Orbscan与EyeSys角膜地形图、角膜曲率计测量角膜曲率的比较

目的比较裂隙扫描角膜地形图/角膜测厚系统(Orbscan Corneal Topography     

角膜地形图仪与角膜曲率计测量结果的比较

目的　探讨角膜曲率计和角膜地形图检查系统测量角膜屈光力的差异。方法　随机选取我院屈光手术门诊LASIK术前 3 65例 ( 681眼 ) ,同时用两种方法测量角膜屈光力 ,比较二者间的差异。结果　两种方法测量的最大角膜屈光力 :角膜曲率计为 ( 4 3 774± 1 5 3 5 )D和角膜地形图仪为 ( 4 3 5 17± 1 5 46)D ,最小角膜屈光力分别为 ( 4 2 75 6± 1 43 0 )D和 ( 4 2 5 13±1 44 0 )D ;平均角膜屈光力分别为 ( 4 3 2 5 6± 1 45 9)D和 ( 4 2 769± 1 42 7)D。以上 3组数字两两比较 ,差异均有非常显著意义(P <0 0 0 1)。结论　角膜地形图仪所测角膜屈光力较角膜曲率计所测结果准确 ,LASIK术前应参考角膜地形图仪所测角膜屈光力。     

角膜塑形术治疗前后角膜曲率计和角膜地形图测量值比较

目的　比较不同方法测量角膜塑形术治疗前后角膜曲率的差异。方法　分别用SRK 90 0 0型角膜曲率计和DICONCT 2 0 0型角膜地形图仪于治疗前及治疗后 3个月分别测量角膜水平曲率和垂直曲率各 3次 ,取其均值比较。结果　角膜塑形术治疗前 ,两种方法测量结果比较差异无显著性(P >0 0 5 )。治疗后 ,角膜曲率计测量值 ,水平曲率、垂直曲率值均低于角膜地形图。结论　角膜塑形术治疗后 ,角膜弯曲度、球面性的改变及其设计理论可能影响角膜地形图的测定结果。给矫正欠佳病例再次配角膜塑形镜时应当用两种方法测量角膜曲率 ,互相参照 ,为再次矫正提供保障。     

三种仪器测量角膜曲率的准确性比较

目的比较手动角膜曲率计、电脑自动验光仪、角膜地形图仪三种仪器测量角膜曲率结果的准确性,指导白内障术前测量应用。方法仪器应用对照研究。对2014年12月至2015年4月在武清区人民医院眼科应用三种仪器分别测量拟实施白内障超声乳化及人工晶状体植入术的患者140例（140只眼）的最大、最小及平均角膜屈光力,应用电脑自动验光仪和角膜地形图仪测量角膜散光值及散光轴位,使用SPSS20．0软件对所测参数进行统计学分析比较。结果三种仪器测得的最大、最小及平均角膜屈光力对比差异无统计学意义（P〉0．05）,电脑自动验光仪和角膜地形图仪测得的角膜散光值对比差异无统计学意义（P〉0．05）,散光轴位对比差异有统计学意义（P〈0．05）。结论三种仪器测量角膜曲率的准确性较好,均适用于白内障术前测量。     

角膜地形图与角膜曲率计在白内障手术前后评价

本文应用计算机辅助的角膜地形图系统TMS-1和角膜曲率计TOPCONOM-4同时测定了200例(278眼)的角膜地形图和中央角膜屈光状态。比较了角膜地形图的模拟角膜曲率SIMK值和角膜曲率计的垂直和水平屈光度。结果显示,白内障术前组116例150眼的SIMK平均值分别为44.22D(垂直轴)和44.26D(水平轴),角膜曲率计的中央屈光度垂直轴平均为44.16D,水平轴为44.23D。统计学处理表明,2种组方法的结果之间差异无显著性(P>0.05),第2种术后组67例90眼的SIMK平均值分别为46.37D(垂直轴)和43.06D(水平轴),角膜曲率计的中央屈光度垂直轴平均为46.09D,水平轴平均为42.88D,统计学处理二种方法的结果之间差异无显著性(P>0.05)。研究提示,角膜地形图系统的模拟角膜曲率SIMK值和角膜曲率计的屈光度无论在白内障手术前还是在手术后其结果是一致的,临床应用具有同等的价值。但是,当角膜中央屈光度异常范围小于3毫米,角膜混浊,角膜严重不规则散光时,角膜曲率计不能满足临床需要。而计算机辅助的角膜地形图系统则具有极大的诊断及检测价值。眼科学报 1994;10:85—89。     

Orbscan-Ⅱ和角膜曲率计对屈光手术前角膜测量比较

目的使用裂隙扫描角膜地形图/角膜测厚系统(Orbscan corneal topography system简称Orbscan-Ⅱ系统)与角膜曲率计对屈光手术前角膜测量进行比较.方法应用Orbscan-Ⅱ系统(Orbtek,Salt Lake City,UT,USA)和KM-450角膜曲率计(NIDEK,JAPAN)分别测量准备行准分子激光手术的近视患者73例140眼的角膜曲率、散光和轴位,对两种仪器的测量结果进行统计学分析(配对t检验).结果Orbscan-Ⅱ测量的角膜曲率值略高于角膜曲率计的测量值,两者差异有统计学意义(P＜0.05).两种仪器测量的散光值和轴位的差异无统计学意义(P＞0.05).结论Orbscan-Ⅱ对于角膜表面屈光状态的检查更为直观和全面,尤其是角膜过陡、过平或不规则散光的患者在屈光手术前不能将角膜曲率计检查的结果作为手术治疗的唯一依据.     

手持式自动角膜曲率计测量角膜屈光度的准确性分析

目的探讨手持式自动角膜曲率计测量角膜屈光度的准确性及临床应用。方法采用天津索维SW-100型手持式自动角膜曲率计及日本TOPCON OM-4型手动角膜曲率计分别对门诊60例118眼进行角膜屈光度测量。结果2种角膜曲率计在平均角膜屈光度最大值K1、平均角膜屈光度最小值K2、平均角膜屈光度（K1＋K2）／2及平均角膜散光度K1-K2上无显著差异，但散光轴向上差异有显著性。结论手持式自动角膜曲率计在测量角膜屈光度上与传统手动角膜曲率计无显著差异，可广泛应用于角膜屈光度的测量。     

Pentacam Topolyzer与角膜曲率计测量角膜屈光力的比较

目的 比较Scheimpflug原理摄像系统Pentacam与Placido盘成像Topolyzer角膜地形图及Topcon自动式角膜曲率计测量角膜屈光力的差异,分析三者的一致性,为临床使用提供依据.方法 随机选取拟行角膜屈光手术角膜形态正常的患者39例(39只眼).术前分别采用Pentacam、Topolyzer及Topcon自动式角膜曲率计测量角膜屈光力,并对测量结果进行统计分析.结果 Topcon自动式角膜曲率计测量值为(43.35±1.36)D,Topolyzer测量值为(43.41±1.35)D;Pentacam测量所得simK、true net power(TNK)、4.0mm Holladay equivalent K-reading(EKR)、4.5mm EKR分别为(43.40±1.34)D,(42.14±1.25)D,(43.44±1.31)D,(43.50±1.32)D.Pentacam测量所得simK、4.0mm EKR与Topolyzer测量所得simK差异无统计学意义(P＞0.05);其余各组K值之间比较差异均有统计学意义(P＜0.01).三种测量方法所得K值两两之间均存在高度正相关(r＞0.90,P＜0.01).TNK比其余各种K值均明显小(-1.21～-1.36)D,一致性较差;其余各组K值之间一致性较好,95％一致性界限较窄.结论 对于角膜形态正常的患者,Pentacam测量所得simK及4.0 mm EKR与Topcon自动式角膜曲率计测量所得Km及Topolyzer测量所得simK具有良好的一致性,不过在临床中互相替代使用仍需要慎重.true net power比其余各种K值均明显小,不能用于人工晶状体屈光度计算.     

角膜曲率计与角膜地形图仪测量角膜屈光度的对比研究

目的：对使用角膜曲率计与角膜地形图仪测量角膜屈光度的结果进行对比研究,提出两种仪器各自在白内障术前测算人工晶状体度数中提供K值的精确性。方法;在无眼表疾病的38例（76只眼）分别使用美国生产的角膜地形图仪和日本生产的角膜曲率计测量角膜屈光度,然后进行统计学处理。结果：角膜曲率计和角膜地形图仪检查结果略有差异,但经统计学处理无显著意义（P＞0．05）。结论：角膜地形图仪系统测量角膜屈光度更为准确、全面,尤其对角膜过陡、过平、有斑翳、云翳者的检测结果更有参考价值。     

自动角膜曲率计与角膜地形图仪测量儿童角膜屈光力的比较研究

目的 比较KR-8100自动角膜曲率计与TMs-4角膜地形图仪测量屈光不正儿童角膜屈光力及散光轴向的差异,并对两种测量方法进行一致性评价.方法 采用KR-8100自动角膜曲率计及TMS-4角膜地形图仪对53例(106只眼)屈光不正儿童进行测量,应用配对t检验对两种方法测量的陡峭 子午线角膜屈光力(Ks)、平坦子午线角膜屈光力(Kf)、角膜散光Ks-Kf大小及轴向进行比较,并应用Bland-Altmann分析对两种测量方法进行一致性评价.结果 角膜地形图仪测量的Ks、Kf、Ks-Kf值均高于角膜曲率计的测量值(P<0.01);角膜地形图仪与角膜曲率计的散光轴向测量值差异有统计学意义(P<0.01).两种仪器测量Ks的差值的均数为1.72D,测量Kf的差值的均数为1.37D,这种测量差别临床上不能接受,说明两种仪器测量角膜屈光力的一致性较差.结论 KR-8100自动角膜曲率计与TMS-4角膜地形图两种测量方法在临床上不能替代使用.     

The effect of head tilt on keratometric measurement using the IOLMaster

Purpose

To investigate the effect of head tilt on keratometric measurement using the IOLMaster.

Methods

Twenty-seven right eyes of 27 volunteers were examined using a manual keratometer (MK), automated keratometer (AK), and an IOLMaster. MK and AK measurements were performed in the upright head position, whereas IOLMaster measurements were performed in five different head positions (upright, 5° or 15° clockwise head tilt, and 5° or 15° counter-clockwise head tilt). The repeatability of IOLMaster was compared with MK and AK. The keratometric measurements (mean keratometric power, magnitude of astigmatism, and steep meridian) in different head positions were compared.

Results

The IOLMaster showed good repeatability of keratometric measurement comparable to MK or AK. 15° and 5° clockwise head tilt resulted in 12.09±9.51 (mean±SD) (P<0.001 vs upright) and 5.51±5.97 (mean±SD) degrees (P<0.001) of clockwise rotation of steep meridian, respectively. 15° and 5° counter-clockwise head tilt resulted in 12.49±7.07 (mean±SD) (P<0.001) and 6.08±5.09 (mean±SD) degrees (P<0.001) of counter-clockwise rotation of steep meridian, respectively.

Conclusions

The patient''s head tilt (5° or 15°, clockwise or counter-clockwise) significantly changed the steep meridian of astigmatism measured using IOLMaster and the steep meridian generally shifted to the direction of head tilt. The importance of maintaining the upright head posture during IOLMaster measurement is demonstrated.     

The value of the Terry keratometer in predicting postoperative astigmatism

The Terry keratometer was used immediately before and immediately after cataract surgery. The results were compared with keratometry readings taken before surgery and readings taken on the morning of the first postoperative day. The mean preoperative cylinder in 27 eyes was 1/2 diopter less than that measured prior to the start of surgery. Preoperative readings and readings obtained prior to the start of surgery differed by more than 1 diopter in 37% of eyes. The keratometer readings obtained at the end of the surgery in 63 eyes were flatter than those obtained on the first postoperative day. Forty-four percent of the intraoperative cylinder readings differed from postoperative readings by more than 2 diopters. The factors which can produce errors with the use of this instrument include changes in intraocular pressure, the effect of the lid speculum, rectus suture tension, the alignment of the eye with respect to the keratometer , and user experience.     

Validation of keratometric measurements obtained with an intraoperative image‐guided system: intra‐session repeatability and interchangeability with an optical biometer

Purpose

To evaluate the intra‐session repeatability of keratometric measurements obtained in healthy eyes with the Verion image‐guided system (Alcon Laboratories Inc, Fort Worth, Texas, USA) as well as the interchangeability of such measurements with those obtained with an optical biometer (Aladdin, Topcon, Tokyo, Japan).

Methods

A total of 53 eyes of 53 patients (age 31–67 years) were enrolled in the study. All eyes received a comprehensive ophthalmologic examination including an analysis with the Verion image‐guided and Aladdin systems. Three consecutive measurements of keratometry were obtained with the Verion system to assess the intra‐session repeatability. Within‐subject standard deviation (S_w) and intraobserver precision (± 1.96 × S_w) were calculated. Bland–Altman analysis was used for the interchangeability analysis.

Results

Mean S_w was 0.26, 0.24 and 0.10 D for the keratometric power in the flattest meridian (K1), keratometric power in the steepest meridian (K2) and astigmatism, respectively. Mean S_w was 4.29° for the axis of the flattest corneal meridian (AX1). Statistically significant but clinically acceptable differences were found in K1, K2 and keratometric astigmatism among systems (p < 0.01). In contrast, differences among systems in AX1 were not statistically significant (p = 0.385) but clinically relevant (mean difference: 15.74°; limits of agreement: ?30.93 to 62.41°).

Conclusions

The Verion system provides consistent measurements of keratometric parameters, with measurements of AX1 that are not interchangeable with that provided by the optical biometer Aladdin, especially in cases of low and oblique astigmatism.

     

Comparing the corneal curvatures obtained from three different keratometers-IOL Master, Bausch & Lomb Manual keratometer and TOPCON KR 8800 autokeratometer

AIM: To compare the corneal curvature and to investigate the agreement between three different keratometers.METHODS: In this prospective study, keratometry was performed using an IOL Master, a Bausch & Lomb manual keratometer and TOPCON KR-8800 autokeratometer on 252 eyes of patients recruited from camps for cataract surgery. The average keratometry values were recorded and compared. The agreements between the instruments were analyzed using the Bland Altman statistical method. The main outcome measure was average keratometry values.RESULTS: The mean corneal power was 44.62±1.52 D with the IOL Master, 44.60±1.52 D with the manual keratometer, and 44.46±1.53 D with the autokeratometer. The paired ttest demonstrated a statistically significant difference in the mean corneal power between the IOL Master and manual keratometer (P=0.001), IOL Master and autokeratometer (P<0.0001), autokeratometer and manual keratometer (P<0.0001). The 95% limits of agreement (LoA) of the IOL Master and manual keratometer were -0.22 to 0.26; IOL Master and autokeratometer were -0.24 to 0.55; autokeratometer and manual keratometer were -0.30 to 0.57 as shown in the Bland-Altman plot.CONCLUSION: Keratometry data obtained with different instruments may not be interchangeable, a fact that has important implications for cataract surgeons with respect to both surgical planning and outcomes auditing.     

VERION数字导航系统测量角膜曲率和散光的可重复性及其与iTrace、Lenstar LS900、手动角膜曲率计检测结果的一致性研究

目的 分析VERION数字导航系统测量角膜曲率和散光的可重复性及其与iTrace、Lenstar LS900、手动角膜曲率计检测结果的一致性.方法 对62名年龄相关性白内障患者分别用上述四种仪器进行角膜生物测量,记录并分析陡峭轴角膜曲率(steep keratometry,Ks)、平坦轴角膜曲率(flat keratometry,Kf)、散光幅度、散光轴位、矢量参数J0和J45.分析VERION测量的可重复性,并比较VERION与其他三种仪器测量结果的一致性.结果 用组内相关系数(intraclass correlation coefficient,ICC)和克隆巴赫系数(Cronbach's alpha,α)分别对Ks、Kf、散光幅度、散光轴位、J0以及J45做出分析,结果均大于0.9(均为P＜0.001),提示VERION测量角膜曲率及散光的可重复性极好.VERION测量的Ks、散光幅度均高于iTrace(均为P＜0.05),其余指标的差异无统计学意义(均为P＞0.05).Bland-Altman分析显示J0、J45及散光轴位的95％ LOA分别为(-0.31 ～0.35)D、(-0.25～0.31)D、-13.5°～12.3°.二者测量的散光轴位差小于10°者占总体的77％ (48/62),在合并角膜散光大于1D的患者中占91％ (42/46).VERION与Lenstar LS900测量结果仅J45差异有统计学意义(P＜0.05),其余指标差异无统计学意义(均为P＞0.05).Bland-Altman分析发现J0、J45及散光轴位的95％ LOA分别为(-0.25 ～0.31)D、(-0.27 ～0.36)D、-13.5°～11.0°.二者测量的散光轴位差小于10°者占总体的85％(53/62),在合并角膜散光大于1D的患者中占93％(43/46).VERION与手动角膜曲率计检测的Kf、散光幅度差异有统计学意义(均为P＜0.05),其余指标差异无统计学意义(均为P＞0.05).Bland-Altman分析显示J0、J45及散光轴位的95％ LOA分别为(-0.38 ～0.35)D、(-0.41 ～0.42)D、-12.6° ～16.4°.二者测量的散光轴位差小于10°者占总体的81％ (50/62),在合并角膜散光大于1D的患者中占91％(42/46).结论 VERION在测量角膜曲率及散光方面具有良好的可重复性.其与iTrace、Lenstar LS900和手动角膜曲率计在角膜曲率、散光幅度的测量方面一致性较好,但对散光轴位的测量差别较大.     

新型眼生物测量仪Tomey OA-2000和IOLMaster获得的白内障患者眼生物参数的比较

目的 比较新型眼生物测量仪Tomey OA-2000与IOLMaster获得的白内障患者眼生物参数的差异性和一致性.方法 前瞻性研究.纳入白内障术前检查者74例(74眼),分别应用Tomey OA-2000和IOLMaster进行测量,获得眼轴长度(axial length,AL)、角膜曲率(keratometry,K)、前房深度(anterior chamber depth,ACD)和角膜横径(white to white,WTW)等参数.配对t检验分析两种设备获得的眼生物参数之间的差异.Bland-Altman散点图分析两种设备获得的各生物参数之间的一致性.结果 Tomey OA-2000获得的AL、平坦K(flat K,Kf)值、陡峭K(steep K,Ks)值、平均K(mean K,Km)值、中央角膜厚度(central corneal thickness,CCT) 、ACD、晶状体厚度(lens thickness,LT)、瞳孔直径(pupil diameter,PD)和WTW值分别为(24.26 ±2.71)mm、(44.09±1.76)D、(45.01±1.73)D、(44.55±1.72)D、(518.41 ±34.18) μm、(3.07 ±0.48)mm、(4.48±0.61)mm、(4.07 ±0.95) mm和(11.50±0.52) mm.IOLMaster获得的AL、Kf、Ks、Km、ACD和WTW值分别为(24.33 ±2.69) mm、(44.21±1.74)mm、(45.15±1.76)D、(44.69±1.74) D、(3.04 ±0.46) mm和(11.65 ±0.41)mm.Tomey OA-2000和IOLMaster获得的AL、Kf、Ks、Km、ACD和WTW差值分别为(-0.07 ±0.10)mm(t=-5.99,P ＜0.01)、(-0.12±0.21)D(t=-4.14,P ＜0.01)、(-0.14 ±0.20) D(t=-5.88,P ＜0.01)、(-0.12±0.13)D(t=-7.44,P＜0.01)、(0.03±0.14)mm(t=1.99,P =0.05)和(-0.14 ±0.32)mm(t=-3.73,P＜0.01).两种设备获得的AL、Kf、Ks、Km、ACD的95％一致性界限(LoA)其上下限最大绝对值分别为0.27 mm、0.50 D、0.53 D、0.38 D、0.30 mm,一致性较好;而WTW的95％ LoA为0.78 mm,一致性较差.结论 Tomey OA-2000和IOLMaster获得的AL、K、ACD差异小,一致性好.     

不同角膜仪测量的角膜曲率值的一致性分析

目的：比较测得后三种不同角膜仪测量的角膜曲率,以评估其测量值之间的一致性。

方法：前瞻性研究。252例患者(252眼)使用IOL Master(IM),Bausch & Lomb手动角膜仪(Man)以及TOPCON KR-8800自动角膜仪(Top)进行角膜曲率测量。记录并对比平均角膜曲率值。使用Bland Altman统计方法进行仪器间的一致性分析。

结果：1)IOL Master 和 手动角膜仪：IOL Master平均角膜曲率为44.62±1.52 D,手动角膜仪为44.60±1.52 D。 t-test显示差异具有统计学意义(P=0.001); Bland-Altman图显示两种仪器间95%一致性区间(LOAs)为-0.22～0.22; 2)IOL Master 和自动角膜仪：IOL Master平均角膜曲率为44.62±1.52 D,自动角膜仪为44.46±1.53 D。t-test显示差异具有统计学意义(P<0.0001)。Bland-Altman图显示两种仪器间95%LOAs为 -0.24～0.55; 3)自动角膜仪和手动角膜仪：自动角膜仪平均角膜曲率为44.60±1.52 D,手动角膜仪为44.46±1.53 D。t-test显示差异具有统计学意义(P<0.0001)。Bland-Altman图显示两种仪器间95%LOAs为-0.30～0.57。

结论：使用不同的仪器获得的角膜曲率数据是不可替换的,这对于白内障外科医生在外科手术计划和结果评估方面具有重要意义。