Lasik worries? Some may see better with alternatives

WASHINGTON -- Frightened by headlines about Lasik side effects? Lasik gets all the advertising, but there are half a dozen alternate eye surgeries _ from a simpler laser approach to implantable lenses _ that might solve your squint.

They all have their own risks. A key is finding a surgeon who doesn't have a favorite but is qualified to evaluate patients for all of the options, to find the best fit.

Topping the list is a pre-Lasik laser that's making a comeback thanks to precision-improving computer software. It goes by two names: Surface ablation, or wavefront-guided PRK, which stands for photorefractive keratectomy. What's most important is that it doesn't require cutting a flap into the cornea, the eye's clear covering, like Lasik does, a cut widely considered that procedure's riskiest step.

"There's a lot of us that are doing more and more surface ablation and much less Lasik," says cornea specialist Dr. Craig Fowler of the University of North Carolina.

PRK accounts for about 15 percent of the roughly 700,000 laser vision correction surgeries performed each year, up from 5 percent during Lasik's peak in popularity earlier this decade, says David Harmon of Market Scope, which tracks the industry.

Other Lasik alternatives have virtually no advertising and attract far fewer patients.

Tragic testimony before the Food and Drug Administration last week reinforced warnings that Lasik does come with risks: lost vision, painful dry eye, glare and other night-vision problems. Serious complications appear rare, affecting 1 percent or fewer cases, and the FDA estimates 5 percent of patients aren't satisfied with the outcome.

But aggressive marketing makes patients falsely believe clear sight is guaranteed, complained Dr. Jayne Weiss of Detroit's Kresge Eye Institute, who chaired the FDA advisory panel.

"Lasik is not a commodity. It's a surgical procedure, but it is being sold as a commodity," she told the meeting.

Here's the real rub: One in four patients who seeks Lasik and undergoes a battery of pre-surgery testing is deemed a poor candidate. Maybe the cornea is too thin, or the pupils too large, or nearsightedness too severe, or their expectations unrealistic. But it's not clear just how many patients get screened appropriately, and some forge ahead anyway.

"Some patients are just not a cornea laser eye surgery patient," stresses Dr. Kerry Solomon of the Medical University of South Carolina, a spokesman for the American Society for Cataract and Refractive Surgery. "There are still other options for them. ... And some are, quite frankly, better suited to staying with their glasses and contacts."

With Lasik, doctors peel back a flap in the cornea's surface and zap the underlying layer to reshape the cornea and ease either nearsightedness or farsightedness. The newest version, considered safer, makes ultra-thin flaps using a second laser instead of the original disposable blade.

Lasik alternatives:

_With PRK, a laser reshapes the cornea's surface, no flap-cutting needed _ important because making a flap cuts nerve receptors that critics say never fully return to normal, thus increasing the risk of painful dry eye. The trade-off: Patients occasionally suffered haze as their corneas healed, not a Lasik risk.

The updated version is wavefront-guided PRK, using computer software actually developed to improve Lasik. It lets surgeons map subtle irregularities in the cornea before zapping, providing a three-dimensional map that customizes treatment, minimizing but not eliminating side effects in both Lasik and PRK.

The Navy compared wavefront-guided PRK to wavefront-guided Lasik, and 12 months after surgery, "the results of both procedures were almost identical," says Dr. Steven Schallhorn, a San Diego ophthalmologist who oversaw the Navy's refractive surgery program until last year.

Still, he says people with thin corneas or corneal irregularities can be better PRK candidates, and UNC's Fowler contends it can provide better night vision. But, it takes a few weeks of healing, with eye drops for the discomfort, before sharper vision emerges.

_CK, or conductive keratoplasty, corrects farsightedness or astigmatism by beaming radiofrequency waves around the cornea's edge.

_Lasers aside, a hard plastic lens can be implanted through a small incision in the eye, in front of the natural lens. These "phakic intraocular lenses" are for severe nearsightedness, too bad for Lasik and PRK. They refocus light entering the eye for improved distance vision. Because the natural lens stays in place, patients seem to retain close-up vision, too.

But they've been on the market only a few years, so long-term effects aren't yet known. Warnings of rare problems include retinal detachment, infections, or an increased risk of cataracts.

_Refractive lens exchange goes the next step and replaces the patient's own lens with an artificial one. It's essentially cataract surgery offered to some cataract-free people who wanted Lasik but are bad candidates, perhaps because of extreme near- or farsightedness. Lens options include a multifocal type that can allow for both distance and reading vision. Again, retinal detachment is a risk.

_Finally, corneal rings are transparent crescents about the thickness of a contact lens implanted to form a ring around the cornea's edge. Called Intacs, their slight weight flattens the cornea without permanently destroying tissue. While they're only for mild nearsightedness, they can be removed if patients suffer side effects such as glare.

http://www.washingtonpost.com/wp-dyn/content/article/2008/04/29/AR2008042901920.html

害怕激光手术吗？看看下面这些选择，可能会有更深的认识。
华盛顿——被关于准分子激光原位角膜磨镶术的标题新闻吓着了？准分子激光原位角膜磨镶术被广泛的宣传，但是还有其他六种眼科手术方法可供选择，从简单的激光到晶状体移植，这些可能会解决你的斜视问题。
他们都有各自的风险。而关键是找到一个没有特别喜好的外科医生，能胜任为病人的各种选择进行评估，做出最适合的选择。
在这个列表上最顶上的是准分子激光原位角膜磨镶术前期激光，由于有高精确度电脑程序，使用这种方法可以使病人康复。它有两个名字：表面烧灼和波正面向导的PRK,这代表光折变角膜切除术。最重要的是这不需要切除角膜的皮瓣——眼睛表面覆盖的透明层，而Lasik需要这样做，切除被认为是这个过程中最危险的一步。
现在许多人越来越多的做表面烧灼，而很少做Lasik了 。
大约每年700，000的激光视力矫正手术中有15%的采用的是PRK，从这十年开始早些时候Lasik流行的高峰时期5%的上升到现在这个水平。
其他Lasik外的选择实际上没有广泛宣传，吸引的病人远远比不上Lasik.
上周食品药品监督管理局的悲观陈述，加强对Lasik危险的警告：失明，眼睛疼痛干涩，炫目和其他夜视问题。严重的并发症出现的很少，影响1%或更少的病人，FDA估计5%的病人对结果不满意。
挑衅的市场行销使病人错误的认为明亮的视力是能得到保证的。Lasik不是日用品。它是一个手术过程，但是它却被和日用品一样销售。
这确实是一个矛盾：四分之一的选择Lasik的病人在经历一些列的术前测试后，被认为不太适合手术。可能角膜太薄，或者瞳孔太大，或者近视太严重，或者他们的期待过高。但是搞不清楚到底多少人是适当的被筛选出来的，一些人不管怎么说还是继续实施手术。
“一些病人甚至不是一个角膜激光眼科医生的病人，”北卡罗林那医科大学的Kerry Solomon博士强调说，他是一个美国白内障和折射外科联合会的发言人。“实际上他们还有其他的选择……其中的一些人，直说吧，带上他们的眼镜更合适。”
Lasik手术是医生削掉晶状体表面的一层皮瓣，修整下面的一层以改造晶状体，以使近视或远视力得到恢复。最新的观点认为，用第二代激光代替原始一次性的刀片进行超薄皮瓣切除可以更安全。
Lasik之外的选择：
PRK，这是一种使用激光对角膜表面整形的方法，不需要皮瓣切除——这很重要，因为切除皮瓣的时候也切掉了神经感受器——批评家说这不可能完全恢复正常了，因此增加了眼镜疼痛干涩的危险。而相应的弊处是：由于晶状体治愈了，病人偶尔会感到视物模糊，Lasik没有这个问题。
更新的观点是波阵面向导PRK，用电脑软件来提高Lasik的方法。这使外科医生在整形之前对角膜的结构有精细的了解，提供一个三维的图像，定制治疗方案，最小化但不是消除Lasik和PRK的副作用。
海军对比了波阵面向导PRK和波阵面向导Lasik，在术后12个月，两种手术的效果几乎是一样的。尽管如此，薄角膜或角膜不规则的人可能接受PRK更好一些，UNC的Fowler声称它可以提供更好的夜视力。但是，这需要几周的时间来愈合，眼睛不适消失之后，明亮的视力就出现了。
-CK，或者说传导性角膜成型术，用在角膜边缘周围播送电磁波的方法矫正远视或散光。
激光辅助，一个硬塑料透镜可以通过在眼睛上一个小切口移植入人的晶状体前面。这些“人工晶状体透镜”是适合于患有严重近视，而又不适合做Lasik和PRK的人。它们把进入眼睛的光线重新聚集，从而提高远距离视力。
但是它们进入市场还只有几年时间，所以长期的效应现在并不清楚。警告还存在少数的问题，包括：视网膜脱落，感染，或者患白内障危险性增加。
折射透镜是另一种选择，用人工透镜替代病人自己的晶状体，这本质上是一个对没有患白内障的人实施的白内障手术，他们要进行Lasik手术，而又并不适合做——也许是由于极端的近视或者说远视。透镜选择是多焦型的，这可以同时改善远距离和阅读的视力。当然，视网膜脱离也是一个风险。
最后，角膜环是一个透明的新月环套在角膜边缘周围，称作圆锥角膜。他们轻微的重量使角膜变平，而不会永久的破坏组织。然而它们只对中度近视有效，如果病人遇到炫目等副作用时，它们可以被取下来。

• 上一篇：卫生部发布《手足口病预防控制指南》(2008年版)