准分子激光角膜切削术前后角膜地形图对比分析

应用角膜地形图仪对比分析了９０例（１７６眼）ＰＲＫ手术前后角膜表面的形态特征及其变化。结果表明,术前角膜地形图以蝴蝶结形为多（７３．３％）;术后７９．０％为圆形或钥匙孔形,半圆形和蝶形为１８．８％中央岛形占２．２％。ＰＲＫ对散光的一次最大矫正量为－１．７５Ｄ,切削中心偏位是最佳矫正视力下降,复视和屈光度回退的重要原因。提示：ＰＲＫ术后角膜地形图的检查可准确显示角膜形态的细微变化,有利于手术设计的不断完善和效果的提高。     

准分子激光屈光性角膜切削术后角膜地形图分析

目的分析准分子激光屈光性角膜切削术（ｐｈｏｔｏｒｅｆｒａｃｔｉｖｅｋｅｒａｔｅｃｔｏｍｙ,ＰＲＫ）术后角膜切削区的形态、偏心情况和屈光的稳定性。方法对３１２例（３６６只眼）ＰＲＫ手术患者进行术后１、３和６个月的角膜地形图检查。结果术后１个月切削区中心偏离瞳孔中心的距离为０．２６６ｍｍ,双眼平均偏离瞳孔中心的方向均为鼻上侧。切削区形态平滑型占４９．５％,半环型、钥匙洞型、肾型和哑铃型占４２．９％,中心岛型占６．０％。中心岛型对术后最佳矫正视力影响较大。术后１～３个月角膜屈折力变化较大,高度近视比低度近视回退明显。结论提示ＰＲＫ术中瞄准中心问题非常重要,直接影响术后的效果,同时也应长期随访角膜地形图,进一步观察术后的稳定性。     

准分子激光角膜切削中心的角膜地形图分析

目的探讨准分子激光角膜切削术（ｐｈｏｔｏｒｅｆｒａｃｔｉｖｅｋｅｒａｔｅｃｔｏｍｙ，ＰＲＫ）的切削中心对视功能的影响。方法采用Ｅｙｅｓｙｓ角膜形态分析系统对随访６个月以上的９８例（１５８只眼）ＰＲＫ前、后１０天的角膜地形图进行分析，确定激光切削中心相对入射瞳孔中心的方向、距离；比较单区和多区域激光切削的偏中心差异。结果切削区中心相对入射瞳孔中心：０～０．５ｍｍ者１００只眼（６３．３％），０．５～１．０ｍｍ者５５只眼（３４．８％），＞１．０ｍｍ者３只眼（１．９％），平均０．４５ｍｍ。多区域切削３８只眼及单区域切削１２０只眼，其偏心量分别为０．５５ｍｍ和０．４４ｍｍ。差异有显著性（ｔ检验，Ｐ＜０．０５）。偏中心切削致术后最好矫正视力下降１～２行者４只眼，其偏心量＞０．５ｍｍ。结论严重的偏心切削将影响术后视功能恢复，术中眼球跟踪系统（ｐａｓｓｉｖｅｅｙｅ－ｔｒａｃｋｉｎｇ，ＰＥＴ）的应用有利于切削中心的确定，减少偏心量。     

LASIK术后切削中心的角膜地形图分析

目的：探讨准分子激光角膜原位磨镶术（laser in situ keratomileusis,LASIK）切削中心对术后最佳矫正视力的影响及与术前屈光度的关系。方法：应用计算机辅助角膜地形图仪对175例（340眼）LASIK术后随访6月以上的术前、术后角膜地形图进行检测、分析，测量准分子激光切削中心相对瞳孔中心的距离，并与最佳矫正视力、术前屈光度进行比较。结果：切削区中心相对瞳孔中心偏离小于0．5mm者242眼（71．2％），0．5－1．0mm者77眼（22．6％），大于1．0mm者21眼（6．2％）。术后最佳矫正视力下降1－2行者，偏心量小于1．0mm，发生率为7．8％；大于1．0mm发生率为38．1％，切削中心偏移致术后最佳矫正视力下降，与术前屈光度无关。结论：LASIK前后角膜地形图检查和分析能清楚地显示角膜表面形态变化及定量评估切削区偏中心问题。严重的偏中心切削是影响术后最佳矫正视力的重要因素。     

准分子激光屈光性角膜切削术后角膜地形图的变化

目的探讨准分子激光屈光性角膜切削术（ＰＲＫ）后角膜表面形态和屈光力变化。方法ＴｏｍｅｙＴＭＳ２ＴＭ角膜地形图检查１２４只近视眼ＰＲＫ术前、术后１、６月和１年统计值的变化。结果ＰＲＫ术后眼绝对等级角膜地形图见梯度明显的蓝色低屈光带。ＳＲＩ和ＳＡＩ术后１月时比术前和术后６月、１年时高，ＩＡＩ术前后无变化。近视眼治疗等值球镜屈光度分别与ＳＲＩ、ＳＡＩ和ＩＡＩ的相关系数为０．７６６、０．４６１和－０．１０５。结论ＰＲＫ术后角膜屈光力稳定性较好，对角膜表面规则性和对称性早期有影响，逐渐恢复正常。ＰＲＫ角膜切削区带越多，对角膜表面形态影响越大。     

准分子激光原位角膜磨镶术后角膜地形图分析

为分析准分子激光原位角膜磨镶术后角膜地形图的动态变化,随访ＬＡＳＩＫ后１月病人共１３７例（１９６眼）,术后３月４８例（７０眼）。采用随机扫描式消融角膜基质。术后用０．３％氟嗪酸,０．１％ＦＭＬ滴眼１０天。记录术前、术后１个月、３个月的视力,屈光度数,角膜地形图。结果：术后１月角膜表面规则系数、角膜表面非对称系数明显大于术前,术后３月无明显改善。术后１月切削形态中平滑型占８９．８％,其他形态占１０．２％。切削形态随时间延长逐步变规则。术后切削中心平均偏心０．６７±０．４８ｍｍ（０～２．２４ｍｍ）,偏心距离在１ｍｍ以内对最佳矫正视力影响不大,偏心方向以鼻侧居多。结论：ＬＡＳＩＫ手术由于保持了角膜上皮层及前弹力层,术后角膜及切削形态较规则,但仍然存在偏心切削的问题。角膜地形图为临床评估ＬＡＳＩＫ效果提供了客观依据。     

角膜屈光手术后角膜地形图变化与散光关系

为探讨角膜屈光手术后角膜地形图变化与临床散光的关系，对ＭＬＫ和ＬＡＳＩＫ术后４８例８６只眼行术前及术后６个月角膜地形图测量分析，并与同期的视力和验光结果进行比较。结果表明，术后柱镜屈光度及ＳＲⅠ、ＳＡⅠ及ＳｉｍＫ较术前明显升高，３２．６％的病人有切削区偏中心，但全部病人的裸眼视力及术后矫正视力均好于术前。裸眼视力好于或等于术前者占７６．３４％。提示以上现象的发生对手术效果无影响，其原因可能与后巩膜葡萄肿导致的视轴偏位使激光切削区偏离角膜光学中心有关     

应用角膜地形图评价PRK矫正近视散光的疗效

目的以ＰＲＫ矫正近视性散光术后１ａ临床结果和角膜地形图检测结果评价ＰＲＫ矫正近视散光的效果。方法对６１只眼近视散光在－２．００Ｄ以上者应用ＰＲＫ治疗，术后随访１ａ，并对手术前后散光的变化进行角膜地形图比较。结果患者ＰＲＫ术后１ａ检查，其中６０只眼散光在０～－１．００Ｄ之间，角膜切削区中心距瞳孔中心均≤０．５ｍｍ，角膜地形图检测术前△Ｋ值为１．８５±０．５９Ｄ，术后△Ｋ值为０．９０±０．４３Ｄ，显示术后散光下降明显。结论ＰＲＫ治疗散光效果明显，但应解决角膜切削区域偏中心情况。     

准分子激光角膜切削术后散光的角膜地形图分析

了解准分子激光角膜切削术（ｐｈｏｔｏｇｒａｃｔｉｖｅｋｅｒａｔｅｃｔｏｍｙ，ＰＲＫ）前、后最大轴性散光的变化及对术后视力的影响。方法对ＰＲＫ后１年以上的６１例（１０９只眼）术前散瞳验光散光度一１．００～－２．００Ｄ的角膜地形图进行分析及视力检查。结果散瞳验光散光轴位与地形图记录散光轴位基本一致，而散光度数有一定差异。地形图检查显示，最大散光轴位以循规性极光最多，计６７只眼（６１％），斜轴性散光３６只眼（３３％），逆规性散光６只眼（６％）。手术前、后散光轴位变化极小。散光度多数在术后１０天及１个月开始增加，以后逐渐减少。６个月或１年趋于稳定。术后的残存散光对视力影响较小，实际矫正度在预期矫正度±１．００Ｄ以内者占９７％。结论采用球柱折算方法，进行ＰＲＫ，对矫正近视合并散光者（－２．００Ｄ以下），可以获得满意的屈光矫正。     

角膜屈光手术后膜地形图变化与散光关系

为探讨角膜屈光手术后角膜地形图变化与临床散光的关系，对ＭＬＫ和ＬＡＳＩＫ术后４８例８６只眼行术前及术后６个月角膜地形图测量分析，并与同期的视力和验光结果进行比较。结果表明，术后柱镜屈光度及ＳＲＩ、ＳＡＩ及ＳｉｍＫ较术前明显升高，３２．６％的病人有切削区偏中心，但全中病人的裸眼视力及术后矫正视力均好于术前。裸眼视力好于或术前者占７６．３４％。提示以上现象的发生对手术效果无影响，其原因可能与后巩膜葡萄     

角膜塑型术前后的角膜地形图分析

分析角膜塑型术后角膜地形图的类型及其动态变化 ,探讨角膜地形图类型与视力的关系。方法 :应用角膜地形图仪对比分析了 36 0例 ( 712眼 )戴OK镜前后角膜表面的形态及与视力的关系。结果 :术前角膜地形图以蝴蝶结型为多 ( 78 6 % ) ;术后角膜地形图分为两类八型 ,即规则型 (均匀型 ,顺轴圆枕型 ,逆轴圆枕型 ,局灶型地形图改变 )和不规则型 (中央岛型 ,半环型 ,钥匙孔型 ,不规则型 ) ,以均匀型和圆枕型占多数 ,各型随时间而改变 ,且趋于平稳。不规则地形图对术后最佳矫正视力的影响较大。结论 :角膜地形图的定量分析对角膜塑型术后角膜表面性状的评价 ,镜片设计的改进 ,塑型疗效的预测等有重要的意义。     

角膜地形图在LASIK术中作用

目的分析角膜地形图在准分子激光原位角膜磨镶术（LASIK）前后形态变化及其与临床效果的关系。方法Eyesys计算机辅助角膜地形图对150例（294眼）施行LASIK术前术后进行榆杏．结果术前对称仆对称领结型较多，共190眼（64．63％）：圆形椭圆形次之，共91眼（30．95％）；不规则形13眼（4．42％）。术后1、3、6月以圆形椭圆形居多，且相对稳定，随术后时间延长形态变化不明显，并以这部分患眼视力最好。术后6月246眼圆形椭圆形类型中229眼（93．09％）裸眼视力≥1．0。结论LASIK术前术后角膜地形图检查对适应证选择、手术参数设计、术后效果评价具有重要的指导作用。     

青少年近视眼角膜地形图的临床分析

目的探讨青少年近视眼角膜地形图特点.方法对236例463眼青少年近视眼患者采用日本TopconKR-7100P角膜彩色地形图自动验光仪进行检测,对检测结果进行统计分析.结果①463眼角膜地形图中圆形67眼,占14.47%;椭圆形35眼,占7.56%;不规则形16眼,占3.46%;各种蝴蝶结形角膜地形图共有345眼,占总眼数73.92%.②各种角膜地形图眼的屈光度、角膜厚度、角膜直径、眼轴、眼压等差异均无统计学意义.③蝴蝶结形组与圆形角膜地形图组比较,其角膜垂直K值、角膜散光度、总散光度差异有统计学意义(P＜0.01).结论①青少年近视患者的各种角膜地形图形态与其角膜屈光度、角膜直径、角膜厚度、眼压等无明显差异.②当角膜有散光时,地形图可呈现蝴蝶结形,蝴蝶结形的轴向与角膜循散光、逆散光、斜轴散光轴向相符合.     

Relationship between topographic patterns and corneal astigmatism in Korean adults

The anterior corneal surface is one of the most important elements determining the optical performance of the eye. Corneal topography provides quantitative data about the anterior corneal surface. We studied the corneal topography of 200 normal corneas in 110 adult subjects. All of the eyes were examined using the Corneal Analysis System (EyeSys 2000, Houston, Texas). The topographic maps were grouped into the following patterns: round, oval, symmetric bow tie, asymmetric bow tie, and irregular. The symmetric and asymmetric bow tie patterns were the most common topographic pattern (33.0%, and 32.5%, respectively) in our study population, followed by oval (14.5%), irregular (12.5%), and round (7.5%) patterns. The mean corneal astigmatism calculated from videokeratographic data was 0.32 D for round, 0.63 D for oval, 1.16 D for symmetric bow tie, 1.21 D for asymmetric bow tie, and 0.43 D for irregular patterns. There were significant differences among the corneal astigmatic values in the topographic patterns (p < 0.01, Gabriel post hoc test). The distributions of symmetric and asymmetric bow tie patterns were skewed toward greater amounts of corneal astigmatism. In conclusion, the results of this study demonstrate the relationship between topographic patterns and corneal astigmatism and should provide one possible normal standard for corneal topography in Korean adults.     

Evaluation of corneal thickness and topography in normal eyes using the Orbscan corneal topography system.

AIMS: To map the thickness, elevation (anterior and posterior corneal surface), and axial curvature of the cornea in normal eyes with the Orbscan corneal topography system. METHODS: 94 eyes of 51 normal subjects were investigated using the Orbscan corneal topography system. The anterior and posterior corneal elevation maps were classified into regular ridge, irregular ridge, incomplete ridge, island, and unclassified patterns, and the axial power maps were grouped into round, oval, symmetric bow tie, asymmetric bow tie, and irregular patterns. The pachymetry patterns were designated as round, oval, decentred round, and decentred oval. RESULTS: The thinnest point on the cornea was located at an average of 0.90 (SD 0. 51) mm from visual axis and had an average thickness of 0.55 (0.03) mm. In 69.57% of eyes, this point was located in the inferotemporal quadrant, followed by the superotemporal quadrant in 23.91%, the inferonasal quadrant in 4.35%, and the superonasal quadrant in 2.17%. Among the nine regions of the cornea evaluated (central, superotemporal, temporal, inferotemporal, inferior, inferonasal, nasal, superonasal, and superior) the central cornea had the lowest average thickness (0.56 (0.03) mm) and the superior cornea had the greatest average thickness (0.64 (0.03) mm). The mean simulated keratometry (SimK) was 44.24 (1.61)/43.31 (1.66) dioptres (D) and the mean astigmatism was 0.90 (0.41) D. Island (71.74%) was the most common elevation pattern observed in the anterior corneal surface, followed by incomplete ridge (19.57%), regular ridge (4.34%), irregular ridge (2.17%), and unclassified (2.17%). Island (32.61%) was the most common topographic pattern in the posterior corneal surface, following by regular ridge (30.43%), incomplete ridge (23. 91%), and irregular ridge (13.04%) patterns. Symmetric bow tie was the most common axial power pattern in the anterior cornea (39.13%), followed by oval (26.07%), asymmetric bow tie (23.91%), round (6. 52%), and irregular (4.53%) patterns. In the pachymetry maps, 47.83% of eyes had an oval pattern, and round, decentred oval, and decentred round were observed in 41.30%, 8.70%, and 2.18% of eyes, respectively. CONCLUSION: The information on regional corneal thickness, corneal elevation and axial corneal curvature obtained with the Orbscan corneal topography system from normal eyes provides a reference for comparison with diseased corneas. The Orbscan corneal topography system is a useful tool to evaluate both corneal topography and corneal thickness.     

准分子激光角膜切削术后角膜地形图的临床观察

目的：准分子激光角膜切削术（PRK）后进行角膜地形图的检测分析。方法：对113例（253眼）近视患者手术后1、3、6个月进行角膜地形图随访。结果：PRK术后能产生一种稳定的角膜外形,角膜地形图主要表现为四种形态：圆形或椭圆形（48．62％）,对称或不对称形（28．06％）,半球形（17．79％）,中央小岛形（5．53％）,且各种态与最佳视力有着一定的关系。术后6个月模拟角膜计读数（Simk)表现一定回退。Simk差值无显著性差异,说明PRK本身不引起散光。结论：角膜地形图定量分析对PRK术后角膜表面的改变、手术设计的改进、手术疗效的预测等是必要的。     

LASIK术前应用Pentacam分析角膜后表面地形图与术后视力改善的关系探讨

目的:应用Pentacam系统对近视LASIK术前角膜后表面地形图分析,探讨地形图与术后视力情况的关系。方法:应用Pentacam眼前节分析仪对患者术前进行表面地形图分析,观察各分类小组术前和术后3,6mo的裸眼视力和最佳矫正视力,观察术前和术后3mo后的散光度数。结果:对称和不对称领结形组、圆形和椭圆形组、不规则形组所占比例为76.13%,19.03%和4.84%,3组比较差异有统计学意义(P<0.05);术后3mo和6mo的裸眼视力均较术前有显著改善(P<0.05),而3mo和6mo的裸眼视力则无明显差异(P>0.05);最佳矫正视力术前、术后3组均无明显区别(P>0.05);但裸眼视力和最佳矫正视力改善情况圆形和椭圆形组最好,对称和不对称领结形组次之,最后为不规则形组。术前、术后3组的散光度数之间有显著性差异(P<0.05),术后3mo与术前差异也有统计学意义(P<0.05)。结论:Pentacam系统在近视LASIK术前角膜后表面地形图的测量分析中应用,发现不同的表面地形图和术后视力恢复情况有相关关系。     

Anterior corneal surface after Nidek EC-5000 multipass and multizone photorefractive keratectomy for myopia

PURPOSE: To evaluate the correlation between the presence of irregularities in corneal ablation and the number of ablation zones with multipass and multizone photorefractive keratectomy (PRK). METHODS: The differential maps obtained from corneal topography performed before and 1 month after PRK in 62 eyes that had undergone PRK with the Nidek EC-5000 excimer laser were assessed for irregularities. PRK treatment ranged from -1.00 to -16.00 D (mean -5.25 +/- 2.72 D), and the number of zones ranged from one to five. RESULTS: Of 62 differential maps, 27 had an irregular pattern according to the Hersh classification, with a non-significant correlation with the number of treatment zones (chi2 = 5.09, P >.1). CONCLUSION: Our results suggest that corneal topography irregularities arising from multizone PRK were not related to the amount of treatment or to the number of ablation zones.     

Topographical analysis of corneal astigmatism in patients with tilted-disc syndrome

PURPOSE: To evaluate the corneal topography in patients with tilted-disc syndrome to determine the relationship between optic disc dysversion and corneal astigmatism and the pattern of astigmatism in these patients. METHODS: The study included 23 eyes of the 13 tilted-disc syndrome patients with spheric refractive errors ranging between +1.00 D and -9.00 D (mean -4.00 +/- 3.4 D) and astigmatic errors ranging between -0.50 and -4.50 D (mean -1.95 +/- 0.93 D). Corneal topography was performed by computer-assisted videokeratoscope topographic modelling system 2 (TMS-2) and incidence of corneal astigmatism, corneal topographic patterns, and mean values of the topographic indices were determined. RESULTS: Corneal topographic analysis showed corneal astigmatism in 22 out of 23 patients with tilted discs. Corneal astigmatism was symmetric bow tie pattern in 10 eyes (45.45%), asymmetric bow tie pattern in 11 eyes (50%) and irregular in 1 eye (4.5%). Among the patients with bow tie pattern group (21 eyes), 14 eyes had with-the-rule astigmatism, 1 eye had against-the-rule astigmatism, and 6 eyes had oblique astigmatism. In 18 eyes, astigmatism was corneal, whereas combined corneal and lenticular in 4 eyes and lenticular in 1 eye. CONCLUSION: In the majority of tilted-disc cases, ocular astigmatism is mainly corneal. Morphogenetic factors in the development of the tilted disc might possibly influence the corneal development in such a way to result in corneal astigmatism.