飞秒激光辅助的角膜透镜植入技术研究进展

目前的准分子激光原位角膜磨镶术、准分子激光上皮下角膜磨镶术、飞秒激光辅助准分子激光原位角膜磨镶术、飞秒激光透镜切除术和小切口透镜切除术等都是以牺牲角膜厚度为前提来矫正屈光不正的,矫正的屈光度必然受到角膜厚度的限制。转变在角膜厚度上做"减法"来矫正屈光不正的理念,尝试在角膜基质层内植入一定度数的透镜,用"加法"来矫正屈光不正已经成为可能。本文就飞秒激光辅助的角膜透镜植入技术近10年来的研究进展及发展前景进行综述。     

飞秒激光在眼表领域的临床应用

飞秒激光是指激光脉冲作用时间以飞秒为单位的激光,是目前在实验条件下所能获得的最短脉冲的激光,具有最大的切削精确度和最小的周围组织损伤,近年在眼科有广泛应用.在眼表领域,可利用飞秒激光制作角膜瓣完成LASIK手术、制作超薄角膜瓣行前弹力层下角膜磨镶术,还可行飞秒激光辅助的角膜活检、角膜层间墨染、散光性角膜切开术以及制作角膜隧道行角膜基质环植入术.近年来有人利用飞秒激光行角膜基质内切除术治疗屈光不正,完全取代了准分子激光.本文就飞秒激光的作用机制及在眼表领域的临床应用进行综述.     

飞秒激光角膜屈光手术的意义与发展趋势

飞秒激光以其扫描的高精确度及安全性,在角膜屈光手术中扮演着越来越重要的角色。目前,飞秒激光在屈光手术中主要用于准分子激光原位角膜磨镶术（LASIK）中辅助角膜瓣的制作。以飞秒激光代替角膜刀,具有较高的安全性、可预测性以及生物力学稳定性。飞秒激光基质透镜切除（ReLEx）代表了角膜屈光手术的最新进展,具有较好的应用前景。此外,飞秒激光角膜基质新型扫描模式也在探索中。     

飞秒激光在角膜屈光手术中的应用进展

准分子激光原位角膜磨镶术是目前矫正近视的主要方法,其术中及术后的并发症主要来源于角膜瓣的制作。激光制作角膜瓣可以减少这些并发症的发生,而飞秒激光是目前所知惟一可以用于角膜瓣制作的激光。本文就飞秒激光的作用原理以及用于角膜瓣制作的动物实验和早期临床结果进行综述。     

高度近视眼3种角膜屈光手术后角膜神经修复情况及角膜光密度的对比研究

目的:探讨高度近视眼行飞秒激光小切口角膜基质透镜取出术（SMILE）、飞秒激光制瓣的准分子激光原位角膜磨镶术（FS-LASIK）及准分子激光上皮瓣下角膜磨镶术（LASEK）术后12个月角膜不同区域上皮下神经的修复情况和角膜透明度的差异。方法:队列研究。收集于2018年6月至2019年10月在山东省青岛大学附属医院眼科就...     

飞秒激光术中角膜基质不透明气泡层的研究进展

飞秒激光辅助的准分子激光原位角膜磨镶术(FS-LASIK)和飞秒激光小切口角膜基质透镜取出术(SMILE)是目前主流的角膜屈光手术方式。虽然临床研究显示其具有很高的安全性、有效性和可预测性,但制作角膜瓣或透镜时需要依赖飞秒激光,不可避免地会发生飞秒激光相关并发症,如负压失吸、不透明气泡层(OBL)等。OBL是飞秒激光在角膜组织中发生光爆破作用时产生的二氧化碳和水蒸气聚集体在角膜基质中无法及时排出而形成,是飞秒激光手术特有的并发症。气泡可能会干扰术中操作和影响术后视觉质量。本文就OBL形成的机制、分级和分类、影响因素及其对术中操作和术后效果的影响进行综述,以期为进一步临床工作提供参考和依据。     

飞秒激光制作角膜瓣并发症的临床观察

准分子激光角膜原位磨镶术（LASIK）具有良好的安全性、有效性及稳定性，角膜瓣的制作是关键步骤之一。目前LASIK手术的许多并发症都与角膜瓣的制作有关。飞秒激光为角膜瓣的制作提供了一个全新的方法，在国外已有较多应用。现对我院行飞秒激光制作角膜瓣的LASIK手术的并发症进行总结。     

激光手术矫正老视的应用和研究进展

尽管老视矫正方法日趋繁多,但手术矫正老视仍是屈光领域一个重大难题.近年来激光手术矫正老视逐渐得到重视.主要包括作用于角膜的激光老视手术如准分子激光原位角膜磨镶术、飞秒激光角膜基质内老视矫正术、激光角膜热成形术、角膜层间镜片植入术,以及作用于晶状体的飞秒激光晶状体老视矫正手术等.本文对激光矫正老视的临床应用和最新研究进展进行综述.     

飞秒激光小切口基质透镜取出术和飞秒激光辅助准分子原位角膜磨镶术的比较

近２０ａ来随着飞秒激光技术的飞速发展,眼科手术应用飞秒激光开展了许多新的应用。飞秒激光小切口基质透镜取出术和飞秒激光辅助准分子原位角膜磨镶术都是应用飞秒激光治疗近视和散光的安全有效的方法。但由于手术机理和手术方式不同,所以在术后角膜形态学、角膜生物力学、术后疗效和并发症等方面会产生一些差异,本文就此展开综述。     

Visumax飞秒激光兔角膜内扫描微囊及基质桥观察

飞秒激光是一种以脉冲形式运转的红外线激光，具有脉冲持续时间极短、瞬间功率极高、热效应的区域极小等特点，在准分子激光角膜原位磨镶术（laser in situ keratomileusis，LASIK）中用于角膜基质瓣的制作。作为新一代飞秒激光器，Visumax飞秒激光采用的是弧形压平模式和向心性螺旋扫描模式，于2007年1月被FDA批准应用于临床。激光扫描角膜瓣成形术后裂隙灯下角膜组织的形态及病理变化是飞秒激光参数的评价指标，目前国内外报道较少。本研究探讨飞秒激光参数的精确度及对角膜生物学的潜在影响。     

Femtosecond laser-assisted corneal surgery

PURPOSE OF REVIEW: The femtosecond laser has potentially improved the safety and precision of creating corneal flaps in laser in situ keratomileusis (LASIK). This review focuses on recent advances in applying femtosecond laser technology to other corneal procedures. RECENT FINDINGS: The femtosecond laser is capable of cutting tissue at various depths and patterns with minimal collateral tissue injury. The laser can now be used to perform corneal pockets for ring segments, arcuate wedge-shaped resection in correction of high astigmatism, lamellar dissections in anterior lamellar keratoplasty, donor tissue preparation in Descemet's stripping endothelial keratoplasty, and shaped full-thickness keratoplasty. SUMMARY: Femtosecond laser-assisted corneal surgery may provide a more precise and safer approach to corneal surgery.     

Ultrafast (femtosecond) laser refractive surgery

Lasers with ultrafast pulses have been developed to decrease the energy necessary to incise tissues and to decrease damage to surrounding tissues. The IntraLase femtosecond (10-15 seconds) laser has been approved by the FDA for lamellar corneal surgery. It uses an infrared (1053 nm) scanning pulse focused to 3 microm with an accuracy of 1 microm to cut a spiral pattern in the corneal stroma creating precise lamellar flaps for LASIK. Clinical studies show that the flaps are uniformly of good quality with no flap complications. The flexibility of this system allows for intrastromal corneal surgery and may make it useful for other refractive and corneal procedures.     

In vivo femtosecond laser-assisted posterior lamellar keratoplasty in rabbits

PURPOSE: To develop a rabbit model for femtosecond laser-assisted posterior lamellar keratoplasty. METHODS: The femtosecond laser was used to make the posterior corneal lamellar interface and trephine (side) cut in 12 eyes of 11 rabbits. Laser parameters were energy 6.0 to 8.7 (lamellar cut) and 6.0 to 8.8 microJ (trephination cut), spot size 2.4 microm, firing rate 15 kHz, and trephination diameter 6.0 to 7.0 mm. In all eyes, the posterior corneal disc was removed from the eye after laser treatment through a blade incision in the peripheral cornea. The same excised corneal disc was repositioned into the posterior stromal bed to simulate posterior lamellar transplantation. Four eyes of 3 rabbits were enucleated immediately after surgery, and 8 eyes of 8 rabbits were enucleated after a mean follow-up of 17.9 +/- 6.5 weeks. The corneal cut surfaces were examined by light microscopy and scanning electron microscopy. RESULTS: The femtosecond laser was successful in producing posterior lamellar and trephination cuts in rabbit eyes. The thickness of the posterior corneal discs was 204.3 +/- 21 microm (56.9% of central corneal thickness), and postoperative keratometry was 49.1 +/- 5.8 D. Clinical appearance consistent with corneal ectasia was noted in 3 eyes. CONCLUSION: The femtosecond laser can make nonmechanical cuts for posterior lamellar keratoplasty with relative ease and reliability in rabbit eyes. A minimum residual anterior corneal thickness may need to be maintained to prevent ectasia.     

Femtosecond laser posterior lamellar keratoplasty: a laboratory model

PURPOSE: To evaluate feasibility of femtosecond laser application in posterior lamellar keratoplasty. METHODS: To evaluate the laser's effectiveness through opaque corneas, anterior corneal caps were resected from opaque corneas induced with 80% acetone solution. To evaluate the femtosecond laser posterior lamellar keratoplasty surgical procedure, human corneoscleral rims were mounted on an artificial anterior chamber. After corneal pachymetry, the femtosecond laser was used to create a 6-mm-diameter, 200-microm-thick endostromal lenticule. Access to the lenticule was provided by a small perilimbal surface opening, also created by the laser. The lenticule was removed using a pair of corneal forceps. A donor lenticule of similar dimensions was created, its endothelial surface coated with viscoelastic, inserted, and positioned on the recipient bed. Two sutures were placed to seal the small surface opening. RESULTS: The femtosecond laser produced an effective and smooth dissection through opaque corneas even at deeper settings. Graft transplantation was fairly simple and effective. CONCLUSION: Femtosecond laser posterior lamellar keratoplasty is a procedure that may provide an alternative to penetrating keratoplasty or the technically challenging manual posterior lamellar keratoplasty.     

Femtosecond-laser-assisted Descemet's stripping endothelial keratoplasty

To our knowledge, we describe the first patient with pseudophakic bullous keratoplasty treated with femtosecond-laser-assisted endothelial keratoplasty. A 5.5 mm corneoscleral tunnel incision was made; after Descemet's membrane was stripped, an 8.0 mm posterior lamellar corneal disk prepared with a femtosecond laser was inserted into the anterior chamber against the recipient cornea without the use of corneal sutures. Four months postoperatively, the posterior corneal disk was clear and the induced astigmatism was 2.1 diopters, demonstrating a functional corneal endothelial layer. The femtosecond laser offers a new surgical approach for minimally invasive endothelial keratoplasty in corneal endothelial disorders.     

Femtosecond laser-assisted deep anterior lamellar keratoplasty for keratoconus and keratectasia

AIM: To describe the initial outcomes and safety of femtosecond laser-assisted deep anterior lamellar keratoplasty (DALK) for keratoconus and post-LASIKkeratectasia.METHODS:In this non-comparative case series, 10 eyes of 9 patients underwent DALK procedures with a femtosecond laser (Carl Zeiss Meditec AG, Jena, Germany). Of the 9 patients, 7 had keratoconus and 2 had post-LASIK keratectasia. A 500 kHz VisuMax femtosecond laser was used to perform corneal cuts on both donor and recipient corneas.The outcome measures were the uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), corneal thickness, astigmatism, endothelial density count (EDC), and corneal power.RESULTS: All eyes were successfully treated. Early postoperative evaluation showed a clear graft in all cases. Intraoperative complications included one case of a small Descemet’s membrane perforation. Postoperatively, there was one case of stromal rejection, one of loosened sutures, and one of wound dehiscence. A normal corneal pattern topography and transparency were restored, UCVA and BCVA improved significantly, and astigmatism improved slightly. There was no statistically significant decrease in EDC.CONCLUSION: Our early results indicate that femtosecond laser-assisted deep anterior lamellar keratoplasty could improve UCVA and BCVA in patients with anterior corneal pathology. This approach shows promise as a safe and effective surgical choice in the treatment of keratoconus and post-LASIK keratectasia.     

Femtosecond laser-assisted intracorneal keratoprosthesis implantation: a laboratory model

PURPOSE: To demonstrate femtosecond laser-assisted intracorneal keratoprosthesis implantation and determine the mechanical stability as a function of intraocular pressure. METHODS: Eight human corneoscleral rims were mounted on an artificial anterior chamber. The femtosecond laser microkeratome was used to create a 2.5-mm diameter posterior corneal cap. A 7.2-mm-diameter lamellar stromal pocket was then created at mid-corneal depth. Finally, a 6-mm arc opening to the corneal surface was created at the periphery of the lamellar cut. The posterior lenticule was removed using corneal forceps and a 7.0-mm biopolymer keratoprosthesis was inserted into the stromal pocket. The surface wound was sealed using two 10-0 nylon sutures. A 3.0-mm anterior corneal opening was trephined to expose the keratoprosthesis. Intrachamber pressure was raised until wound leak was observed. RESULTS: Seven of the 8 implants withstood pressures of at least 135 mm Hg without implant extrusion. CONCLUSION: Femtosecond laser corneal dissection provides an alternative to more challenging manual dissection methods for keratoprosthesis implantation. Use of the femtosecond laser microkeratome will further refine keratoprosthesis surgical technique and may allow rapid and easy execution of the surgery.     

A practical femtosecond laser procedure for DLEK endothelial transplantation: cadaver eye histology and topography

PURPOSE: The manual dissection technique for deep lamellar endothelial keratoplasty (DLEK) surgery is technically difficult and may not be smooth enough for consistently optimal postoperative vision. We evaluated the feasibility and efficacy of using a femtosecond laser to perform the dissections in the DLEK procedure. METHODS: The Intralase femtosecond laser (with standard LASIK surgery spot settings) was used to create a 9.4-mm wide, 400-microm deep lamellar pocket dissection and a 5.0-mm wide side cut near-exit incision in 10 "recipient" whole cadaver eyes and in 10 "donor" cadaver corneal-scleral caps mounted onto an artificial anterior chamber. Recipient and donor disks were resected with special scissors, and the donor tissue was transplanted using the small incision (5.0-mm) DLEK technique. Topography of the recipient eyes was measured pre- and postlaser dissection, and the recipient and donor tissues were sent for scanning electron microscopy (SEM) analysis of the smoothness of the dissections. RESULTS: Successful lamellar dissections were obtained in all tissues. The mean recipient topographic corneal curvature postoperatively was 43.3 +/- 1.7 diopters, which was not a significant change from the preoperative curvature of 44.0 +/- 0.8 diopters (P = 0.430). The mean recipient topographic astigmatism postoperatively was 1.7 +/- 0.8 diopters, which was not a significant change from the preoperative recipient astigmatism of 1.6 +/- 0.7 diopters (P = 0.426). Comparison of the histology of the laser-formed stromal dissections by scanning electron microscopy, however, did not appear significantly better than histology after manual DLEK dissections in either the recipient or the donor tissues. CONCLUSIONS: A femtosecond laser can create the lamellar dissections for the DLEK procedure, making this procedure easier and faster. As in the manual technique, corneal topography is unchanged by this surgery. More work will need to be done, however, to optimize the laser settings to provide even smoother interface surfaces.     

飞秒激光在治疗性角膜手术及晶状体手术中的应用

飞秒激光代表了目前屈光手术领域的最新技术．其新型扫描模式的屈光效应正在探索中。飞秒激光以其扫描的高精确度及安全性,已从单纯角膜屈光矫正向全方位治疗性应用方向转变,已被应用于穿透角膜移植、板层角膜移植、基质环隧道的制作以及辅助角膜胶原交联以治疗圆锥角膜,此外其在角膜缘移植和角膜活组织检查中的应用分别为眼表重建及角膜病理学诊断提供了新的手段,而飞秒激光辅助白内障手术及经晶状体矫正老视等方面的应用尚处于实验探索阶段。随着相关技术的日趋完善,飞秒激光的临床应用将更加广阔。就飞秒激光在治疗性角膜手术及晶状体手术中的应用进行综述。