明显眼部器质性病变的空间视力低下。弱视存在多种视功能障碍,并且不同类型弱视的视功能损害还表现出不同程度的差异。本文从视力、光栅视力、游标视力、对比敏感度、双眼视觉、视知觉以及色觉等方面对弱视的视功能损害特点进行探讨,以期有助于弱视的评估和治疗。     

阿尔茨海默病与原发性开角型青光眼的关系

阿尔茨海默病(Alzheimer's disease,AD)作为一种神经系统的老年退行性疾病,近年来发病率有逐年上升的趋势.研究发现AD患者常伴有眼部异常,包括视力、色觉、对比敏感度、瞳孔大小、瞳孔运动、视觉电生理的改变等,同时伴有视网膜神经节细胞数量的减少以及神经纤维层厚度降低.AD患者出现各种眼部异常的比例明显增加...     

色觉的分子生物学研究

本文对人类正常色觉，红－绿色觉异常、蓝色觉异常、蓝锥细胞单色视的分子生物学研究进展进行介绍。叙述了各种色觉类型基因型的特点，多态性及变异的可能机制。     

数字式Mars对比敏感度检查表在国人低视力患者中的应用

目的评估数字式Mars对比敏感度检查表的精确性和准确性,探索其能否应用于中国低视力患者的对比敏感度检查。方法前瞻性对照研究。正常视力者40例,双眼习惯矫正视力≥1.0,排除明显眼部疾病;低视力患者43例,双眼中好眼最佳矫正视力≤0.3。所有被检者在视力矫正的前提下采取单眼测试,检查程序如下：①由第一名检查者从3张数字式Mars对比敏感度检查表中采取抽签法随机抽取一张表格,对被检者进行测试,并记录结果。②由第一名检查者随机用数字式Mars对比敏感度检查表和字母式Mars对比敏感度检查表分别再次测试被检者,分别记录每次的测试结果。③第二名检查者用步骤1中使用的那张数字式Mars对比敏感度检查表对被检者进行测试并记录结果。重复性和再现性通过统计组内标准差（Sw）、精确度（1.96Sw）、组内变异系数（CVw）和组内相关系数（ICC）进行评估;一致性比较采用Pearson线性相关分析、ICC及Bland-Altman分析法综合分析。结果数字式Mars对比敏感度检查表的重复性参数和再现性参数1.96Sw、CVw较小,而ICC值较高,大于0.75。数字式Mars对比敏感度检查表和字母式Mars对比敏感度检查表之间的一致性示两者之间呈高度正相关（r=0.995,P＜0.01）。ICC为0.997,Bland-Altman分析结果为95%LoA的范围非常窄,为（-0.053,0.092）logCS,表明2个表之间具有高度的一致性。结论数字式Mars对比敏感度检查表具有较高的准确性和精确性,能够应用于中国低视力患者的对比敏感度检查。     

《眼视光学杂志》2003年第5卷1～4期总目次(卷终)

专　　稿　虚拟斜视 :模拟斜视检查的软件Klaus HeikoWassill,ThomasKowarsch(6 5 )……………………………………………　视锥细胞营养不良和Stargardt’s病多焦视网膜电图潜伏期的差异余敏忠 ,吴经纬 ,RajK .Maturi(12 9)……………　美国太平洋大学视光学院简介LindaCasser,LelandCarr(193)…………………………………………………………　外伤后的假性近视分析RichardLondon ,BruceWick ,DavidKirschen(194 )………………………………………………　视觉评估领域的SLCT和锥细胞对比敏感度测试的临床应用分析JeffRabin(199)……     

色觉的分子生物学研究

本文对人类正常色觉、红－绿色觉异常、蓝色觉异常、蓝锥细胞单色视的分子生物学研究进展进行介绍。叙述了各种色觉类型基因型的特点、多态性及变异的可能机制。     

利用视动性转鼓视力仪对豚鼠色觉和对比度视力的检测

目的 研发一种可以快速定量检测动物的对比敏感度视力、色觉的装置,并用该装置来评价豚鼠的对比敏感度视力和色觉.方法 实验研究.根据豚鼠视细胞的光谱敏感性函数曲线,选取绿、蓝、黄三种不同颜色,制作绿-白、蓝-白和黄-绿三种颜色组合且空间频率均为0.6 c/d的方波条栅视标,每种颜色组合的条栅视标分别又具有高、中、低三种对比度.对于黑白方波条栅,选用3.0 c/d空间频率,制作对比度分别为100%、50%、25%的条栅.将条栅视标贴附在可以转动的圆形鼓内壁,利用豚鼠对运动物体会产生有规律的视动性头部追随运动这一生理现象,在受试豚鼠保持清醒的自然状态下,用视动性转鼓视力仪来初步检测豚鼠的色觉及对比敏感度视力.采用非参数检验中的Kruskal-Wallis检验分析豚鼠在不同对比度下的头部运动追随率.结果 用视动性转鼓视力仪,可以在行为学上验证豚鼠的色觉.豚鼠对空间频率为0.6 c/d的绿、蓝、黄三种颜色组合的方波条栅表现出良好的头部追随运动,在低对比度下,豚鼠的头部运动追随率分别为1.06±0.14（实际对比度为2.41%）、1.12±0.17（实际对比度为1.87%）、1.05±0.15（实际对比度为6.50%）.对于空间频率为3.0 c/d的黑白方波条栅,当对比度降到25%时,豚鼠仍可表现出明确的头部追随运动,其头部运动追随率为0.74±0.08,与高对比度条栅下的追随率经非参数检验分析,差异无统计学意义（x2=2.47,P＞0.05）.结论 转鼓视力仪可以检测豚鼠的颜色视觉并定量确定其颜色对比敏感度视力.该实验装置及实验流程操作简单,可以用于豚鼠色觉和视力的检查.     

Alport综合征眼部表现及其病理机制研究进展

Alport综合征(Alport syndrome，AS)是一种累及肾脏、耳、眼的基底膜结构异常的遗传性疾病，发病率约为1：5000。其眼部异常的报道较少见，但对疾病的诊断却有重要的价值，眼部异常相关病理机制分析将为我们揭开眼部异常发生的真正原因，对于疾病的认识和治疗具有重要意义。     

阿尔茨海默病与原发性开角型青光眼的关系

阿尔茨海默病(Alzheimer's disease,AD)作为一种神经系统的老年退行性疾病,近年来发病率有逐年上升的趋势.研究发现AD患者常伴有眼部异常,包括视力、色觉、对比敏感度、瞳孔大小、瞳孔运动、视觉电生理的改变等,同时伴有视网膜神经节细胞数量的减少以及神经纤维层厚度降低.AD患者出现各种眼部异常的比例明显增加.随着青光眼相关研究的深入,发现AD与原发性开角型青光眼在病理改变、发病机制上有很多相似之处.AD与原发性开角型青光眼是否相关需进一步研究证实.     

色觉对比敏感度阈值检测在原发性开角型青光眼早期诊断中的应用

目的 探讨色觉对比敏感度阈值测试在原发性开角型青光眼早期诊断中的应用价值.方法 前瞻性病例对照研究.选取82只可疑开角型青光眼作为可疑青光眼(SOAG)组,80只已确诊为原发性开角型青光眼作为青光眼(POAG)组,75只正常眼作为对照组.3组均采用计算机图像辅助系统检测双眼红-绿色轴和蓝-黄色轴上四个象限的色觉对比度阈值,6个月后对SOAG组进行随访.组间及组内象限间采用单因素方差分析,SOAG组随访前后采用配对t检验,视野随访检查阳性率与色觉对比敏感度检查一致性检验采用Kappa评价方法.结果 ①3组红-绿色轴和蓝-黄色轴上色觉对比敏感度阈值为POAG组＞SOAG组＞对照组.红-绿色轴上仅POAG组与对照组在四个象限间差异有统计学意义(F=4.16、3.57、4.58、5.10,P＜0.01);蓝-黄色轴上POAG组与对照组的四个象限间,POAG组与SOAG组的颞下象限间与鼻下象限间,SOAG组与对照组的颢上象限间,颞下象限间和鼻上象限间差异无统计学意义(F=16.58、15.32、9.76、10.86,P＜O.05).②SOAG组6个月随访红-绿色轴和蓝-黄色轴各个象限阈值均高于初次阈值,蓝-黄色轴在颞上和颞下象限差异有统计学意义(t=2.12、2.03,P＜0.05);视野检查与色觉对比敏感度检查方法一致性较好(Kappa=0.47).结论 色觉对比敏感度阈值能较好的反映病情变化,6个月随访其视野变化与色觉对比敏感度检出异常变化有较好的一致性,可作为青光眼早期筛选与监测的一项辅助手段.     

Quantification of color vision with cone contrast sensitivity

Human color vision is based fundamentally on three separate cone photopigments. Hereditary color deficiency, which affects up to 10% of males, results from an absorption shift or lack of L or M cone phototoreceptors. While hereditary S cone deficiency is rare, decreased S cone sensitivity occurs early in eye disease, underscoring the importance of quantifying S cone function. Our purpose is to describe a novel approach for quantifying human color vision based on the photopigments of normal color vision. Colored letters, visible to a single cone type, are presented in graded steps of cone contrast to determine the threshold for letter recognition. This approach quantifies normal color vision, indicates type and severity of hereditary deficiency, and reveals sensitivity decrements in various diseases.     

Learning to identify contrast-defined letters in peripheral vision

Performance for identifying luminance-defined letters in peripheral vision improves with training. The purpose of the present study was to examine whether performance for identifying contrast-defined letters also improves with training in peripheral vision, and whether any improvement transfers to luminance-defined letters. Eight observers were trained to identify contrast-defined letters presented singly at 10 degrees eccentricity in the inferior visual field. Before and after training, we measured observers' thresholds for identifying luminance-defined and contrast-defined letters, embedded within a field of white luminance noise (maximum luminance contrast=0, 0.25, and 0.5), at the same eccentric location. Each training session consisted of 10 blocks (100 trials per block) of identifying contrast-defined letters at a background noise contrast of 0.5. Letters (x-height=4.2 degrees) were the 26 lowercase letters of the Times-Roman alphabet. Luminance-defined letters were generated by introducing a luminance difference between the stimulus letter and its mid-gray background. The background noise covered both the letter and its background. Contrast-defined letters were generated by introducing a differential noise contrast between the group of pixels that made up the stimulus letter and the group of pixels that made up the background. Following training, observers showed a significant reduction in threshold for identifying contrast-defined letters (p<0.0001). Averaged across observers and background noise contrasts, the reduction was 25.8%, with the greatest reduction (32%) occurring at the trained background noise contrast. There was virtually no transfer of improvement to luminance-defined letters, or to an untrained letter size (2 x original), or an untrained retinal location (10 degrees superior field). In contrast, learning transferred completely to the untrained contralateral eye. Our results show that training improves performance for identifying contrast-defined letters in peripheral vision. This perceptual learning effect seems to be stimulus-specific, as it shows no transfer to the identification of luminance-defined letters. The complete interocular transfer, and the retinotopic (retinal location) and size specificity of the learning effect are consistent with the properties of neurons in early visual area V2.     

Color vision

Many visual disorders produce acquired color vision defects. Color vision theory emphasizes several stages of visual processing: prereceptoral filters (lens, macular pigment, pupil), cone photopigments (L-, M-, and S-cones), and postreceptoral processes (red-green, S-cone, and luminance channels). Congenital color defects, which affect 8% to 10% of males and 0.4% to 0.5% of females, result from alterations in the photopigment absorption spectra or the absence of one or more photopigments. The most common defects are color vision deficiencies (protan and deutan defects), which are milder than the rarer achromatopsias (complete loss of color vision). Acquired color vision defects can be attributed to a number of different causes: alteration of prereceptoral filters, reduced cone photopigment optical density, greater loss of one cone type than the others, and disruption of postreceptoral processes. Acquired color vision defects have been divided into three classes: type 1, red-green defect with scotopization; type 2, red-green defect without scotopization; and type 3, blue defects (with or without pseudoprotanomaly). Blue defects are usually type 3 acquired defects because congenital tritan defects have an incidence of one in several tens of thousands. Red-green defects can be acquired or congenital, and ruling out acquired defects can require a battery of tests (plates and arrangement tests, anomaloscopy, perhaps genetic analysis). Color vision tests must be administered carefully (with a standard illuminant and protocol), and pupillary miosis or high lens density should be noted and their possible effects considered when interpreting test results. Plate tests provide a simple screening method but do not provide a diagnosis. Arrangement tests and anomaloscope testing take more time and make greater demands on the tester, but they provide a more thorough evaluation. When standard protocols are followed and results are interpreted in terms of prereceptoral filters, photopigment optical density, cone loss, and disruption of postreceptoral processes, a battery of color vision tests can be useful in the differential diagnosis, after progression of the disease, and for evaluating the effectiveness of treatment.     

Evaluation of acquired color vision deficiency in retinal vein occlusion using the Rabin cone contrast test

Graefe's Archive for Clinical and Experimental Ophthalmology - To investigate acquired color vision deficiency (CVD) using the Rabin cone contrast test (RCCT) in patients with retinal vein...     

Spatial-frequency characteristics of letter identification in central and peripheral vision

Spatial-frequency characteristics of letter identification are much better understood in the fovea than in the periphery. The purpose of this study was to compare the spatial-frequency characteristics of letter identification in central and peripheral vision. We measured contrast thresholds for identifying single, Times-Roman lower-case letters that were spatially band-pass filtered. Each of the 26 letters was digitally filtered with a set of nine cosine log filters, with peak object spatial frequencies ranging from 0.63 to 10 c/letter, in half-octave steps. Bandwidth of the filters was 1 octave. Three observers with normal vision were each tested monocularly at the fovea, and at 5 degrees and 10 degrees in the inferior visual field. Letter sizes were 0.2, 0.4 and 0.6 log units larger than high contrast, unfiltered acuity letters. Plots of contrast sensitivity for letter identification vs. frequency of the band-pass filters exhibit spatial tuning. In general, the spatial-frequency characteristics of letter identification are fundamentally identical between central and peripheral vision. These characteristics include the scaling of the peak frequency of the spatial-tuning functions with letter size and the bandwidth of the tuning functions. The only difference between the fovea and the periphery is that for the same physical letter size, peak sensitivity of the spatial-tuning functions occurs at a higher retinal frequency at the fovea than in the periphery. To test whether or not the contrast sensitivity function (CSF) can account for the differences in the spatial-frequency characteristics of letter identification between central and peripheral vision, we incorporated a human CSF into an ideal-observer model, and tested the performance of this ideal-observer on the same letter identification task used with the human observers. Data from this CSF-ideal-observer resemble closely those of human observers, suggesting that the spatial-frequency characteristics of human letter identification can be accounted for by the CSF and the letter-identity information, without invoking selection among narrow-band spatial-frequency channels.     

Differences in the legibility of letters at contrast threshold using the Pelli-Robson chart

One disadvantage of using high-contrast letters as test objects when measuring visual acuity is the fact that they are not of equal legibility. A number of charts are now commercially available that assess contrast sensitivity using letter targets. This study attempted to assess the legibility of letters at contrast threshold on the Pelli-Robson letter contrast sensitivity chart by determining the percentage of correct responses for each of the ten Sloan letters at contrast threshold. Results of 493 contrast sensitivity measurements taken in optometric practice indicated that there is a definite difference in legibility between letters at contrast threshold as for letters at acuity threshold. The data suggest that the probability of correctly identifying two out of a group of three letters at threshold on the Pelli-Robson chart varies between 67% and 97% due to letter type alone. Because of the very regular and pronounced miscalling of the letter C as an O, we suggest that this should be accepted as a correct call during threshold measurements on the Pelli-Robson chart. This helps to balance the legibility of different groups of letters.     

Contrast sensitivity for letter and grating targets under various stimulus conditions

Measurement of visual acuity for letters of different contrasts has been suggested as a clinical way to evaluate contrast sensitivity in patients with vision abnormalities. If variable-contrast letter acuity provides information similar to the contrast sensitivity function (CSF), then comparable effects should be seen in stimulus manipulations which simulate decreased vision. Using both our own and published data, we compared the effects of diffusive blur, dioptric blur, and eccentric viewing on contrast sensitivity for letter and grating targets. A diffuser placed close to the eye reduces contrast sensitivity fairly evenly across all spatial frequencies, with similar results for letters and gratings. However, dioptric blur reduces sensitivity substantially more to letters than to comparably fine gratings. Eccentric viewing also produces a larger sensitivity loss for letters than for gratings. Because some stimulus manipulations produce dissimilar changes in contrast sensitivity for letters and gratings, it is questionable whether the results of one measure can be used to draw inferences about the other. It is proposed that local or relative phase discrimination has an important role in explaining the different responses to letter and grating targets.     

Detection and identification of crowded mirror-image letters in normal peripheral vision

Performance for discriminating single mirror-image letters in peripheral vision can be as good as that in central vision, provided that letter size is scaled appropriately [Higgins, K. E., Arditi, A., & Knoblauch, K. (1996). Detection and identification of mirror-image letter pairs in central and peripheral vision. Vision Research, 36, 331-337]. In this study, we asked whether or not there is a reduction in performance for discriminating mirror-image letters when the letters are flanked closely by other letters, compared with unflanked (single) letters; and if so, whether or not this effect is greater in peripheral than in central vision. We compared contrast thresholds for detecting and identifying mirror-image letters “b” and “d” for a range of letter separations, at the fovea and 10° eccentricity, for letters that were scaled in size. For comparison, thresholds were also determined for a pair of non-mirror-image letters “o” and “x”. Our principal finding is that there is an additional loss in sensitivity for identifying mirror-image letters (“bd”), compared with non-mirror-image letters (“ox”), when the letters are flanked closely by other letters. The effect is greater in peripheral than central vision. An auxiliary experiment comparing thresholds for letters “d” and “q” vs. “b” and “d” shows that the additional loss in sensitivity for identifying crowded mirror-image letters cannot be attributed to the similarity in letter features between the two letters, but instead, is specific to the axis of symmetry. Our results suggest that in the presence of proximal objects, there is a specific loss in sensitivity for processing broad-band left-right mirror images in peripheral vision.     

Color vision in an elderly patient with protanopic genotype and successfully treated unilateral age-related macular degeneration

We investigated differences in color discrimination between the fellow eye and the affected eye successfully treated for unilateral age-related macular degeneration (AMD) in a 69-year-old male patient with protanopia. His best-corrected visual acuity (BCVA) was 1.2 in the right eye (RE) and 0.2 in the left eye (LE). Fundus and angiographic findings showed classic choroidal neovascularization (CNV) secondary to AMD in the LE. BCVA of the LE improved to 0.4, and CNV resolved by 15 months after initiating combined anti-vascular endothelial growth factor and photodynamic therapies. After CNV closure, the Farnsworth dichotomous was performed, showing confusion patterns of the protan axis in either eye. The Farnsworth-Munsell 100-hue test showed a total error score of 520 in the LE, much higher than the score of 348 in the RE. Complete genotypes of the long-wavelength-sensitive (L−) cone and middle-wavelength-sensitive (M−) cone opsin genes were determined by polymerase chain reaction, revealing that the patient had a single 5′ L–M 3′ hybrid gene (encoding an M-cone opsin), with this genotype responsible for protanopia (the L-cone opsin gene was non-functional), instead of the L-cone and M-cone opsin gene arrays. Poorer color vision discrimination in the LE than the RE remained present despite closure of CNV. The presence and type of congenital color vision defect can be confirmed using molecular genetic testing even if complications of acquired retinal diseases such as AMD are identified.     

The role of color vision disturbances in diagnostics of early diabetic retinopathy

PURPOSE: The evaluations of color vision sensitivity in children with type I diabetes mellitus without retinopathy. MATERIAL AND METHOD: We examined 96 young patients. They was divided into three groups: I: 35 children from 7 to 16 years old with insulin-dependent diabetes mellitus duration of 1-8 years, II: 30 children with type I diabetes lasting more then 8 years, III--31 non-diabetic subjects as a control-matched for age and sex, without visual or systemic symptoms. The examinations of colour vision sensitivity were done with the IF-2AII-color Anomaloscope. In all cases were tested the dynamic blue-green equation of Moreland and two variables were determined: setting (matching) range (SR), calculated mid point (matching mid point) (CMP). RESULTS: In the blue-green equation setting range (SR) was significantly (p < 0.01) enlarged in the II group (diabetes mellitus duration > 8 years) and calculated mid point (CMP) was shifted but no significant. The results indicate a diminution of the colour discriminating sensitivity in the short wavelength half of the visible spectrum and diminution of the blue cone sensitivity in early diabetic retinopathy. CONCLUSIONS: Blue-green colour vision testing with the anomaloscope may serve as an additional test in the diagnosis of early diabetic retinopathy in children without vascular changes at the eye fundus.