像差仪在主观验光中的应用价值

目的评估像差仪检测结果在主观验光中的作用。方法选择2004年5月至2004年11月于本院行近视屈光手术患者129例,252眼。根据患者在睫状肌麻痹前的电脑验光的球镜度数,分成<-6.0D、-6.0～9.0D、>9.0D三组,分别称为一般度数组、高度数组和超高度数组。患者被随机选择先行电脑验光或像差检查,再经综合验光仪(Nidek)行主观验光。对同一眼的球镜量、散光量、轴向在电脑验光、像差测量和综合验光仪检查(均未予睫状肌麻痹)等三种检查方法之间的相关性情况进行分析。结果①一般度数组:综合主观验光、电脑验光、像差仪三种方法球镜度数分别为(-3.28±2.52)D、(-3.18±2.93)D、(-2.86±2.89)D;散光度数分别为(-1.24±1.86)D、(-1.99±1.56)D、(-1.35±1.28)D;散光轴向分别为81.68±73.26、70.11±58.99、89.14±78.90,所有参数各种方法之间无明显差异(P>0.05),有很好的相关性(P<0.05)。②高度数组:综合主观验光、电脑验光、像差仪三种方法球镜度数分别为(-7.43±1.27)D、(-7.38±1.03)D、(-7.81±1.19)D;散光度数分别为(-1.16±1.02)D、(-1.12±0.75)D、(-1.41±1.64)D;散光轴向分别为86.50±71.24、94.71±65.03、100.62±74.07,所有参数各种方法之间无明显差异(P>0.05),有很好的相关性(P<0.05)。③超高度数组:综合主观验光、电脑验光、像差仪三种方法球镜度数分别为(-14.07±4.09)D、(-12.12±3.66)D、(-11.75±3.19)D,各种方法之间无明显差异(P>0.05),有很好的相关性(P<0.05);散光度数分别为(-2.02±1.59)D、(-0.74±0.71)D、(-1.05±0.77)D,各种方法之间有明显差异(P<0.05);散光轴向分别为86.27±63.87、77.68±57.85、110.36±70.83,各种方法之间无明显差异(P>0.05),有很好的相关性(P<0.05)。结论在一般近视中,像差仪检查可替代电脑验光作为客观验光的方法,但在超高度近视中偏差则较大。     

波前像差仪与常规验光法对眼屈光不正测量的对比观察

目的　通过波前像差仪、客观电脑验光仪及主观插片验光 3种方法对屈光不正度测量方法和结果的比较 ,了解波前像差仪对低阶像差测量的准确性及几种方法的优缺点。方法　选取来我院接受准分子激光屈光手术的近视患者 4 8例 (48眼 ) ,分别进行MEL 70WASCA波前像差仪、客观电脑验光仪与主观插片验光法检查 ,对所得近视度数、散光度数、散光轴向进行统计分析、比较。结果　波前像差仪、客观电脑验光仪、主观插片验光 3种方法测得的等效球镜度分别为 (-7.0 1± 3.0 6 )D ,(- 6 .97± 3.5 2 )D ,(- 7.4 0± 3.6 0 )D ;近视球镜度分别为 (- 6 .77± 3.0 7)D ,(- 6 .6 1± 3.4 6 )D ,(- 7 11±3 5 5 )D ;散光度分别为 (- 0 .5 8± 0 .4 4 )D ,(- 0 70± 0 6 0 )D ,(- 0 5 8± 0 6 5 )D ;散光轴向度分别为 94 3°± 5 6 6°,81 5°±6 7 9°,81 1°± 73 2° ;差异均无显著性意义。而且波前像差仪与客观电脑验光法所测得的屈光不正度数更为接近。结论　运用MEL 70WASCA波前像差仪在暗视原瞳状态下测得的低阶像差能够较准确地反映眼的屈光不正状态。     

Zywave波前像差仪测量屈光不正的准确性研究

目的评价Zywave波前像差仪测量近视眼屈光不正的准确性。方法对56例行屈光不正矫正术的怠者（106只限）分别用电脑验光（睫状肌麻痹和非睫状肌麻痹下）、显然验光、Zywave波前像差仪法测量眼屈光不正，并将患者按屈光不正度数分为三组：低度近视组（-0．50～-3．00D），中度近视组（-3．25--6．00D），高度近视组（-6．25D-）。对测量的结果进行单因素方差分析（ANOVA）。结果四种验光方法测量的验光结果（球镜、拄镜、等效球镜）除低度近视组电脑验光和睫状肌麻痹状态下验光的球镜度数（P=0．029）及等效球镜度数之间的比较差异有显著性（P=0．024）外，余在低度近视组、中度近视组及高度近视组两两之间比较差异均无显著性（ANOVA，P〉0．05）。Zywave波前像差仪和显然验光及睫状肌麻痹状态下验光测量结果比较，随屈光不正度数增加，球镜相符率降低，柱镜相符率升高。结论Zywave波前像差仪测量屈光不正有较高的准确性，可以很好地用于Zyoptix系统个体化切削治疗使用，但与显然验光和睫状肌麻痹状态下验光比较仍有差异，可以作为以上两种验光方法的参考和补充。     

Wavescan波前像差仪测量屈光不正的准确性研究

目的:评价Wavescan波前像差仪测量近视眼屈光不正的准确性。方法:对33例66眼行屈光不正矫正术的患者分别用电脑验光(睫状肌麻痹和非睫状肌麻痹下)、显然验光、Wavescan波前像差仪法测量眼屈光不正,并将患者按屈光不正度数分为3组:低度近视组(-0.50～-3.00D)17眼,中度近视组(-3.00～-6.00D)27眼,高度近视组(-6.00～D)22眼。对测量的结果进行两两比较,采用配对t检验分析。结果:四种验光方法测量的验光结果(球镜、柱镜、等效球镜)显示,低度近视及高度近视组,显然验光与Wavescan波前像差仪验光球镜及柱镜度数比较没有统计学差异(P=0.289,P=0.814,P=0.057,P=0.246),睫状肌麻痹状态下验光与Wavescan波前像差仪验光在中高度近视组,球镜度数及柱镜度数之间的比较差异没有统计学意义(P=0.052,P=0.111,P=0.539,P=0.154),并且结果不随屈光状态的不同而不同,而等效球镜度数之间的差异具有统计学意义。Wavescan波前像差仪和显然验光及睫状肌麻痹状态下验光测量,结果比较,随屈光不正度数增加,球镜相符率降低,柱镜相符率升高。结论:Wavescan波前像差仪测量屈光不正有较高的准确性,可以很好地用于VISXSTARS4准分子激光治疗系统个体化切削治疗使用,但与显然验光和睫状肌麻痹状态下验光比较仍有差异,可以作为以上两种验光方法的参考和补充。     

波前像差仪测量近视患者低阶像差的临床研究

目的:通过波前像差仪与自动验光仪、综合验光仪3种方法测量近视患者屈光状态结果的对比观察,探讨波前像差仪对低阶像差测量的准确性。方法:随机选取2005-06/2005-09来我院进行LASIK术前检查的近视患者67例100眼,分别应用波前像差仪、自动验光仪、综合验光仪对其球镜度数、柱镜度数、散光轴向测量后进行统计分析、比较。结果:波前像差仪、自动验光仪、综合验光仪3种方法测得的球镜度数分别为-6.18±2.77,-5.80±2.80,-5.88±2.72D;柱镜度数分别为-0.73±0.57,-0.75±0.59,-0.72±0.56D;散光轴向中位数分别为66.00°,45.50°,27.50°,四分位数间距分别为162.75°￣11.25°,160.00°～4.25°,161.00°～5.00°;等效球镜度分别为-6.55±2.90,-6.17±2.91,-6.24±2.81D;统计学上均无显著性差异。结论:波前像差仪在准确测量眼高阶像差的同时,能够准确地测量近视患者的低阶像差。     

波前像差仪与主观验光对屈光度检查的结果分析

目的:比较波前像差仪与主观验光法对屈光度检查的结果,探讨波前像差仪对低阶像差测量的可靠性和准确性。方法:对2007-07/2007-10在我院拟行准分子激光角膜屈光手术的患者88例168眼,分别使用以Hartmann-Shack原理为基础设计的德国蔡司WASCA波前像差仪分析系统以及主观插片验光方法进行检查,并对近视球镜、近视柱镜、散光轴向的结果比较、分析。结果:波前像差仪与主观验光测量的屈光度较为接近,等效球镜度分别为-6.53±1.64D和-6.44±1.89D;近视球镜度分别为-5.93±1.65D和-5.83±1.80D;近视柱镜度分别为-1.22±0.66D和-1.27±0.70D;散光轴向度分别为110.67±75.69°和119.24±74.21°;四组数据的统计学分析均无显著性差异(P>0.05)。结论:波前像差仪在无需散瞳的情况下能够较为准确地反映眼屈光度的情况。     

便携式电脑验光仪筛查屈光不正的可行性探讨

目的 探讨便携式电脑验光仪的准确性及用其筛查屈光不正的可行性.设计诊断试验.研究对象2008年6月至9月南通大学附属医院眼科就诊的屈光不正患者65例（130眼）.方法 对所有病例分别行SHIN-NIPPON SRH-2000便携式电脑验光仪验光及视网膜检影.主要指标屈光值（球镜度数、柱镜度数及轴向）的差异性检验、相关分析及受试者工作特征（ROC）曲线分析.结果 以视网膜检影为金标准,电脑验光的球镜度数轻度偏正,其中睫状肌麻痹后电脑验光与检影的差值为（＋0.33±0.56）D,呈高度正相关（r=0.98,P〈0.01）,差异有统计学意义（t=6.87,P〈0.01） 电脑验光的柱镜度数轻度偏负,其中睫状肌麻痹后电脑验光与检影的差值为（-0.23±0.45）D,呈中度正相关（r=0.81,P〈0.01）,差异有统计学意义（t=-5.85,P〈0.01）.电脑验光在睫状肌麻痹前后比较无统计学差异（球镜度数t=1.31,P=0.26 柱镜度数t=-0.28,P=0.78）.电脑验光对散光的检出率高,但主要是≤0.75D的低度散光,且与视网膜检影的轴向差值多数≤150.以视网膜检影的等效球镜为参考指标,电脑验光的ROC曲线下面积〉0.95（睫状肌麻痹后为0.984,睫状肌麻痹前为0.979）.结论 便携式电脑验光仪筛查屈光不正的准确性与视网膜检影一致,可用在群体眼病流行病学调查中筛查屈光不正.     

波前像差仪在激光原位角膜磨镶术前屈光度测量的意义

目的 评价Zywave波前像差仪在激光原位角膜磨镶术(LASIK)前测量屈光度的作用.方法 随机选取2011年6月至2011年8月在我院接受LASIK术前检查近视46例(84眼).应用电脑验光、检影验光、主觉验光、综合验光及Zywave波前像差仪对其球镜度、柱镜度及等效球镜度测量并行统计分析.结果 低度近视组电脑验光与波前像差仪验光球镜度、等效球镜度间差异有统计学意义,柱镜度间差异无统计学意义,综合验光、主觉验光分别与波前像差仪验光比较,3种屈光度之间差异均无统计学意义,检影验光与波前像差仪验光的3种屈光度之间差异均有统计学意义.中度近视组及高度近视组常规验光分别与波前像差仪验光比较,柱镜度间差异有统计学意义,其余差异无统计学意义.结论 应用Zywave波前像差仪对LASIK术前屈光度测量有一定准确性.对中高度近视波前像差仪验光与其他验光存在差异,可以此对综合验光与主觉验光进行细微调整.     

波前像差仪与综合验光仪测量近视屈光度的对比研究

目的通过波前像差仪和综合验光仪测量近视屈光度的对比观察,探讨波前像差仪测量近视屈光度的准确性。方法回顾性分析2010年7月至2011年7月在我院行近视眼矫正术术前常规行综合验光检查并行波前像差检查的患者586例(1160只眼),年龄18～40岁。按其综合验光屈光度分为轻度组(0～-3.00 DS),中度组(>-3.00 D～-6.00 D),高度组(>-6.00 D以上)分别应用综合验光仪和波前像差仪检查其球镜度、柱镜度和散光轴位,将其结果进行统计分析。结果轻度近视组综合验光与波前像差仪球镜检查结果分别为(-1.83±0.76)和(-1.88±0.77),二者差异无统计学意义(P>0.05);中度组分别为(-4.47±0.75)和(-4.38±0.99),二者差异无统计学意义(P>0.05);高度组分别为(-7.04±0.86)和(-7.16±0.88)二者差异无统计学意义(P>0.05)。散光综合验光与波前像差检查结果分别为(-0.63±0.63)和(-0.69±0.50)二者差异无统计学意义(P>0.05)。散光轴位综合验光与波前像差检查结果分别为(129.76±62.95)和(125.76±64.05)二者差异无统计学意义(P>0.05)。结论波前像差仪在准确测量眼的高阶像差的同时能准确地测量近视患者的低阶像差,可以很好的反映整个眼球屈光系统的异常。     

iTrace波前像差仪表达眼屈光状态的临床研究

目的 研究iTrace波前像差仪在单眼闭合式和双眼开放式两种状态下,客观验光表达近视患者屈光状态的准确性.方法 对前瞻性研究近视患者39例77只眼,球镜-0.75-9.50D,柱镜0.00-2.50D.以主觉验光(综合验光仪标准流程)作为标准,主觉验光和iTrace波前像差仪单眼闭合式(iTrace单眼)和双眼开放式(iTraee双眼),客观验光之间的差值作为衡量iTrace波前像差仪客观验光准确性的指标.用矢量分析法分析验光结果.分别计算主觉验光、iTrace单眼验光和iTrace双眼验光之间的矢量差值和绝对屈光度差值(m值),再把矢量差值的平均值转换成球镜、柱镜和轴向差值的形式.结果 iTrace单眼验光和主觉验光比较,球镜、柱镜和轴向差值分别为:-0.02D、-0.25D和74.81度,m值的平均值为(0.53±0.31)D,其中m值小于0.75D的占81.82%;iTrace双眼验光和主觉验光比较,球镜、柱镜和轴向差值分别为:-0.27D、-0.20D、67.46度,m值的平均值为(0.56±0.29)D,其中m值小于0.75D的占75.32%;iTrace单眼验光和iTrace双眼验光与主觉验光比较,m值小于0.75D所占的百分比之间差异无统计学意义(P＞0.05).结论 iTrace波前像差仪能客观表达人眼的屈光状态,其结果能为主觉验光提供参考,但欲以iTrace单眼验光或iTrace双眼验光替代主觉验光尚有诸多问题有待解决.     

近视眼患者波前像差的分析研究

目的：对近视眼患者存在的波前像差进行相关因素分析。 方法：用波前像差仪对前来我院行LASIK手术的115例218眼进行波前像差的检查,并进行常规角膜屈光手术的各项术前检查,同时用对比敏感度检查表进行对比敏感度的检查,将各项结果分别与波前像差进行相关性分析。 结果：像差成分以低阶像差为主,高阶像差有明显的个体差异,最大值是最小值的62倍;术前像差和瞳孔直径呈正相关关系,即随着瞳孔直径的增加高阶像差增加;高阶像差与中频区对比敏感度存在弱的负相关性;波前像差和患者的屈光度的高低有关系;随着散光度数的增加,波前像差增加。术前像差各成分和性别无显著相关性。 结论：近视眼患者的波前像差受患者具体条件的影响,个性化手术去除波前像差应考虑周全。     

在准分子激光治疗散光中单独应用虹膜定位技术的临床体会

目的：探讨单独应用虹膜定位技术在准分子激光治疗散光中的应用价值。方法：2010-11/2012-11在我院行LASIK术治疗的复合性近视散光患者203例406眼,分为两组,使用虹膜定位的观察组及常规手术方式的对照组。观察组患者100例200眼,年龄18～43岁,球镜屈光度为-1.25～-8.75D,散光度为-1.0～-3.25D。对照组患者103例206眼,年龄19～44岁,球镜屈光度为-1.75～9.50D,散光度为-1.0～-3.25D。观察组术前应用WaveScan波前像差仪检查获取虹膜影像、球镜、柱镜和散光轴的数据,手术中只单独应用虹膜定位,不使用波前像差引导技术,激光切削模式为常规LASIK模式,球镜、柱镜和散光轴的数据源于术前波前像差仪检查结果。对照组接受常规LASIK。术前、术后1wk和6mo,分别在电脑验光基础上应用综合验光方法测定散光度和轴向。应用SPSS 17.0统计软件分析,两组间残余散光度及散光轴向进行独立样本t检验。结果：术后残余散光度,观察组明显优于对照组。术后散光轴向测量,观察组明显小于对照组。术后6mo裸眼视力,观察组优于对照组。差异均具有统计学意义。结论：对于不能完成波前相差引导治疗散光的患者,可单独应用波前像差仪虹膜自动识别定位技术提高散光治疗的精准性,充分发挥设备先进技术性能,有较好的应用价值。     

Laser in situ keratomileusis for the correction of myopia and myopic astigmatism

PURPOSE: To evaluate the efficacy, safety, predictability, and surgically induced astigmatism (SIA) of laser in situ keratomileusis (LASIK) for the correction of myopia and myopic astigmatism. SETTING: Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan. METHODS: This retrospective study comprised 69 eyes that had LASIK to correct myopia and 74 eyes that had LASIK to correct myopic astigmatism. The excimer laser keratectomy was performed using a Summit Apex Plus machine. Refraction, visual acuity, and computerized corneal videokeratography data from the preoperative and postoperative examinations were collected. The astigmatic change was calculated by the Alpins vector analysis method. RESULTS: The preoperative spherical equivalent at the glasses plane in the myopia and myopic astigmatism groups was -8.08 diopters (D) and -9.73 D, respectively. At 6 months, the spherical equivalent and residual corneal astigmatism were -0.25 D and 0.85 D, respectively, in the myopia group and -0.71 D and 0.82 D, respectively, in the myopic astigmatism group. In the myopia group, 88% of eyes were within +/-1.0 D of the intended myopia correction and in the myopic astigmatism group, 85% were within +/-1.0 D of the targeted spherical equivalent and 90% were within +/-1.0 D of the intended astigmatism correction. The uncorrected visual acuity was 20/40 or better in 94.1% of eyes in the myopia group and 92.5% of eyes in the myopic astigmatism group. The SIA magnitude was 0.66 D with the axis randomly distributed in the myopia group. The mean astigmatism correction index was 0.97, the mean magnitude of error was 0.13 D +/- 0.62 (SD), and the mean angle of error was -3.70 +/- 13.73 degrees in the myopic astigmatism group. CONCLUSION: Laser in situ keratomileusis had similar predictability, safety, and efficacy in the treatment of myopia and myopic astigmatism. The astigmatism correction was effective, but the results suggest that subjective astigmatism of less than 1.0 D need not be treated with the Summit Apex Plus laser.     

睫状肌麻痹前后综合验光仪与常规验光比较分析

目的 对比分析睫状肌麻痹前后综合验光仪主觉验光和常规主觉插片屈光度的差异变化,探讨科学规范的验光方法.方法 选取2009年8月行屈光检查的近视患者108例,年龄17～28岁,睫状肌麻痹前后用电脑验光仪或检影镜进行客观验光,然后在此基础上进行综合验光仪主觉验光和常规主觉插片.将检测结果用统计软件SPSS11.0进行统计学分析.结果 综合验光仪主觉验光球镜和柱镜度数在睫状肌麻痹前后变化不大,差异无统计学意义(P＞0.05).而常规验光球镜度数睫状肌麻痹前后差异有统计学意义(P＜0.01).柱镜度数散瞳前后差异无统计学意义(P＞0.05).结论 对于成人屈光不正患者,规范科学的综合验光仪主觉验光无需散瞳松弛睫状肌即可获得准确的屈光不正度数,是一种简便准确可靠的验光方法.     

近视眼全眼散光及角膜散光对LASIK术矫正近视散光的影响

目的:探讨全眼散光和角膜散光对LASIK手术矫正散光的影响。方法:回顾性分析84例162眼行LASIK手术矫正的近视散光患者,根据全眼散光与角膜散光轴向相差<15°,全眼散光度数<2倍角膜散光度数和全眼散光与角膜散光轴向相差≥15°,全眼散光度数≥2倍角膜散光度数分为A(112眼)、B(50眼)两组,分析术后视力、散光矫正效果。结果:患者中69%的全眼散光轴与角膜散光轴向相关,差异在15°以内,术后两组眼散光度数分别为-0.39±0.43,-0.73±0.21D,差异有统计学意义(P<0.05)。B组有4例患者主诉夜晚有眩光,近视力差、疲劳。结论:近视眼全眼散光与角膜散光有高度相关性。LASIK矫正散光术前应根据验光和角膜地形图结果分析,合理设计散光的切削量和轴位,选择个性化治疗方案。     

散光相关性屈光不正近视化状况

目的 探究散光相关性屈光不正近视化进程的状况.方法 病例系列研究.选取4～6岁散光儿童210例（412眼）,男114例,女96例.检测其最佳矫正视力、眼轴长度、扩瞳验光度数（1%硫酸阿托品滴眼液）等指标,随访24个月.应用SAS 9.2统计软件中的混合效应模型,分析不同度数和轴向的散光对球性屈光不正度数和眼轴长度的影响.结果 2年内,210例儿童中散光度数越高,眼轴长度和近视度数增加越显著（F分别为7.380、10.636,P均＜0.01）;超高度组明显重于轻、中、高度组（P均＜0.05）,而轻度与中度组差异不明显;眼轴长度和近视度数增加值在轻度组分别为（0.19±0.10）mm、（0.78±0.79）D,中度组为（0.20±0.14）mm、（0.94±0.79）D,高度组为（0.33±0.14）mm、（1.36±0.68）D,超高度组为（0.38±0.12）mm、（1.60±0.58）D.2年内,散光轴向对儿童眼轴长度和近视度数存在影响（F分别为12.351、12.384,P均＜0.01）;顺规性散光组近视度数增加最少,斜轴性散光组眼轴长度增加最多（P＜0.05）,而斜轴和逆规组眼轴、近视程度增加值组间差异无统计学意义：眼轴长度和近视度数增加值在顺规组分别为（0.20±0.17）mm、（0.74±0.49）D,逆规组为（0.28±0.17）mm、（1.26±0.98）D,斜轴组为（0.43±0.20）mm、（1.61±0.74）D.结论 在眼睛近视化过程中,散光度数越高,近视化进程越快：斜轴散光对近视进展的影响较顺规散光、逆规散光大.故在近视防治工作中要充分考虑到散光对近视化的影响. 关键词：散光;近视化;眼轴;儿童     

In vivo and in vitro repeatability of Hartmann-Shack aberrometry

PURPOSE: To assess the in vivo and in vitro repeatability of objective refraction and higher-order aberrations (HOAs) measured by a commercially available Hartmann-Shack wavefront sensor. SETTING: Department of Ophthalmology, Johann-Wolfgang-Goethe University, Frankfurt am Main, Germany. METHODS: After pupil dilation of 40 myopic or myopic, astigmatic eyes of 20 patients, wavefront measurements were performed 6 times in each eye and in a test object provided by the manufacturer by 2 experienced examiners using a Hartmann-Shack wavefront sensor (Zywave, software version 3.21, Bausch & Lomb). The mean standard deviation (SD) and the coefficient of variation (CV) for sphere, cylinder, and each Zernike polynomial were computed for a 7.0 mm pupil diameter. Vector analysis was performed for the astigmatism. After the data were subdivided into 2 groups with 3 measurements in each, one measurement that best matched the subjective manifest refraction was chosen in each group and the difference between them was calculated. RESULTS: The mean SD (CV) was 0.15 diopter (D) (7%) for the sphere value of the predicted phoropter refraction and 0.16 D (22%) for astigmatism. Thirty-two eyes had an axis deviation of at least 10 degrees. Vector analysis revealed a mean SD of 0.24@109.8. Other results for mean SD and mean CV were as follows: total in vivo higher-order RMS, 0.097 microm, 13.4%; sphere in myopic test device, 0.034 D, 0.65%; sphere in hyperopic test object, 0.035 D, 0.72%. The difference between the 2 best-matched refractions was significantly different from zero (0.11 D, P<.001). The CV was significantly higher for HOAs than for the 2nd-order aberrations (defocus and astigmatism). CONCLUSIONS: Repeatability of Hartmann-Shack aberrometry by the Zywave wavefront sensor was not satisfactory, particularly for small amounts of HOAs. Under these conditions, aberrometry measurements should be repeated several times and outliers should be excluded in calculating the means.     

Corneal wavefront-guided ablation with the Schwind ESIRIS laser for myopia

PURPOSE: To evaluate the outcome of corneal wavefront-guided LASIK for the treatment of myopia and myopic astigmatism. METHODS: This study included 56 myopic virgin eyes of 28 patients with a mean spherical equivalent refraction of -4.40 +/- 1.83 diopters (D) (range: -1.25 to -9.75 D) and astigmatism < 2.50 D. The corneal wavefront aberrations were analyzed using a corneal topography system. The preoperative corneal wavefront aberration data obtained from the above analyses combined with manifest refraction were used to generate a customized ablation profile. The safety, efficacy, and predictability of the correction, contrast sensitivity, and corneal higher order wavefront aberrations were evaluated. RESULTS: At 1-year follow-up, the mean residual spherical equivalent refractive error was -0.15 +/- 0.3 D (range: 0 to -1.25 D) and mean cylinder was -0.54 +/- 0.34 D (range: 0 to -1.50 D). Ninety-five percent of eyes were in the residual refractive error range of +/- 0.50 D and uncorrected visual acuity improved by 1.00 D or better in 94% of eyes. The safety index and efficacy index were 1.13 and 0.92, respectively. After treatment, corneal higher order wavefront aberrations with a 6-mm pupil diameter increased significantly (paired sample t test, P < .01), and contrast sensitivity with glare had small reductions at high spatial frequencies. Changes in spherical-like aberration (R = 0.708, P < .001) and higher order wavefront aberration (R = 0.449, P = .001), except for coma-like aberration (P = .238), were positively correlated with the amount of achieved correction. CONCLUSIONS: Evaluation of clinical results showed that corneal wavefront-guided LASIK for the correction of myopia and myopic astigmatism was safe and effective. There was an increase in all higher order aberrations postoperatively.     

Surgically induced astigmatism after hyperopic and myopic photorefractive keratectomy

PURPOSE: To compare the axis and magnitude of surgically induced refractive astigmatism (SIA) after hyperopic and myopic photorefractive keratectomy (PRK). SETTING: Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, USA. METHODS: In this single-center retrospective study, the VISX Star S2 excimer laser was used to create a peripheral annular ablation profile to correct spherical hyperopia in 23 eyes of 16 consecutive patients. Attempted corrections ranged from +0.50 diopter (D) to +4.25 D with 0 to 1.00 D of astigmatism. The same laser was used to create a central ablation profile to correct spherical myopia in 25 eyes of 17 consecutive patients. Attempted corrections ranged from -2.25 to -6.50 D with 0 to 1.00 D of astigmatism. The absolute change in refractive astigmatism was calculated by taking the difference in magnitudes of astigmatism before and after laser treatment without regard to axis. Axis and magnitude of SIA were analyzed by vector differences. Magnitudes were compared using the Student t test, and axial shifts were compared using the chi-square test. All patients were followed for a minimum of 6 months. RESULTS: The mean changes in absolute astigmatism were 0.29 +/- 0.28 D at 3 months and 0.34 +/- 0.29 D at 6 months after hyperopic PRK and 0.40 +/- 0.35 D at 3 months and 0.39 +/- 0.36 D at 6 months after myopic PRK. The mean vectoral magnitudes were 0.49 +/- 0.29 at 3 months and 0.52 +/- 0.25 at 6 months after hyperopic PRK and 0.48 +/- 0.39 at 3 months and 0.44 +/- 0.38 at 6 months after myopic PRK. The mean values for SIA (the centroid) were 0.10 +/- 0.57 D x 113 degrees at 3 months and 0.15 +/- 0.57 D x 131 degrees at 6 months after hyperopic PRK and 0.04 +/- 0.63 D x 160 degrees at 3 months and 0.08 +/- 0.58 D x 171 degrees at 6 months after myopic PRK. There was no statistically significant difference between the 2 groups in vectoral axis or magnitude of SIA. CONCLUSION: Surgically induced astigmatism after hyperopic PRK was comparable to astigmatism induced by myopic PRK. A peripheral annular ablation for hyperopic correction, similar to a central ablation in myopic PRK, did not appear to result in uneven corneal healing causing astigmatism.