PRK后角膜的中央岛改变

为研究ＰＲＫ术后角膜中央岛（ｓｔｅｅｐｃｅｎｔｒａｌｉｓｌａｎｄ,ＳＣＩ）的改变及其对视力的影响,探讨其成因和消除方法。对ＰＲＫ后１年以上的７７例（１４６眼）出现角膜ＳＣＩ进行了复习。结果：ＰＲＫ后１周时,出现ＳＣＩ的有４１眼（２８．１％）;１月时为２０眼（１３．７％）;３月时为８眼（５．５％）;６月时为５眼（３．４％）;术后１年时未发现合符标准的ＳＣＩ。ＳＣＩ的屈光度改变有逐渐由陡峭变扁平的趋势,其直径在术后３个月前有逐渐缩小的趋势,但以后的改变趋于稳定。在术后１个月或１个月以上时,存在ＳＣＩ的眼中,最佳视力的丧失比无ＳＣＩ的眼要多（Ｐ＜０．００５）。随着ＳＣＩ的减轻或消失,视力逐渐提高。结论：最佳矫正视力的丧失与ＳＣＩ的形成有关,ＳＣＩ的出现将会延长最佳矫正视力的恢复期     

Nd:YAG laser treatment for epithelial ingrowth after laser refractive surgery

Epithelial ingrowth under refractive surgery flaps occurs in primary treatment and in further flap lift. Nd:YAG treatment was first described in 2008. In the only series published to date, 100% of patients treated had topographic and symptomatic improvement. The authors pictorially illustrate two cases of epithelial ingrowth following laser in situ keratomileusis achieving complete symptomatic relief and marked microscopic improvement following Nd:YAG laser treatment.     

準分子激光角膜屈光手術中的個體化切削

准分子激光角膜屈光性手术,随著激光设备的改进及控制系统的逐步完善,已经得到很大的发展。个体化切削,是根据个体的特性及需要去建立、适应或改变准分子激光屈光手术方式的一仪系列方法。许多新的和发展的技术,通过增加视网膜成像的对比度,达至更高的清晰度,以克服以往手术的某些弊端,更大程度地提高视力,减少并发症。屈光手术的未来十年将会有更加美好的前景。     

Strategic planning in topography-guided ablation of irregular astigmatism after laser refractive surgery

PURPOSE: To identify an optimal customized ablation strategy in the treatment of eyes with secondary irregular astigmatism. METHODS: Corneal anterior surface elevation maps of 50 eyes with secondary irregular astigmatism after decentered laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) and 50 virgin eyes were used for customized ablation simulations. Two ablation simulations with targeted postoperative surfaces perpendicular to either the visual or corneal morphological axis were made for each eye. All ablations were programmed for correction of corneal irregularities, including corneal astigmatism. The manifest refractive error was not corrected. Optical diameter was 6.5 mm and total diameter was 7.5 mm. Maximum ablation depths and maximum transition zone gradients were registered and analyzed. RESULTS: In eyes with secondary irregular astigmatism, mean maximum ablation depth was 48.21 +/- 25.96 microm and 26.31+/- 14.08 microm, whereas mean maximum transition zone gradient was 29.07 +/- 25.15 microm and 9.88 +/- 6.41 microm in ablation simulations based on the visual and corneal morphological axes, respectively. The difference between the ablation strategies was highly statistically significant for both parameters (P < .001). In virgin eyes, only a minor difference was noted between the visual and corneal morphological axis ablation simulations (P = .15 for maximum ablation depths and P=.19 for maximum transition zone gradient). CONCLUSIONS: In secondary irregular astigmatism, ablation based on the corneal morphological axis appears to minimize corneal tissue consumption and allows a smoother transition zone.     

Complications after laser refractive surgery

The laser refractive surgery is very effective method of refractive errors correction. The method is very popular, but serious complications may occur and the visual acuity may decrease. In this article authors show the possible complications after the laser refractive procedures.     

准分子激光角膜屈光手术偏中心切削

偏中心切削是准分子激光角膜屈光手术较常见的并发症,可造成患者裸眼视力（UCVA）和最佳矫正视力（BCVA）下降,眩光、光晕、单眼复视、不规则散光、眼部高阶像差增加等,严重影响患者视觉质量和手术效果,用常规方法难以处理,成为困扰患者和手术医师的一大难题。就偏中心切削的发生原因、临床表现及预防和治疗进行综述。     

准分子激光屈光手术上皮下雾状混浊的发生机制

准分子激光屈光矫正手术已经广泛开展,而上皮下雾状混浊(haze)作为其术后主要的并发症之一却一直困扰着眼科医师。研究表明,haze的发生受到许多因素影响,包括手术方式、术后的创伤愈合过程以及个体差异等,其中角膜上皮基底膜在haze形成中的作用为近几年研究的热点。     

非球面切削准分子激光角膜屈光手术的早期临床观察膊

目的 前瞻性研究非球面切削引导准分子激光角膜屈光手术的临床疗效.方法 将球镜-6.00D以下,柱镜0.00～2.00D的近视患者随机分成2组,Q调整组32例64眼行非球面切削引导准分子激光角膜屈光手术,对照组32例64眼行传统准分子激光原位角膜磨镶术(LASIK).观察术后裸眼视力,残余屈光度,高阶像差中的慧差、球差、总高阶像差均方根增加值和满意度等指标.结果 术后裸眼视力和残余屈光度两组比较差异无统计学意义,但Q调整组高阶像差的增加较对照组小,差异有统计学意义(P＜0.05).术后Q调整组患者的满意度情况比较,两组差异有统计学意义(P＜0.05).结论 非球面切削引导准分子激光角膜屈光手术可以减少术后角膜波面像差的增加,尤其是减少球差增加,明显改善视觉质量.     

激光角膜屈光手术后的神经修复

干眼症是激光角膜屈光手术后常见的并发症之一,与角膜神经损伤密切相关。角膜神经损伤修复缓慢,术后6个月仍未恢复至术前水平。不同的激光角膜屈光手术带来的神经损伤亦不相同。角膜神经修复涉及角膜细胞分泌细胞因子、角膜细胞的分化、角膜缘血管内淋巴细胞和巨噬细胞的迁移、角膜中心部基质下神经丛中性粒细胞的迁移及其生长因子的分泌等复杂过程。一些细胞因子、信号素、自体血清等参与角膜神经的修复,但目前多为动物实验,临床研究较少。（国际眼科纵览,2019, 43： 405-410)     

Infectious keratitis after laser refractive surgery.

PURPOSE: To report two cases of infectious keratitis, one fungal after photorefractive keratectomy (PRK) and the other bacterial after laser in situ keratomileusis (LASIK). DESIGN: Two interventional case reports. PARTICIPANTS: Case 1 is a male who was seen 3 weeks after PRK with a corneal ulceration. Case 2 involves a female who was seen 7 weeks after LASIK with interface granularity. RESULTS: Cultures in case 1 were identified as Scopulariopsis species, and despite intensive treatment, a therapeutic penetrating keratoplasty (PK) was eventually performed. Case 2 had cultures identified as Mycobacterium chelonae and also ultimately required a therapeutic PK. CONCLUSIONS: Two unusual infectious keratitides are reported after different laser refractive surgery techniques.     

Astigmatic changes after excimer laser refractive surgery

PURPOSE: To compare the astigmatic changes induced by spherical and elliptical excimer laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). SETTING: University-based refractive surgery practice. METHODS: Three-month refractive data from 317 eyes of consecutive patients having spherical PRK, astigmatic PRK (A-PRK), spherical LASIK, and astigmatic LASIK (A-LASIK) by a single surgeon (J.S.P.) using VISX 2020B and Star lasers over 2 years were studied for astigmatic changes resulting from the surgical procedure. RESULTS: At 3 months, the mean change in absolute astigmatism was +0.15 diopter (D) and -0.07 D in the spherical PRK and LASIK groups, respectively. Photorefractive keratectomy tended to induce with-the-rule (WTR) astigmatism, while LASIK was astigmatically neutral. As expected, the eyes treated with A-PRK and A-LASIK achieved a greater reduction in absolute astigmatism (-1.02 D and -1.28 D, respectively) than those treated with spherical PRK and LASIK. The qualitative nature of the astigmatic change was different between flap-based and PRK-based procedures. CONCLUSIONS: Spherical PRK is more likely than spherical LASIK to induce astigmatism, with a tendency toward WTR astigmatism. The eyes treated with spherical LASIK had no preponderant change in the direction of astigmatic magnitude or axis. Astigmatic PRK and LASIK effectively reduced astigmatism along the preoperative axis; A-LASIK tended to induce a random resultant axis in most patients.     

提高准分子激光角膜屈光手术后角膜的安全性

自70年代至今,屈光手术经过不断的革新、改进,目前准分子激光角膜屈光手术成为矫正近视的重要方法。由于其在正常的角膜组织上通过不同方式制作各种角膜瓣后进行激光切削,因而其术后长期的安全性一直是眼科医生担心和关注的主题。本文通过比较临床应用的不同技术方法的利弊,从角膜安全性角度阐述其各自的适应证,以期为临床合理治疗提供资料。     

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。     

Arcuate keratotomy for asymmetrical steep islands after laser in situ keratomileusis and automated lamellar keratoplasty

PURPOSE: To determine the safety and efficacy of arcuate keratotomy (AK) to reduce or eliminate steep asymmetrical islands after laser in situ keratomileusis (LASIK) and automated lamellar keratoplasty (ALK). SETTING: Rancho Bernardo Laser and Vision Center, San Diego, California, USA. METHODS: This retrospective and noncomparative interventional study comprised 8 eyes of 5 patients who received arcuate incisions to reduce topographically defined asymmetrical steep islands after LASIK (n = 7) and ALK for hyperopia (n = 1). The islands occurred unexpectedly after standard excimer laser treatment (VISX Star and S2) for myopic astigmatism that induced irregular astigmatism and unwanted optical effects. Cases occurred consecutively over 16 months, an incidence of less than 1%. Arcuate incisions extended 30 or 45 degrees in LASIK eyes based on the amount of residual refractive astigmatism and were placed at 7.0 mm on the steep axis. Radial incisions were limbal sparing to a 5.0 mm optical zone following the Casebeer nomogram. Outcome measures were uniformity of postenhancement topography, uncorrected visual acuity (UCVA), postenhancement refraction, and reduction in unwanted optical effects. RESULTS: The preenhancement mean spherical equivalent (SE) in the LASIK eyes was -0.99 diopters (D) +/- 0.48 (SD); the astigmatism ranged from 0.50 to 1.75 D. After incisional keratotomy, the mean SE was -0.21 +/- 0.12 D and the net residual astigmatism was reduced to a range of 0 to 0.75 D. All 8 eyes had AK to reduce topographically defined steep islands that were causing visual blurring and unwanted optical effects including ghosting, halos, and polyplopia. After enhancement, there was a marked reduction in the asymmetrical steep islands by topography, fewer unwanted optical effects, less refractive astigmatism, and improved UCVA. Two patients retained small inferior steep areas that may indicate forme fruste keratoconus, although this condition was not detected preoperatively by topographical indices. CONCLUSION: Uncorrected visual acuity improved and unwanted optical effects were reduced after AK on the peripheral axis of asymmetrical steep islands that occurred after uneventful LASIK and hyperopic ALK. This relatively simple incisional approach may be used until more advanced topography-linked ablations with rapid and precise eye tracking are perfected and widely available.     

Intraocular pressure after excimer laser myopic refractive surgery

The aim of this study was to determine whether intraocular pressure (IOP), as measured by Goldmann applanation or non-contact tonometry, shows systematic changes in patients who have undergone photorefractive keratectomy (PRK) or laser in situ keratomileusis (LASIK). IOP was measured by central Goldmann and non-contact tonometry in 54 patients pre and post-PRK, and in 43 patients pre- and post-LASIK. An interval of 12 months was allowed after surgery. Patients were selected to have one of four specific initial values of refractive error (-2.5, -5.0, -7.5 and -10.0 D). Fellow unoperated eyes were used as controls. A paired Student's t-test and a one-way ANOVA test were used for statistical analysis. After PRK and LASIK, a statistically significant decrease (p < 0.01) was observed in the IOP of the treated eyes (but not for control eyes; p > 0.01). Although the magnitude of the change increased with the attempted refractive correction, this trend was not statistically significant (p > 0.01). No statistically significant differences were found between the results obtained following the two types of surgery, although the recorded fall in IOP was smaller following LASIK (p > 0.01). The IOP measured after PRK and LASIK for myopia may be reduced because of reduced corneal thickness and curvature and, possibly, tissue softening after natural healing. The presence or absence of Bowman's membrane does not appear to be important in this context. The reduction in measured IOP following refractive surgery, by about 0.5 mmHg/D of myopic correction, needs to be remembered when possible abnormality of IOP in such patients is being considered.