Stability of wavefront aberrations during the daytime after 6 months of overnight orthokeratology corneal reshaping

PURPOSE: To evaluate the stability of wavefront aberrations during the daytime after 6 months of overnight orthokeratology corneal reshaping. METHODS: A prospective study of 26 eyes using the Ultravision BE lens design during 6 months of overnight wear. Uncorrected visual acuity (UCVA), cycloplegic refraction, and wavefront aberrometry were measured at 8 AM (within 1 hour after awakening and removing lenses), 1 PM (5 to 6 hours after lens removal), and 6 PM (10 to 12 hours after lens removal). RESULTS: There was no significant difference in UCVA between 8 AM, 1 PM, and 6 PM (P=.383). Spherical power from wavefront aberrometry showed significant regression from 8 AM to 1 PM (P<.001) and stabilized near zero diopters. Total root-mean-square (RMS) increased and higher order aberration RMS and defocus (Z4) decreased between 8 AM and 1 PM (P<.001) but did not change for the rest of the day (P>.001). There was no statistically significant change in astigmatism (Z3 and Z5) (P=.449) and coma (Z7 and Z8) (P=.145) between 8 AM, 1 PM, and 6 PM. Spherical aberration (Z12) showed regression throughout the day (P<.001). CONCLUSIONS: After 6 months of overnight orthokeratology wear, some optical aberrations showed regression during the day. Despite no significant change in UCVA during 10 to 12 hours, there was a significant increase in defocus (Z4) within the first 5 hours after removing the orthokeratology lens and a decrease in spherical aberration (Z12) throughout the day.     

Sustainability of orthokeratology as demonstrated by corneal topography

PURPOSE: To determine the sustaining effects of orthokeratology. METHODS: This study enrolled 58 eyes with moderate myopia. LK-DM lenses (Lucid Korea Dream Lens) were fitted daily for at least eight hours on an overnight regimen. The effects of orthokeratology and it's sustainability throughout the day were recorded twice; immediately after removal in the morning and eight hours later. Sustainability was measured by comparing the changes from morning to afternoon for best uncorrected visual acuity, apical corneal power, keratometric values, spherical equivalent and induced astigmatism. RESULTS: UCVA demonstrated improved values at all follow up periods. Fluctuations during the day stabilized after 4 weeks of lens wear. K values averaged a mean of 42.4 mm at baseline, and reduced to 40.9 mm by week 12. Unaided logMAR visual acuity changed from 0.94+/-0.14 at baseline to -0.11+/-0.17 by week 12. The sustainability of orthokeratology, defined as the difference between morning and afternoon values of unaided logMAR visual acuity, increased from -0.82 on day 1 to -0.11 on week 12. CONCLUSIONS: UCVA and spherical refractive error did not change to a significant degree after 4 weeks. Although statistically insignificant minute fluctuations during the day were observed up to week 12, these fluctuations decreased to a statistically significant level after week 4.     

Spherical aberration and coma with an aspherical and a spherical intraocular lens in normal age-matched eyes

PURPOSE: To study optical aberrations in eyes having uneventful cataract surgery and in-the-bag implantation of an aspherical Tecnis Z9000 intraocular lens (IOL) (AMO) or a spherical CeeOn Edge 911 IOL (Pharmacia) and compare the results with those in a group of phakic age-matched eyes. SETTING: Ophthalmic Unit, Hospital and University of Verona, Verona, Italy. MATERIALS: Three groups, each with 30 patients (30 eyes), were examined with the Topcon KR-9000PW topographer/aberrometer. Spherical aberration and coma were analyzed in detail for 4.0 mm optical zone. Internal values were obtained by subtracting corneal aberrations from ocular aberrations. Point spread function and modulation transfer function (MTF) were considered for optical quality. RESULTS: The mean internal spherical aberration Z(4)(0) was -0.048 microm +/- 0.017 (SD) in the Tecnis group, +0.033 +/- 0.026 microm in the 911 Edge group (P<.001), and -0.013 +/- 0.056 microm in the phakic group (P = .149). The mean internal vertical coma Z(3)(-1) was 0.087 +/- 0.056 microm, 0.054 +/- 0.043 microm (P = .005), and 0.044 +/- 0.044 microm (P<.001), respectively. The internal horizontal coma Z(3)(+1) showed a similar pattern; however, total resulting coma was similar in the 3 groups. The mean Strehl ratio was 0.284 +/- 0.166 in the Tecnis group, 0.145 +/- 0.077 in the 911 Edge group (P<.01), and 0.164 +/- 0.097 in the phakic group (P<.01). The MTF curve was better in the Tecnis group (P<.001). CONCLUSIONS: After uneventful implantation, the aspherical IOL yielded better ocular aberration and optical quality results than the spherical IOL. Induced coma was somewhat higher in the Tecnis group; however, the overall results were not affected. Physiologic IOL decentration after correct in-the-bag implantation did not negate the advantages of asphericity.     

Optical aberrations of the human anterior cornea

PURPOSE: (1). To investigate the distribution of anterior corneal higher-order aberrations (HOAs, 3rd to 6th orders) in the population; (2). to evaluate the symmetry of anterior corneal aberrations between right and left eyes of individuals; and (3). to study the variations in anterior corneal aberrations with aging. SETTING: Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA. METHODS: Using the CTView program (Sarver and Associates, Inc.), corneal HOAs were computed from the central 6.0 mm zone of the corneal topographic maps (Humphrey Atlas, Carl Zeiss, Inc.) of 228 eyes of 134 subjects (mean age 50 years +/- 17 (SD); range 20 to 79 years; manifest spherical equivalent between -3.0 and +3.0 diopters [D]). Correlation analysis was performed to investigate the aberration symmetry between the right and left eyes and to assess the association between anterior corneal HOAs and age. RESULTS: There was wide individual variability in aberrations with ranges of individual Zernike terms from -0.579 to +0.572 microm. The mean coefficient of the 4th-order spherical aberration (SA) (Z(4)(0)) was 0.280 +/- 0.086 microm and was positive in all corneas. The mean root-mean-square (RMS) values were 0.479 +/- 0.124 microm for HOA, 0.281 +/- 0.086 microm for SA (Z(4)(0)and Z(6)(0)), and 0.248 +/- 0.135 microm for coma (Z(3)(-1), Z(3)(1), Z(5)(-1), and Z(5)(1)). Moderate to high correlations were found between right and left eyes for HOA, SA, and coma (Pearson r = 0.565, 0.751, and 0.565, respectively; all P<.001); 8 of the 9 Zernike terms in the 3rd and 4th orders were significantly correlated between eyes (Bonferroni correction P'<.05/22). Higher-order aberration RMS and coma RMS increased with aging (r = 0.434 and 0.290, respectively; both P<.001); SA RMS was not correlated with change in age (r = 0.034). CONCLUSION: Anterior corneal wavefront aberrations varied greatly among subjects and increased slightly with aging. All corneas had positive 4th-order SAs, and the values did not change with aging. A moderate to high degree of mirror symmetry existed between right and left eyes.     

球差和彗差在角膜塑形镜控制近视中的作用

近视作为全球高发疾病，严重影响我国青少年的眼部健康。角膜塑形镜是一种能有效控制近视增长速度的硬性角膜接触镜，但其作用机制尚未完全探明。而高阶像差作为影响视觉质量的因素之一，在角膜塑形术后会发生显著变化，其中以球面像差(球差)、彗形像差(彗差)较为关键。角膜塑形镜使角膜形态发生改变后，导致球差和彗差显著正向增加，球差和彗差的增加量与角膜塑形术后眼轴增长的速度呈显著负相关。球差与离焦和调节、彗差与散光和伪调节等存在的相互作用可能是其在角膜塑形镜控制近视中发挥作用的机制。     

基弧区非球面设计角膜塑形镜对客观视觉质量的影响

目的：:观察基弧区非球面设计角膜塑形镜对客观视觉质量的影响。方法：:前瞻性临床研究。选择2019年8月至2020年3月在沈阳爱尔眼视光医院验配角膜塑形镜的近视患者60例（60眼）,根据患者所选择的角膜塑形镜基弧区设计不同进行分组,非球面组30例（30眼）配戴基弧区非球面设计的角膜塑形镜;球面组30例（30眼）配戴基弧区...     

Corneal refractive therapy with different lens materials, part 2: effect of oxygen transmissibility on corneal shape and optical characteristics.

PURPOSE: To compare the effects of two different oxygen transmissible (Dk/t) lenses on corneal shape and optical performance after one night of corneal refractive therapy (CRT(R)) for myopia. METHODS: Twenty myopic subjects were fit with Menicon Z (MZ) (Dk/t = 90.6, Paragon CRT(R) lenses) on one eye and an Equalens II (EII) CRT lens (Dk/t = 47.2) on the contralateral eye (eye randomized). Corneal topography, refractive error and aberrations were measured before lens insertion (baseline), and the following day after overnight lens wear, on lens removal and 1, 3, 6, 12 h later. Root mean square wavefront errors were measured using 4.5 mm pupils. RESULTS: Averaged over position and time, the horizontal corneal curvature was statistically different between the MZ and EII lens-wearing eyes (p = 0.011). The central cornea flattened similarly (p = 0.886) and the mid-periphery steepened in both eyes (p = 0.061) from baseline. The EII lens-wearing eyes were steeper in the mid-periphery than the MZ eyes immediately after lens removal and at the 1-h visit (p < or = 0.032). Central corneal flattening and mid-peripheral corneal steepening regressed over time (all p < 0.001) but did not recover to baseline by 12 h (all p < 0.004). Myopia was reduced equally by 0.84 +/- 0.83 D for the MZ-lens wearing eyes and 0.84 +/- 0.87 D for the EII eyes (p = 0.969). Coma increased from baseline 1.85X (0.056 +/- 0.081 microm) for the MZ-lens wearing eyes and 1.72X (0.048 +/- 0.084 microm) for the EII eyes (both p < 0.001). Spherical aberration increased from baseline 4.55X (0.101 +/- 0.077 microm) for the MZ-lens wearing eyes and 4.31X (0.085 +/- 0.076 microm) for the EII eyes (both p < 0.001), but there were no differences between the MZ and EII eyes (all p > or = 0.308). Coma and spherical aberration did not return to baseline by 12 h (both p < or = 0.007). CONCLUSIONS: After one night of CRT lens wear, changes in corneal shape were slightly different, with more mid-peripheral steepening in the EII eyes compared to the MZ eyes. Change in central corneal curvature and optical performance were similar in both eyes.     

常规角膜塑形术应用于较高度角膜散光患者的治疗效果

目的观察常规角膜塑形术矫治较高度角膜散光患者的临床效果。方法回顾性研究。近视度为-0.50~-6.25 D,顺规角膜散光为-1.76~-3.02 D,年龄为6~18岁的患者33例（60眼）,观察戴角膜塑形镜1 d、1周、1个月、3个月、6个月、1年后的视力改变情况,并结合角膜地形图改变情况对矫治效果进行分级。用logistic回归分析较高度角膜散光患者成功验配角膜塑形镜的影响因素。结果配戴角膜塑形镜前,患者的裸眼视力（UCVA）为4.15±0.23,配戴后1 d、1周、1个月、3个月、6个月、1年后的视力分别为4.59±0.23、4.90±0.11、4.96±0.07、4.86±0.25、4.93±0.10、4.93±0.11,配戴后UCVA与戴镜前比较,差异有统计学意义（F=148.08,P<0.01）。配戴角膜塑形镜1个月后矫治效果Ⅰ级35眼（58%）,Ⅱ级15眼（25%）,Ⅲ级8眼（13%）,Ⅳ级2眼（3%）。患者屈光度、角膜散光度、角膜下方与上方平均屈光度差值（I-S值）、角膜陡K（SK）值和角膜e值对矫治效果均无显著影响。结论采用改良的验配方法,常规球面角膜塑形镜也可以选择性用于自身条件较好的1.50 D以上角膜散光近视患者,并取得良好的矫治效果。     

角膜塑形术后光学治疗区大小及偏心对光学及视觉质量的影响

目的：分析角膜塑形镜配戴后角膜高阶像差、对比敏感度的变化,以及光学治疗区大小及偏心对二者的影响。方法：前瞻性临床研究。选取2017年3-8月于温州医科大学附属第三医院验配角膜塑形镜的近视儿童31例（31眼）,测量戴镜前及戴镜1个月后的角膜地形图、对比敏感度、角膜高阶像差,分析光学治疗区大小及偏心情况对角膜高阶像差、对比敏感度变化的影响。对比敏感度以对比敏感度函数对数曲线下面积（AULCSF）衡量大小。采用配对t检验、Pearson相关分析、逐步多项线性回归分析等方法进行统计。结果：角膜塑形镜配戴1个月后,光学治疗区直径（3.48±0.49）mm,偏心距离（0.64±0.27）mm,偏心方向以颞下方为主（45%）。角膜总高阶像差、球差、垂直彗差、水平彗差均较配戴前明显增加（t=10.99、10.19、-2.21、-3.50,P<0.05）;光学治疗区垂直偏心距离（标准化B=0.620,P=0.001）和水平偏心距离（标准化B=0.422,P=0.049）分别是影响角膜垂直彗差增加量和水平彗差增加量的唯一因素。配戴1个月后亮环境及暗环境AULCSF有下降趋势,但与戴镜前相比无差异无统计学意义;亮环境AULCSF下降幅度与屈光度改变量有关（标准化B=0.452,P=0.021）,而暗环境AULCSF下降幅度则与屈光度改变量（标准化B=0.528,P=0.004）、偏心距离（标准化B=0.458,P=0.027）均相关。结论：角膜塑形镜偏心会导致角膜高阶像差增加,但对对比敏感度影响不大。     

Intacs for the correction of keratoconus: two-year follow-up

PURPOSE: To evaluate the long-term safety and efficacy of Intacs segments (Addition Technology, Inc.) for the treatment of keratoconus in terms of intraoperative and postoperative complications, visual outcome, restoration of contact lens tolerance, and inhibition of disease progression. SETTING: Service d'Ophtalmologie, CHU Pellegrin, Bordeaux, France. METHODS: This prospective, 2-year follow-up study comprised 100 keratoconic eyes with clear central corneas and contact lens intolerance. The best spectacle-corrected visual acuity (BSCVA), uncorrected visual acuity (UCVA), refractive error, keratometry, pachymetry, and slitlamp examination were assessed preoperatively and 1 and 2 years after Intacs implantation. RESULTS: At 2 years, the UCVA and BCVA improved in 80.5% and 68.3% of eyes, respectively (P<.001). The proportion of eyes with a BCVA >or=0.5 (20/40) increased from 22.0% at baseline to 51.2% and 53.7% at 1 year and 2 years, respectively (P<.001). The manifest refraction spherical equivalent improved from a mean of -6.93 diopters (D) +/- 3.91 (SD) preoperatively to -4.01 +/- 3.16 D at 1 year and -3.80 +/- 2.73 D at 2 years (P<.001). The mean keratometry readings decreased from 50.1 +/- 5.6 D preoperatively to 46.4 +/- 5.3 D at 1 year and 46.8 +/- 4.9 D at 2 years (P<.001). Contact lens tolerance was restored in over 80% of cases. Postoperative slitlamp observations revealed no clinically significant issues. The segments were removed from 4 eyes without complications or sequelae. CONCLUSION: Intacs implantation was a safe and efficacious treatment for keratoconus. Significant and sustained improvements in objective visual outcomes were achieved in most cases, with restoration of contact lens tolerance.     

Toric设计角膜塑形镜矫正近视伴高度散光对角膜高阶像差的影响

目的 分析Toric设计角膜塑形镜矫正近视伴高度散光后角膜高阶像差的变化.设计回顾性病例系列.研究对象2018年5月至2019年2月内江市第一人民医院配戴Toric设计角膜塑形镜患者35例(67眼),近视屈光度-1.00～-4.00 D,散光-1.50～-3.00 D.方法 测量戴镜前,戴镜后1、3、6、12个月的裸眼...     

角膜塑形术后角膜生物力学属性研究

【摘要】 目的 观察角膜塑形术后1天角膜形态变化和角膜生物力学变化。设计 前瞻性病例系列。 研究对象 等效球镜度-1.50~-6.00 D的青少年近视患者15例（30眼）。方法 双眼配戴夜戴型角膜 塑形镜,配戴前、配戴一夜摘镜时和摘镜后4小时分别测量等效球镜度、Pentacam分析系统测量角 膜平坦、陡峭K值和中央角膜厚度,眼反应分析仪测量角膜生物力学特性。主要指标 等效球镜度, 角膜曲率,中央角膜厚度,角膜黏滞性CH值,角膜阻力因子CRF值。结果 配戴角膜塑形镜一夜后等 球镜效度由配戴前（-3.72±1.82） D下降到（-2.12±1.93） D,角膜曲率平坦K1值从（41.95± 1.12） D下降到（41.22±1.34） D,摘镜4小时后等效球镜度回升到（-2.59±1.98）D,角膜曲率 平坦K1值回升到（41.44±40.10） D。中央角膜厚度在配戴一夜后由（535.9±34.5）μm增加到（ 553.3±36.6）μm（P=0.000）,摘镜4小时恢复至（535.0±40.3）μm。配戴一夜后CRF值由 （10.0±1.4）mm Hg升高至（10.7±1.5）mm Hg（P=0.037）。CH值由（10.6±1.4）mm Hg略有升 高至（10.7±1.3） mm Hg（P=0.208）。摘镜后4小时,与刚摘镜时比CRF值回降至（9.6±1.2）mm Hg（P=0.000）,与配戴前比差异无统计学意义（P=0.148）。CH与配戴后的差异无统计学意义 （P=0.163）。结论 配戴角膜塑形镜后1天角膜生物力学随角膜形态变化而改变,角膜生物力学测 量可作为配戴角膜塑形镜后角膜微观结构变化的一种观察手段。（眼科, 2012, 21： 381-383）     

Age-related changes in corneal and ocular higher-order wavefront aberrations

PURPOSE: To investigate age-related changes in ocular and corneal higher-order wavefront aberrations and elucidate relative contributions of the cornea and the lens in the age-related changes. DESIGN: Observational case series. METHODS: Corneal and ocular higher-order wavefront aberrations in the central 6 mm diameter were measured with videokeratography and the Hartmann-Shack wavefront aberrometer in 75 normal eyes of 75 patients with a mean age of 43.5 +/- 11.7 years (range, 18-69 years). Higher-order wavefront aberrations were calculated with Zernike polynomials up to sixth order. From the Zernike coefficients, we calculated root mean square (RMS) of coma and spherical aberration. To examine age-related changes of the polarity of spherical aberration, the changes of the Zernike coefficient Z(4)(0) was also investigated. RESULTS: Both corneal (r =.307, P =.007) and ocular (r =.334, P =.0033) coma RMS showed positive correlations with age. There was a positive correlation between corneal and ocular coma RMS (r =.468, P <.0001). The RMS of corneal spherical aberration did not change with aging (r =.153, P =.1895), whereas the RMS of ocular spherical aberration had a positive correlation with aging (r =.308, P =.0068). CONCLUSIONS: These results suggest that the ocular coma increases with age, mainly because of the increase in the corneal coma, and the ocular spherical aberration increases with age, mainly because of the increase in the spherical aberration in the internal optics.     

角膜塑形镜的临床疗效及安全性

目的观察角膜塑形镜矫正青少年儿童近视的疗效,探讨角膜塑形镜对近视进展控制的临床效果,并观察其安全性。方法回顾性病例分析。选取2011-2012年间在上海瑞视维景眼科门诊部验配角膜塑形镜的近视青少年儿童58例,均以左眼作为研究对象,年龄（11.1±2.0）岁,平均等效球镜度（SE）（-3.68±1.36）D。选用Boston EqualensⅡ和Boston XO 2种不同材料角膜塑形镜,按照所验配的角膜塑形镜材料为A组（38例）和B组（20例）,再以-3.00 D为界分为低度近视组（19例）和中度近视组（39例）,患者连续配戴角膜塑形镜2年后停戴4周复诊,分别比较戴镜2年前后的SE、眼轴长度、角膜内皮细胞计数、中央角膜厚度、角膜平坦曲率值、角膜陡峭曲率值和角膜散光。采用独立样本t检验,符号秩和检验,Pearson相关分析等进行数据分析。结果配戴角膜塑形镜的患者在戴镜2年后均有近视度数加深[（-0.35±0.64）D,t=4.132,P<0.01],眼轴长度增加[（0.33±0.33）mm,t=4.411,P<0.01],角膜平坦曲率值减少[（-0.33±0.25）D,t=10.001,P<0.01]和角膜散光增加[（-0.34±0.38）D,t=6.873,P<0.01];但A组与B组之间的差异无统计学意义。低度近视组的SE、眼轴长度和角膜散光改变量分别为（-0.70±0.68）D,（0.47±0.36）mm,（-0.54±0.37）D,均高于中度近视组的改变量[（-0.17±0.54）D,（0.26±0.29）mm,-0.25（-1.00,0.25）D],差异均有统计学意义（t=3.193、-2.384,Z=-2.598,P＜0.01）。结论青少年儿童配戴角膜塑形镜2年后仍有少量近视进展和眼轴增长,并且中度近视的近视增加量可能低于低度近视者。     

Toric intraocular lenses for correcting astigmatism in 130 eyes

OBJECTIVE: This study evaluated the results after implantation of toric intraocular lenses (IOLs) to correct preexisting corneal astigmatism in patients undergoing either cataract or clear lens extraction surgery. DESIGN: Retrospective, noncomparative case series. PARTICIPANTS: One hundred thirty eyes of 99 patients who underwent phacoemulsification and posterior chamber toric IOL implantation from January 1997 through February 1998 were included in the study. INTERVENTION: Implantation of a toric IOL was performed after cataract surgery (122 eyes) or clear lens extraction surgery (eight eyes). Both preoperative corneal cylinder and refractive cylinder powers were more than 1.50 diopters (D) for all the eyes included in this study. To provide a comparison, we also studied 51 eyes of 45 patients meeting the same preoperative criteria for degree of corneal and refractive cylinder who underwent implantation of a spherical (nontoric) IOL combined with limbal relaxing incisions. The data for both study and comparison groups were analyzed retrospectively. The selection for the two groups was arbitrary. MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA), mean spherical equivalent, residual refractive cylinder, and toric IOL axis. RESULTS: In the toric IOL group, 84% of eyes achieved 20/40 or better UCVA. In the spherical IOL group, 76% achieved 20/40 or better UCVA. The mean postoperative refractive cylinder was -1.03 +/- 0.79 D in the toric IOL group and -1.49 +/- 0.75 D in the spherical IOL group. CONCLUSIONS: Our results indicate that phacoemulsification and posterior chamber toric IOL implantation is a largely predictable new surgical option to correct preexisting corneal astigmatism in cataract or clear lens extraction surgery.     

Laser in situ keratomileusis in patients with corneal guttata and family history of Fuchs' endothelial dystrophy

PURPOSE: To report 1-year results of laser in situ keratomileusis (LASIK) in 7 eyes with corneal endothelial guttata and a family history of Fuchs' endothelial dystrophy. SETTING: John Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. METHODS: A retrospective chart review was performed of 4 patients (7 eyes) who had trace to 1+endothelial guttata and a family history of Fuchs dystrophy and then had uneventful LASIK for the correction of myopia and myopic astigmatism. Preoperative and postoperative measurements included uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), corneal pachymetry, endothelial cell density (ECD), manifest refraction, and spherical equivalent. The changes in ECD, pachymetry, and spherical equivalent after LASIK were subjected to statistical analysis using a paired Student t test to determine significance. RESULTS: Transient corneal edema was noted in the early postoperative period in 3 eyes of 2 patients. At 1 year, 6 of the 7 (86%) eyes had lost > or =2 lines of BSCVA. A statistically significant decrease in ECD of 12.4% +/- 2.7% was observed at 1 year compared with baseline (P < .001). An increase in corneal thickness (P = .006) and a statistically significant myopic shift in spherical equivalent (P = .017) was also noted at 1 year compared with 3 months. CONCLUSIONS: Patients with mild corneal guttata and a family history of Fuchs' dystrophy are prone to transient corneal edema, loss of BSCVA, endothelial cell loss, and myopic regression after uneventful LASIK for correction of myopia and myopic astigmatism.     

Long-term outcomes of photorefractive keratectomy in eyes with previous epikeratophakia for keratoconus

PURPOSE: To determine the long-term safety and effectiveness of photorefractive keratectomy (PRK) in the treatment of refractive errors after epikeratophakia (EP) for keratoconus. METHODS: Ten patients (14 eyes) who had refractive errors after EP for keratoconus received PRK surgery. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refractive error, corneal astigmatism, pachymetry, corneal topography, and complications were monitored. RESULTS: Mean follow-up after PRK was 63.4 +/- 19.8 months. Mean spherical equivalent was -5.5 +/- 3.9 D before PRK, -0.9 +/- 0.5 D at 1 month after PRK, and -1.5 +/- 1.0 D at 3 years. Mean astigmatism was 4.2 +/- 2.1 D before PRK, 1.2 +/- 0.5 D at 1 month after PRK, and 1.5 +/- 0.6 D at 3 years. Thirteen (93%) eyes had an UCVA <20/40, and 12 (86%) had a BSCVA of 20/40 or better before PRK. At 1 year, the UCVA was 20/40 or better in 8 (57%) eyes, and the BSCVA was 20/40 or better in all eyes. Mean central corneal thickness was 749 +/- 35 microm before PRK and 621 +/- 56 mum at 3 years. During the follow-up period, haze (grade no more than 1.0) was observed in 2 eyes. No immune rejection episode or recurrent keratoconus was found. CONCLUSIONS: PRK appears to be reliable and safe for the correction of residual ametropia after EP for keratoconus, and the visual acuity can remain stable after PRK for a long time.     

LASIK、SBK和LASEK对角膜高阶像差的影响

目的探讨于不同深度角膜基质面进行的近视矫正性激光角膜切削对人眼角膜高阶像差的影响。方法前瞻性队列研究。行准分子激光原位角膜磨镶术（LASIK）54例（106只眼）,前弹力层下角膜磨镶术（SBK）80例（159只眼）,准分子激光角膜上皮下磨镶术（LASEK）16例（32只眼）,采用眼前节扫描仪（Allegretto Oculyzer）搜集这些患者手术前后的眼前节数据,转换得到角膜像差数据（以Zernike多项式形式表示高阶像差）。对数据采用方差分析;chisq：Kruskal-Wallis检验。结果术后所有眼裸眼视力〉0.8。三组手术后测量角膜垂直彗差（Z3-1）、水平彗差（Z31）、彗差（Z33）、球差（Z40）值较术前的差异均存在统计学意义;三种手术后角膜垂直彗差（Z3-1）和球差（Z40）变化随时间变化有统计学差异。结论 LASIK和SBK及LASEK手术均会增加角膜高阶像差,但超薄瓣手术（SBK）和表面切削术（LASEK）对角膜高阶像差的影响低于标准的LASIK手术。     

European clinical evaluation: use of Intacs for the treatment of keratoconus

PURPOSE: To evaluate the safety and efficacy of Intacs inserts in keratoconic eyes to alter corneal shape and refractive power and stabilize the progression of corneal ectasia. SETTING: Service d'Ophtalmologie, Bordeaux, France. METHODS: In this prospective study, 57 eyes with clear central corneas that were diagnosed with keratoconus and contact lens intolerant were followed for up to 1 year. The primary objectives were to assess the safety of Intacs and the visual outcomes by measuring uncorrected visual acuity (UCVA), best corrected visual acuity, manifest refraction spherical equivalent, keratometry, intraocular pressure (IOP), pachymetry, and patient satisfaction. The stability of the refraction, keratometry, and visual acuity measurements was also assessed. RESULTS: At the 6-month examination, 78% of patients showed improvement of 2 lines or more in UCVA (P<.001). Best corrected visual acuity of 20/40 or better improved from 53% of patients preoperatively to 74% of patients (P< or =.033). Manifest refraction spherical equivalent improved to 3.1 +/- 2.5 diopters (D) (P<.001) compared with the preoperative examination. Keratometry decreased a mean of -4.3 +/- 2.8 D from the preoperative readings (P< or =.002). These changes appeared to be stable over time. At 6 months, there were no adverse events, no clinically significant increase in IOP, and no decrease in central corneal thickness. In 7 of 57 eyes (12%), the Intacs were removed due to dissatisfaction with visual symptoms. There were no adverse effects or complications associated with the Intacs removal. CONCLUSIONS: Intacs were safe and effective for treating keratoconus. All patients demonstrated improved objective visual outcomes; functional vision was restored in most patients. Intacs were removed without permanent sequelae.     

2 mm与4 mm切口SMILE术后视觉效果对比

目的探讨行2 mm与4 mm切口的飞秒激光小切口角膜基质透镜取出术（SMILE）患者术后的视力、屈光度、高阶像差和角膜地形图的变化。方法前瞻性对照研究。接受SMILE手术矫正近视和近视散光的患者34例（68眼）,按手术中切口大小分成2 mm切口组（44眼）和4 mm切口组（24眼）。分别测量并记录患者术前,术后1周,术后1、3、6个月的裸眼远视力（UCVA）、最佳矫正视力（BCVA）、屈光度、总高阶像差（HOAs）、球差（Z40）、垂直彗差（Z3-1）、水平彗差（Z31）、角膜前表面散光、角膜不规则指数（CIM）和形状因子（SF）等。应用重复测量方差分析比较2组之间手术前后各参数的差异。结果2组之间各个时间点的UCVA、BCVA和屈光度差异均无统计学意义。术后1周时,4 mm切口组的Z3-1较2 mm切口组大（t=-2.031,P＜0.05）;术后1周和1个月时,4 mm切口组的角膜前表面散光较2 mm切口组高（t=-2.126、-2.108,P＜0.05）;术后1周和1个月时,4 mm切口组的CIM较2 mm切口组大（t=-2.360、-2.395,P＜0.05）。结论在角膜前表面散光、Z3-1和CIM方面,2 mm切口的SMILE比4 mm切口的SMILE更有优势。