LASIK术后角膜前表面屈光力变化与矫治等效球镜度数的关系

目的:研究LASIK术矫治1.00D的等效球镜度数时角膜前表面屈光力发生的变化。方法:以角膜地形图所测得的角膜前表面屈光力(K值)为标准,角膜前表面屈光力变化量ΔK=K术前-K术后,按矫治等效球镜度数(SE矫治)将患者分成低、中度近视(SE矫治≤-6.00D)及高度近视(SE矫治>-6.00D)两组,计算ΔK/SE矫治,并与由经验公式推导出的0.8进行统计学分析。结果:当矫治1.00D的等效球镜度数时,总体研究对象:低、中度近视组和高度近视组的角膜前表面屈光力分别变化0.89±0.24D,0.94±0.28D和0.83±0.18D;切削的角膜组织分别为11.46±0.76μm,11.87±0.65μm和11.08±0.65μm;角膜的切削量与矫治等效球镜度数呈负相关关系。结论:LASIK术后低、中度近视的角膜前表面屈光力变化大于高度近视。     

应用优化计算方法与计算机软件计算角膜屈光手术后人工晶状体屈光力

目的 对准分子激光角膜屈光手术后人工晶状体屈光力的计算方法进行优化,并开发为计算机软件,评价其准确性与可靠性.方法 对人工晶状体屈光力计算方法进行优化,包括：角膜屈光力的矫正计算 人工晶状体有效位置的计算与双K值法（double-K method）的应用 标准化计算公式的应用.将计算方法编写为计算机应用软件（IOL calculator for post-refractive cases）.应用该软件对49例角膜屈光手术后的白内障患者的人工晶状体屈光力进行计算,以白内障手术后实际屈光状态为标准,预测屈光状态与实际屈光状态之间的差异为预测误差,预测误差的绝对值为绝对预测误差.以SPSS 11.0软件分析预测误差与绝对预测误差的平均值与分布.结果 白内障手术后屈光状态为-2.50～0.75 D,平均为（-0.78±o.83）D,3眼（6.1%）为正视,36眼（73.5%）为近视,10眼（20.4%）为远视.预测误差为-1.26～1.96 D,平均（-0.02±0.75）D,接近于正视性屈光状态.绝对预测误差为0～1.96 D,平均（0.62±0.42）D,绝对预测误差≤0.5 D者19眼（38.8%）,＞0.5 D且≤1.0 D者22眼（44.9%）,＞1.0 D且≤1.5 D者7眼（14.3%）,＞1.5 D 且≤2.0 D者1眼（2.0%）.结论 通过优化计算方法与开发计算机软件,可以充分简化准分子激光角膜屈光手术后人工晶状体屈光力的计算过程,并提高计算的准确性与可靠性.     

屈光参差儿童屈光成分与双眼视功能相关性研究

目的 分析屈光参差儿童的不同屈光成分对双眼立体视功能的影响。方法 收集63例屈光参差儿童的相关资料,将其双眼球镜差、双眼柱镜差、双眼轴长度差、双眼平均角膜曲率差分别与同视机Ⅰ～Ⅲ级功能、Titmus近立体视检查结果的相关性进行比较分析。结果 (1)双眼球镜差值与远、近立体视相关性具有显著性差异(与远立体视P=0.04,与近立体视P=0.01);双眼柱镜差值与近立体视相关性具有显著性差异(P=0.02);双眼轴长度差值与近立体视相关性具有显著性差异(P=0.03);双眼平均角膜曲率差与远、近立体视相关性均无显著性差异(P>0.05)。(2)远、近立体视功能比较,有显著统计学差异(P=0.03)。(3)双眼轴长度差、双眼球镜差与Titmus圈近立体视的相关性具有统计学差异(两者均为P=0.01)。同视机Ⅰ级和Ⅱ级视功能与双眼球镜差、双眼柱镜差、双眼轴长度差、双眼平均角膜曲率差相关性均无明显差异(P>0.05)。结论儿童屈光参差不同的屈光成分对双眼视功能的影响不同,双眼球镜差和双眼轴长度差对双眼立体视影响更明显,对远立体视的损害更为常见,对同视机Ⅰ级和Ⅱ视功能无明显相关性。     

屈光手术中应用交叉柱镜法治疗中高度散光的疗效分析

应用准分子激光原位角膜磨镶术（laser in situ keratomileusis,LASIK）和交叉柱镜法治疗中、高度散光68例（110眼）,比较两种方法的疗效,现报告如下。     

LASIK术中应用交叉柱镜法矫治大度数散光

目的 探讨在LASIK术中应用交叉柱镜法矫正大度数散光的临床效果.方法 选取同一时期内年龄、性别、屈光度(包括球镜和柱镜)相近的两组患者,即交叉柱镜组和常规LASIK组(以下也称对照组)各30只眼,比较两组术后3月内视力、屈光度以及高阶像差等视觉质量指标的变化,将所得数据应用统计学方法处理.结果 交叉柱镜组在术后1 d、1周、1月时裸眼视力均较对照组恢复快;术后1月及3月平均柱镜度数明显小于对照组(P<0.05);术后3月慧差亦较对照组减小,视觉质量明显改善.结论 在LASIK术中应用交叉柱镜法矫正大度数散光较常规LASIK切削模式能取得更理想的临床效果.     

湖北省0～6岁早产儿屈光度参考值范围的调查

目的：探讨湖北地区0～6岁早产儿屈光度的正常参考值范围,为学龄前早产儿屈光异常的临床诊治提供依据。方法：系列病例研究。在2016年5月至2017年5月期间,回访既往于武汉大学人民医院眼科行视网膜筛查的0～6岁无早产儿视网膜病变（ROP）的早产儿1 505例,行睫状肌麻痹后进行屈光检查。按照矫正胎龄后的年龄进行分组,了解各年龄组双眼球镜度及柱镜度的P 50 参考值和75%参考值范围。采用两独立样本秩和检验比较不同出生体质量、不同胎龄早产儿的屈光度差异。结果：①0～6岁早产儿球镜度的参考值分别为：<0.5岁组+2.02 D,≥0.5岁且<1.0岁组+1.87 D,≥1.0岁且<2.0岁组+1.60 D等。②各年龄段柱镜度的绝对值分别为：<0.5岁组2.54 D、≥0.5岁且<1.0岁组2.29 D、≥1.0岁且<2.0岁组2.14 D。③随着年龄增长,各年龄段早产儿球镜度P 50 参考值呈现逐渐下降的趋势（P<0.05）,5～6岁早产儿基本完成正视化过程;0～3岁早产儿柱镜度P 50 参考值随着年龄增长呈现逐渐下降的趋势（P<0.05）,3岁以上趋于稳定。④<0.5岁组及1～6岁各年龄组,出生体质量<1.5 kg比出生体质量≥1.5 kg的早产儿球镜度小（P<0.05）;出生体质量<1.5 kg早产儿在出生后早期远视度增加（P<0.05）,后逐步向正视化方向发展,4～5岁基本完成正视化。⑤0～0.5岁及2～6岁年龄段,胎龄<32周比胎龄≥32周的早产儿球镜度小（P<0.05）。0～6岁各年龄段,胎龄<32周比胎龄≥32周的早产儿柱镜度高（P<0.05）;0～6岁各年龄段,出生体质量<1.5 kg比出生体质量≥1.5 kg的早产儿柱镜度高（P<0.05）。结论：随着年龄增长,早产儿远视度逐渐减小,5～6岁早产儿基本完成正视化过程;0～3岁早产儿柱镜度随年龄增长呈现逐渐缩小的趋势,3岁以上柱镜度数趋于稳定。出生体质量及胎龄是早产儿屈光度的重要影响因素。     

检影验光在眼屈光检查中的应用

检影验光是一种唯一可以获得患者眼睛真实屈光状态的好方法，更是验光师及眼科医师必须掌握的一门技术。通过检影镜观影动，并用镜片消解影动，最终找到中和点的位置，从而判断被检者屈光不正的性质及程度。     

间接眼底镜在取出球内磁性异物的应用

间接眼底镜在取出球内磁性异物的应用哈尔滨市眼科医院钱丽敏，王世和，李颖，张力威，王桂荣眼球穿通伤合并球内磁性异物，在玻璃体混浊程度较轻时，我们应用间接眼底镜直视下定位取出异物１１例。均获得良好效果，现分析报告如下：临床资料：１１例中男７例，女４例。１...     

球周麻醉在眼科手术中的应用

在球周麻醉下成功施行眼科手术33例,其中老年性白内障23例,青光眼4例,裂源性网脱6例。用计分法主观评价三种手术球周麻醉的效果,结果表明以白内障囊外摘除术(显微)的麻醉效果最为满意。球周麻醉具有球后麻醉和眼轮匝肌麻醉的双重效果,它不但可以替代球后麻醉,还可免除面神经阻滞麻醉。由于麻药仅注射在眼球周围,不达球后,故能避免球后麻醉所引起的球后出血及突发性黑蒙等严重并发症。     

Reduction of artefact in scatter plots of spherocylindrical data

Round-off of spherocylindrical powers, to multiples of 0.25 D (for example) in the case of sphere and cylinder, and 1 or 5 degrees in the case of axis, represents a type of distortion of the data. The result can be artefacts in graphical representations, which can mislead the researcher. Lines and clusters can appear, some caused by moiré effects, which have no deeper significance. Furthermore artefacts can obscure meaningful information in the data including bimodality and other forms of departure from normality. A process called unrounding is described which largely eliminates these artefacts; each rounded power is replaced by a power chosen randomly from the powers that make up what is called the error cell of the rounded power.     

Refractive index of the crystalline lens in young and aged eyes

Background : When the ageing crystalline lens is modelled on the basis of a constant equivalent lens, the changes in ocular dimensions would lead to an increase in power of the order of two dioptres. A comparable increase in myopia is usually not evident with increasing age and this inconsistency has been referred to as the lens paradox. It has been proposed that this paradox can be resolved if the refractive index is modelled as a gradient refractive index. The purpose of this paper was to study differences in the equivalent, gradient and surface refractive index of the crystalline lens between a young and old age group. Methods : Biometric data was collected for 96 subjects: 48 young adults with an age range 19 to 31 years (mean 22.10 ± 2.93 years) and 48 old adults with an age range 49 to 61 years (mean 53.88 ± 3.88 years). The equivalent refractive index was determined for each subject by paraxial ray tracing and a merit function based on refractive error and Purkinje image height. The refractive index gradient was determined by modelling the crystalline lens as a bi-elliptical iso-indicial structure in a three-surface Gullstrand-Emsley schematic eye and a merit function based on the surface power, the gradient refractive index power and the equivalent power of the lens. The central refractive index of the lens was assumed to be 1.406. Results : The differences between the groups included a decrease in the mean equivalent refractive index from 1.427 ± 0.007 to 1.418 ± 0.006, an increase in surface refractive index from 1.386 ± 0.007 to 1.394 ± 0.006 with a concurrent change in the gradient refractive index profile. The refractive index changes maintained a constant mean lens power in each group. Conclusions : The so-called ‘lens paradox’ whereby an increase in the power of the crystalline lens does not lead to an increase in myopia is resolved by a decrease in the equivalent refractive index of the lens or when modelled as a gradient refractive index structure, by an increase in the surface refractive index and an associated change in gradient for an assumed central refractive index of 1.406.     

IOL calculation using paraxial matrix optics

Matrix methods have a long tradition in paraxial physiological optics. They are especially suited to describe and handle optical systems in a simple and intuitive manner. While these methods are more and more applied to calculate the refractive power(s) of toric intraocular lenses (IOL), they are hardly used in routine IOL power calculations for cataract and refractive surgery, where analytical formulae are commonly utilized. Since these algorithms are also based on paraxial optics, matrix optics can offer rewarding approaches to standard IOL calculation tasks, as will be shown here. Some basic concepts of matrix optics are introduced and the system matrix for the eye is defined, and its application in typical IOL calculation problems is illustrated. Explicit expressions are derived to determine: predicted refraction for a given IOL power; necessary IOL power for a given target refraction; refractive power for a phakic IOL (PIOL); predicted refraction for a thick lens system. Numerical examples with typical clinical values are given for each of these expressions. It is shown that matrix optics can be applied in a straightforward and intuitive way to most problems of modern routine IOL calculation, in thick or thin lens approximation, for aphakic or phakic eyes.     

Analysis of changes in crystalline lens thickness and its refractive power after laser in situ keratomileusis

AIM: To evaluate changes in the anterior chamber depth (ACD), crystalline lens thickness (LT) and its refractive power after laser in situ keratomileusis (LASIK). METHODS: In all cases, the preoperative and postoperative central ACD which were measured with Pentacam, Orbscan, IOL-Master and A-scan ultrasonography, central corneal true net power which was measured with the Pentacam, Orbscan and IOL-Master, axial length (AL) which was measured with IOL-Master and LT which was measured with the A-scan ultrasonography were compared using the paired sample t test. Ocular refractive errors and lens refractive power at corneal plane were calculated and their correlations were also evaluated before and after LASIK. RESULTS: At 1 week after LASIK, LT and crystalline lens refractive power at corneal plane (Dlens) which were associated with the IOL-Master and Pentacam increased significantly (P≤0.005), ACD decreased significantly (P≤0.001), but no significant increase was observed in the Dlens which was associated with the Orbscan (P=0.261). Significant correlations between the changes in the ocular refractive errors and Dlens which were associated with the Pentacam were observed at 1 week and 6 months after LASIK (P=0.028; P=0.001). CONCLUSION: LT increased significantly after LASIK, and this might partially lead to ACD decrease, Dlens increase and a small quantity of myopic regression.     

角膜总屈光力的评估方法及其临床应用进展

角膜总屈光力的评估在角膜接触镜的验配和角膜屈光手术的术前评估中至关重要.测算角膜总屈光力的设备多种多样.根据测算原理的不同,角膜总屈光力大致可分为3类：模拟角膜屈光力、基于高斯厚透镜公式的角膜总屈光力和光路追击法获得的角膜总屈光力.角膜屈光术后角膜总屈光力的准确评估在提高预测拟植入人工晶状体屈光力的准确性中起关键作用.目前,对于角膜屈光术后角膜总屈光力的评估缺乏统一标准,很多学者根据各自的研究提出了不同的修正公式.本文着重综述角膜总屈光力尤其是角膜屈光术后眼角膜总屈光力的评估方法及其研究应用进展.     

角膜屈光手术后人工晶状体屈光力的计算

目的探讨角膜屈光手术后不同人工晶状体（IOL）屈光力计算公式的准确性及Orbscan对角膜屈光力测量准确性和对IOL屈光力计算准确性的影响。方法以OrbscanⅡZ对18例角膜屈光手术后白内障患者的角膜屈光力进行检查,分析角膜中央直径3min区域的角膜总体屈光力（KbackH）与角膜地形图屈光力（Kback）;根据高斯光学理论推导优化的IOL屈光力计算公式,应用SRK／T、HofferQ、Holladay、Holladay2与本公式分别计算IOL屈光力和IOL植入眼屈光状态的预测值（REpackt）,以IOL植入眼的实际屈光状态（REpact）为标准,REpcediet与REpost的差异为预测误差（PE）,PE的绝对值为绝对预测误差（AE）,比较不同计算公式的PE与AE的差异;将REpost分别代人IOL屈光力计算公式与Holladay2公式回推计算角膜屈光力的理论值,比较本公式计算所得角膜屈光力（Kback）、Holladay2公式的计算值（KbackH）与KT、KK的差异。结果IOL屈光力计算公式、Holladay2的PE值（D）均小于Holladay、HofferQ、SRK／T公式的PE和AE,均小于其他计算公式（P〈0．05）,IOL屈光力计算公式与Holladay2公式比较差异无统计学意义（P〉0．05）。KbackH值、Kabck值与K,值间的比较差异无统计学意义,但均小于Kk值（P〈0．05）。应用KT计算IOL屈光力产生的AE小于KK产生的AE。结论本公式与Holladay2公式测试角膜屈光手术后IOL的屈光力较为准确;Orbscan分析所得角膜中央直径3rnm区域K,可获得较为准确的结果,KT联合本公式或Holladay2公式计算IOL屈光力可得到较为准确的计算结果。     

儿童前房深度与各屈光参数关系

目的:研究前房深度与年龄、晶状体屈光力、角膜屈光力及眼轴之间的关系.方法:通过睫状肌麻痹检影验光及光学生物测量仪(IOL Master)获得44例88眼的屈光不正度数、眼轴、角膜屈光力、前房深度等参数,经计算得到晶状体度数.直线相关与回归比较前房深度和年龄及各屈光参数之间的关系.结果:受试者44例88眼,平均年龄9.04±2.39岁,等效球镜(SE)-3.50 ～ +8.75D;三组间前房深度无明显差别,男性与女性间前房深度无差别;前房深度与年龄之间存在负相关关系,相关系数r=-0.323,ACD/AL与年龄呈负相关,相关系数r=-0.516;晶状体屈光力与年龄呈正相关,相关系数为0.414;前房深度与晶状体屈光力呈负相关,相关系数r=-0.392;角膜屈光力与年龄呈负相关,相关系数r=-0.461;前房深度与角膜屈光力之间呈微弱的正相关,相关系数r=0.295.结论:受试儿童眼球的前房随年龄逐渐变浅,在眼轴中所占的比例不断降低;由角膜、晶状体、房水及前房组成的组合透镜屈光力随年龄下降,同时玻璃体腔变长,正符合儿童眼球正视化的要求.     

角膜曲率对正常眼轴白内障患者屈光度计算准确性的影响

目的:研究角膜曲率对正常眼轴白内障患者人工晶状体(IOL)屈光度计算准确性的影响。方法:选取2020-06/2021-06在我院行白内障手术的患者157例157眼,根据术前角膜曲率(K)分为3组,A组(53眼)K<42D,B组(55眼)42D≤K≤46D,C组(49眼)K>46D。术前分别采用SRK/T、Hoffer Q、Holladay 2、Haigis、Kane、BarrettⅡ公式计算IOL屈光度,术后1mo行主觉验光检查,计算并分析三组患者屈光预测误差(RPE)和平均绝对值误差(MAE)的差异。结果:A、C组每个公式的RPE与0D比较均有差异(P<0.05),且BarrettⅡ公式与SRK/T、Hoffer Q、Holladay 2、Haigis公式比较均有差异(P<0.01),与Kane公式比较无差异(P>0.01);B组所有公式的RPE与0D比较均无差异(P>0.05)。A组BarrettⅡ公式MAE≤0.5D的比率显著高于SRK/T、Hoffer Q、Holladay 2、Haigis公式(均P<0.01),但与Kane公式比较无...     

足月新生儿屈光度和眼球生物学参数特征及其相关性

目的：探讨足月新生儿屈光度和眼球生物学参数的特征,并分析屈光度及眼球生物学参数的相关性。方法：横断面研究。采用简单随机抽样的方法纳入2021年9月至2022年2月在北京市海淀区妇幼保健院出生的足月新生儿71例（142眼）,在出生后7 d内进行检查。通过睫状肌麻痹后检影验光获得其屈光度,手持电脑验光仪测量角膜曲率（Km）,眼部A型超声测量获得前房深度（ACD）、晶状体厚度（T）、玻璃体腔深度（V）和眼轴长度（AL）。根据Km计算角膜曲率半径（CR）,根据AL和CR计算眼轴角膜曲率比（AL/CR）,并根据AL、ACD、Km、等效球镜度（SE）等计算晶状体屈光度（LP）。采用Spearman相关分析屈光度数、AL、LP等各参数之间的相关关系,使用线性回归分析获得影响AL 及屈光状态的回归方程。结果：新生儿的SE为+3.00（+2.00,+5.25）D,Km为46.25（44.63,47.63）D,AL为（16.99±0.49）mm,LP为（46.10±5.13）D。SE与AL、LP呈负相关（r=-0.52,P<0.001;r=-0.21,P=0.014）,与Km无相关性（r=-0.16,P=0.053）;AL与胎龄（GA）呈正相关（r=0.24,P=0.005）相关回归分析显示：AL=11.937+0.129×GA（R2 =0.07,F=10.75,P=0.001）;SE=60.362 -2.835×AL-0.190×LP（R2 =0.39,F=44.95,P<0.001）。结论：足月新生儿屈光度为中高度远视,AL较成人短,LP较成人大。SE与AL呈负相关,与Km无相关关系,AL是影响SE的关键因素。