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ASCRS打造一站式超声乳化手术培训网络----ASCRS主席David F. Chang教授专访

2013-7-3 10:59| 发布者: Sonia| 查看: 9971| 评论: 0 |来自: 国际眼科时讯

摘要:美国的大多数眼科医师认为符合手术适应证的白内障患者应当被告知这些IOL的信息,作为手术告知内容的一部分。

       <International Ophthalmology Times>:What is the most common cause of iris prolapse during phaco and how do you manage it.
  Dr. Chang:Intraoperative floppy iris syndrome (IFIS) in association with current or prior tamsulosin use was first described by John Campbell and me in 20051[Chang DF, Campbell JR. Intraoperative floppy iris syndrome associated with tamsulosin (Flomax). J Cataract Refract Surg 2005; 31: 664-673.]. Besides a tendency for poor preoperative pupil dilation, severe IFIS exhibits a triad of intraoperative signs – iris billowing and floppiness, iris prolapse to the main and side port incisions, and progressive intraoperative miosis. However, there is a wide range of clinical severity seen in clinical practice. When surgeons have not recognized or anticipated IFIS, the rate of reported intraoperative complications has been increased. Complications of iris prolapse or aspiration include iridodialysis, iris sphincter damage, hyphema, and significant iris stromal or transillumination defects.
  Intracameral injection of alpha agonists such as phenylephrine or epinephrine is a safe and inexpensive strategy for IFIS. By presumably saturating the alpha 1-A receptors, these agonists can further dilate the pupil. Even if they do not, the alpha agonist will often increase iris dilator muscle tone, reducing billowing and the tendency for prolapse or sudden miosis.
  In the United States, preservative-free 1:1000 epinephrine is packaged in single use 1 ml vials (1 mg/ml). Epinephrine taken directly from the vial has a low pH of approximately 3.0. Therefore, direct intracameral injection of undiluted 1:1000 epinephrine should be avoided. Instead, a 1:4000 epinephrine solution can be easily constituted by adding 0.2 mL of commercially available 1:1000 epinephrine to 0.6 mL of plain balanced salt solution (BSS) or BSS Plus in a 3-mL disposable syringe. This dilution raises the pH to a physiologic level and appears to sufficiently dilute the bisulfite stabilizing agent. Several publications report the safety and efficacy of unpreserved 1.5% intracameral phenylephrine for both IFIS prevention and routine surgical mydriasis.  Preservative-free phenylephrine 2.5% (Minims) is only commercially available outside the United States. Because these preparations still contain bisulfite, a 1:3 dilution with BSS is also recommended.
  Mechanical pupil expansion with iris retractors or devices such as the Malyugin ring produces a reliably wide pupil diameter that cannot abruptly constrict during surgery. If one uses iris hooks, placing them in a diamond configuration has several advantages. The subincisional hook retracts the iris downward and out of the path of the phaco tip. This provides excellent access to subincisional cortex, and avoids tenting the iris in front of the phaco tip, such as occurs when the retractors are placed in a square configuration. This configuration also maximizes temporal exposure directly in front of the phaco tip as well as nasal exposure for placement of the chopper tip.
  《国际眼科时讯》:超声乳化手术中出现虹膜脱出最常见的原因是什么?如何进行处理?
  Dr. Chang:术中虹膜松弛综合征(IFIS)是2005年由我和John Campbell首次报道的[1],与术前或者术中使用坦洛新相关。除了术前瞳孔不易散大以外,严重的IFIS还会出现术中的三联征:虹膜松弛、涌动,虹膜从主切口或者侧切口脱出,术中进行性瞳孔收缩。但是,在临床上其严重程度不一。倘若手术医师没有意识到或者关注IFIS的话,报道的术中并发症会增加。虹膜脱出的并发症包括虹膜根部离断、虹膜括约肌受损、前房出血、虹膜基质受损。
  前房内注入α受体激动剂(如肾上腺素或者去氧肾上腺素)是应对IFIS安全而又经济的方法。这些激动剂通过饱和α1A受体使瞳孔进一步扩大。即使没能使瞳孔扩大,α受体激动剂通常也可以增加虹膜开大肌的张力,降低涌动,减少虹膜脱出和突然瞳孔缩小的可能。
  在美国,不含防腐剂的1:1000肾上腺素装在一个单独的1ml小瓶中,浓度为1mg/ml。瓶中的肾上腺素pH值低至3.0。因此,应当避免直接前房内注入未经稀释的1:1000肾上腺素。而应该使用1:4000的肾上腺素溶液,这很容易配置:将市面上很容易买到的1:1000肾上腺素取 0.2ml,加入到0.6ml平衡盐溶液(BBS)中。这一稀释过程将pH值增加到生理水平,充分稀释了亚硫酸氢盐稳定剂。多篇文献报道,无防腐剂的 1.5%去氧肾上腺素前房内注射既安全又有效,不仅可以预防IFIS,还可以用于术中的常规散瞳。无防腐剂的2.5%去氧肾上腺素只有在美国以外的地区可以买到。因为他们仍然含有亚硫酸盐,推荐与BBS进行1:3稀释再使用。
  使用例如Malyugin环之类的虹膜牵拉器机械性地扩张瞳孔可以有效地增大瞳孔的直径,使术中不会突然出现瞳孔收缩。应用虹膜拉钩使瞳孔形成菱形有很多益处。切口下方的虹膜拉钩使虹膜向下方收缩,为超声乳化头留下了可操作空间。放置成菱形的虹膜拉开器也使切口下方的皮质更方便被吸出,避免超声乳化头挡在虹膜前;也使鼻侧的超声乳化头和颞侧的劈核沟前面的视野最大地被暴露。

  <International Ophthalmology Times>:There is increasing interest among cataract surgeons in learning phaco chop. Why is this, and what resources do you recommend for those wanting to learn this technique?
  Dr. Chang:There has been a steady increase in the percentage of surgeons preferring chop during the past 15 years. According to the ASCRS Leaming surveys, this percentage was 11% in 1997, and increased to 18% by 1998, 24% by 2002, and was 41% in the 2011 survey. The fact that the phaco chop technique is generally more difficult to learn may be an important factor underlying these statistics.
  In addition to improved surgical efficiency, safety is enhanced by several advantages of phaco chop compared to divide and conquer. These key attributes are reduced ultrasound power, reduced zonular and capsular stress, decreased reliance on the red reflex, and the supracapsular and central location of emulsification. These universal features make chopping the optimal technique for difficult and complicated cases that entail greater risk of posterior capsule rupture or corneal decompensation. This improved ability to handle brunescent nuclei, white cataracts, loose zonules, posterior polar cataracts, crowded anterior chambers, capsulorrhexis tears, and small pupils should be the primary motivation for a divide-and-conquer surgeon to transition to phaco chop. Of course, in order to reap the benefits of phaco chop for difficult cataracts, one needs to have first mastered this technique in routine eyes.
  I’ve always been a strong proponent of phaco chop and have just completed my new cataract surgical textbook in time for the ASCRS annual meeting. Phaco Chop and Advanced Phaco Techniques: Strategies for Complicated Cataracts covers chopping techniques, configuration of machine parameters, and the management of complicated cases and complications. It is also the first cataract textbook to include instructional 3D and 2D video that complements and supplements the book content. 

  I am hoping to have the textbook translated into Mandarin sometime within the next year. We will also be adding more videos and course content on phaco chop to the ASCRS phaco fundamentals classroom, which is available for free to any ophthalmologist in the world . You can always find a link through our ASCRS home page

  《国际眼科时讯》:白内障手术医师对于超声乳化劈核技术产生了越来越大的兴趣,为什么会这样呢?对于想学习这门技术的医师您推荐什么学习材料?
  Dr. Chang:过去的15年里,喜欢劈核的手术医师的百分比在增长。根据ASRS调查,1997年时这一比例是11%,到1998年增长到18%,2002年为24%,2011年是41%。这些数据表明超声乳化劈核技术较难学习是主要因素。
  超声乳化劈核技术有很多好处,除了提高手术效率,手术安全性也得以增加。这些关键步骤减少了超声能量,降低了悬韧带和囊袋的张力,减少了对于红光反射的依赖性,降低了囊袋前和中心区的乳化能量。对于存在后囊膜破裂或者角膜失代偿危险因素的复杂疑难病例,超声乳化劈核技术的上述特征使之成为用于这些病例的最佳技术。从裂核转向劈核技术的最初目的是处理膨胀的“大白核”、悬韧带松弛、后极性白内障、浅前房、囊膜撕裂以及小瞳孔患者。当然,要想在复杂白内障中尝到超声乳化劈核的好处,我们需要首先掌握这项技术在普通白内障手术中的应用。
  我是超声乳化劈核技术的忠实支持者,在ASCRS年会来临时,我已经完成了新版的白内障手术教材。超声乳化劈核与高级超声乳化技巧:包括并发性白内障的劈核技术、仪器的构成参数、并发性白内障的治疗方法以及并发症的处理技巧。这也是第一本包含了3D和2D视频的白内障教材。
  我希望明年能够将这本教材翻译为中文。我们将会在ASCRS超声乳化基础课程中添加更多的视频和超声乳化劈核技术的相关内容,向全世界的眼科医师免费提供。您也可以通过ASCRS>的主网页找到链接。

       <International Ophthalmology Times>:What are your thoughts about the role of cataract surgery as a therapy for glaucoma?
  Dr. Chang:Certainly, cataract removal is one way to prevent chronic or acute angle closure glaucoma. The prevalence of chronic angle closure glaucoma is much higher in the Chinese patient population compared to in Caucasians. Therefore, earlier timing for phaco-IOL surgery should be considered in those patients at anatomic risk, who also have a visually significant cataract. What about patients with open angle glaucoma? We have also learned that phaco through a clear corneal incision is associated with a postoperative reduction in intraocular pressure (IOP) that is proportional to the preoperative starting IOP. In other words, eyes that have the highest preoperative IOP levels, such as those with ocular hypertension, will experience the greatest degree of IOP lowering. Some have speculated that this reduction in IOP relates to opening up of the angle once the crystalline lens is removed. Perhaps this relates to spatial compression of the ciliary body and trabecular meshwork due to crowding by the enlarged cataractous lens.
  Regardless of the mechanism, this is an important consideration with respect to the timing of phaco in eyes with cataract and open angle glaucoma. Particularly in patients who have poor access to topical medications and eye examinations, or those who simply have poor compliance with using their eyedrops, phaco may be one of the most effective treatments for mild to moderate glaucoma.
  In the United States, we are now gaining experience with a micro-trabecular bypass stent called the iStent (Glaukos) that was approved last fall by the FDA. The stent is implanted at the time of phaco as a combined procedure in eyes with mild to moderate glaucoma. These patients are typically on at least two topical medications and needing cataract surgery. This FDA approved implantable titanium stent is 1 mm long with a 120 micron diameter lumen, and is implanted through the phaco incision after the IOL has been inserted. It promotes increased aqueous outflow through Schlemm’s canal by bypassing the trabecular meshwork.

  《国际眼科时讯》:您对于白内障手术可以治疗青光眼有什么看法?
  Dr. Chang:事实上,摘除白内障是预防慢性或者急性闭角型青光眼的方法之一。中国的慢性闭角型青光眼患者明显多于白种人。因此,对这些存在解剖学危险因素同时又有严重影响视力的白内障患者,应当早期做白内障超声乳化联合人工晶状体(IOL)植入手术。对于开角型青光眼的患者是否同样适用呢?我们已经知道,经透明角膜切口的超声乳化手术会出现手术后眼内压降低,降低的程度与最开始的手术前眼压成比例。也就是说,手术前眼压特别高的患者在手术后将会降低非常多的眼压。有些人猜测眼内压的降低与摘除晶状体以后房角被打开有关。也许高眼压是由于膨胀的晶状体使睫状体和小梁网受挤压所致。
  不管机制怎样,对于既有白内障又有开角型青光眼的患者,施行超声乳化手术的时机非常重要。对于慎用或者禁用药物、不能做眼部检查或者药物依从性不好的患者,超声乳化手术是对轻中度青光眼最有效的治疗方法之一。
  在美国,我们目前正在尝试使用小梁网滤过通道支架,称做“iStent”,去年秋天已经通过FDA批准。这一支架在轻中度青光眼患者做超声乳化手术时联合植入眼内。手术人群至少使用两种降眼压药物,并且符合白内障的手术指征。这一钛支架长1 mm,管腔直径120 μm,在IOL植入后通过超声乳化切口植进眼内。它促进房水的流出,使其通过Schlemm管流进小梁网。

  <International Ophthalmology Times>:Multifocal IOLs are always a hot topic at the ASCRS meeting. Assuming that they want to reduce spectacle wear, how do you decide which cataract patients are good candidates for a multifocal IOL?
  Dr. Chang:Particularly as new IOLs become available, and as more Baby Boomers require cataract surgery, interest in refractive options will continue to climb. Most ophthalmologists in the United States believe that appropriate cataract patients should be informed about these options as part of the surgical informed consent. Determining which patients are good candidates for a multifocal IOL is a complex process, but if properly selected and informed, a certain percentage of our cataract population will be thrilled with the results.
  Careful patient selection, and effective preoperative education and counseling are time consuming, but extremely important. Patient satisfaction is very much a function of preoperative expectations, and our messaging competes with the internet, boastful friends, comparison to LASIK, and the power of suggestion that they will be rid of eyeglasses. Understandable and effective communication about expectations is just as important as the ability to make a proper capsulorhexis.
  Creating a multifocal optic with two disparate focal points entails some optical compromise. Preoperative preparation and the patient’s personality and motivation can facilitate adaptation to unwanted images such as halos. Summation from bilateral multifocality helps to offset the slight reduction in contrast sensitivity. However, these same tradeoffs mean that the multifocal IOL performance is very unforgiving of any additional optical or functional compromise. Poor image quality may result from residual refractive error, poor centration, and otherwise minor concomitant ocular abnormalities, such as a subtle epiretinal membrane or an irregular ocular surface.
  There is no question that the optical performance of multifocal IOLs is much less tolerant of residual refractive error compared to monofocal IOLs. Adaptive optics wavefront studies from Scott MacRae, MD, and colleagues at the University of Rochester show that this is particularly true for astigmatism1[1. Zheleznyak L, Kim MJ, MacRae S, Yoon G. Impact of corneal aberrations on through-focus image quality of presbyopia-correcting intraocular lenses using an adaptive optics bench system. J Cataract Refract Surg. 2012; 38: 1724-1733.
  ]. By measuring through-focus image quality of different presbyopia-correcting IOLs in a pseudophakic model eye, these researchers demonstrated that the image quality and depth of focus of multifocal IOLs dropped noticeably with more than 0.75D of corneal astigmatism. For this reason, the preoperative assessment and intraoperative management of astigmatism are extremely important if a multifocal IOL is contemplated. Preoperatively, it is important to discuss the possible need for postoperative excimer laser enhancement of residual astigmatism and spherical error.
  For cataract patients with moderate and higher degrees of astigmatism, mini-monovision with toric IOLs may be a better alternative. This is a very common approach in my practice for eyes with at least a diopter of astigmatism, because of the critical need to virtually eliminate astigmatism with multifocal IOLs. I usually operate on the dominant eye first and target emmetropia. I then aim for 1.00 – 1.50 D of myopia in the second eye. This is generally a safe strategy that most patients who dislike spectacles will tolerate, and the anisometropia can always be reversed with eyeglasses.

  《国际眼科时讯》:多焦点IOL一直是ASCRS会议的热点话题。对于不想戴眼镜的患者,您认为具备什么条件适合的白内障患者适合植入多焦点IOL?
  Dr. Chang:随着新型可用的IOL越来越多,加之人口增多导致需要白内障手术的人也越来越多,大家会更加关注衍射型IOL。美国的大多数眼科医师认为符合手术适应证的白内障患者应当被告知这些IOL的信息,作为手术告知内容的一部分。决定哪些患者比较符合植入多焦点IOL是一个很复杂的过程,但是一旦经过合理的筛选并告知患者,很大比例的患者都会对手术结果喜出望外。
  仔细地筛选患者、有效地书签宣教和咨询是非常费时的,但是却非常重要。患者的满意度与术前的期望值密切相关,我们向患者提供的信息要盖过患者从网络、喜欢夸夸其谈的朋友那里获得的信息,包括与LASIK的比较以及认为自己从此便摆脱了眼镜。关于期望值与患者进行有效的沟通,其重要性不亚于做好一个撕囊的能力。
  植入有两个不同焦点的多焦点IOL会使一些光学元件妥协。术前准备、患者的性格和目的会帮助患者适应一些眼前出现的不好的影像,例如光晕。双眼植入多焦点IOL可以消除轻微的对比敏感度下降。但是,这也意味着多焦点IOL与其他光学元件不可兼容。较低的视觉质量可能来源于残余屈光不正、光轴不佳以及伴随的轻微眼部异常,例如微小的视网膜前膜或者眼表不规则。
  毫无疑问,相比单焦点IOL,多焦点IOL的光学性能对残余屈光不正的容忍度较差。Dr. Scott MacRae及其罗切斯特大学的同事们的自适应光学波前研究证明了对于散光患者尤其是这样[2]。通过测量不同植入IOL的老视眼焦点处的视觉质量,这些研究表明角膜散光大于0.75D时,多焦点IOL的视觉质量和景深明显下降。因此,如果打算植入IOL,术前的评估和术中对散光的处理非常重要。在术前,考虑到术后可能使用准分子激光矫正残余散光和球面相差也很重要。
  对于伴有中重度散光的白内障患者,单眼植入环面IOL也是一个很好的选择。对于大于1D的散光患者,我常用这种方法,因为多焦点IOL对消除散光有严格的要求。我常常先给主导眼做手术,并且预留目标度数是正视眼。然后我会给第二只眼预留1.00~1.50 D的近视。这是一个很安全的方法,对于大多数不想戴眼镜的患者都可以耐受,产生的屈光参差也可以通过戴镜抵消。

  <International Ophthalmology Times>:Congratulations on becoming the first ASCRS president of Asian descent. Please tell us about some of the new ASCRS initiatives introduced during your term this past year.
  Dr. Chang:In my address as the incoming president one year ago, I highlighted several core values that make our profession uniquely rewarding, including charity and our remarkable willingness to teach one another. Let me highlight several new ASCRS initiatives in this realm of education.
  The exploding demand of aging populations worldwide will require many more phaco surgeons to be trained in the next decade. We are proud and excited to officially introduce the new, online ASCRS Phaco Fundamentals Classroom . Intended as a one-stop website to support phaco training,  the site hosts phaco courses, lectures, teaching videos, articles, and textbook chapters - all selected and indexed by an editorial board made up of leaders in resident phaco education. This free, web-based classroom features our best teaching resources and faculty and can be accessed by any ophthalmologist in the world through our website .
  This year, we also launched a unique web portal called the Global Sight Alliance funded by the ASCRS Foundation. Any ophthalmologist that links to Global Sight Alliance through will find a centralized educational devoted to cataract blindness in the developing world. Complementing our web-based phaco classroom, Globalsight has an online classroom devoted to learning manual small incision extracapsular surgery, with educational videos, lectures, and teaching manuals.
  I am also the chief medical editor of the ASCRS monthly trade journal, EyeWorld. The newly launched digital version of EyeWorld allows every ophthalmologist in the world with internet access to view each edition on your desktop, laptop, or iPad through  now feature four regular columns of special interest to phaco trainees. ASCRS continues to embrace this core value of ophthalmologists teaching and helping one another, which we believe is the best way to advance eye care around the world.

  《国际眼科时讯》:祝贺您成为第一个亚裔的ASCRS主席,请您谈谈在过去一年您的任期中,ASCRS发生的一些新动向。
  Dr. Chang:从我去年担任主席以来,我强调了一些核心价值观使我们行业特别受益,包括慈善举动和义务教育。我强调一下教育方面ASCRS的一些新举动。
  全球人口爆炸进入老龄化社会将导致在以后10年里需要更多接受过培训的超声乳化手术医师。我们激动而荣幸地正式引出全新ASCRS超声乳化基础在线课堂。打造超声乳化训练一站式网站,包括超声乳化课程、讲座、教学录像、文献以及教材,由教授超声乳化的领军者组成的编委会负责所有的选材和索引。这一免费网络课堂突出了我们最佳的教学资源和能力,能够被全世界的眼科医师访问。
  今年,我们又注册了一个独特的门户网站,称作“全球视觉联盟”,由ASCRS基金会资助。所有眼科医师可以通过链接到“全球视觉联盟”,可以找到对致力于发展中国家白内障防盲的集中培训课程。作为超声乳化教室培训的补充,“全球视觉联盟”的网络课程通过教学视频、讲座以及教学手册致力于手法小切口白内障囊外摘除术。
  我也是ASCRS发行月刊《眼科世界》的医学编辑部主任。新推出的《眼科世界》电子版可以让全世界的眼科医师通过台式电脑、笔记本电脑以及苹果平板电脑查看每一期。目前,我们有4个专栏用来关注超声乳化受训者。ASCRS <目前,我们有4个专栏用来关注超乳受训者。ASCRS>将继续维持其核心价值观--进行眼科教学以及互相帮助,我相信这是加强全世界眼部护理的最好方式。
  参考文献
  [1] Chang DF, Campbell JR. Intraoperative floppy iris syndrome associated with tamsulosin (Flomax). J Cataract Refract Surg 2005; 31: 664-673.
  [2] Zheleznyak L, Kim MJ, MacRae S, Yoon G. Impact of corneal aberrations on through-focus image quality of presbyopia-correcting intraocular lenses using an adaptive optics bench system. J Cataract Refract Surg. 2012; 38: 1724-1733.

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