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


       <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.
  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。
  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。

  <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

  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。

       <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.

  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。
  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.

  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。
  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.

  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。
  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。
  [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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