非缺血型视网膜中央静脉阻塞的临床特点研究

目的 探讨非缺血型视网膜中央静脉阻塞(CRVO)患者在≤40岁和＞40岁年龄组中的发病特点和发病危险因素及其视力预后.方法 回顾性系列病例研究.将随访6个月以上的非缺血型CRVO患者按年龄分为≤40岁和＞40岁组两组,对其临床资料进行回顾性分析,包括矫正视力、眼底彩色照像及荧光素眼底血管造影检测资料等.结果 共148例(151只眼)CRVO患者,随访时间6个月至15年,平均1年零5个月.其中≤40岁组39例(40只眼),发病年龄15～40岁,平均27岁;男性20例(20只眼),占51%;女性19例(20只眼),占49%.＞40岁组共109例(111只眼),发病年龄41～76岁,平均57岁;男性53例(54只眼),占49%;女性56例(57只眼),占51%.≤40岁组中,仅有2例患者有高血压病史,无其他全身疾病;而＞40岁组中,40%以上的患者合并有全身疾病史(包括高血压和糖尿病等).两组患者初诊视力差异无统计学意义(Pearson检验,x2=0.087,P=0.769).但两组间末诊视力差异有统计学意义Pearson检验,x2=4.692,P=0.047);其中≤40岁组中,有18只眼视力≥0.3(45%);＞40岁组中,有25只眼视力≥0.3(23%).＞40岁组中发生并发症的患者较≤40岁组中明显增多,两组间差异有统计学意义(Pearson检验,x2=8.763,P=0.006).结论 高血压或糖尿病等全身性疾病为＞40岁组患者CRVO的致病危险因素,但对视力预后无明显影响.≤40岁组患者较少发生并发症,视力预后虽然较＞40岁组者佳,但仍有35%的患者末诊视力≤0.1.相比之下＞40岁组患者视力预后较差,发生并发症者较多.两组患者均需积极治疗.     

年龄相关性黄斑变性及息肉状脉络膜血管病变患者房水中不同亚型VEGF含量的测定

背景 息肉状脉络膜血管病变（PCV）是湿性年龄相关性黄斑变性（nAMD）的一个亚型还是独立于nAMD一种病变目前仍有不同的观点,而两种疾病的治疗效果可能不同.抗血管内皮生长因子（VEGF）在nAMD的治疗中发挥重要作用,但由VEGF可变剪切而产生的促新生血管生成VEGF（VEGFxxx）家族和抑新生血管VEGF（VEGFxxxb）家族,两者功能相反,其在nAMD和PCV中的表达及作用尚不清楚. 目的 检测和比较VEGFxxx家族和VEGFxxxb家族在nAMD患者和PCV患者房水中的变化及其意义. 方法 收集2013年3-12月在北京大学人民医院眼科确诊的nAMD患者34例及PCV患者26例,同期纳入16例年龄相关性白内障患者作为对照.收集被检者前房水0.1 ml,采用酶联免疫吸附试验（ELISA）测定前房水中VEGF及VEGF165b质量浓度,比较3组患者房水中VEGF及VEGF165b质量浓度的差异. 结果 nAMD组、PCV组、对照组患者房水中VEGF质量浓度分别为（4 210.00±998.40）、（387.00±51.31）和（377.40±69.97） pg/ml,组间总体差异有统计学意义（F=12.851,P=0.000）.nAMD组、PCV组、对照组VEGF165b质量浓度分别为（205.50±12.59）、（159.40± 16.25）、（347.90±29.18） pg/ml,组间总体比较差异有统计学意义（F=23.752,P=0.000）.与对照组比较,nAMD组患眼房水中VEGF质量浓度升高,VEGF165b质量浓度下降,PCV组患眼房水中VEGF165b表达下降,差异均有统计学意义（均P=0.000）,但PCV组与对照组患眼房水中VEGF含量差异无统计学意义（P=0.992）.nAMD组较PCV组房水中VEGF质量浓度升高,差异有统计学意义（P=0.001）,但两组间VEGF165b质量浓度差异无统计学意义（P=0.097）. 结论 nAMD患者前房水中的VEGF质量浓度明显高于PCV患者和年龄相关性白内障患者,nAMD患者与PCV患者房水中VEGF165b质量浓度接近,但均低于年龄相关性白内障患者,说明VEGF165b质量浓度的相对下降与nAMD和PCV的发生和发展密切相关.     

254例息肉样脉络膜血管病变的临床特征分析

目的 观察息肉样脉络膜血管病变(PCV)的临床特征.方法 回顾性分析254例临床确诊的PCV患者306只眼的临床资料.所有患者均行矫正视力、裂隙灯显微镜、间接检眼镜、眼底彩色照相、荧光素眼底血管造影、吲哚青绿血管造影以及光相干断层扫描检查(OCT).结果 254例患者中,男性152例,占59.8％;女性102例,占40.2％.年龄38～91岁,平均年龄(65.4±8.9)岁.双眼52例,占20.5％;单眼202例,占79.5％.患眼矫正视力无光感～1.2.其中,矫正视力＜0.1者167只眼,占54.6％;≥0.1且＜0.3者92只眼,占30.1％;≥0.3者47只眼,占15.4％.有玻璃体积血61只眼,占19.9％.202例单眼PCV患者中,另眼可见玻璃膜疣68例,占33.7％;渗出型老年性黄斑变性24例,占11.9％;对侧眼有中心性浆液性脉络膜视网膜病变病史9例,占4.5％.306只眼中,可见脉络膜高通透性表现43只眼,占14.1％.PCV病变位于黄斑区下1 99只眼,占65.0％;颞侧视网膜血管弓下49只眼,占16.0％;视盘旁15只眼,占4.9％.形态表现为孤立样110只眼,占35.9％;簇样176只眼,占57.5％;串样3只眼,占1.0％;分支样4只眼,占1.3％;既有孤立样同时也有簇样13只眼,占4.2％.存在神经视网膜下液性暗区125只眼,占40.8％;出血性视网膜色素上皮脱离121只眼,占39.5％;浆液性视网膜色素上皮脱离73只眼,占22.9％.结论 PCV双眼发病率、女性患病比例较高;病灶位于视盘旁比例较低.     

20G与23G玻璃体切割手术治疗感染性眼内炎临床效果分析

目的 比较20G与23G玻璃体切割手术治疗感染性眼内炎的疗效和安全性.方法 回顾性病例研究.有外伤史或内眼手术史,经最佳矫正视力、眼压、裂隙灯显微镜、间接检眼镜、B型超声及CT检查确诊的感染性眼内炎患者67例67只眼纳入本研究.其中,男性49例49只眼,女性18例18只眼.年龄18～72岁,平均年龄(43±13)岁.外伤史60例60只眼,内眼手术后7例7只眼.因仪器拥有与否之原因分为20G玻璃体切除手术组(20G组)和23G玻璃体切除手术组(23G组).前者35例35只眼,后者32例32只眼.两组患者手术开始时常规抽取脓性玻璃体液作细菌和真菌培养以及药物敏感试验.手术中均行人工玻璃体后脱离,切除大部分玻璃体,酌情行内界膜剥离和(或)眼内激光光凝、冷冻治疗并联合眼内填充硅油或气体.手术后全身应用广谱抗生素及适量糖皮质激素1周,真菌感染者忌用糖皮质激素.随访2～9个月,平均随访时间(7±1)个月.对比分析两组患者手术时间、手术后炎症控制情况、手术后视力、眼压变化,视网膜复位率,医源性视网膜裂孔发生率,球结膜瘢痕形成率,再次手术及最终眼球保存情况等,比较两组治疗效果差异.结果 手术时间,20G组83～165 min,平均时间(126±12) min,23G组65～125 min,平均时间(89±12)min;两组间手术时间比较,差异有统计学意义(t=3.125,P＜0.05).手术中主要并发症为锯齿缘离断或其它医源性视网膜裂孔,共34只眼,其中,20G组30只眼,占85.71％;23G组4只眼,占12.50％(x2=35.85,P＜0.05),均为异物取出患眼.67只眼中65只眼眼内炎得到控制,治疗成功率97.01％.其中,20G组34只眼,治疗成功率97.14％;23G组31只眼,治疗成功率96.88％.两组治疗成功率比较,差异无统计学意义(x2=0,004,P＞0.05).末次随访时,两组患者视力比较,差异无统计学意义(t=3.12,P＞0.05).硅油填充共14只眼,其中,20G组13只眼,硅油填充率37.14％;23G组1只眼,硅油填充率3.13％.两组硅油填充率比较,差异有统计学意义(x2=11.703,P＜0.05).再手术眼共9只眼,均为再次手术行硅油填充,占13.43％.其中,20G组8只眼,再手术率22.86％;23G组1只眼,再手术率3.13％.两组再手术率比较,差异有统计学意义(x2=5.597,P＜0.05).再手术眼中,20G组中感染复发1只眼,手术后视网膜脱离7只眼,23G组中感染复发1只眼.手术后两组的视网膜脱离发生率比较,差异有统计学意义(x2=7.147,P＜0.05).球结膜瘢痕形成共40只眼,其中,20G组35只眼,占100.00％,均为切口处球结膜维痕形成;23G组5只眼,占15.63％,均为原有外伤所致.结论 20G与23G玻璃体切割手术均能有效控制感染性眼内炎,但是在缩短手术时间、减少再手术率、降低手术后视网膜脱离和瘢痕形成发生率等方面,23G玻璃体切除手术系统有着明显的优势.     

伴发视网膜病变的系统性红斑狼疮患者的临床特征

[目的]观察伴发视网膜病变的系统性红斑狼疮(SLE)患者的临床特征.[方法]采用临床对比研究方法.临床确诊为SLE的97例患者纳入本研究.根据眼底检查结果分为视网膜病变组(阳性组)和无视网膜病变组(阴性组).其中,阳性组23例32只眼,阴性组74例148只眼.对比分析两组患者年龄、病程、临床表现、实验室检查结果的异同.[结果]SLE患者中视网膜病变阳性率为23.7％.阳性组中17例22只眼视网膜可见不同程度的棉绒斑、出血、静脉纡曲扩张、动脉痉挛、微动脉瘤、硬性渗出,占阳性例数的73.9％其余6例10只眼以视网膜大血管阻塞为主要表现,占阳性例数的26.1％.阳性组患者皮疹、皮肤血管炎、血红细胞沉降率(ESR)升高、补体C3下降、抗双链DNA(ds-DNA)抗体阳性的发生率较阴性组患者高,相关指标比较,差异均有统计学意义(x2 =9.206,6.987,7.824,8.581,6.599;P＜0.05).阳性组与阴性组患者之间年龄、病程、黏膜溃疡、关节炎、发热、头痛、白细胞减少、血小板减少、蛋白尿≥+++、血尿素氮升高、肌酐升高、抗核抗体(ANA)阳性、抗Sm抗体阳性的发生率相比较,差异无统计学意义(t=0.321,0.063;x2 =0.135,0.046,0.176,0.002,0.036,0.113,0.053,0.032,0.012,0.000,0.004;P＞0.05).[结论]伴发视网膜病变的SLE患者眼底主要表现为静脉纡曲扩张、棉绒斑和视网膜大血管阻塞.皮疹、皮肤血管炎、ESR升高、补体C3下降、抗ds-DNA抗体阳性是伴发视网膜病变的SLE患者的主要临床特征.     

362例息肉样脉络膜血管病变患者的临床特征分析

目的 观察华中地区息肉样脉络膜血管病变(PCV)患者的临床特征.方法 经眼底检查、荧光素眼底血管造影(FFA)、吲哚青绿血管造影(ICGA)和光相干断层扫描(OCT)检查确诊为PCV的362例患者403只眼纳入研究.回顾分析最佳矫正视力(BCVA)、眼底表现、影像学检查结果等临床特征.结果362例患者中,男性249例,占68.8％;女性113例,占31.2％.年龄45～91岁,平均年龄(64.81±9.31)岁.双眼发病41例,占11.3％;单眼发病321例,占88.7％.BCVA手动～1.2.403只眼中,眼底可见典型橘红色病灶162只眼,占40.2％;黄白色渗出185只眼,占45.9％;面积较大的不同程度视网膜下出血268只眼,占66.5％;玻璃膜疣23只眼,占5.7％;色素增生20只眼,占5.0％;纤维血管性瘢痕96只眼,占23.8％.PCV病灶位于黄斑区386只眼,占95.8％;位于视盘周53只眼,占13.2％;PCV病灶呈多灶性67只眼,占16.6％.病灶呈囊袋样荧光积存304只眼,占75.4％;脉络膜异常血管网152只眼,占37.7％.出血性视网膜色素上皮脱离(PED) 200只眼,占49.6％;浆液性PED 96只眼,占23.8％;同时存在出血性及浆液性PED 25只眼,占6.2％.视网膜神经上皮层间囊样暗腔56只眼,占13.9％;视网膜色素上皮与Bruch膜层分离,出现“双层征”109只眼,占27.0％.RPE层下穹窿状隆起274只眼,占68.0％;神经上皮层脱离151只眼,占37.6％.结论 华中地区PCV患者单眼发病率、男性患病率较高;病灶绝大多数位于黄斑区,眼底多可见视网膜下出血、息肉样病灶及脉络膜异常血管网,出血性PED比例较浆液性PED高.     

息肉样脉络膜血管病变的分类与视力改变

目的 了解不同类型息肉样脉络膜血管病变(PCV)患者视力改变情况.方法 收集经眼底彩色照相、荧光素眼底血管造影、吲哚青绿血管造影(ICGA)以及光相干断层扫描检查确诊的67例PCV患者68只眼的临床资料.根据PCV的活动性与病理特征分为静止性、渗出性和出血性PCV;根据ICGA检查中息肉样病灶的形态特征以及是否合并分支状脉络膜血管网(BVN)分为葡萄状病灶型、单个病灶型和合并BVN的混合病灶型PCV;根据息肉样病灶分布部位分为黄斑区、血管弓区、视盘旁区、中周部和混合区PCV.观察各组的视力情况.结果 静止性、渗出性、少量出血性、多量出血性PCV分别有16、19、19、14只眼,其平均最小分辨角对数(logMAR)视力分别为0.34±0.52、0.70±0.98、0.60±0.50、0.91±0.75.静止性PCV患眼平均视力显著优于渗出性、少量出血性与多量出血性PCV患眼,组间比较,差异有统计学意义(q＝4.75、4.26、5.13,P＜0.05).渗出性PCV与少量出血性PCV患眼平均视力比较,差异没有统计学意义(q=0.98,P＞0.05).葡萄状病灶型、单个病灶或多处单个病灶型、合并BVN的混合病灶型PCV分别有22、38、8只眼,其平均logMAR视力分别为0.52±0.55、0.59±0.43、0.80±0.95.伴有BVN的混合病灶型PCV患眼平均视力显著差于葡萄状病灶型和单个病灶或多处单个病灶型PCV患眼,组间比较,差异有统计学意义(q=3.81、3.02,P＜0.05).黄斑区、血管弓区、视盘旁区、混合区PCV分别有34、1 3、8、13只眼,其平均logMAR视力分别为0.78±0.43、0.57±0.37、0.38±0.27、0.74±0.41.黄斑区PCV患眼平均视力差于血管弓区与视盘旁区PCV患眼,组间比较,差异有统计学意义(q=4.61、5.11,P＜0.05);黄斑区PCV与混合区PCV患眼平均视力比较,差异无统计学意义(q=0.73,P＞0.05).结论 PCV患者视力改变情况不一,且与PCV的活动性与病理特征、息肉样病灶的形态特征和分布部位以及是否合并BVN有关.     

极高度近视黄斑裂孔性视网膜脱离手术后C3F8与硅油填充的疗效比较

目的 比较极高度近视黄斑裂孔性视网膜脱离(MHRD)手术后C3F8与硅油填充的疗效.方法 眼轴长度≥29 mm,视网膜色素上皮(RPE)及脉络膜明显萎缩及存在明显巩膜后葡萄肿的极高度近视MHRD住院患者32例32只眼纳入研究.采用随机数字表法将患眼随机分为C3F8组、硅油组,分别为15、17只眼.所有患者均行玻璃体切割手术,手术完毕时C3F8组患眼眼内填充C3F8,硅油组患眼眼内填充硅油.手术后发生视网膜再脱离者行再次手术.C3F8组、硅油组患者性别(P=1.000)、年龄(t=0.444,P=0.660)、最佳矫正视力(t=0.084,P=0.934)、屈光度(t=0.449,P=0.978)、晶状体状态(P=1.000)、症状出现时间(t=0.375,P=0.710)及视网膜脱离程度(x2=0.014,P=0.907)比较,差异均无统计学意义.手术后1周及1、3、6、12个月,观察患者视网膜复位、黄斑裂孔闭合及并发症的发生情况.对比分析两组患者视网膜复位率、黄斑裂孔闭合率及视力情况.结果 第1次手术后,C3F8组、硅油组视网膜复位率分别为60.00％、82.35％,黄斑裂孔闭合率分别为13.33％、29.41％.两组第1次手术后视网膜复位率、黄斑裂孔闭合率比较,差异均无统计学意义(P=0.243、0.402).第2次手术后,C3F8组、硅油组视网膜复位率分别为86.67％、94.12％,黄斑裂孔闭合率分别为20.00％、29.41％.两组第2次手术后视网膜复位率、黄斑裂孔闭合率比较,差异均无统计学意义(P=0.589、0.691).手术后12个月,C3F8组视力提高5只眼,视力不变7只眼,视力下降3只眼;硅油组视力提高7只眼,视力不变8只眼,视力下降2只眼.两组视力情况比较,差异无统计学意义(x2 =0.209,P=0.647).结论 极高度近视MHRD患眼手术后硅油填充较C3F8填充视网膜复位率及黄斑裂孔闭合率高,但差异无统计学意义.     

糖尿病与非糖尿病患者白内障术后黄斑水肿分析

目的 通过比较糖尿病患者与非糖尿病患者白内障术后发生黄斑水肿(ME)的差异,探讨差异产生的原因.方法 前瞻性研究.选取2011年4月至2013年5月于北京大学眼科中心行白内障超声乳化+人工晶状体植入术患者112例175只眼,其中糖尿病患者72只眼,非糖尿病患者103只眼.主要检测指标是两组术前、术后1月及术后3月的最佳矫正视力(BCVA)及黄斑中心亚区域平均厚度(CSMT).结果 非糖尿病组术前、术后1月及术后3月BCVA均明显好于糖尿病组,差异有统计学意义(t =-2.237,P=0.027;t=-2.504,P=0.013;t=-2.233,P=0.027).非糖尿病组术前、术后1月及术后3月CSMT均明显低于糖尿病组,差异有统计学意义(t=-2.200,P=0.029;t =-3.906,P=0.000;t=-3.399,P=0.001).术后1月非糖尿病组发生黄斑水肿为1只眼(0.97％1/103),糖尿病组黄斑水肿为9只眼(12.5％ 9/72),差异有统计学意义(x2=10.455,P=0.001);术后3月非糖尿病组发生黄斑水肿为1只眼(0.97％1/103),糖尿病组黄斑水肿为6只眼(8.33％ 6/72),差异有统计学意义(x2=5.982,P=0.014).黄斑水肿与糖尿病视网膜病变严重程度相关(P =0.015).结论糖尿病患者行白内障超声乳化术后黄斑水肿的发生率高,糖尿病视网膜病变的严重程度是主要影响因素.     

23G和20G玻璃体手术治疗增生型糖尿病视网膜病变的对比观察

目的 对比观察20G和23G玻璃体手术治疗增生型糖尿病视网膜病变(PDR)的临床效果.方法 前瞻性随机对照研究.具有玻璃体手术指征的PDR患者126例142只眼纳入研究.所有患者均行视力、眼压、间接检眼镜、眼B型超声、泪膜破裂时间(BUT)、基础泪液分泌试验(SIT)以及角膜前后表面6 mm区域散光度、散光轴向检查.采用随机数字表法,将患者分为20G手术组和23G手术组,分别为66例74只眼和60例68只眼.手术后平均随访时间,20G手术组15.0个月,23G手术组12.5个月;以手术后6个月为评价两组疗效的时间点.对比分析两组患者手术中并发症、手术时间以及手术后视力、眼压、并发症及BUT、SIT、角膜前后表面散光度和散光轴向变化.结果 手术后6个月随访时,20G手术组74只眼中,视力≥0.05者49只眼,占本组患眼的66.2％;23G手术组68只眼中,视力≥0.05者47只眼,占本组患眼的69.1％.两组间视力≥0.05者比较,差异无统计学意义(x2=0.14,P＞0.05).20G手术组、23G手术组,手术中发生医源损伤18、7只眼,分别占本组患眼的24.3％、10.3％.两组间手术中医源性损伤发生率比较,差异有统计学意义(x2=4.81,P＜0.05).20G手术组、23G手术组平均手术时间分别为(69.0±8.2)、(51.0±6.3)min.两组间平均手术时间比较,差异有统计学意义(t=3.65,P＜0.05).手术后3d,20G手术组、23G手术组发生低眼压3、11只眼,分别占本组患眼的4.1％、14.7％.两组间低眼压发生率比较,差异有统计学意义(x2=5.85,P＜0.05).20G手术组、23G手术组发生高眼压或继发性青光眼24、14只眼,分别占本组患眼的32.4％、20.6％,两组间手术后高眼压或继发性青光眼发生率比较,差异无统计学意义(x2=2.54,P＞0.05).手术后1个月,20G手术组BUT、SIT长度、角膜前后表面散光度、散光轴向与手术前相应检测指标比较,差异均有统计学意义(t=3.35,4.12,-3.12,-3.22;P＜0.05);手术后3、6个月BUT、SIT长度、角膜前后表面散光度、散光轴向与手术前相应检测指标比较,差异均无统计学意义(3个月:t=0.45、0.98、-2.12、-1.02,P＞0.05;6个月:t=0.95、1.48、-1.02、-2.11,P＞0.05).手术后1、3、6个月,23G手术组BUT、SIT长度、角膜前后表面散光度、散光轴向与手术前相应检测指标比较,差异均无统计学意义(1个月:t=1.21、1.46、-2.32、-1.61,P＞0.05;3个月:t=1.45、2.21、-2.19、-1.89,P＞0.05;6个月:t=1.92、1.25、-1.75、-2.35,P＞0.05).结论 23G微创玻璃体手术治疗PDR安全有效,可缩短手术时间,减少手术并发症,减轻手术后眼表改变.     

Segmentation and accuracy in copying and drawing: Experts and beginners

As part of an ongoing investigation into real-world copying and drawing, I recorded the eye-hand drawing strategies of 16 subjects with drawing experiences ranging from expert to novice while they copied a line drawing of a standing nude. The experts produced accurate copies whereas all the beginners produced marked inaccuracies of overall scaling, proportion and shape. Analysis of eye and hand movements showed that the experts alone segmented the original drawing into simple line sections that were copied one at a time using a direct eye-hand strategy not requiring intermediary encoding to visual memory. The results suggest that segmentation into simple lines defines the task-specific process of accurate copying, and that this process is restricted to experts, i.e. acquired through training and practice. Additional preliminary tests also suggest that a similar process may apply to drawing a model from life.     

Paraneoplastic and non-paraneoplastic retinopathy and optic neuropathy: Evaluation and management

Paraneoplastic syndromes involving the visual system are a heterogeneous group of disorders occurring in the setting of systemic malignancy. Timely recognition of one of these entities can facilitate early detection and treatment of an unsuspected, underlying malignancy, sometimes months before it would have otherwise presented, and gives the patient an increased chance at survival. We outline the clinical features, pathogenesis, and treatment strategies for the retinal- and optic nerve–based paraneoplastic syndromes: cancer-associated retinopathy; melanoma-associated retinopathy; paraneoplastic vitelliform maculopathy; bilateral diffuse uveal melanocytic proliferation; paraneoplastic optic neuropathy; and polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes syndrome. Distinguishing these disorders from their non-paraneoplastic counterparts (e.g., autoimmune-related retinopathy and optic neuropathy, and acute zonal occult outer retinopathy) and determining appropriate systemic evaluation for the responsible tumor can be challenging. In addition, we discuss the utility and interpretation of autoantibody testing.     

Nodes and nodal points and lines in eyes and other optical systems

The typical stigmatic optical system has two nodal points: an incident nodal point and an emergent nodal point. A ray through the incident nodal point emerges from the system through the emergent nodal point with its direction unchanged. In the presence of astigmatism nodal points are not possible in most cases. Instead there are structures, called nodes in this paper, of which nodal points are special cases. Because of astigmatism most eyes do not have nodal points a fact with obvious implications for concepts, such as the visual axis, which are based on nodal points. In order to gain insight into the issues this paper develops a general theory of nodes which holds for optical systems in general, including eyes, and makes particular allowance for astigmatism and relative decentration of refracting elements in the system. Key concepts are the incident and emergent nodal characteristics of the optical system. They are represented by 2 × 2 matrices whose eigenstructures define the nature and longitudinal position of the nodes. If a system's nodal characteristic is a scalar matrix then the node is a nodal point. Otherwise there are several possibilities: Firstly, a node may take the form of a single nodal line. Second, a node may consist of two separated nodal lines reminiscent of the familiar interval of Sturm although the nodal lines are not necessarily orthogonal. Third, a node may have no obvious nodal line or point. In the second and third of these classes one can define mid-nodal ellipses. Astigmatic systems exist with nodal points and stigmatic systems exist with no nodal points. The nodal centre may serve as an approximation for a nodal point if the node is not a point. Examples in the Appendix , including a model eye, illustrate the several possibilities.     

Sensitivity to first- and second-order motion and form in children and adults

We compared the sensitivity of adults and children aged 3-10 years to first- and second-order motion and form. For first-order stimuli, at all ages sensitivity was better for motion than form, and motion thresholds were better at 6 Hz than at 1.5 Hz. For second-order stimuli, at all ages sensitivity was better for form than motion, and motion thresholds were better at 0.25 cyc/deg than at 1 cyc/deg. Thresholds became adult-like later for motion than for form and later for first-order than second-order stimuli. For first-order stimuli, the changes with age were larger and more protracted.     

Ethics and optometry: concepts and applications

Ethics refers both to the study of behaviour, and moral principals. The related concepts of justice and law are also relevant to optometry. A profession typically claims specialist knowledge and ethical behaviour – putting the interests of clients above its own. However, professional codes fail as ethical directives, and their goals are questioned. Beginning with broad principles, institutional ethics and issues of general health care provision are considered, and applications to optometry are made. Ethical theory can guide us in interacting with our patients, utilising resources and ordering priorities. The conservative approach to consumerism and advertising is defended on the basis of protecting public and professional interests. Ethical behaviour can be fostered, and this process should begin in undergraduate education.     

Nutritional antioxidants and age-related cataract and maculopathy

Loss of vision is the second greatest, next to death, fear among the elderly. Age-related cataract (ARC) and maculopathy (ARM) are two major causes of blindness worldwide. There are several important reasons to study relationships between risk for ARC/ARM and nutrition: (1) because it is likely that the same nutritional practices that are associated with prolonged eye function will also be associated with delayed age-related compromises to other organs, and perhaps, aging in general, (2) surgical resources are insufficient to provide economic and safe surgeries for cataract and do not provide a cure for ARM, and (3) there will be considerable financial savings and improvements in quality of life if health rather than old age is extended, particularly given the rapidly growing elderly segment of our population. It is clear that oxidative stress is associated with compromises to the lens and retina. Recent literature indicates that antioxidants may ameliorate the risk for ARC and ARM. Given the association between oxidative damage and age-related eye debilities, it is not surprising that over 70 studies have attempted to relate antioxidant intake to risk for ARC and ARM. This article will review epidemiological literature about ARC and ARM with emphasis on roles for vitamins C and E and carotenoids. Since glycation and glycoxidation are major molecular insults which involve an oxidative stress component, we also review new literature that relates dietary carbohydrate intake to risk for ARC and ARM. To evaluate dietary effects as a whole, several studies have tried to relate dietary patterns to risk for ARC. We will also give some attention to this emerging research. While data from the observational studies generally support a protective role for antioxidants in foods or supplements, results from intervention trials are less encouraging with respect to limiting risk for ARC/ARM prevalence or progress through antioxidant supplementations, or maintaining higher levels of antioxidants either in diet or blood. Without more information it is difficult to parse these results. It would be worthwhile to determine why the various types of studies are not yielding similar results. However, there are many common insults and mechanistic compromises that are associated with aging, and proper nutrition early in life may address some of these compromises and provide for extended youthful function later in life. Indeed, proper nutrition, possibly including use of antioxidant supplements for the nutritionally impoverished, along with healthy life styles may provide the least costly and most practical means to delay ARC and ARM. Further studies should be devoted to identifying the most effective strategy to prevent or delay the development and progress of ARC/ARM. The efforts should include identifying the right nutrient(s), defining useful levels of the nutrient(s), and determining the age when the supplementation should begin.     

Exogenous attention and color perception: performance and appearance of saturation and hue

Exogenous covert attention is an automatic, transient form of attention that can be triggered by sudden changes in the periphery. Here we test for the effects of attention on color perception. We used the methodology developed by Carrasco, Ling, and Read [Carrasco, M., Ling, S., & Read, S. (2004). Attention alters appearance. Nature Neuroscience, 7 (3) 308-313] to explore the effects of exogenous attention on appearance of saturation (Experiment 1) and of hue (Experiment 2). We also tested orientation discrimination performance for single stimuli defined by saturation or hue (Experiment 3). The results indicate that attention increases apparent saturation, but does not change apparent hue, notwithstanding the fact that it improves orientation discrimination for both saturation and hue stimuli.     

晶状体细胞与信号转导和通讯

细胞信号转导和通讯在维持细胞的正常发育、增殖、分化、代谢及死亡中起到关键作用,是近几年研究的热点。本文对晶状体细胞信号转导系统中的信号、受体、主要转导通路和细胞通讯,以及它们的异常与白内障的关系进行综述,以期对白内障的发病机制作深入研究,为白内障的药物防治提供新的研究方向。