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1.
Wang CX  Lü F 《中华眼科杂志》2011,47(7):618-622
目的 在傅里叶频谱分析的基础上,采用心理物理学方法确定汉字视标的可视性,获得视标物理刺激均等与心理反应均等的异同,确定心理物理学方法在汉字视标选择中的重要作用.方法 28位志愿者,裸眼视力或最佳矫正视力为-0.11±0.06(LogMAR值).分别从汉字图像傅里叶频谱分析所得到的50个各空间频率的频谱能量均值相似的少笔画汉字和40个中笔画汉字中筛选出尽可能包含横、竖、撇、捺结构的中性少笔画和中笔画汉字17个和20个作为备选视标.分别将以上少笔画汉字和中笔画汉字的平均视敏度阈值作为参考值,每个汉字制作成6种字体大小的汉字图片.取所有被试对每个汉字图片在不同字体大小时的辨认准确率的平均值,并用韦伯函数(Weibull function)进行拟合,得到字体大小--辨认准确率曲线,并获取每个汉字的阈值大小(tb值)和斜率(β值).结果 17个少笔画汉字的阈值大小为6.16±0.54(单位:分),斜率为5.91±2.18;20个中笔画汉字的阈值大小为8.20±0.71(分),斜率为11.18±3.55.以阈值大小最接近且斜率尽可能接近为筛选指标,最终确定可视性相似的10个少笔画汉字和10个中笔画汉字.选做少笔画汉字视力表视标的汉字为"斤、长、文、尺、万、月、又、不、才、卫"(tb值为5.84±0.36,β值是4.72±0.85),选做中笔画汉字视力表视标的汉字为"孩、郑、怪、构、肾、择、染、秋、软、祝"(tb值为8.38士0.24,β值是10.47±3.9).结论 傅里叶频谱分析方法可以非常客观地从众多汉字中选择出物理刺激相等的汉字,由于汉字视标之间相似的可视性同时表现为视标的物理刺激相似和心理反应的一致性,因此汉字视标的最终选择还需要进行心理物理学的测试.
Abstract:
Objective This study investigated the legibility in use of psycho-physical methods to select Chinese characters for visual acuity charts. Methods Twenty-eight subjects with the raw visual acuity or best corrected visual acuity of - 0. 11 ± 0. 06 ( LogMAR) were recruited for this study. Ninety Chinese characters with similar Fourier frequency spectrum were used as candidates for the selection of visual targets.Thirty-seven Chinese characters with each consisted of horizontal, vertical and oblique strokes were selected from these candidates. Six different-sized BMP images for each selected Chinese character were made based on the average visual acuity threshold of all the selected characters. The accuracy rate for all subjects to read each size of the BMP images was averaged. Graphs correlating the font sizes with the accuracy rates were formed using Weibull function imitation, which provided a visual acuity (VA) threshold and slope for each Chinese character selected. Results Among the 37 Chinese characters selected, 17 had a VA threshold 6. 16 ±0. 54 (unit: arc) and 20 had a VA theshold of 8. 20 ±0. 71. The slope for characters with low stroke number and medium stroke number was 5.91 ± 2. 18 and 11. 18 ± 3.55, respectively. Based on the finally determined as the visual targets for a lower stroke-number Chinese visual acuity chart (tb: 5. 84 ±β: 10. 47 ±3. 9) were determined as the visual targets for a medium stroke- number Chinese visual chart. Conclusion Analysis using Fourier frequency spectrum provides an objective method in the selection of Chinese characters for Chinese visual acuity charts. A psychological test for this selection would further confirm the legibility of the method used in this study.  相似文献   

2.
基于傅里叶频谱分析设计的汉字近视力表   总被引:1,自引:1,他引:1  
本研究介绍一种汉字近视力表。本视力表将傅里叶频谱分析和心理物理学测试应用于汉字视标的选择,筛选出可视性相似的汉字作为同一张视力表的视标。在视力表的设计中,每行视标的个数保持一致,每相邻两行视标之间的行间距为下一行视标的高度,每一行的字间距为该行所在字的字宽,视标的增率采用0.1对数单位,增加可重复测试的小视标及低对比度视力表等。因被检者的阅读习惯距离存在差异,故规定标准检查距离为40cm的同时设置25cm作为备选测量距离。将它应用于常规测试对预测被检者辨认汉字的阈值和早期发现与视觉有关的眼病有一定的临床价值。  相似文献   

3.
目的探讨字频、空间频率、笔画数和近视程度对汉字图片辨认正确率的影响。方法矫正视力或裸眼视力不低于1.0的33位被试者参加本实验,按照近视程度分成高、中、低度近视三组,测量他们在110cm距离处对3种笔画数(少、中、多)、2种字频(常用字和生僻字)和9个截止空间频率(1.00cpc、1.25cpc、1.58cpc、1.99cpc、2.51cpc、3.98cpc、6.30cpc、9.98cpc、无滤波)随机组合的低通滤波下汉字图片辨认的正确率。对每位被试者的测试结果进行最小二乘法拟合.得到汉字临界截止空间频率及最大辨认正确率。结果少笔画汉字组:常用字和生僻字的临界截止空间频率均值分别为(1.73±0.71)cpc和(2.20±0.68)cpc,最大辨认正确率均值为(99.33±0.09)%和(99.18±0.10)%;中笔画汉字组:常用字和生僻字的临界截止空间频率均值分别为(1.89±0.14)cpc和(2.38±0.25)cpc,最大辨认正确率均值为(98.93±1.04)%和(96.00±2.35)%:多笔画汉字组:常用字和生僻字的临界截止空间频率均值分别为(2.43±0.63)cpc和(6.17±1.41)cpc,最大辨认正确率均值为(97.02±0.35)%和(88.59±1.33)%。相同空间频率和笔画数组.常用字与生僻字的辨认正确率差异显著(P〈0.01)。截止空间频率≤2.51cpc时,汉字辨认正确率差异显著(P〈0.01);截止空间频率〉2.51cpc时,汉字辨认正确率差异无显著性(P=0.392)。不同近视程度组汉字辨认正确率差异没有统计学意(P〉0.05)。结论低通滤波下汉字图片辨认的正确率受到字频、笔画数和空间频率成分的影响,但是不受近视程度影响。  相似文献   

4.
汉字视标视力表研究的焦点问题及其剖析   总被引:2,自引:0,他引:2  
L 《中华眼科杂志》2008,44(7):581-583
各种不同字、词、句特点设计的近视力表及其相关研究成果颇丰,并在临床中得到一定的应用.但以汉字为视标的近视力表颇有争议,主要是因为汉字构架的多样性使其难以达到基本视标的要求;汉字的认知在视标识别中起一定作用,增加了临床检测中如何确定其科学表达视力或视功能的复杂性.由此,一些学者对汉字为视标的近视力表的研究和应用价值提出质疑,本文将就相关争论焦点进行分析.  相似文献   

5.
目的研究时间频率和空间频率对扫描图像翻转诱发电位视力准确度的影响。方法比较10例20眼正常志愿者SPVER视力和对数视力表视力。在SPVER视力的测定中用7个不同空间频率的光栅条纹连续扫描。所得的数据经离散傅立叶分析后,获得振幅-空间频率曲线,并通过外推法估计其视力。诱发电位测定的时间频率分别为8、12、16、20、24Hz,根据测试距离来调整空间频率。结果与视力表视力比较各时间频率测定的SPVER视力有良好的相关r=0.87~0.5,各空间频率间测定的视力有良好的相关性r=0.72~0.96。三种不同空间频率测试的SPVER视力和视力表视力比较在低视力段无差异在高视力段所设空间频率越高结果越接近视力表视力。结论SPVEP视力与视力表视力有良好的相关性。但为使测定的结果更准确可根据条件选取相应的时间和空间频率。  相似文献   

6.
目的 分析白内障超声乳化人工晶状体植入术后对比敏感度与眩光对比敏感度变化.方法 选取我院2009年1月至2010年6月行超声乳化人工晶状体植入术的白内障患者45例(60眼),术后随访1~6个月,平均3.5个月.观察患者术前及术后随访末期BCVA,并于术前及术后1个月检测患者对比敏感度和眩光对比敏感度.结果 患者术后BCVA较术前显著提高,差异有统计学意义(P<0.05).明视无眩光及明视眩光条件下,患者术后各空间频率下的对比敏感度及眩光对比敏感度较术前均明显提高,差异均有显著统计学意义(均为P<0.01).暗视无眩光及暗视眩光条件下,除高空间频率(18.0c·d-1)外,患者术后其他空间频率下的对比敏感度及眩光对比敏感度较术前均明显提高,差异均有显著统计学意义(均为P <0.01).明视及暗视条件下,眩光对于患者术前、术后高空间频率(12.0 c·d-1、18.0c·d-1)下的对比敏感度均无明显影响(P>0.05),但对术前、术后其他空间频率下的对比敏感度均有明显影响(P<0.01).与暗视眩光条件相比,明视眩光条件下的患者术前、术后各空间频率对眩光比敏感度均较高,差异均有统计学意义(均为P <0.05).结论 对比敏感度及眩光对比敏感度检查可以作为白内障患者更客观有效的视功能检查方法.  相似文献   

7.
目的 评价扫描视觉诱发电位(sweep visual evoked potential,SVEP)对成年野生型C57BL/6J小鼠客观视力评估的可靠性。方法 选取6只鼠龄32~33 d的正常野生型C57BL/6J小鼠,雌雄不限,麻醉小鼠将记录电极 (2 mm直径的钨电极) 放置在λ缝旁3 mm的左皮质(受刺激右眼的对侧),深度为皮层下400 μm,额部的针状电极作为参考电极,尾部的针状电极作为接地电极,记录过程中遮盖左眼(未受刺激眼),屏幕放置在小鼠眼前20 cm处,视野范围为100°(水平)×82°(垂直),平均亮度为25 cd·m-2;采用垂直方向的正弦波光栅刺激,刺激对比度为100%,包括11个空间频率,时间频率为1 Hz;整个扫描过程需要12 s(11 s空间频率+ 1 s预适应),数据的误差值稳定后取其平均值。分别记录左右眼对应的视皮层VEP波形。不同刺激频率给予20次刺激,每眼重复测量3~4次,取其平均值,左右眼交替试验。以空间频率对数作为x轴,经离散傅里叶分析所得反应振幅为y轴建立坐标系,选取临近噪点的4个有效测定点行线性回归,回归曲线外推法至振幅为0处的空间频率即为推断的客观视力。结果 空间频率为0.05 c·deg-1时,SVEP提示N100波振幅达到峰值。随着逐步增加刺激空间频率,SVEP振幅降低﹑潜伏期延迟,空间频率为0.65 c·deg-1时视皮层电反应几乎无法与噪点区分;6只小鼠右眼空间频率视力为(0.56±0.04)c·deg-1,左眼为(0.50±0.04)c·deg-1,两眼空间频率视力比较差异无统计学意义(P>0.05);12眼空间频率视力为(0.53±0.03)c·deg-1。结论 可以使用SVEP评估小鼠客观视力,此方法与行为方法测得的视力相近,但SVEP评估小鼠视力结果更为客观精确,所需时间更短。  相似文献   

8.
目的 研究传导性角膜成形术(CK)术后早期远近视力变化、暗视/明视下对比敏感度函数(CSF)变化及眩光刺激对CSF的影响,评估患者术后早期的视觉质量.方法 对24例有老视症状者单眼行CK治疗以改善近视力,其中11例伴轻度远视者另一眼同时手术以提高远视力,并分别于术前及术后1、3、6个月测量2种模拟背景光(暗视/明视)下的CSF和暗视/明视下有眩光刺激下的CSF. 结果 双眼术后各空间频率CSF较术前差异无统计学意义(P>0.05).双眼明视下手术前后眩光刺激对各空间频率的CSF差异均无统计学意义(P>0.05),暗视下眩光刺激明显降低了术后3个月的1.5、3、6个月1.5cpd的CSF(P<0.05).术眼暗视下术后1、3、6个月眩光刺激引起的CSF的降低在低频区(1.5cpd、3cpd),差异有统计学意义(P<0.05). 结论 CK术后,明视/暗视下各空间频率CSF均无明显变化.眩光刺激对CSF的影响主要集中在暗视下中、低频率.  相似文献   

9.
特发性视神经炎患者视力恢复后对比敏感度检测   总被引:2,自引:0,他引:2  
目的 探讨特发性视神经炎患者对比敏感度水平的变化规律.方法 病例对照研究.收集临床确诊的特发性视神经炎患者22例,经过不同时间的治疗视力恢复正常,神经系统MRI检查无异常.同时纳入24名健康人作为对照.采用OPTEC 6500型对比敏感度测试仪检测患眼5个空间频率的对比敏感度值,并进行统计学分析.组间相同频率间比较采用t检验或u检验,组内不同空间频率间比较采用方差分析或H检验,分析与年龄、病程和性别的关系时采用简单直线相关方法,并总结两组走行趋势.结果 特发性视神经炎组与埘照组远、近距离对比敏感度值最大均出现在6.0 c/d,分别为70.27±40.44、53.32±29.50及78.86±36.37、109.39±44.98.最小均出现在18.0 c/d,分别为8.27±6.11、12.09±8.57和15.67±9.02、22.22±14.56.视神经炎组在远、近距离的5个空间频率上的对比敏感度与对照组比较差异有统计学意义[空间频率从1.5至18.0 c/d,远距离t(u或t')值分别为4.19,5.59,3.06,2.50,3.13;P值分别为0.00,0.00,0.00,0.01,0.00.近距离t(u或t')值分别为3.54,3.98,2.72,3.20,3.39;P值分别为0.00,0.00,0.01,0.00,0.00],其水平与病程无关.两组内远、近距离不空间频率对比敏感度值比较,多数频率间的差异有统计学意义(视神经炎组远、近距离H值分别为52.38和64.96,对照组分别为64.77和60.53,P值皆<0.01).最大H值出现在视神经炎组的近距离.H值最大为64.96,出现在视神经炎组的近距离.特发性视神经炎组和对照组部分频率自身远、近距离对比敏感度值间的差异有统计学意义(空间频率南低到高,视神经炎组F值分别为6.36,0.03,2.52,1.53,2.90;P值分别为0.02,0.87,0.12,0.22,0.10.对照组F值分别为5.31,5.69,6.06,0.61,3.14;P值分别为0.03,0.02,0.02,0.44,0.08).结论 具有正常视力的视神经炎患者各频率对比敏感度值显著下降,对比敏感度可以作为评价特发性视神经炎后视觉质量的重要手段.  相似文献   

10.
目的 观察妊娠高血压疾病伴发眼底病变患者的对比敏感度(CS)恢复情况.方法 前瞻性队列研究.对98例妊娠高血压疾病患者(患者组)进行矫正视力、眼底、CS检查,随诊6个月,观察矫正视力、CS变化情况.选取同期在产科门诊就诊的50例无妊娠高血压孕妇作为正常对照组.2组的矫正视力和患者组的2种分娩方式下各空间频率CS比较采用两独立样本t检验进行分析.3个期别眼底病变各空间频率CS和随诊各时间段各空间频率的CS比较采用Kruskal-Wallis秩和检验,多组间两两比较采用Satterthwaite近似检验.结果 首诊时及随访6个月后患者组矫正视力均比正常对照组差(t=13.67、2.27,P<0.05).随着眼底病情的加重各空间频率CS值均下降(×2-93.35、88.28、89.73、102.48、102.26,P<0.01).随诊6个月,患者组各空间频率CS逐渐接近正常,至随访结束,除了空间频率6 c/d接近正常对照组(P>0.05)外,其他各空间频率仍较正常对照组有所降低(t=2.74、-5.42、-8.67、-4.60,P<0.01).随诊过程中,空间频率1.5 c/d的CS恢复最快,12 c/d恢复得最慢.患者组2种分娩方式下的各空间频率CS比较差异均无统计学意义(P>0.05).结论 妊娠高血压疾病患者眼底病情越重,CS下降越严重;低空间频率恢复最快,高空间频率恢复最慢;2种分娩方式对于患者CS的恢复没有影响.CS较视力检查可更好地反映妊娠高血压患者视网膜功能的情况.  相似文献   

11.
To design a Chinese characters reading acuity chart with high and low contrast by selecting some Chinese sentences that have the equal legibility as the optotypes. Methods Experimental study. Choose the sentences with the same legibility as the optotypes by the following steps: ①Standardizing the sentences: the length of the sentence was got statistically by calculating collected the sentences on the daily reading materials; based on the junior middle school Chinese teaching materials and within 2500 most common Chinese characters, 95 sentences were constructed in Chinese with the same length of words, highly comparable syntactical structure and the same lexical and grammatical difficulty. ②Psychophysical experimental method: choose those university students, with the best corrected far and near visual acuity of 1.0 or better, normal amplitude, no uncomfortable complaints recently as volunteers. Sentences were statistically selected and standardized in these volunteers. The optotypes were selected following the rule of the minimum scope and the maximum intersection of the reading speed and the total strokes of the sentences. The principles of international universal visual chart design were applied in designing the Page layout. With high (100%) and low (10%) contrast. Results 52 sentences with the same legibility were selected after the firstly standardized sentences and secondly psychophysical experimental method; the Chinese characters reading acuity chart with high and low contrast was designed by following the principles of International universal visual chart design. Conclusion The high and low contrast Chinese characters reading acuity chart, with the equal legibility optotypes, were designed scientifically, which hoped to be used in measuring reading acuity and assessing reading behavior etc.  相似文献   

12.
To test visual acuity in children, we developed a chart constructed so that the mean Fourier transform of the luminance of the figures on the chart at zero spatial frequency is the same as the background luminance. When the eye reaches its limit of resolution, the figures vanish into the gray background of the chart rather than becoming "blurred" as in conventional visual acuity charts. We compared the number of errors in determining the visual acuity of children aged 3-4.5 years using this high-frequency chart and a standard black-and-white high-contrast chart. Significantly fewer errors were found with the high-frequency chart, suggesting that this type of testing may improve the accuracy of visual acuity measurements in children.  相似文献   

13.
Purpose In order to compare the amplitude-spatial frequency (A-SP) regression method with amplitude-logVA (A-logVA) regression methods in extrapolating the sweep pattern visual evoked potential (SPVEP) acuity. Methods We measured SPVEPs in 21 children and three adults using sinusoidally-modulated horizontal gratings as stimuli. The responses were averaged and displayed through discrete Fourier transformations. SPVER acuity was then estimated by using both the SPVEP amplitude- spatial frequency function (A-SP function regression method) and the SPVEP amplitude-log visual-angle function (A-logVA function regression method). Furthermore, the Bailey Lovie logMAR chart was employed to define visual acuity. Curve estimates were calculated to derive a correlation index (R) for each method. Results There are significant differences (t = 2.71, P < 0.05) between the correlation indices of curves obtained using the A-logVA function (logarithmic model, 0.95 +/- 0.01) and that obtained by the A-SP function (inverse model, 0.92 +/- 0.02). The overall correlation coefficient (r) between logMAR acuity and acuity calculated by the A-logVA regression method was 0.32 (P < 0.05). The overall correlation coefficient (r) between logMAR acuity and acuity calculated by the A-SP regression method was 0.41 (P < 0.05). Paired t-tests show that SPVEP acuity from the A-logVA function was not significantly different from acuities of the logMAR function (t = 1.77, P = 0.09). The difference in their mean values is 0.14 +/- 0.08. However, SPVEP acuity calculated using the A-SP function regression method is significantly different from the acuity calculated from the logMAR function (t = 10.09, P < 0.01). The difference in their mean values is 0.41 +/- 0.04. Conclusions The amplitude-logVA function regression method is more accurate in estimating SPVEP acuity in normal subjects with good visual acuity.  相似文献   

14.
PURPOSE: Written Chinese contains an enormous number of characters with a wide range of spatial complexities. Consequently, the legibility of Chinese characters is expected to vary significantly, and this variability offers the challenge of deriving a simple visual function measurement for the Chinese reading population. The purpose of this study was to suggest a solution to the challenge through psychophysical studies of Chinese character legibility. METHODS: To illustrate legibility variations in Chinese characters, visual acuities for six groups of Chinese characters from low to high spatial complexities and one group of Sloan letters were determined in six normal-sighted Chinese observers. The relationship between legibility and optical defocus were then determined for the Landolt C, the Snellen E, and three groups of Chinese characters representing low, medium, and high spatial complexities in 26 normal-sighted Chinese readers. RESULTS: The acuity size of Chinese characters increased steadily with stimulus complexity, though at a slower rate than would be expected if visual acuity were based on the finest details of the stimuli. The acuity size versus optical defocus functions of three Chinese character groups and the Snellen E had similar slopes and differed only by a vertical shift, depending on the optotype spatial complexity. The function of the Landolt C was significantly steeper. CONCLUSIONS: The findings indicate that visual acuity assessment in Chinese readers is complicated by the spatial complexity of Chinese characters, but the fact that the Snellen E, which is the current national standard of acuity measurement in China, and Chinese characters showed similar dependence on optical defocus may indicate a potentially valid way to infer functional vision in Chinese readers with Snellen E acuity.  相似文献   

15.
PURPOSE: To compare the sensitivity and specificity of a widespread method of screening for refractive errors in Singapore schoolchildren using a simplified acuity screening chart with a more rigorous method using the Early Treatment Diabetic Retinopathy Study (ETDRS) chart. A secondary aim is to estimate the best cutoff values for the detection of refractive errors using these two methods. METHODS: This is a population-based study, involving 1779 schoolchildren from three schools in Singapore. Logarithm of the minimum angle of resolution (logMAR) visual acuity was recorded using a modified Bailey-Lovie chart by trained optometrists, and visual acuity measurement was also undertaken using a simplified 7-line visual acuity screening chart by school health nurses. The main outcome measures were the receiver-operating characteristics (ROC's) of logMAR and the simplified screening visual acuity to detect myopia or any refractive errors. The difference between measurements, simplified screening visual acuity--logMAR visual acuity, was calculated. RESULTS: The optimal threshold using the simplified screening visual acuity chart for the detection of myopia or any refractive error was 6/12 or worse. Using logMAR visual acuity, the most efficient threshold for the detection of myopia was 0.26, but this was 0.18 for the detection of any refractive error. The area under the ROC curves was significantly greater in the case of the logMAR visual acuity measurement compared with the simplified screening visual acuity measurement for the detection of myopia or any refractive errors. The 95% limits of agreement for the two methods (simplified screening--logMAR acuity) was -0.219 to +0.339. CONCLUSIONS: Bearing in mind that the visual acuity measurements were performed by two different groups of professionals, visual acuity screening using the ETDRS method appears to be more accurate than the simplified charts for the detection of myopia or any refractive errors in children.  相似文献   

16.
目的:分析智能视力表投影仪在视力检查中的可重复性及其与传统视力表测量结果的比较。方法:系列病例研究。收集2022年1月4—22日在首都医科大学附属北京同仁医院就诊的眼部不适患者60例(120眼)。先通过智能视力表投影仪(LSJ-IVAC-6000A)对患者进行3次视力检测,并采用组内相关系数(ICC)评价3次测量结果之间的可重复性;再用传统灯箱的国家标准视力表测量1次,并分别采用ICC和Bland-Altman图表法分析智能视力表投影仪与传统视力表检测结果的一致性。结果:同一受检者右眼、左眼使用智能视力表投影仪测量3次的ICC值分别为0.830和0.868,双眼的ICC值均>0.8(P<0.001);同一受检者右眼、左眼使用智能视力表投影仪和传统灯箱的国家标准视力表测量的ICC值分别为0.846和0.873,双眼的ICC值均>0.8(P<0.001)。右眼、左眼使用智能视力表投影仪和传统灯箱的国家标准视力表测量差值的95%一致性界限分别为-0.25~0.20和-0.24~0.17。结论:智能视力表投影仪的可重复性较好,与传统灯箱的国家标准视力表的测量结果相比一致性较强,应用于临床工作中可提高视力筛查的效率并节省人力和物力。  相似文献   

17.
PURPOSE: To develop software to measure the severity of posterior capsule opacification (PCO) using analysis of retroillumination images and to correlate the results with clinical evaluation of PCO severity and visual function. SETTING: Department of Physics, King's College, and Department of Ophthalmology, St. Thomas' Hospital, London, United Kingdom. METHODS: A technique for calculating PCO severity was developed based on calculating the variance of intensity by transforming retroillumination images to a similar mean intensity. The computer-derived severity was compared to grading of clinical severity by 3 independent observers using a library of 100 retroillumination images ranging from clear posterior capsules to very severe PCO. The computer results were also compared with the following other current methods of measuring PCO: Evaluation of Posterior Capsule Opacification (EPCO), POCOman, and Automated Quantification of After-Cataract. A further 35 images were used to compare the results of computer-derived severity with the results of visual function analysis (high-contrast acuity, 100%; low-contrast acuity, 9%) using the Early Treatment Diabetic Retinopathy Study chart, contrast sensitivity testing using the Pelli-Robson chart, and glare assessment using the van den Berg straylight meter. RESULTS: The severity scores showed a good correlation with clinical severity scores for the library of images (r=0.86) and with severity scores using POCOman and EPCO (r=0.85 and r=0.81, respectively). The correlations with visual function tests were also good, with low-contrast visual acuity (9%) showing the best correlation (r=0.87). CONCLUSION: Variance in intensity of PCO was successfully used to calculate the severity of PCO.  相似文献   

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