望远隐形眼镜

Lights， mirrors， action！ Scientists are developing smart contact lenses embedded with miniscule mirrors that can magnify your vision by almost three times.

The 1.55mm-thick lenses incorporate a thin reflective telescope made of mirrors and filters; when light enters the eye it bounces off the series of mirrors and increases the perceived view of an object or person. It is hoped that the lens will improve the sight of people with age-related macular degeneration （AMD）—the third leading cause of blindness globally.

AMD causes the loss of central vision due to gradual damage to the eyes retina and there are few options for cure or treatment. “AMD is the biggest problem where magnification is a proven visual aid，” says Eric Tremblay， research scientist at EPFL in Switzerland.

Tremblay led the optical design of the lens， which is based on a surgically implantable telescope currently used by some patients with AMD， but which is more invasive than a lens. “With a contact lens， its easy to try it，” says Tremblay.

Making the Switch

A key innovation with the lenses is the added ability to switch between magnified and regular vision through a complementary pair of glasses. The battery-powered glasses use LCD technology to watch the movement of the eye and a simple wink can alter their polarization and determine whether light entering is magnified or not.“Having the ability to switch on demand is attractive，” says Tremblay.

The ability to selectively magnify your vision makes the design of the glass-lens combination more suitable for daily life. “When magnified you lose a lot of your field of view， your peripheral vision，” says Tremblay. A strategic wink will enable users to keep an eye on their periphery， such as cars approaching them as they cross a street， whilst also being able to zoom in and recognize the faces of those around them.

The team developed their technology on scleral lenses， which have an increased thickness and diameter， making them commonly used for more special purpose eye care. “They provide a lot more area to work with，”says Tremblay. The challenge these lenses bring with them， however， is comfort， as they impede the amount of oxygen reaching the eye.

The most recent prototype， unveiled by the team in February， overcame this challenge by introducing air channels to aid the flow of oxygen to the eye. But the team hopes to improve this further still by instead developing a contact lens solution saturated with oxygen， which can be stored and slowly released into the eye. “We will build reservoirs into the back of the lens，” says Tremblay…

The lenses have only been trialled on a handful of humans to test for comfort， with the majority of research to date performed in the lab using a model chemical eye. But more human trials are in the cards， with the eventual goal of daily wearable contacts to aid the visually impaired.

“We want it to move in the direction of a real world vision aid，” says Tremblay.

Getting Smarter

These are not the first smart contact lenses. Other prototypes have been developed to monitor， as well as improve， health in both the eye and across the body.

Alcon， the eye care division of Novartis， formed a partnership with Google X in 2014 to develop smart-lens technologies for a range of medical eye care applications. One of the first examples of using lenses in this form was Sensimed， a spin-off also emerging from EPFL. Sensimeds Triggerfish technology monitors the progression of glaucoma—the second leading cause of blindness， affecting more than 4.5 million people globally.

Glaucoma is a progressive cause of blindness caused by deterioration of the eyes optic nerve. The traditional test used by optometrists to monitor patients uses puffs of air to measure pressure in the eye， but such measurements are not ideal.

“The big need in glaucoma is for a 24-hour picture of whats happening inside the eye，” says David Bailey， CEO of Sensimed. Its smart lens uses strain gauges and sensors embedded inside a chip located in the lens to measure changes in the volume of liquid in the eye as a surrogate measurement of pressure. It can be worn over a 24-hour period to monitor pressure patterns and communicate data wirelessly to a recording device worn around the users neck.

Optometrist James Wolffsohn， spokesperson for the British Contact Lens Association， looks forward to one day using technologies like the telescopic lens in clinical practice.“The lens seems an interesting concept to provide optical magnification to the retina when required，” he says. But he adds that there will be challenges in reaching that stage： “It is currently a scleral lens and thick， including rigid mirror elements which are likely to affect corneal physiology and comfort.” Wolffsohn has seen colleagues trial the more established Triggerfish technology to monitor glaucoma， and is optimistic about the future of the field. “There are also many other exciting developments in innovative uses of contact lenses，” he says.

“The eye is the window to many disease states，” says Bailey， who believes contact lenses are the future for eye care， both in terms of clinical use and lifestyle management. More than 30 million people wear contact lenses in the United States alone， according to the Centers for Disease Control， which means they could be a non-invasive path to health management—be it blindness progression or even insulin or alcohol level monitoring.

“Eye-sensing on contact lenses is here to stay…in one form or another，” says Bailey.

光线，镜片，行动！科学家目前正在研发一种置入细微镜片的智能隐形眼镜，它能把视觉成像放大将近三倍。

这1.55毫米厚的镜片包含了由镜面和滤光镜组合而成的一片薄薄的反射望远镜;当光线进入眼睛，这几层镜片会对其作出折射，增强眼睛对物体或人的感知。老年性黄斑变性是导致失明的全球第三大祸根，而这种隐形眼镜有望改善该病患者的视力。

老年性黄斑变性会逐步损害视网膜，进而导致中心视力丧失，而现有的药物和治疗方案屈指可数。“老年性黄斑变性是最大的难题，已知的视觉辅助解决手段就是放大（视觉成像）。”瑞士洛桑联邦理工学院的科学家埃里克·特莱姆布雷说道。

特莱姆布雷带领团队完成了这种望远隐形眼镜的光学设计。目前一些老年性黄斑变性患者通过外科手术把望远镜镜片植入到眼球中，望远隐形眼镜的光学设计以这种手术为基础，但比外科手术少了侵入性。特莱姆布雷说：“通过隐形眼镜的形式，人们想要尝试就容易了。”

开发切换功能

望远隐形眼镜的主要创新之处就是配上一副框架眼镜来增加切换放大视野和常规视野的功能。这副框架眼镜由电池提供动力，采用液晶显示技术来监测眼球的动态，简单的一次眨眼就能更改光的偏振状态，决定进入的光线是否放大。“按需切换功能很吸引人。”特莱姆布雷说道。

选择性放大视觉成像的功能让这种结合框架眼镜和隐形眼镜的设计更适应日常使用。“放大的时候，人眼能看到的外围视野就减少了很多。”特莱姆布雷说道。特意眨眼调整，能够让人留意外围，如在過马路时留意有没有汽车开过来，但通过不同的眨眼方式，也能够拉近视觉成像，使人看清近处的人脸。

研发团队改进了巩膜透镜的技术，通过增加其厚度和直径，使其能普遍地适用于更特殊的眼睛保健用途。“更大更厚的巩膜透镜可开发的用途更多。”特莱姆布雷说。然而，更大更厚的镜片却是对舒适度的挑战，因为眼睛能接触到的氧气会受限。

研发团队在二月揭晓的最新模型，通过置入空气通道来帮助把氧气流引入眼睛，克服了这个挑战。但团队仍希望进一步完善这个模型，不再采用空气通道来解决阻氧问题，而是研发一种溶入氧气的隐形眼镜护理液，护理液被储存起来，再慢慢释放，进入眼睛。“我们会在隐形眼镜的背面建一个储液室。”特莱姆布雷说道。

望远隐形眼镜只经过少数几个人的试用来测试舒适度，到目前为止大部分研究的试验对象只是实验室的一只化学眼睛模型。不过更多的人体测试是肯定会有的，因为最终目标是研发出适宜日常佩戴的隐形眼镜，来帮助视觉障碍患者。

“我们希望它能往实际应用的方向发展，成为现实的视觉辅助工具。”特莱姆布雷说道。

进一步智能化

望远隐形眼镜不是世界最早的智能隐形眼镜。其他用于监控并改善眼部及全身健康状况的模型也有研发先例。

瑞士诺华公司旗下的眼保健公司爱尔康于2014年与谷歌X实验室建立了合作伙伴关系，共同为一系列医用护眼产品开发智能隐形眼镜技术。瑞士洛桑联邦理工学院的派生公司Sensimed公司研发的一项技术是最早把隐形眼镜技术应用到医用护眼产品的例子之一。该公司的“扳机鱼”技术可监测青光眼的病变过程——青光眼是第二大致盲祸根，全球患者超过450万人。

青光眼由视神经退化引起，是一种日益加重的致盲因素。验光师检验青光眼所采用的传统方法是用气流来测量眼压，但是这种测量方法效果并不理想。

“全天候的眼内监测是治疗青光眼的迫切需要。”Sensimed公司的执行总裁大卫·贝利说道。该公司在智能隐形眼镜的芯片中植入了应变仪和感测器来测量眼中液体容量的变化，作为测量眼压的替代方法。这种隐形眼镜可以24小时佩戴，监测眼压变化情况并通过无线电向使用者佩戴在颈部的记录仪传送数据。

英国隐形眼镜协会的发言人，验光师詹姆斯·沃尔夫佐恩，期盼有一天像变焦隐形眼镜这样的技术能在临床实践中应用。他说：“能按需把视觉成像放大到视网膜上，变焦镜片似乎是个有趣的概念。”不过他补充说要发展到这一阶段还会面临一些挑战：“目前的挑战包括巩膜透镜的厚度和坚硬的镜片质地，都会影响角膜的生理机能和舒适度。”沃尔夫佐恩目睹同事们运用更成熟的“扳机鱼”技术来监测青光眼的病变过程，他对这个领域的前景持乐观态度。他说：“在隐形眼镜的创新运用上，还有很多振奋人心的其他新进展。”

“眼睛是观测很多疾病状况的窗户。”贝利说道。他相信，隐形眼镜的眼保健功能在临床应用和生活管理方面都有着不错的前景。根据美国疾病控制中心的数据，仅在美国，就有超过3千万人佩戴隐形眼镜，这意味着隐形眼镜能够成为不具侵入性的健康管理途径——用于监测失明的发病过程，甚至监测胰岛素水平或人体含酒精指数。

“利用隐形眼镜来感知眼睛的状况是大势所趋……只是利用形式各异。”贝利说道。