视力低常学龄前儿童散光特征及分析

目的了解学龄前儿童散光性质、散光度、散光轴向分布情况。方法 1%阿托品眼膏常规散瞳检影验光。结果学龄前儿童散光度大多分布在0.50D～2.00D之间,散光轴向：顺规散光占96.24%,逆规散光占2.14%,斜轴散光1.62%。结论学龄前儿童散光以顺规散光为主,逆规散光次之,斜轴散光最少见,散光情况则以远视散光为主。     

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     

云南省高海拔农村多民族聚居区屈光不正患病率调查

目的:调查中国西南部高海拔农村多民族聚居区人群屈光不正患病率,获得该地区整体人群屈光不正的流行病学资料。方法:采用整群随机抽样的方法选取云南省贡山县常住居民做为调查对象。所有调查对象均接受全面的眼科检查及屈光状态检查。分析屈光不正整体情况及屈光不正发生与年龄、性别、文化程度等相关因素的关系。结果:入选对象3070例中实际接受调查人数为2422例(受检率78.9%)。对4843眼的屈光不正数据进行统计分析:正视眼2635眼(54.4%);近视1106眼(22.8%);远视1102眼(22.8%),其中散光4451眼(91.9%)。正视所占比率随年龄增长呈下降趋势(P<0.05),近视患病率不随年龄增长而增长(P>0.05),远视眼患病率随年龄增长呈上升趋势(P<0.05)。散光的发生中,顺规散光81·6%,随年龄增长顺规呈下降趋势,逆规散光15.1%,随年龄增长呈上升趋势(P<0.05)。女性远视眼患病率较男性人群高(P<0.05)。初中学历以上人群中重度近视发生率较初中以下学历人群为高(P<0.05)。结论:获得中国西南部高海拔偏远山区整体人群屈光不正统计数据,表明受教育程度越高近视发生率越高,年龄改变与散光轴向改变相关。     

儿童散光的流行病学研究现状

散光已成为影响儿童视觉健康的主要原因之一.儿童散光的患病率在不同国家和地区、不同种族间差异较大,如亚洲的新加坡、中国台湾及大陆较高,欧美国家较低.顺规散光是儿童散光的主要类型.遗传因素、视近工作、种族、年龄、球性屈光不正等因素对儿童散光状态均有影响.     

江门市17201名学龄前儿童屈光不正性弱视普查

目的 探讨学龄前儿童屈光不正性弱视的患病率以及与屈光不正的关系等.方法 对广东省江门市10所幼儿园17201名学龄前儿童进行了视力普查、医学验光及屈光状态的调查等,分析视力异常儿童的屈光状态.结果 在17201名学龄前儿童中,视力低常率15.44%.弱视患病率为2.96%,以3～4岁组视力低常率和弱视患病率为最高,分别为19.28%和4.16%.6岁以上组视力低常率最低,为13.35%,5～6岁组弱视患病率最低,为2.45%.远视患病率为79.59%,随着年龄增长,远视发病率渐趋降低.近视患病率为2.05%,随着年龄的增长,近视患病率逐渐增加,3岁儿童近视患病率为1.83%,6岁为4.35%.散光患病率为58.00%,各年龄组散光患病率较为稳定.屈光不正性弱视以轻中度居多,引起弱视的最小远视度为+1.75 D,近视为-3.25 D,散光为1.0D.屈光参差性弱视的球镜最小差值为1.25 D,柱镜最小差值为0.75 D.但也有个例近视性届光参差达6.75 D,远视性屈光参差达3.00 D也未形成弱视.结论 视力低常率15.44%.弱视患病率为2.96%,随着年龄增长,远视患病率逐渐降低,近视患病率逐渐增加,散光则较稳定.屈光不正性弱视以轻中度居多,多为远视和散光引起.导致弱视的最小远视度为+1.75 D,近视为-3.25 D,散光为1.0 D.屈光参差球镜最小差值为1.25 D,柱镜最小差值为0.75 D.     

1 238例近视手术患者散光状况分析

目的统计青年近视人群散光状况,分析散光组成和分布特征。方法横断面研究。收集2011年5月至2012年10月在山东医专附属眼科医院准分子激光中心接受近视治疗的1 238例患者（2 476眼）,年龄（21.5±4.1）岁。分别统计这些患者全眼散光度、角膜散光度、晶状体散光度以及散光轴向分布,计算各项所占百分比。结果本组2 476眼中散光眼占65.14%,平均全眼散光度为（0.58±0.62）D,角膜散光占优势地位,平均为（1.06±0.59）D,晶状体散光为（0.58±0.40）D。全眼散光中顺规散光占49.39%,逆规散光占8.19%,斜轴散光占7.56%,单纯近视占34.86%。在角膜散光轴向中,85.26%为顺规性,3.19%为逆规性,6.99%为斜轴散光,4.56%的角膜无散光。在晶状体散光轴向中,4.16%为顺规性,73.10%为逆规性,7.19%为斜轴散光,15.55%的晶状体无散光。引起散光的因素中,单纯角膜散光占13.25%,单纯晶状体散光占1.78%,混合因素引起的散光占81.99%,各因素均无散光占2.99%。结论山东医学高等专科学校附属眼科医院欲行近视手术的青年患者中,角膜散光是眼散光的主要来源,全眼散光和角膜散光以顺规散光为主。     

学龄前儿童视力和屈光状态分析

目的:了解北京市通州区学龄前儿童的视力现况,并对其屈光状态进行分析。方法:横断面调查研究。于2021-12/2022-01采用整群随机抽样法选取北京市通州区9所幼儿园3～6岁儿童1 513人3 026眼,均进行视力和屈光度检查,并分析不同年龄段儿童视力和屈光度分布情况。结果:纳入儿童视力低常率为15.47%,屈光异常率为14.24%,且随着年龄增长,屈光异常检出率减少,而屈光异常类型以单纯近视性散光为主(11.46%),随着年龄增加,单纯性远视率逐渐降低,单纯性近视率逐渐增加。屈光度检查结果显示,纳入儿童球镜度为0.50(0.25,1.00)D,柱镜度为-0.25(-0.50,-0.25)D,等效球镜度为0.375(0,0.625)D。不同年龄段儿童球镜度和等效球镜度均无差异(P>0.05),但柱镜度有差异(P<0.001)。结论:3～5岁儿童视力低常率随年龄增加逐渐降低,6岁后又呈增加趋势。3～6岁儿童屈光异常以单纯近视性散光为主。学龄前儿童视力发育情况应重点关注,应定期进行视力和屈光状态检查。     

角膜地形图在预测学龄前儿童散光中的应用

目的探讨角膜地形图检查在预测学龄前儿童散光中的作用。方法分析356例(679只眼)角膜地形图检查散光与睫状肌麻痹后视网膜检影的散光度数和散光轴的相互关系,采用SPSS11统计软件包分析,作配对t检验。结果角膜地形图方法组,循规散光性散光占94.62%,逆规性散光占2.15%,斜轴性散光占3.23%。散瞳检影验光方法组,循规散光性散光占95.74%,逆规性散光占2.78%,斜轴性散光占1.48%。角膜地形图方法组散光度数的分布以1.00~3.00D为主,散瞳检影验光方法组的分布以0.50~2.00D为主。角膜地形图测得的散光度为1.92±0.88D,散瞳检影验光测得的散光度为1.39±0.83D,两者比较差异有统计学意义(t=8.974,P<0.01)。角膜地形图测得的柱镜轴向为101.46±32.57度,散瞳检影验光测得的柱镜轴向为99.73±48.12度,两者比较差别无统计学意义(t=1.08,P>0.05)。结论角膜地形图检查仅反映角膜屈光状况,对验光中散光轴的确定有一定的价值,但临床最终检查结果仍应以睫状肌麻痹后检影作为确定散光度及散光轴的标准。     

儿童先天性下睑内翻合并倒睫的手术时机对眼内屈光发育的影响

目的:研究儿童先天性下睑内翻合并倒睫的手术对于眼内屈光发育的影响,进一步探讨患儿的最佳手术时机。方法:前瞻性队列研究。纳入2016-09/2018-06在我院确诊为先天性下睑内翻合并倒睫并接受下睑内翻矫正手术的患儿30例59眼。将其分为低龄组(2~3岁)10例20眼,中龄组(4~6岁)10例20眼和大龄组(7~12岁)10例19眼。所有患儿在全身麻醉下接受下睑皮肤眼轮匝肌切除术,合并内眦赘皮患儿同时接受内眦切开联合L型缝合术式,轻度下睑内翻不伴眼轮匝肌肥厚的患儿接受缝线术,术后3mo合并弱视及屈光不正者接受屈光矫正,随访6~12mo。测定三组患儿术前及术后6mo眼内屈光状态,视力发育情况及角膜地形图结果。结果:所有患儿术后下睑内翻矫正效果良好,无欠矫,外翻或眼睑角状畸形者。手术前后角膜散光(CC)三组患儿均有差异(P<0.05),视网膜检影总散光值(RC)、BCVA,低龄组和中龄组患儿有差异(P<0.05),大龄组无差异(P>0.05)。结论:先天性下睑内翻合并倒睫患儿在6岁以内接受手术矫正可以改善眼球散光值。4~6岁患儿术前顺规散光发病率高,应尽早接受手术治疗及屈光矫正。     

温州市152名幼儿屈光状态调查分析

目的:调查和了解幼儿屈光状态,加强幼儿视力保健。方法:采用随机整群抽样方法,对152名(299眼)3岁至6岁的幼儿用0.50％托吡卡胺滴眼液麻痹睫状肌后检影验光,采用SPSS 11.0进行统计学分析。结果:屈光状态:全体儿童不同年龄组间两两比较,方差分析提示对于球镜和等效球镜,4岁组和3、5、6岁组之间差异有显著性(P<0.05),其余各组之间差异无显著性。对于柱镜,3岁组和4岁组女性差异有显著性,其余各组之间差异无显著性。4岁时各类屈光不正患病率最高。儿童屈光状态中,散光以低度顺规散光为主;总体以单纯远视最多见,复合远视散光次之。结论:幼儿中各类屈光不正患病率很高,应该引起必要的关注。提倡早期检查和早期治疗。     

Astigmatism in children with epiblepharon

PURPOSE: To study the relationship between astigmatism and epiblepharon in Taiwanese children that need surgical correction. METHODS: In a retrospective case-control study, a total of 254 eyes in 134 children surgically treated for lower-lid epiblepharon were studied. A further 205 eyes in 104 children 4-7 years of age were included as controls. Data on age, sex, severity of preoperative corneal erosion, best-corrected visual acuity, and preoperative and postoperative refractive errors were recorded. The data of astigmatism were decomposed into P90 (at 90 degrees) and its oblique meridian Pobl. Nonparametric tests were used to compare the severity of astigmatism. RESULTS: No significant difference between age group (<4, 4-7, >7 years) in P90 was shown in children with epiblepharon. Pobl was trivial in each group of epiblepharon. Children with epiblepharon 4-7 years of age had significantly (P < 0.001) greater P90 than controls (1.12 vs. 0.47 D). P90 and Pobl were not significantly changed postoperatively. In the same individual, the eye with the more severely affected cornea had greater astigmatism (P = 0.002), even after the corneal erosion healed. CONCLUSIONS: Children with epiblepharon who needed surgery had greater with-the-rule astigmatism than controls. More severe corneal erosion was associated with higher astigmatism. Surgical correction of skinfold and promotion of reepithelialization did not attenuate astigmatism significantly.     

High prevalence of astigmatism in the 40- to 64-year-old population of Shahroud, Iran

Background: The prevalence of astigmatism, its axis and determinants were determined in the 40‐ to 64‐year‐old population of Shahroud, Iran. Design: Population‐based cross sectional study. Participants: Using random cluster sampling, 6311 subjects were invited for eye examinations. Of 5190 participants (response rate = 82.2%), data of 5020 were eligible for analysis. Methods: Participants received visual acuity measurement, manifest refraction and eye examinations. Main Outcome Measures: The prevalence of astigmatism based on cylinder powers of more than 0.5, 1 and 3 D were studied. Results: The prevalence (and 95% confidence interval) of astigmatism based on a cylinder power worse than 0.5, 1, and 3 D was 49.1% (47.6–50.5), 24.1% (22.9–25.3), and 3.4% (2.9–3.9), respectively. In a multiple logistic regression model, the prevalence of astigmatism was higher in men (odds ratio = 1.25) and increased with age (odds ratio for each 5 years = 1.21). Higher education was found to be inversely correlated to astigmatism (P < 0.001). The prevalence of with‐the‐rule, against‐the‐rule and oblique astigmatism was 12.6%, 25.9% and 10.6%, respectively. Oblique astigmatism was significantly higher in women and the older age groups (P < 0.001). Against‐the‐rule astigmatism increased with age from 19.9% in the age group of 40–44 to 37.0% in the age group of 60–64 (P < 0.001). Conclusions: In comparison with those studies conducted in Iran and other countries, the prevalence of astigmatism was higher in this study. Astigmatism was higher in men and age had an important role in astigmatism and its axis. The prevalence of against‐the‐rule and oblique astigmatism increased with age.     

儿童屈光不正状态的临床分析

目的：了解2～15岁视力低常的儿童屈光不正的分布规律。 方法:对我院2009-04/2010-04视光学门诊2～15岁的1638例3266眼(男725例1446眼,女913例1820眼)视力低常者进行散瞳验光并统计分析。 结果：在3131眼中,男生近视性屈光不正为1056眼,远视性屈光不正317眼,以近视性屈光不正为主,其中以复性近视散光多见,占35.48％。女生近视性屈光不正为1455眼,远视性屈光不正303眼,也以近视性屈光不正为主,其中以复性近视散光多见,占40.71％。散光的分布中男女童均是以复性近视散光为主,复性远视散光次之。顺规散光、逆规散光和斜轴散光的弱视发生率存在显著性差异（P＜0.01）。 结论：随着学习压力的增大儿童长时间看书学习和电脑的使用大大增加了近视性屈光不正发生的概率。逆规散光是弱视发生的重要影响因素,矫正逆规散光可能有利于儿童弱视的治疗。     

Change in vision disorders among Hong Kong preschoolers in 10 years

Background: To determine the change in refractive error and the prevalence of amblyopia and strabismus among preschool children in Hong Kong over a period of 10 years. Design: Two cross‐sectional population‐based studies conducted in 1996 to 1997 (part A) and 2006 to 2007 (part B) Participants: Children attending randomly selected kindergarten participated in the study. Methods: Ocular alignment, visual acuity, cover and uncover tests, cycloplegic refraction, slit‐lamp and fundi examination were performed under a standardized testing environment. Main Outcome Measures: The prevalence of amblyopia (best‐corrected visual acuity ≤6/12 in one or both eyes, or a bilateral difference of ≥2 best‐corrected visual acuity lines), strabismus and significant refractive error (hyperopia ≥+2.50 D; myopia ≥?1.00 D; astigmatism ≥2.00 D) among preschool children. Results: Of the 601 children in part A of the study, reduced visual acuity was presented in 3.8%; whereas strabismus was found in 1.8%. The commonest type of refractive error was astigmatism in 6.3% of children, followed by hyperopia (5.8%) and myopia (2.3%). Among 823 children in part B, reduced visual acuity was presented in 2.7% of children, and strabismus was found in 1.7%. The commonest type of refractive error was myopia (6.3%), followed by astigmatism (5.7%) and hyperopia (5.1%). The percentage of children having myopia has significantly increased (P = 0.001). Conclusion: A significant increase in myopia has been noted in Hong Kong preschoolers. Visual screening programmes may need to be tailored to correspond to the local population and be adjusted accordingly from time to time.     

Astigmatism and its components in 6-year-old children

PURPOSE: The purpose of the present study was to report the prevalence of refractive (RA), corneal (CA), and internal astigmatism (IA) in a population of 6-year-old children; examine their variation with gender, ethnicity, and refraction; and examine the effects of gender, ethnicity, and spherical equivalent refraction on the relationship between CA and RA in this population. METHODS: The Sydney Myopia Study is a population-based survey of refraction and eye health in 6-year-old children. A random cluster design was used to recruit children from schools across Sydney, Australia, during 2003 to 2004. Data collection used a detailed questionnaire and comprehensive eye examination. Keratometric and cycloplegic autorefraction data from right eyes were analyzed. RESULTS: Of 2238 eligible children, 1765 (78.9%; 50.7% boys) had parental consent to participate. Overall prevalence of RA (> or =1.0 diopter [D]) was 4.8% (95% confidence interval [CI] 3.8%-6.1%), CA (> or =1.0 D) 27.7% (CI 23.8%-32.3%), and IA (> or =1.0 D) 21.1% (CI 19.0%-23.5%). The RA axis was fairly evenly distributed, with predominance of oblique axis (39.1%; CI 35.9%-42.6%). CA axis was mainly with the rule (75.1%; CI 72.6%-77.8%), while IA axis was mainly against the rule (76.7%; CI 74.2%-79.3%). After adjustment for multiple variables, girls had significant, marginally greater mean CA and IA than boys. East Asian and South Asian children had significantly greater prevalence and mean RA and CA than European Caucasian children. There were no significant ethnic differences of mean IA. Compared to reference (spherical equivalent [SEq] 1.01-1.50 D), mean RA and CA increased significantly with more hyperopic and more myopic refractions. Mean IA was significantly greater only for hyperopic refractions (SEq > 2.00 D). CONCLUSIONS: The prevalence of astigmatism found in this population of 6-year-old children was relatively low, and showed significant variation with ethnicity. The data suggest that emmetropization for RA occurs by a compensatory process between CA and IA.     

Astigmatism in Chinese preschool children: prevalence, change, and effect on refractive development

AIM: To study the prevalence, type, and progression of astigmatism in Chinese preschool children, and its effect on refractive development. METHODS: A cross sectional study of preschool children was carried out in two randomly selected kindergartens. A cohort study was performed on a subset of children, five years after initial examination. Refractive error (measured by cycloplegic autorefraction) and axial ocular dimensions (measured by ultrasonography) were the main study outcomes. RESULTS: 522 children participated in the study; the mean age was 55.7 months (SD 10.9; range 27 to 77). Mean cylinder reading was -0.65 D (SD 0.58; range 0.00 to -4.75), and with the rule astigmatism was predominant (53%). In the 108 children studied longitudinally, the mean cylinder reading reduced from -0.62 D to -0.50 D (p = 0.019). The presence of astigmatism in initial examination predisposed the eyes towards greater myopisation (p<0.001). In addition, children with increased astigmatism had greater myopic progression (p<0.001) and axial length growth (p = 0.002). CONCLUSIONS: This study reports a high prevalence of astigmatism in Chinese preschool children. The presence of astigmatism, and particularly with increasing astigmatism, appears to predispose the children to progressive myopia. Further studies are warranted.     

Distribution of refractive error in healthy infants

PURPOSE: Few data exist regarding the upper limits of refractive error distributions in healthy infants; the data that do exist are biased because they were selected from the records of pediatric ophthalmology practices. We sought to obtain these data to validate examination failure criteria for vision screening. METHODS: We reviewed records from all children age birth to 5 years seen at the Tennessee Lions Eye Center at Vanderbilt Children's Hospital with a billing diagnosis of nasolacrimal duct obstruction and no comorbid ocular diagnoses except for refractive error. This was to avoid referral bias for any condition that could have influenced refractive error. All patients received a complete eye examination and cycloplegic refraction. Cumulative probability distribution (CPD) plots and means for spherical and cylindrical refractive error and anisometropia were prepared. RESULTS: One hundred thirty patients were studied; mean age was 15.5 +/- 9.9 months (range, 2 days to 66 months). The mean refractive error (spherical equivalent) was +1.4 D +/- 1.1 D. CPD plot analysis showed 95% of hyperopia to be < +3.25 D. Two children had myopia +1.00 D in one eye. CPD plot analysis showed 95% of astigmatism to be < +1.50 D and 95% of meridional anisometropia to be < 1.50 D. Six children had anisometropia >/=1.50 D, and 3 children had anisometropia > 3.00 D. CONCLUSIONS: At least 95% of children have hyperopia < +3.25 D, astigmatism < +1.50 D, and anisometropia < 1.50 D. This information will prove useful in identifying the natural history and prevalence of amblyogenic factors identified during preschool vision screening.     

"With the rule" astigmatism is not the rule in the elderly. Reykjavik Eye Study: a population based study of refraction and visual acuity in citizens of Reykjavik 50 years and older. Iceland-Japan Co-Working Study Groups

PURPOSE: To study refractive state and visual acuity in citizens of Reykjavik 50 years and older. METHODS: 1700 persons were randomly selected from the national population census. 1379 could be located and qualified whereof 1045 participated. Evaluation of refraction was performed using Nidek ARK 900 autorefracto-keratometer. Visual acuity was tested on a Snellen chart. RESULTS: The prevalence of hypermetropia increases with age by 0.3 D in five years. The prevalence of "against the rule" astigmatism increased on average 5.3% and oblique 3.9% in five years. Analysis of corneal astigmatism measured by keratometer shows an "against the rule" change with age. CONCLUSIONS: Hypermetropia increases by age. The prevalence of astigmatism increases and the axis turns to "against the rule". The changes in total astigmatism and corneal astigmatism is almost parallel which might indicate that the "against the rule" change is related to changes in the cornea.     

Astigmatism and its determinants in the Tehran population: the Tehran eye study

PURPOSE: To determine the prevalence of astigmatism and its epidemiological risk factors in Tehran via a population-based study. METHODS: By means of a stratified random cluster sampling, 6497 citizens representing a cross-section of the population of Tehran were selected from 160 clusters. Eligible people were recruited through a door-to-door household survey in the selected clusters and transferred to a clinic for an extensive eye examination and interview. The refractive status was determined with manifest refraction. Astigmatism was defined as cylinder worse than or equal to 0.5 D. High astigmatism was defined as a manifest cylinder > or =1.5 D. RESULTS: Between August and December 2002, 4565 of the 6497 eligible individuals in the sample attended the interview and ophthalmic examination (a participation rate of 70.3%). The age- and gender-standardized prevalence of astigmatism was 50.2% (95% CI, 48.4% to 51.9%) on manifest refraction. High astigmatism was found in 490 right eyes (11.1%; 95% CI, 10.1% to 12.0%). Of 2532 participants with ametropia, 59.6 (95% CI, 57.6-61.5) had astigmatism. The percentages of with-the-rule, against-the-rule and oblique astigmatism were 33.6%, 36.9% and 29.3%, respectively. The proportion of type of astigmatism was significantly related to age (p < 0.001). The univariable analysis of astigmatism between family members yielded odds ratios of 1.47 (95% CI, 1.14 to 1.89, p = 0.003) for the association of astigmatism among siblings. After controlling for age, refractive errors and education, the pairwise sibling association remained statistically significant (OR 1.43, 95% CI, 1.08 to 1.88). CONCLUSION: These findings revealed a high prevalence of astigmatism in the population. Age, education and ametropia were the main predictors of astigmatism in Tehran. Our findings should be considered for case finding and astigmatism correction programs. Our data confirmed a modest familial aggregation for astigmatism.     

Surgically induced astigmatism after implantation of intacs intrastromal corneal ring segments

PURPOSE: To analyze surgically induced astigmatism (SIA) after implantation of Intacs intrastromal corneal ring segments. SETTING: Multicenter clinical trials in the United States. METHODS: Data from 11 investigational sites involved in the Phase II and III trials of Intacs for the United States Food and Drug Administration were retrospectively analyzed. The distribution of Intacs thicknesses implanted in 449 eyes was 0.25 mm in 148 eyes, 0.30 mm in 151 eyes, and 0.35 mm in 150 eyes. Refractive astigmatism was measured by subjective manifest refraction preoperatively and 1 week and 1, 2, 3, 6, 9, and 12 months postoperatively. The mean simple change in astigmatism and the surgically induced refractive change were determined by vector analysis. RESULTS: Mean induced astigmatism at 12 months was 0.13 diopter (D) +/- 0.52 (SD). Induced astigmatism was more frequently with the rule (44%) than against the rule (26%) or oblique (30%). Maximal mean astigmatism was 0.50 +/- 1.09 D and occurred at 7 days. Mean induced astigmatism increased with segment thickness (0.01 D, 0.17 D, and 0.21 D for the 0.25 mm, 0.30 mm, and 0.35 mm segments, respectively). Mean surgically induced refractive change in cylinder power in all eyes at 12 months by vector analysis was 0.17 D x 92. CONCLUSION: Mean SIA was not clinically meaningful 12 months after Intacs implantation.