望遠隱形眼鏡

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.

光線，鏡片，行動！科學(xué)家目前正在研發(fā)一種置入細微鏡片的智能隱形眼鏡，它能把視覺成像放大將近三倍。

這1.55毫米厚的鏡片包含了由鏡面和濾光鏡組合而成的一片薄薄的反射望遠鏡;當(dāng)光線進入眼睛，這幾層鏡片會對其作出折射，增強眼睛對物體或人的感知。老年性黃斑變性是導(dǎo)致失明的全球第三大禍根，而這種隱形眼鏡有望改善該病患者的視力。

老年性黃斑變性會逐步損害視網(wǎng)膜，進而導(dǎo)致中心視力喪失，而現(xiàn)有的藥物和治療方案屈指可數(shù)?！袄夏晷渣S斑變性是最大的難題，已知的視覺輔助解決手段就是放大（視覺成像）?！比鹗柯迳Ｂ?lián)邦理工學(xué)院的科學(xué)家埃里克·特萊姆布雷說道。

特萊姆布雷帶領(lǐng)團隊完成了這種望遠隱形眼鏡的光學(xué)設(shè)計。目前一些老年性黃斑變性患者通過外科手術(shù)把望遠鏡鏡片植入到眼球中，望遠隱形眼鏡的光學(xué)設(shè)計以這種手術(shù)為基礎(chǔ)，但比外科手術(shù)少了侵入性。特萊姆布雷說：“通過隱形眼鏡的形式，人們想要嘗試就容易了?！?/p>

開發(fā)切換功能

望遠隱形眼鏡的主要創(chuàng)新之處就是配上一副框架眼鏡來增加切換放大視野和常規(guī)視野的功能。這副框架眼鏡由電池提供動力，采用液晶顯示技術(shù)來監(jiān)測眼球的動態(tài)，簡單的一次眨眼就能更改光的偏振狀態(tài)，決定進入的光線是否放大?！鞍葱枨袚Q功能很吸引人?！碧厝R姆布雷說道。

選擇性放大視覺成像的功能讓這種結(jié)合框架眼鏡和隱形眼鏡的設(shè)計更適應(yīng)日常使用。“放大的時候，人眼能看到的外圍視野就減少了很多。”特萊姆布雷說道。特意眨眼調(diào)整，能夠讓人留意外圍，如在過馬路時留意有沒有汽車開過來，但通過不同的眨眼方式，也能夠拉近視覺成像，使人看清近處的人臉。

研發(fā)團隊改進了鞏膜透鏡的技術(shù)，通過增加其厚度和直徑，使其能普遍地適用于更特殊的眼睛保健用途?！案蟾竦撵柲ね哥R可開發(fā)的用途更多?！碧厝R姆布雷說。然而，更大更厚的鏡片卻是對舒適度的挑戰(zhàn)，因為眼睛能接觸到的氧氣會受限。

研發(fā)團隊在二月揭曉的最新模型，通過置入空氣通道來幫助把氧氣流引入眼睛，克服了這個挑戰(zhàn)。但團隊仍希望進一步完善這個模型，不再采用空氣通道來解決阻氧問題，而是研發(fā)一種溶入氧氣的隱形眼鏡護理液，護理液被儲存起來，再慢慢釋放，進入眼睛?！拔覀儠陔[形眼鏡的背面建一個儲液室?！碧厝R姆布雷說道。

望遠隱形眼鏡只經(jīng)過少數(shù)幾個人的試用來測試舒適度，到目前為止大部分研究的試驗對象只是實驗室的一只化學(xué)眼睛模型。不過更多的人體測試是肯定會有的，因為最終目標(biāo)是研發(fā)出適宜日常佩戴的隱形眼鏡，來幫助視覺障礙患者。

“我們希望它能往實際應(yīng)用的方向發(fā)展，成為現(xiàn)實的視覺輔助工具。”特萊姆布雷說道。

進一步智能化

望遠隱形眼鏡不是世界最早的智能隱形眼鏡。其他用于監(jiān)控并改善眼部及全身健康狀況的模型也有研發(fā)先例。

瑞士諾華公司旗下的眼保健公司愛爾康于2014年與谷歌X實驗室建立了合作伙伴關(guān)系，共同為一系列醫(yī)用護眼產(chǎn)品開發(fā)智能隱形眼鏡技術(shù)。瑞士洛桑聯(lián)邦理工學(xué)院的派生公司Sensimed公司研發(fā)的一項技術(shù)是最早把隱形眼鏡技術(shù)應(yīng)用到醫(yī)用護眼產(chǎn)品的例子之一。該公司的“扳機魚”技術(shù)可監(jiān)測青光眼的病變過程——青光眼是第二大致盲禍根，全球患者超過450萬人。

青光眼由視神經(jīng)退化引起，是一種日益加重的致盲因素。驗光師檢驗青光眼所采用的傳統(tǒng)方法是用氣流來測量眼壓，但是這種測量方法效果并不理想。

“全天候的眼內(nèi)監(jiān)測是治療青光眼的迫切需要?！盨ensimed公司的執(zhí)行總裁大衛(wèi)·貝利說道。該公司在智能隱形眼鏡的芯片中植入了應(yīng)變儀和感測器來測量眼中液體容量的變化，作為測量眼壓的替代方法。這種隱形眼鏡可以24小時佩戴，監(jiān)測眼壓變化情況并通過無線電向使用者佩戴在頸部的記錄儀傳送數(shù)據(jù)。

英國隱形眼鏡協(xié)會的發(fā)言人，驗光師詹姆斯·沃爾夫佐恩，期盼有一天像變焦隱形眼鏡這樣的技術(shù)能在臨床實踐中應(yīng)用。他說：“能按需把視覺成像放大到視網(wǎng)膜上，變焦鏡片似乎是個有趣的概念。”不過他補充說要發(fā)展到這一階段還會面臨一些挑戰(zhàn)：“目前的挑戰(zhàn)包括鞏膜透鏡的厚度和堅硬的鏡片質(zhì)地，都會影響角膜的生理機能和舒適度?！蔽譅柗蜃舳髂慷猛聜冞\用更成熟的“扳機魚”技術(shù)來監(jiān)測青光眼的病變過程，他對這個領(lǐng)域的前景持樂觀態(tài)度。他說：“在隱形眼鏡的創(chuàng)新運用上，還有很多振奮人心的其他新進展?！?/p>

“眼睛是觀測很多疾病狀況的窗戶?！必惱f道。他相信，隱形眼鏡的眼保健功能在臨床應(yīng)用和生活管理方面都有著不錯的前景。根據(jù)美國疾病控制中心的數(shù)據(jù)，僅在美國，就有超過3千萬人佩戴隱形眼鏡，這意味著隱形眼鏡能夠成為不具侵入性的健康管理途徑——用于監(jiān)測失明的發(fā)病過程，甚至監(jiān)測胰島素水平或人體含酒精指數(shù)。

“利用隱形眼鏡來感知眼睛的狀況是大勢所趨……只是利用形式各異。”貝利說道。