头位倾斜对黄斑中心凹-视盘中心夹角度数的影响

目的探讨头位倾斜对于黄斑中心凹-视盘中心夹角（FDA）度数的影响。方法自身对照研究。使用3D OCT-1000对26例（52眼）非斜视受检者分别拍摄正位、头右倾30°、头左倾30°时眼底照片,并用CorelDRAW X4绘图软件测量照片中FDA度数。数据进行t检验、方差分析及线性回归分析。结果FDA度数：右眼头右倾时为13.53°±3.36°,正位时为6.56°±2.28°,头左倾时为-0.53°±3.88°,三者差异具有统计学意义（F=115.866,P＜0.05）;左眼头右倾时为1.08°±3.31°,正位时为7.31°±2.80°,头左倾时为13.45°±3.44°,差异具有统计学意义（F=98.437,P＜0.05）。不同性别间FDA值差异无统计学意义（t=0.906,P＞0.05）。年龄与时间无相关性（r=0.001,P＞0.05）。结论头位倾斜对于FDA度数有显著的影响,临床工作中采用眼底照相评价患者的眼底旋转状态时应注意头位的摆放。     

改良式多焦软性角膜接触镜矫正老视的视觉效果

目的：探讨改良式多焦点软性角膜接触镜（多焦软镜）和单光软性角膜接触镜（单焦软镜）联合验配方式矫正老视的视觉效果。方法：前瞻性研究。于2018 年1—12 月在温州医科大学附属眼视光医院招募20例老视观察对象（老视度数+1.00～+2.00 D）,分别按多焦法（双眼配戴多焦软镜）、单眼视法（一眼配戴远用单焦软镜,一眼配戴近用单焦软镜）和改良法（主视眼配戴单焦软镜,非主视眼配戴多焦软镜）3种方法验配角膜接触镜。每种方法配戴1周,间隔1周作为洗脱期,分析选用单光框架眼镜和3种接触镜矫正方法矫正下的观察对象双眼远、中、近距离100%及10%的双眼对比度视力（后文中视力均为双眼视力）,同时采用VFQ-25汉化版视觉质量量表评估视觉效果。通过单因素方差分析不同方法下视力的差异。结果：在远距视力对比中,多焦法视力低于单光框架眼镜（t=3.91,P=0.001）和改良法（t=2.94,P=0.008）。在50 cm处100%和10%对比度时,多焦法（100%：t=-4.76,P<0.001;10%：t=-4.22,P<0.001）、单眼视法（100%：t =-3.50,P=0.002;10%：t=-4.76,P<0.001）和改良法视力（100%：t=-4.22,P<0.001;10%：t=-3.90,P=0.001）均高于单光框架眼镜;在30 cm处100%和10%对比度时,多焦法（100%：t=-4.36,P<0.001;10%：t=-5.48,P<0.001）、单眼视法（100%：t =-7.43,P<0.001;10%：t =-4.03,P=0.001）和改良法（100%：t =-5.67,P<0.001;10%：t=-3.93,P=0.001）视力均高于单光框架眼镜。所有观察对象中有1 例认为单光框架眼镜最佳,7 例认为多焦法最佳,2 例认为单眼视法最佳,10 例认为改良法最佳。结论：联合多焦法和单眼视法的改良验配方法能很好地矫正老视,提供不弱于单眼视法和多焦法的视觉效果,更容易被老视患者接受。     

快速序列视觉呈现方式与其他类型视标实时调节反应的差异

目的：分析受检者在阅读快速序列视觉呈现方式（RSVP）与其他不同类型视标进行实时调节反应及调节微波动测量差异。方法：前瞻性研究。收集2019年4─10月期间在温州医科大学附属眼视光医院就诊的近视患者33例，年龄15～28（22.1±4.8）岁，等效球镜度（SE）为（-3.81±1.67）D。试验视标分为以下4类：RSVP、随机字符RSVP、马耳他视标和文本窗。每组视标试验时间为5 min，使用Grand Seiko WAM-5500红外验光仪进行实时的调节反应、调节微波动的测量。使用单因素方差分析比较受检者阅读或者注视不同视标时调节参数的差异，使用配对t检验比较试验初期10 s内与5 min内平均调节反应值的差异。结果：5 min试验显示，与RSVP、随机字符RSVP和文本窗比较，马耳他视标调节反应最低，差异均有统计学意义（t=2.45，P=0.016；t=2.57，P=0.011；t=3.85，P<0.001）；注视马耳他视标时，调节变异度大于阅读RSVP和文本窗，差异均有统计学意义（t=4.32，P<0.001；t=2.93，P=0.04）。调节微波动能量分析显示，与RSVP相比，注视马耳他视标时低频区能量明显增高（t=30.32，P<0.001）；与RSVP相比，阅读文本窗时中频及高频区能量明显增高（t=32.41，P<0.001；t=38.26，P<0.001）。RSVP、随机字符RSVP及马耳他视标在最初10 s的调节反应均高于5 min内调节反应的均值（t=2.30，P=0.028；t=2.45，P=0.020；t=3.71，P=0.001）。结论：阅读或注视不同类型的视标时，人眼的调节反应及调节微波动存在差异。阅读或注视持续一段时间后，调节反应会随着时间发生变化，最初的测量结果无法完全代表持续阅读或者注视时的调节反应。     

间歇性外斜视的调节灵活度和调节反应

目的：比较间歇性外斜视和正常眼位人群之间,间歇性外斜视注视眼和非注视眼之间的调节灵活度和调节反应。方法：病例对照研究。选取2016年10月至2017年1月在温州医科大学附属眼视光医院门诊就诊的35例间歇性外斜视患者作为间歇性外斜视组,另选取24例正位眼或外隐斜斜视度≤6 △ 的门诊患者作为对照组。采用±2.00 D的反转拍和开放视野式自动验光仪分别测量受试者在单眼和双眼注视近距视标时的调节灵活度和调节反应。采用t检验对数据进行分析。结果：间歇性外斜视组的双眼调节灵活度为（8.8±4.1）cpm,显著低于对照组[（10.9±3.1）cpm],两者差异有统计学意义（t=-2.165,P=0.035）。间歇性外斜视组的非注视眼调节灵活度显著低于注视眼（t=4.657,P<0.001）。双眼注视40 cm处视标时,间歇性外斜视组的注视眼调节反应高于对照组的主导眼（t=-2.163,P=0.035）。双眼注视状态下,间歇性外斜视组注视眼的调节反应为（1.89±0.30）D,高于其在单眼注视状态下的调节反应[ （1.64±0.34）D],两者差异有统计学意义（t=3.801,P=0.001）。结论：间歇性外斜视患者的双眼调节灵活度低于对照人群,其注视眼和非注视眼的调节灵活度和调节反应均不一致,且双眼注视时调节反应高于单眼注视状态。     

FS-LASIK术中不同掀瓣时机进行静态眼球自旋识别成功率的对比

目的：探讨在飞秒激光辅助的准分子激光原位角膜磨镶术（FS-LASIK）中不同的掀瓣时机之间静态眼球自旋（SCC）定位识别成功率的差异。方法：前瞻性临床研究。选取2017年7-9月在南京医科大学附属明基医院眼科行角膜屈光手术的近视患者205例（410眼），其中行FS-LASIK的患者183例（366 眼）为FS-LASIK组，行经上皮准分子激光角膜切削术（TransPRK）的患者22例（44眼）为TransPRK 组。FS-LASIK组的366眼根据SCC定位识别时机不同分别为掀瓣前测量组（130眼）、掀瓣后测量组（126眼）和掀瓣后再覆盖测量组（110眼）。测量各组术眼的SCC方向和程度。采用卡方检验比较各组间SCC定位识别成功率差异。采用独立样本t检验和方差分析比较不同组别的SCC度数差异。结果：所有患者的SCC定位识别成功率为77.3%。FS-LASIK组和TransPRK组SCC成功率分别为74.9%和 97.7%，2组比较差异有统计学意义（χ²=11.71，P<0.001）。右眼SCC成功率为82.4%，左眼为72.2%，两眼间差异有统计学意义（χ²=6.13，P=0.013）。性别在SCC成功率方面差异无统计学意义。掀瓣前测量组、掀瓣后测量组和掀瓣后再覆盖测量组SCC定位识别成功率分别为63.8%、84.1%和77.3%，3 组间差异有统计学意义（χ²=14.47，P<0.001）。所有识别成功患者（317眼）SCC度数为3.0°±2.3°。而性别、眼别在SCC度数方面差异无统计学意义。FS-LASIK组和TransPRK组SCC度数分别为3.1°±2.4° 和2.2°±1.7°，组间比较差异有统计学意义（t=1.99，P=0.007）。掀瓣前测量组、掀瓣后测量组和掀瓣后再覆盖测量组SCC度数比较差异无统计学意义。SCC>2°的占59.3%，>4°的占28.7%，>6°的占9.2%。结论：在FS-LASIK术中，掀开角膜瓣后进行SCC定位识别的成功率较高。     

年龄相关性白内障老年患者的平衡功能与视觉功能障碍的关系

目的：研究年龄相关性白内障老年患者的平衡功能与视觉功能障碍的关系。方法：系列病例研究。选择2017年4-10月在温州医科大学附属眼视光医院白内障专科中心诊断为年龄相关性白内障的患者87例，评估受试者的视觉功能（LogMAR视力）、静态平衡功能（Berg平衡量表）、动态平衡功能[ “站起-走”（TUG）计时]以及认知（MMSE问卷）和抑郁状态（GDS-15问卷）。采用方差检验、回归线、多元逐步线性回归进行数据分析。结果：87例受试者的Berg平衡量表分值为（50.0±2.8）分，TUG计时值为（12.1±3.5）s。Berg平衡量表分值和TUG计时主要与双眼视力、年龄相关，多元线性回归方程分别为Berg平衡量表分值=62.27-4.37×双眼视力-0.12×年龄（F=23.87，P<0.001），TUG计时=-5.07+3.83×双眼视力+0.19×年龄（F=15.22，P<0.001）。不同性别间的Berg平衡量表分值（F=3.45，P=0.067）和TUG计时（F=3.88，P=0.052）差异没有统计学意义。结论：随着视觉功能障碍的加重和年龄的增加，白内障老年患者的静态平衡和动态平衡功能逐渐下降，年龄对平衡功能的影响程度低于视觉功能。视觉功能障碍主要以影响动态平衡功能从而引发跌倒事件，性别差异对平衡功能没有显著影响。     

散光矫正型多焦点人工晶状体植入术后临床效果

评价白内障超声乳化联合散光矫正型多焦点人工晶状体（MIOL）植入术后患者的长期临床效果。方法：前瞻性自身前后对照研究。选择在大庆油田总医院行白内障超声乳化联合散光矫正型多焦点IOL植入术患者50例（82眼），术后随访1年，分别观察术前，术后3个月、6个月、1年的裸眼远中近视力（LogMAR）、最佳矫正远中近视力（LogMAR）、离焦曲线、对比敏感度（CS）、全眼像差、预计残留散光和IOL轴位偏差分析及脱镜率。对手术前后各参数进行重复测量的方差分析，两两比较采用Bonferroni法及t检验。结果：散光矫正型MIOL植入术后，所有患者术后3个月、6个月、1年时远、中、近距离均可获得优于0.3的较好视力。术后3个月、6个月、1年时各距离视力较术前显著提高（远距离：F=26.39，P<0.001；中距离：F=13.68，P<0.001；近距离：F=12.90，P<0.001）。矫正远距离视力较裸眼视力略有提高，但差异无统计学意义，矫正前后近距离视力差异无统计学意义。术后6个月时，所有患者裸眼远视力接近0.0，且-4.0～+1.2 D离焦下视力均可优于0.3 LogMAR。术后 1年时明视带眩光CS最好，明视、暗视的CS比明视眩光有所下降，暗视眩光分辨率最差，而在高频区（18 c/d），CS随时间推移有显著提高，差异有统计学意义。术后1年全眼总散光（0.24±0.15）D，与术前[（1.56±0.38）D]相比，差异有统计学意义（t=3.31，P=0.023）。术后全眼总散光与术前预计残留散光[（0.15±0.07）D]接近，差异无统计学意义（t=2.31，P=0.102）。术后1年，IOL轴位平均偏离（3.12±1.51）°。术后脱镜率为100%。结论：散光矫正型MIOL能为白内障患者提供满意的全程视力、视觉质量和脱镜率，可预测性好，并有良好的旋转稳定性。     

上斜肌肌腱劈开延长术在上斜肌功能亢进引起的A型斜视中的应用

目的：探讨上斜肌肌腱劈开延长术治疗上斜肌亢进A型斜视的安全性及有效性。方法：回顾性临床病例研究。收集和分析安徽医科大学第一附属医院眼科2020年6月至2021年6月行上斜肌肌腱劈开延长术8例（14眼）患者的术前术后临床资料。所有患者根据上斜肌亢进程度行上斜肌肌腱劈开延长术，上斜肌亢进+1者延长4~5mm，+2者延长5~6mm，+3者延长7~8mm，+4者延长8~10mm。观察手术对患者A型斜视、眼球客观旋转及立体视功能影响。正态分布数据采用配对t检验，非正态分布数据采用MannWhitney检验，两变量间的相关性使用Spearman秩相关检验分析。结果：8例（14眼）行上斜肌肌腱劈开延长术，同时矫正患者水平斜视。其中2例患者行单眼上斜肌肌腱劈开延长术，6 例患者行双眼上斜肌肌腱劈开延长术。除1例患者外，余患者术后A型斜视消失；所有患者术后上下转25°斜视度差较术前明显减小，6例双眼手术患者术后上下转25°斜视度差较术前[(22.5±9.4）PD]减小为[（3.3±10.1）PD](t=10.78，P<0.001)，A型斜视矫正量为（19.2±4.4）PD；14眼术后上斜肌亢进程度[+0（0~0.2）]轻于术前[2.0（2.0~3.0）]（U=6.50，P<0.001）；客观旋转度使用Image-proplus 6.0软件进行测量，14眼术后旋转斜视（-0.6°±6.0°）较术前（+5.7°±5.7°）明显改善（t=6.98，P<0.001），旋转矫正量为6.3°±3.4°。术后所有患者均未出现继发性上斜肌麻痹及V型斜视改变。术前所有患者原在位均无立体视，术后2例患者获得原在位周边立体视（400″），1例患者获得中心凹立体视（20″）。结论：上斜肌肌腱劈开延长术可明显改善上斜肌亢进A型斜视，可改善患者客观内旋及部分患者原在位立体视功能，且术后不易继发上斜肌麻痹等并发症。     

4~12岁儿童周边视网膜离焦状态分析

目的：运用多光谱视网膜屈光地形图（MRT）测量4~12岁儿童不同区域周边视网膜的离焦量（RPRE），探讨RPRE与近视发展之间的关系。方法：病例对照研究。连续性纳入2021年9月至2022年3月在长沙湘江爱尔眼科医院门诊就诊的4~12岁儿童170例，根据屈光状态分为轻度近视组78例，轻度远视组49例，正视组43例。所有儿童在充分散瞳后，运用带状检影镜检测屈光度数，并以等效球镜度（SE）记录；运用Lenstar LS900光学生物测量仪检测生物学参数，包括眼轴长度（AL）、中央角膜厚度（CCT）、前房深度（AD）、晶状体厚度（LT）、角膜曲率度数（K1、K2）和散光（AST=K2-K1）；采用MRT测量儿童不同区域的RPRE并汇总得出其平均值，记录如下：周边视网膜总RPRE的平均值（TRVD）、0°~15°周边视网膜的离焦量平均值（RDV-15°）、周边视网膜15°~30°方向的RPRE 平均值（RDV-30°）、周边视网膜30°~45°方向的RPRE平均值（RDV-45°），所有检测结果均取右眼。通过非参数检验分析不同偏心度RPRE的差异；Spearman相关性分析不同屈光度与RPRE的关系、多元线性回归检验不同偏心度RPRE与眼球生物参数之间的相关性。结果：在偏心度15°~45°范围，低度近视儿童RPRE为远视性离焦，且RPRE随着偏心度增大而增加；相反，低度远视儿童RPRE为近视性离焦，且RPRE随着偏心度增大而减少；正视儿童偏心度30°以内的屈光状态与黄斑中心凹处的屈光状态基本相同，而偏心度30°~45°时，RPRE随着离黄斑中心凹距离增大而增加，且为远视性离焦；偏心度0°~15°时，RPRE与AL均无相关性（P>0.05）。偏心度15°~30°和30°~45°时，RPRE与AL呈正相关（r=0.33、0.40，均P<0.001）。偏心度0°~15°时，RPRE与眼生物学参数无相关性（P>0.05）；偏心度15°~30°和30°~45°时，AL是RPRE的独立危险因素（均P<0.001）。结论：4~12岁低度近视和正视儿童RPRE为远视性离焦，低度远视儿童RPRE为近视性离焦，且在偏心度15°~45°范围内RPRE可能与儿童轴性近视发生发展密切相关。     

不同屈光状态学龄期儿童角膜前表面区域Q值的研究

目的：应用Pentacam眼前节分析仪测量我国学龄期儿童角膜形态,通过正切曲率半径计算各区域 角膜前表面Q值,分析不同屈光状态下各区域角膜前表面Q值的特点。方法：系列病例研究。选取 2018年9月至2019年10月在温州医科大学附属第二医院育英儿童医院眼科门诊就诊的学龄期儿童 192例,以右眼作为研究对象,按右眼等效球镜度（SE）分成中度近视组、低度近视组、正视组、低 度远视组、中度远视组这5组。应用Pentacam眼前节分析仪测量其角膜形态,通过正切曲率半径计 算鼻侧（315°-45°）、上方（45°-135°）、颞侧（135°-225°）、下方（225°-315°）这4个区 域角膜前表面Q值。采用方差分析比较各区域角膜Q值差异和各区域角膜Q值在不同屈光组间的差 异;采用Pearson相关分析SE和角膜Q值的相关性。结果：鼻、上、颞、下4个区域角膜前表面Q值 分别为-0.50±0.13、-0.62±0.15、-0.31±0.10、-0.42±0.18,4个区域角膜Q值差异有统计学意义 （F=215.19,P<0.001）,颞、下、鼻、上4个区域角膜前表面变平坦趋势依次增快。不同屈光组间仅鼻侧、 下方角膜前表面Q值存在差异（F=6.00,P<0.001;F=2.95,P=0.022）。随着SE的增加,鼻侧、下方角 膜Q值变小,呈负相关（r=-0.38,P<0.001;r=-0.16,P=0.031）。不同屈光组在上方和颞侧2个区域 角膜前表面Q值差异均无统计学意义。不同屈光组的鼻颞侧Q值差值差异存在统计学意义（F=10.40, P<0.001）,且随SE的增加,鼻颞侧Q值差异增大,二者有相关性（r=-0.42,P<0.001）。结论：学龄期 儿童各区域的角膜前表面Q值存在差异,不同屈光状态的鼻侧及下方角膜Q值、鼻颞侧差值均存在 差异,且均与SE存在相关性,提示不同屈光度的儿童矫正屈光不正时需考虑各区域角膜Q值,以提 高成像质量。     

Ocular dominance and the interocular suppression of blur in monovision

Presbyopic contact lens patients with monocular corrections (monovision) see clearly at all distances by virtue of an interocular suppression of anisometropic blur that occurs regionally between corresponding retinal areas. This suppression fails to occur with small high-contrast targets viewed under low luminance conditions. The effect of target size and contrast upon interocular suppression of blur was quantified by reducing contrast of a bright test spot, viewed binocularly while wearing various plus lenses monocularly, until the out-of-focus image was suppressed. The strength of interocular suppression was equivalent when the plus lens was before either eye. However, after subjects wore a plus lens over their nonsighting eye for one day, interocular suppression of blur became enhanced when the nonsighting eye was blurred, and it became reduced when the sighting eye was blurred. Successful monovision subjects suppressed blur at higher contrast levels than did unsuccessful subjects. These results suggest a possible clinical test for quantifying adaptation to monovision.     

Comparison of multifocal and monovision soft contact lens corrections in patients with low-astigmatic presbyopia.

PURPOSE: The purpose of this study was to assess visual performance and patient satisfaction with two presbyopic soft contact lens modalities. METHODS: A crossover study of 38 patients with presbyopia was conducted. Patients were randomized first into either multifocal (Bausch & Lomb SofLens Multifocal) or monovision (SofLens 59) for 1 month. Visual performance was measured with high- and low-contrast visual acuity at distance and near and near stereoacuity. Patients' satisfaction was measured by the National Eye Institute Refractive Error Quality of Life Instrument questionnaire and by recording the patient's final lens preference. RESULTS: Patients maintained at least 20/20 binocular vision with both multifocal (MF) and monovision (MV) contact lenses under high-contrast conditions at distance and near. Under low-contrast conditions, patients lost less than a line of vision from the best spectacle correction to either multifocal or monovision contact lens correction at distance (pMF = 0.001, pMV = 0.006). Under low-contrast conditions at near, multifocal wearers lost five to six letters and monovision wearers lost two letters of vision (pMF < 0.001, pMV = 0.03, pMF/MV = 0.005). The average stereoacuity decreased by 79 s arc with monovision vs. multifocal contact lenses (p = 0.002). On the NEI-RQL, patients reported worse clarity of vision (pMF = 0.01, pMV < 0.001), more symptoms (pMF = 0.09, pMV = 0.01), and an improvement in their appearance with contact lens wear (pMF < 0.001, pMV < 0.001). Seventy-six percent of patients reported that they preferred multifocal contact lenses, and 24% preferred monovision contact lenses (p = 0.001). CONCLUSION: The majority of our patients preferred multifocals to monovision, most likely because the Bausch & Lomb SofLens Multifocal provides excellent visual acuity without compromising stereoacuity to the same degree as monovision.     

On the generality of crowding: visual crowding in size, saturation, and hue compared to orientation

Perception of peripherally viewed shapes is impaired when surrounded by similar shapes. This phenomenon is commonly referred to as "crowding". Although studied extensively for perception of characters (mainly letters) and, to a lesser extent, for orientation, little is known about whether and how crowding affects perception of other features. Nevertheless, current crowding models suggest that the effect should be rather general and thus not restricted to letters and orientation. Here, we report on a series of experiments investigating crowding in the following elementary feature dimensions: size, hue, and saturation. Crowding effects in these dimensions were benchmarked against those in the orientation domain. Our primary finding is that all features studied show clear signs of crowding. First, identification thresholds increase with decreasing mask spacing. Second, for all tested features, critical spacing appears to be roughly half the viewing eccentricity and independent of stimulus size, a property previously proposed as the hallmark of crowding. Interestingly, although critical spacings are highly comparable, crowding magnitude differs across features: Size crowding is almost as strong as orientation crowding, whereas the effect is much weaker for saturation and hue. We suggest that future theories and models of crowding should be able to accommodate these differences in crowding effects.     

Crowding during restricted and free viewing

Crowding impairs the perception of form in peripheral vision. It is likely to be a key limiting factor of form vision in patients without central vision. Crowding has been extensively studied in normally sighted individuals, typically with a stimulus duration of a few hundred milliseconds to avoid eye movements. These restricted testing conditions do not reflect the natural behavior of a patient with central field loss. Could unlimited stimulus duration and unrestricted eye movements change the properties of crowding in any fundamental way? We studied letter identification in the peripheral vision of normally sighted observers in three conditions: (i) a fixation condition with a brief stimulus presentation of 250 ms, (ii) another fixation condition but with an unlimited viewing time, and (iii) an unrestricted eye movement condition with an artificial central scotoma and an unlimited viewing time. In all conditions, contrast thresholds were measured as a function of target-to-flanker spacing, from which we estimated the spatial extent of crowding in terms of critical spacing. We found that presentation duration beyond 250 ms had little effect on critical spacing with stable gaze. With unrestricted eye movements and a simulated central scotoma, we found a large variability in critical spacing across observers, but more importantly, the variability in critical spacing was well correlated with the variability in target eccentricity. Our results assure that the large body of findings on crowding made with briefly presented stimuli remains relevant to conditions where viewing time is unconstrained. Our results further suggest that impaired oculomotor control associated with central vision loss can confound peripheral form vision beyond the limits imposed by crowding.     

The effects of monocular refractive blur on gait parameters when negotiating a raised surface.

Falls in the elderly are a major cause of mortality and morbidity. Elderly people with visual impairment have been found to be at increased risk of falling, with poor visual acuity in one eye causing greater risk than poor binocular visual acuity. The present study investigated whether monocular refractive blur, at a level typically used for monovision correction, would significantly reduce stereoacuity and consequently affect gait parameters when negotiating a raised surface. Fourteen healthy subjects (25.8 +/- 5.6 years) walked up to and on to a raised surface, under four visual conditions; binocular, +2DS blur over their non-dominant eye, +2DS blur over their dominant eye and with their dominant eye occluded. Analysis focussed on foot positioning and toe clearance parameters. Monocular blur had no effect on binocular acuity, but caused a small decline in binocular contrast sensitivity and a large decline in stereoacuity (p < 0.01). Vertical toe clearance increased under monocular blur or occlusion (p < 0.01) with a significantly greater increase under blur of the dominant eye compared with blur of the non-dominant eye (p < 0.01). Increase in toe clearance was facilitated by increasing maximum toe elevation (p < 0.01). Findings indicate that monocular blur at a level typically used for monovision correction significantly reduced stereoacuity and consequently the ability to accurately perceive the height and position of a raised surface placed within the travel path. These findings may help explain why elderly individuals with poor visual acuity in one eye have been found to have an increased risk of falling.     

Crowding is size and eccentricity dependent

Crowding is a form of lateral interaction in which flanking items interfere with the detection or discrimination of a target stimulus. It is believed that crowding is a property of peripheral vision only and that no crowding occurs at fixation. If these two claims are true, then there must be a change in the nature of crowding interactions across the visual field. In three different tasks, we determined target size and flanker separation at threshold for eccentricities of 0 to 16° in the lower visual field for 7 relative separations (1.25 to 8 times target size). In all three tasks, the magnitude of crowding increases with eccentricity; there was no crowding at fixation and extreme crowding at 16°. Using a novel double-scaling procedure, we show that the non-foveal data in all three tasks can be characterized as shifted versions of the same psychometric function such that different sections of the function characterize data at each eccentricity. This pattern of results can be understood in terms of size-dependent responses to the target and distance-dependent interference from the flankers. The data suggest that the distance-dependent interference increases with eccentricity.     

玻璃体切割联合超声乳化人工晶状体巩膜层间固定治疗外伤性晶状体半脱位

目的　探讨玻璃体切割联合超声乳化人工晶状体巩膜层间固定术治疗外伤性晶状体半脱位的疗效。方法　 对2015年6月至2018年6月来我院就诊的保守治疗无效的外伤性晶状体半脱位12例患者采用囊袋拉钩辅助进行白内障超声乳化联合23G玻璃体手术处理半脱位晶状体，之后进行人工晶状体巩膜层间固定。对术前及术后视力、眼压、散光度等进行统计学分析，并对术后人工晶状体情况及手术并发症进行评估。结果　12例12眼患者均顺利进行玻璃体切割联合超声乳化摘除脱位晶状体，同时行巩膜层间固定植入人工晶状体；术后3个月裸眼视力及最佳矫正视力均较术前提高显著，裸眼视力从治疗前0.14±0.12提高至治疗后0.44±0.17（t=-5.031，P＜0.001）；最佳矫正视力从治疗前0.29±0.17提高至治疗后0.57±0.15（t=-4.366，P＜0.001）；术前眼压为（28.30±8.87）mmHg（1 kPa=7.5 mmHg），术后3个月眼压为（14.70±3.47）mmHg，差异有统计学意义（t=4.94，P＜0.05）；术后3个月总散光度为（-1.35±0.73）D，角膜散光度为（-1.48±0.70）D，两者具有相关性（r=0.91，P＜0.01）。术后1眼发生人工晶状体襻与光学区分离，取出人工晶状体再次使用相同方法治疗。术后3个月所有人工晶状体位置稳定，无偏心、扭曲等，术后眼前节炎症反应轻。结论　玻璃体切割联合超声乳化人工晶状体巩膜层间固定术治疗外伤性晶状体半脱位效果较好，手术并发症少，值得在临床推广应用。     

Configuration specificity of crowding in peripheral vision

Peripheral vision is characterized in part by poor spatial resolution and impaired visual performance, particularly when the object is surrounded by flanking elements, a phenomenon popularly known as “crowding”. Crowding scales with eccentricity irrespective of the target size, both in terms of magnitude and spatial extent, which is determined by varying the target-flanker separation. However, the extent to which crowding depends upon the flanking stimuli parameters alone without separating target and flankers is poorly understood. In the present study, we investigated the effect of flanking stimulus parameters on crowding in orientation and contrast discrimination tasks using closely located “chain” lateral Gabor stimuli in order to enhance our understanding of the underlying mechanisms of crowding in peripheral vision. We found a strong configural effect on crowding in both orientation and contrast discrimination tasks, with reduced crowding when the flanker parameters enhanced the target salience and increased crowding when the flankers were perceptually grouped with the target. While in orientation discrimination crowding was dependent on eccentricity, and in contrast discrimination it was dependent on flanker contrast and eccentricity, crowding showed little dependence on the number of flankers in either task. We conclude that crowding in peripheral orientation and contrast discrimination is configuration specific, which can be reduced without alterations to the target-flanker separation and that crowding is a combination of low-level as well as high-level cortical processing.     

双元件可调节人工晶状体设计

目的：设计一种新的双元件可调节人工晶状体,并对其成像质量进行评估。方法：通过光学设计软 件Zemax,建立新设计的双元件可调节人工晶状体和人眼模型,模拟仿真其在不同视距下（L=6 m、 L=70 cm、L=40 cm以及L=25 cm）的成像结果,得到空间频率为100 cycles/mm时的调制传递函数 （MTF）值。与Simonov等研究结果进行对比分析,同时分析仿真结果是否满足人工晶状体植入光学 特性和测试标准。结果：通过光学设计软件模拟仿真新设计的双元件可调节人工晶状体眼模型,其 结果显示无论α=0°还是α=5°,瞳孔大小为3 mm时,单色光（λ=0.546 μm）空间频率100 cycles/mm 对应的MTF值均大于0.43,满足人工晶状体植入光学特性和测试标准。在α=0°时,仿真结果相较 于Simonov等研究结果有较大提升;在α=5°时,无明显提升。结论：本研究设计的双元件可调节人 工晶状体仿真结果满足人工晶状体植入光学特性和测试标准要求,相较于Simonov的研究结果,其 整体性能有所提升。