When it comes to treating glaucoma, the goal of eye doctors is assuring their patient don’t go blind.

    That would seem relatively easy. Give them eye drops or refer them to surgery, which helps relieve what is known as intraocular pressure (IOP) inside the eye. But with current technology, it can often be difficult to measure this pressure because it fluctuates so much and those measurements have to be done in a doctor’s office.

    That soon could change, thanks to a new device described in Nature Medicine.

    A team of researchers from Stanford University and Bar-Ilan University in Israel has designed an implantable sensor that can be read with a smartphone camera. This allows the patient to take readings themselves and should improve the accuracy of pressure data.

    “We believe this self-monitoring capabilities of the implant can significantly enhance the treatment and make it significantly better for the patient,” said Bar-Ilan’s Yossi Mandel, who co-authored the paper with Ismail Araci, Baolong Su and Stephen R. Quake of Stanford.

    “Today, we think we are not treating them good enough,” he added. “They come once in a while and we take a single point in time of measurement. This probably is not good enough and we know from other studies that there is large variation in the IOP. In the same day, it can vary a lot.”

    Glaucoma is a group of eye diseases that in most cases produces increased pressure within the eye and affects more than 65 million people worldwide. When the eye pressure is increased, the optic nerve becomes damaged, resulting in the death of the retinal cells, degeneration of the nerve fibers and eventually permanent loss of vision.

    There are several good methods to diagnosing glaucoma but only one that monitors the disease to ensure the prescribed treatments are working. Called the Goldman applanationtonometery, or GAT, the method requires that the eye be anesthetized in a physician’s office and then a plastic prism makes contact with the cornea to measure the pressure. Not only is this uncomfortable and complex but this technique has been found in several studies to be inaccurate.

    “Unfortunately, the patient can’t today measure his own IOP like he would with hypertension where you can measure your own blood pressure. Glaucoma patients have to go to their physicians,” Mandel said in a phone interview. “In one study, they measured IOP over 24 hours and saw there were large variations. In about 80 percent of the patients, they changed the treatment.”

    The self-monitoring device, Mandel said, is about 50 microns in diameter and a few millimeters long. Looking much like a small tube, Mandel said the device developed in Quake’s lab is implanted in the eye.

    在治疗青光眼上，眼科医生的目标通常是确保病人不会失明。

    这个目标看似不难，只要给他们开点眼药水或让他们去做手术就行了，手术主要是为了降低眼压。但是凭借现有技术，测量眼压是有难度的，因为眼压的波动比较大，而且测眼压的过程必须要在医生的办公室里完成。

    但是借助于《自然医学》杂志描述的一种新设备，这种情况可能很快就会改变。

    美国斯坦福大学（Stanford University）和以色列巴伊兰大学（Bar-Ilan University）的研究团队设计了一款可植入式的传感器，通过智能手机摄像头就可以获得它的读数。因此患者完全可以自行读取读数，同时它也提高了眼压数据的准确性。

    巴伊兰大学的约西•曼德尔表示：“我们认为，这款可植入眼压传感器带来的自我监测能力，可以显著提高青光眼的治疗，并改善患者的处境。”《自然医学》杂志上的这篇论文就是曼德尔与斯坦福大学的伊斯梅尔•阿拉西、苏宝龙（音译）和史蒂芬•R•奎克合作撰写的。

    曼德尔补充道：“现在，我认为我们对青光眼治疗得还不够好。患者偶尔到医院来一趟，然后我们测量到的是他们在某个时间点上的眼压。这可能不够好。我们从其它研究得知，眼压会有很大变化。哪怕在同一天里，眼压也会有很大的变化。”

    青光眼是一系列眼科疾病的统称，在大多数情况下会导致眼内压增高，全球青光眼患者超过6500万人。一旦眼压升高，视神经就会受到损伤，导致视网膜细胞死亡，神经纤维退化，最终直至永久失明。

    青光眼有好几种不错的诊断方法，但是能对病情进行监测，以了解治疗是否有效的办法只有一种——它叫做Goldman压平眼压计测量法或GAT。用这种方法测量眼压，首先需要在医生的办公室里将患者的眼部麻醉，然后用一根塑料棱镜按压患者的角膜来测量眼压。这种方法不仅难受、复杂，而且根据多项研究显示，并不是非常精确。

    曼德尔在接受电话采访时表示：“可惜的是，现在病人还不能像量血压一样自行监测自己的眼压。青光眼病人必须到医院去。在一项研究中，研究人员测量了患者24小时内的眼压，发现患者一天内的眼压有很大波动。所以他们对80%的患者改变了治疗方法。”

    曼德尔表示，这款自测试备的直径只有50微米，长度只有几毫米，看起来像一根极微小的管子。曼德尔称，这款在奎克的实验室开发出来的设备可以植入人的眼中。

    “It looks very simple,” Mandel said. “The pressure in the eye causes a shift in the position of the fluid column in the device which then can be read much like the temperature in a thermometer.”

    Glaucoma experts welcomed news of the device, saying it offers several advantages over the current methods including that it reads the pressure and does it around the clock.

    “If patient comes in for cataract surgery and, if at the same time you can implant the device that would allow monitoring IOP more accurately and remotely, that has a huge benefit,” Dr. Andrew Iwach, chairman of board for the Glaucoma Research Foundation and executive director Glaucoma Center of San Francisco said. He also founded the foundation’s annual event, Glaucoma 360, which brings together researchers, industry executives and philanthropist to find a cure for glaucoma.

    “So if you look at the risk benefit ratio the question wouldn’t be why did you put it in but why you didn’t put it in,” he said.

    There is a similar device available in Europe to measure pressure around the clock called the Sensimed Triggerfish. But this contact lens sensor doesn’t measure the eye pressure directly, which makes it less accurate and, according to a 2012 study in Arch of Ophthalmol, caused blurred vision and other adverse reactions in over 80 percent of the patients.

    Iwach said the lack of a reliable device to measure pressure in the American market has prompted a competition of sorts with at least five companies vying to be the first to get a device inserted into the eye, which transmits an electronic signal out onto the American market.

    “This is an exciting a horse race,” Iwach said. “Different camps realize the first to market, the one who figures out how to do this best, is going to potentially revolutionize how we manage glaucoma and ultimately patients will be better for it.”

    While showing promise to be the first, the latest device still is several years away from being commercially feasible. It has only been tested in pigs so the next step, Mandel said, is to do further research to ensure the device is safe in humans and can remain in the eye for an extended period of time.

    “As scientist we are always skeptical about what we and others do,” Mandel said. “There are challenges that have to overcome but this device shows a lot of promise.”

    曼德尔解释道：“它的原理非常简单。眼内压会导致设备内的液柱位置变化，然后读取它的读数即可，原理很像温度计。”

    青光眼专家们都对这款设备表示欢迎，并表示它与以往的测量方法相比有很多优点，包括它可以显示读数，而且可以随时监测。

    美国青光眼研究基金会（Glaucoma Research Foundation）的董事会主席、旧金山青光眼中心常务主任安德鲁•伊瓦施表示：“如果患者做了白内障手术的话，如果在做手术的同时，你把这款设备植入进去，那么就能更精确地监测眼压，这是有巨大好处的。”伊瓦施还是青光眼基金会“青光眼360”活动的发起人，这个活动旨在召集青光眼研究专家、行业高管和慈善人士来寻找治疗青光眼的方法。

    他表示：“因此，如果你看看风险收益比，问题就不会是你为什么要植入，而是你为什么不植入。”

    欧洲也有一款类似的可以随时测量眼压的设备，名叫Sensimed Triggerfish。不过这款接触式镜片传感器并非直接测量眼压，导致测量结果精确度不高。另外根据《眼科学报》（Arch of Ophthalmol）2012年的一份研究显示，它会导致80%的患者出现视觉模糊和其它负作用。

    伊瓦施指出，由于美国市场缺乏一款可以测量眼压的可靠设备，现在至少有五家以上的公司都在这个领域进行竞争，他们都希望能第一个在美国市场上推出植入式眼压测量设备。

    伊瓦施表示：“这是一场令人兴奋的竞争。大家都意识到，第一个进入市场、第一个知道怎样最好地测量眼压的公司，可能会给青光眼的治疗带来革命性的效果，而且最终会造福患者。”

    虽然上文提到的这款微传感器还是该领域的第一款设备，但它离正式商用还有好几年。目前它只在猪身上测试过。因此曼德尔表示，下一步重点是要进一步深入研究，以确保它对人体的安全性，并且确保它能长期妥善地存在于眼部。

    曼德尔表示：“作为科学家，我们总是对我们和其他人做的事感到怀疑。不过虽然前路还有一些挑战需要克服，但这款设备的确带给我们很多希望。”（财富中文网）

    译者：朴成奎