Profoundly blind people could get their best shot yet of restored vision with a more advanced "bionic eye", researchers have announced.
研究人員宣布，完全失明的人可以試一試用一種更先進的"仿生眼"恢復視力。
Trials of the new retinal prosthesis will begin shortly, following the success of a prototype that has enabled six blind people to see again.
在6名盲人試用人造視網膜雛形機後視力成功恢復之後，針對新型視網膜修復術的試驗將在不久將來進行。
Within a few weeks all could detect light, identify objects and even perceive motion again. For one patient, this was the first time he had seen anything in half a century, after his sight was destroyed by retinitis pigmentosa, a virus that attacks retinal cells.
幾周之內，這6名盲人都能察覺到光線，辨別物體甚至還能察覺動作。其中一個盲人，自從他的視力被色素性視網膜炎(一種侵襲視網膜細胞的病毒引起的)所損壞後，這是他半個世紀以來，首次有了視覺。
"We hoped they might get some sense of light and dark, but it's really amazing how much they can see - how the brain is able to fill in the gaps," says Mark Humayun, who carried out the implant surgery and developed the device with colleagues at Doheny Eye Institute at the University of Southern California in the US.
「我們本希望讓病人可以感知光明與黑暗，但他們視力恢復得如此好，真令人驚奇——他們的大腦是怎麼與儀器完全聯接融合的呢?」美國南加利福尼亞大學Doheny眼科學院的Mark Humayun說。他與他的同事們研發了人造視網膜並主刀植入手術。
For the technique to work, the patient must still have some functioning ganglion cells - nerve cells that transmit visual information from the retinal cells to the optic nerve - as well as a fully-functioning optic nerve. A tiny electronic pad is placed onto the retina of one eye, so that the electrodes are in direct contact with the ganglion cells. Each of the devices' 16 electrodes can stimulate 20 to 30 cells.
為了該技術能夠應用，盲人身上必須安裝一些官能神經節細胞——把視覺信息從視網膜細胞傳導到視神經的神經細胞。這就象是整套視神經的工作原理一樣。一個微小的電子襯墊被放置在單側眼睛的視網膜上，這樣電極就可以與神經節細胞直接接觸了。仿生眼的16個電極中，每一個都能激發20到30個視網膜細胞。
Real-time vision
The user wears a pair of glasses that contain a miniature camera and that wirelessly transmits video to a cellphone-sized computer in the wearer's pocket. This computer processes the image information and wirelessly transmits it to a tiny electronic receiver implanted in the wearer's head.
實時視力
使用者佩戴一副裝有小型攝像機的眼鏡，將視頻信號無線傳輸到隨身攜帶的掌上電腦中。這臺電腦處理完圖像信息，同樣以無線傳輸的方式將信號傳輸給植入攜帶者腦部的微型電子接收器。
The received in the implanted chip, the digital information is transformed into electrical impulses sent into the ganglion cells. From there, the brain takes over as the information travels down the optic nerve to the visual cortex at the back of the brain. The whole process occurs extremely rapidly, so that patients see in real-time. This is important any noticeable lag could stimulate the "vestibular-ocular reflex", making people feel dizzy and sick.
植入晶片接收到數位訊號後，將其轉化為電氣脈衝，並發給神經節細胞。在大腦的控制下，視覺信息從神經節細胞傳輸給視神經，再傳輸給大腦後部的視覺大腦皮層。整個過程發生得極快，所以病人感覺就是實時的。重要的是，任何明顯的視覺滯後都可能引起"前庭視覺反射"，那樣的話，會讓人感到頭暈噁心。
Humayun's team is about to embark on a new trial of an improved device, which they will fit into 50 to 75 people aged over 50, who are also blind as a result of retinitis pigmentosa. The trial will involve monitoring them for two years and will take place in five centres across the US.
Humayun的研究小組即將對改良「仿生眼」進行新一輪的試驗，他們將把改良後的「仿生眼」用於50到75名因色素性視網膜炎而失明的年過半百的人身上。試驗將包括對受測試者歷時2年的監測，並同時在全美的5個試驗中心進行。
Field of view
The first implant had just 16 electrodes on the retinal pad and, as a result, visual information was limited. The new device has 60 electrodes and the receiver is shrunk to one-quarter of the original's size. It is now small enough to be inserted into the eye socket itself. The operation to fit the implant will also last just 1.5 hours, down from 7.5 hours.
視野
首個植入晶片在視網膜襯墊上只有16個電極，導致視覺信息受到限制。新型「仿生眼」有60個電極，而接收器也縮小到原來尺寸的1/4。這樣，接收器的大小就適合於植入眼窩中了。植入手術會耗時1.5小時，不會超過7.5小時。
Currently recipients of the device experience a relatively narrow view, but more electrodes should provide a greater field of vision, Humayun says. By stimulating more ganglion cells, he hopes that visual acuity will increase dramatically. His team's next goal is to design a device with 1000 electrodes.
目前的接收器只會產生相對狹窄的視野，但增多電極就能提供更廣闊的視野，Humayun說。通過刺激更多的神經節細胞，他希望視覺靈敏度也能顯著增長。他們團隊的下一個目標是設計出具有1000個電極的「仿生眼」。
Regaining sight has felt like a miracle to those involved in the preliminary trial. At the beginning, it was like seeing assembled dots "now it's much more than that," says Terry Bryant, aged 58, who received the implant in 2002 after 13 years of blindness. "I can go into any room and see the light coming in through the window. When I am walking along the street I can avoid low hanging branches and I can cross a busy street."
恢復視力對於那些參與初步試驗的人來說簡直就象一個奇蹟。起初，就好像看見集中的小點，「現在可比原先清楚多了，」Terry Bryant，一個58歲受測試者說。他經歷了13年不見天日的生活後，於2002年植入了「仿生眼」。我可以進出任何一個房間，並能看見光線從窗戶射進來。走在街上時，我可以避開低垂的樹枝，穿越繁忙的街道。
If the trial is successful, the new device may be available commercially by 2009, priced around $30,000 - similar to a cochlear implant, Humayun says. People whose blindness results from a range of causes, including retinitis pigmentos and macular degeneration could benefit from it.
如果試驗成功，也許在2009年新型仿生眼就能夠商業運營，價格大約在3萬美元——與一個植入式耳蝸相似，Humayun說。由於各種原因失明的人，比如，色盲症和視力退化症的患者都能從中獲益。