准分子激光屈光性角膜手术后角膜后表面改变的研究进展

准分子激光屈光性角膜手术通过激光切削角膜组织改变角膜前表面曲率,从而矫正屈光不正。由于偶有术后医源性角膜扩张的病例发生,手术后角膜发生怎样的改变是眼科医师一直关注的问题。本文综述了准分子激光屈光性手术后角膜后表面是否发生前移改变、角膜后表面屈光力、曲率、散光度、轴度、非球面特性以及最适球面等是否发生改变的研究进展。     

Aesthesiometry of the cornea after refractive corneal surgery]

The corneal sensibility was examined with the aesthesiometer of Draeger in 41 patients after refractive corneal surgery, 31 patients after radial keratotomy, 5 after epikeratophakia, 5 after excimer laser ablation. It could be shown that after radial corneal incisions the sensibility remains normal. After epikeratophakia the corneal sensibility is asensible even 3 years after operation. The lenticle periphery shows an increase of sensibility after 6 months. Excimer patients with "haze" showed a significant hyposensibility in the centre. The central sensibility showed normal values after a normal corneal wound healing.     

Biomechanics of the cornea and wavefront-guided laser refractive surgery

PURPOSE: Wavefront-guided laser refractive surgery induces postoperative optical aberrations that are not explained by the ablation profile. METHODS: A conceptual model is presented for a potential mechanism of surgically-induced corneal shape change that is dependent on structural modification, rather than ablation profile. RESULTS: Examples are provided from clinical and basic studies that are consistent with the proposed model. CONCLUSION: Corneal biomechanical response to ablative surgery may significantly affect outcomes, and should be taken into account when planning customized procedures.     

Assessment of cornea thickness in patients after refractive surgery

PURPOSE: To assess changes of central cornea thickness after Excimer laser procedures--photorefractive keratectomy (PRK) and in situ keratomileusis (LASIK). MATERIAL AND METHODS: In 80 eyes of 40 patients the Excimer laser procedure was performed. Patients were divided into 2 groups: the 1st after PRK and the 2nd after LASIK procedure. Pachymetric measurements of cornea were performed before and 6 months after procedure. RESULTS: In both groups the thickness of the cornea was significantly lower after procedure. In the 2nd group the changes were greater. CONCLUSION: Excimer laser refractive surgery produces significant decrease in cornea thickness. The change in corneal thickness correlates with the change in spherical equivalent refraction.     

Wound healing in the cornea: a review of refractive surgery complications and new prospects for therapy

PURPOSE: The corneal wound healing response is of particular relevance for refractive surgical procedures since it is a major determinant of efficacy and safety. The purpose of this review is to provide an overview of the healing response in refractive surgery procedures. METHODS: Literature review. RESULTS: LASIK and PRK are the most common refractive procedures; however, alternative techniques, including LASEK, PRK with mitomycin C, and Epi-LASIK, have been developed in an attempt to overcome common complications. Clinical outcomes and a number of common complications are directly related to the healing process and the unpredictable nature of the associated corneal cellular response. These complications include overcorrection, undercorrection, regression, corneal stroma opacification, and many other side effects that have their roots in the biologic response to surgery. The corneal epithelium, stroma, nerves, inflammatory cells, and lacrimal glands are the main tissues and organs involved in the wound healing response to corneal surgical procedures. Complex cellular interactions mediated by cytokines and growth factors occur among the cells of the cornea, resulting in a highly variable biologic response. Among the best characterized processes are keratocyte apoptosis, keratocyte necrosis, keratocyte proliferation, migration of inflammatory cells, and myofibroblast generation. These cellular interactions are involved in extracellular matrix reorganization, stromal remodeling, wound contraction, and several other responses to surgical injury. CONCLUSIONS: A better understanding of the complete cascade of events involved in the corneal wound healing process and anomalies that lead to complications is critical to improve the efficacy and safety of refractive surgical procedures. Recent advances in understanding the biologic and molecular processes that contribute to the healing response bring hope that safe and effective pharmacologic modulators of the corneal wound healing response may soon be developed.     

穿透性角膜移植术后角膜屈光力改变与三联手术

目的研究穿透性角膜移植术后角膜屈光力的改变,探讨对侧健眼角膜屈光参数在穿透性角膜移植联合白内障摘除、人工晶体植入术(三联手术)中的意义.方法穿透性角膜移植术(PKP)患者41例,其中单纯PKP25例,三联手术10例,PKP联合白内障摘除6例,其中5例术后1～1.5年行二期人工晶体植入.对术眼手术前后角膜曲率及眼轴的改变进行对比观察,并与健眼进行比较.结果术前角膜屈率为36.685～48.935D,平均40.935±3.569D;术后角膜屈率为39.190～50.31D,平均43.955±3.414D,配对T检验示两者有显著性差异(P=0.021);手术前后的眼轴分别为20.92～29.29mm(平均24.179±0.511mm)和22.76-30.86mm(平均24.85±2.35mm),配对T检验示两者无显著性差异(P=0.081);健眼的角膜屈率为42.125～44.810D,平均43.963二1.224D,经配对T检验与患眼术后角膜屈率无显著性差异(P=0.36).1例三联手术患者术后因高度近视而行人工晶体取出,另有两例因高度复性近视散光行LASIK;5例PKP联合自内障,人工晶体二期植入的患者,4例裸眼视力在0.5以上.结论PKP术后角膜屈率发生显著性变化,健眼角膜屈光参数是三联手术中人工晶体计算的重要参数,但患眼术后角膜屈率的改变有很大的不可预测性,PKP联合白内障摘除,二期再植入人工晶体可使患者获得更好的裸眼视力.     

准分子激光角膜屈光术后角膜感染诊断与治疗回顾

目的回顾性分析准分子激光角膜屈光术后早期角膜感染的诊断与治疗策略及视力转归。方法对2008年1月至2014年3月我院收治的因准分子激光术后早期角膜感染患者7例(8只眼)进行回顾性分析。根据患者病史、共焦显微镜或角膜病灶组织刮片等检查明确其感染类型,对症采用局部及全身药物治疗,对药物不能控制的感染采取手术治疗,并观察视力转归情况。结果患者8只眼全部诊断为细菌性角膜溃疡,其中8只眼病灶组织刮片检查为阳性,5只眼细菌培养阳性。4只眼(50.0%)经抗菌药物治疗达到溃疡愈合,4只眼(50.0%)行板层性角膜移植术治愈。治愈病例至溃疡愈合时,8只眼视力均较治疗前提高。结论感染性角膜炎是准分子激光术后早期发生的严重并发症,尽早明确诊断并积极治疗是控制感染、保存视力的关键。     

波前像差技术及其在屈光手术中的应用

介绍测量人眼像差的几种主要方法及其在屈光手术中的应用。以Hartmann-Schack、Tsherning or Scheiner-Smirnov theories理论为基础的像差仪或像差镜能测量人眼屈光系统所有的像差,所得到的数据与屈光手术系统相结合后设计个性化切削方案,从而能提高PRK、LASIK等屈光手术术后的视觉质量。     

角膜近视屈光手术的个性化设计进展

近视是亚洲地区影响青壮年视力的主要眼病之一。角膜屈光手术是近视患者摘除眼镜,提高生活质量的主流选择。随着科技的进步,角膜屈光手术的方式逐渐多样化,患者对术后视觉质量的要求也不断提高。如何为患者进行个性化的手术设计,达到满意的术后视觉质量是每个屈光手术医师都面临的问题。笔者就角膜近视屈光手术的手术方式、参数、设备和切削模式的个性化设计方面做一简要综述。     

应高度重视角膜屈光手术的设计环节

角膜屈光手术,尤其是准分子激光角膜屈光手术,在我国开展已有近20年的历史了,随着科技与社会的不断发展,人们对屈光手术的要求也从单一的视力标准向更高的目标--视觉质量迈进;为此,近年来屈光手术领域的新技术不断涌现,为医师提供了更多的设计空间,以满足患者看得清晰、看得舒服这一更高需求.本文就手术设计这一环节中目前最应注意的暗视觉(如薄角膜、大散光、暗环境下的大瞳孔、角膜特殊形态的手术设计思路)与最佳屈光度参数的个体化理念来剖析手术设计环节对视觉质量的影响与重要性.     

Interferometric technique to measure biomechanical changes in the cornea induced by refractive surgery

PURPOSE: To develop a technique to quantify biomechanical changes in the cornea after microkeratome incisions as would be performed in laser in situ keratomileusis. SETTING: St Thomas' Hospital, London, and the Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, United Kingdom. METHODS: Corneal displacements of whole sheep eyes were studied under hydrostatic loading using electronic speckle pattern interferometry before and after microkeratome incisions. RESULTS: After hydrostatic loading, there was a 20.7% increase in corneal displacement in corneas with microkeratome incisions compared to unoperated corneas; this was statistically significant (P=.0068, unpaired t test). CONCLUSIONS: Results show that in the formation of the microkeratome flap, collagen fibers are severed and minimal biomechanical loading is distributed through the flap. Corneal biomechanical integrity is compromised after microkeratome incisions.     

角膜屈光手术后角膜生物力学变化特点的研究进展

角膜生物力学是对角膜黏性阻力、整体硬度等特性进行研究和分析的一门科学。角膜的生物力学特性是影响角膜屈光手术可预测性及稳定性的重要因素之一,且与不同的手术方式和切削深度相关,如板层切削较表层切削对角膜硬度影响大,厚角膜瓣术后角膜滞后量和阻力因子均较术前显著下降,切削深度大者角膜阻力因子明显下降。这些改变与术后发生角膜扩张、屈光回退等并发症有高度相关性。     

角膜屈光手术后人工晶状体度数计算的初步研究

目的 对准分子激光角膜屈光手术后的白内障患者,分析其超声乳化白内障吸除联合人工晶状体(IOL)植入术后的屈光状态以及各种IOL度数计算方法的准确性.方法 回顾性系列病例研究.17例(24只眼)患者根据是否提供准分子激光术前(包括准分子激光角膜切削术和准分子激光角膜原位磨镶术)角膜屈光度数资料分为两组(有历史资料组和无历史资料组).所有患者在白内障术前接受自动角膜曲率计、角膜地形图、Pentacam、IOL Master综合检查,分别采用临床病史法、Feiz-Mannis公式法、Feiz-Mannis法等多种公式进行IOL度数计算.白内障术后3个月时进行客观验光.采用非配对t检验,Pearson相关分析及线性回归分析,配对t检验以及Bland-Ahman一致性检验对数据进行分析.结果 有历史资料组患者准分子激光术前的平均屈光度数与平均等效球镜分别为(43.28±1.21)D与(-15.33±4.36)D;无历史资料组的平均等效球镜为(-10.11±3.12)D.白内障术前两组平均角膜屈光度数为(36.96 ± 2.07)D与(36.85±1.40)D.白内障术后两组平均屈光误差分别为(-0.66±1.27)D与(-0.47 ± 0.82)D.Hamed Wang Koch法、Masket法、Koch/Maloney法、Shammar法与Pentacam ERK法计算值低于平均真实值,易造成术后欠矫;Feiz-Mannis公式法、Latkany法、Savini法与Armberri Double K的计算值高于真实值.临床病史法,角膜忽略法和Haigis-L法的计算值与真实值之间差异无统计学意义(P=0.364,0.318,0.069;t=0.956,-1.057,-1.911).Feiz-Mannis法和Haigis-L法计算结果与真实值之间具有一定相关性(r=0.921,0.915;P=0.000,0.000).但无一种方法计算结果与真实值具有一致性.结论 为避免术后发生屈光欠矫,需要通过综合方法计算IOL度数,应联合临床病史法、Feiz-Mannis法、角膜忽略法、Haigis-L法进行IOL度数计算.     

Father Waclaw Szuniewicz--Polish missionary, ophthalmologist, pioneer of refractive surgery of the cornea

The article presents the life and work of Polish missionary of Saint Vincent a Paulo order, an ophthalmologist, Father Wac?aw Szuniewicz. He was born in 1891 in the Vilnius region. He completed his medical studies in Moscow in 1916. He specialised in ophthalmology at Stefan Batory University in Vilnius. In 1927 he entered the missionary order and after being ordained n 1930, he was sent for mission to China. There he developed his involvement in ophthalmology and established the ophthalmic ward in Shuntehfu that became very renowned. After taking over by the communist in China, he went to US in 1948. He continued his experimental work on surgical method on changing corneal curvature at Yale University in New Haven. In 1952 he went to Brasil where he continued his work as a missionary and an ophthalmologist. He was a man of great kindness and knowledge. He had particular language skill. At high school and during his medical and theological studies, he mastered Russian, French, English, Latin and Hebrew. He also learnt Chinese and Portugese. He was able to communicate in Lithuanian and Byelorus. He died in Brazil on 16 october 1963. His scientific accomplishments make him one of the pioneers of refractive surgery of cornea.     

角膜屈光手术后人工晶状体度数计算的初步研究

Objective To evaluate the results of cataract surgery in myopia patients after laser in situ keratomileusis(LASIK)and to compare the predictability of various methods of intraccular lens(IOL)power calculation.Method Seventeen cases (24 eyes)who had LASIK for myopia were divided into two group by with or without history of corneal power data.Corneal power was obtained by autokeratometry,corneal topography.Pentacam and IOLMaster.The IOL power was calculated with the clinical history method,Feiz-Mannis formula,Feiz-Mannis method and other methods.Postoperative final refraction and the deviation of the final spherical equivalent (SEQ) from the refractive target were measured 3 month after the surgery.Two sample t-test.linear correlation and regression analysis,paired t-test and Bland-Altman method of agreement were used to analyze these data.Results In the group with history data,the mean corneal power was(43.28±1.21)D and the mean SEQ was(-15.33±4.36)D before the LASIK surgery.In the group without history data,the mean SEQ was(-10.11±3.12)D.Before cataract surgery,the mean corneal power was(36.96±2.07)D and(36.85±1.40)D in these two groups.The mean arithmetic refractive prediction error after cataract surgery was(-0.66±1.27)D and(-0.47 ± 0.82)D in these two groups, respectively. Data calculated by using Hamed-Wang-Koch method, Masket Formula, Koch/Maloney method, Shammar method and Pentacam ERK method were lower than the emmetropic IOL power. Data calculated by using Feiz-Mannis Formula, Latkany Method, Savini method, Armberri Double K method were overestimated. The mean arithmetic errors of clinic history method, Corneal Passby Method and Haigis-L Formula were not significantly different from the predict refraction (P=0. 364, 0. 318 and 0. 069;t=0. 956,-1. 057 and -1. 911, respectively). There was strong correlation between the value calculated by using Feiz-Mannis Method or Haigis-L Formula and the true power (r = 0. 921,0. 915; P = 0. 000 and 0. 000,respectively). But none of the values calculated by these method could fully agree with the true value.Conclusions IOL power should be calculated accurately to avoid undercorrection. We recommend the combination of clinical history method, Feiz-Mannis Method, Corneal Passby Method and Haigis-L Formula for the calculation of IOL power.     

角膜屈光手术后人工晶状体度数计算的初步研究

Objective To evaluate the results of cataract surgery in myopia patients after laser in situ keratomileusis(LASIK)and to compare the predictability of various methods of intraccular lens(IOL)power calculation.Method Seventeen cases (24 eyes)who had LASIK for myopia were divided into two group by with or without history of corneal power data.Corneal power was obtained by autokeratometry,corneal topography.Pentacam and IOLMaster.The IOL power was calculated with the clinical history method,Feiz-Mannis formula,Feiz-Mannis method and other methods.Postoperative final refraction and the deviation of the final spherical equivalent (SEQ) from the refractive target were measured 3 month after the surgery.Two sample t-test.linear correlation and regression analysis,paired t-test and Bland-Altman method of agreement were used to analyze these data.Results In the group with history data,the mean corneal power was(43.28±1.21)D and the mean SEQ was(-15.33±4.36)D before the LASIK surgery.In the group without history data,the mean SEQ was(-10.11±3.12)D.Before cataract surgery,the mean corneal power was(36.96±2.07)D and(36.85±1.40)D in these two groups.The mean arithmetic refractive prediction error after cataract surgery was(-0.66±1.27)D and(-0.47 ± 0.82)D in these two groups, respectively. Data calculated by using Hamed-Wang-Koch method, Masket Formula, Koch/Maloney method, Shammar method and Pentacam ERK method were lower than the emmetropic IOL power. Data calculated by using Feiz-Mannis Formula, Latkany Method, Savini method, Armberri Double K method were overestimated. The mean arithmetic errors of clinic history method, Corneal Passby Method and Haigis-L Formula were not significantly different from the predict refraction (P=0. 364, 0. 318 and 0. 069;t=0. 956,-1. 057 and -1. 911, respectively). There was strong correlation between the value calculated by using Feiz-Mannis Method or Haigis-L Formula and the true power (r = 0. 921,0. 915; P = 0. 000 and 0. 000,respectively). But none of the values calculated by these method could fully agree with the true value.Conclusions IOL power should be calculated accurately to avoid undercorrection. We recommend the combination of clinical history method, Feiz-Mannis Method, Corneal Passby Method and Haigis-L Formula for the calculation of IOL power.     

Influence of cornea thickness changes after refractive surgery on intraocular pressure measurements

PURPOSE: Assessment of influence of of the cornea thickness decrease on intraocular pressure (IOP) measurements with Goldmann applanation tonometry in patients after refractive surgery procedures (PRK and LASIK). MATERIAL AND METHODS: 80 eyes in 40 patients (pts) qualified for myopia correction with laser surgery were divided into two groups: in Ist group--20 pts (40 eyes)--PRK procedure was performed and in IInd group--40 eyes (20 pts) LASIK was performed. IOP was measured by Goldmann applanation tonometry. The cornea thickness was assessed in its central region with endothelial microscope with pachymetric facility (Cooper Vision). The eyes were evaluated twice: before and 1 month after the procedure. RESULTS: In all eyes after laser surgery procedures IOP was lower because of the decrease of central cornea thickness. CONCLUSIONS: The central cornea thickness is an important factor influencing intraocular pressure measurements with Goldmann applanation tonometry. Refractive surgery procedures leading to the decrease of central cornea thickness result in lower intraocular pressure measurements in applanation tonometry.