Pablo Artal
This year’s Frontiers in Optics + Laser Science (FiO LS) conference and industry showcase will take place in Tacoma, WA, USA, from 9 to 12 October. One of the plenary speakers is Pablo Artal, the director for the Center for Research in Optics and Nanophysics at the University of Murcia, Spain. Artal’s career has focused on methods for studying the human eye and the factors that limit human vision, and his talk will cover the use of adaptive optics for vision correction and testing. OPN chatted with Artal before the event to get a preview of his upcoming talk and learn more about developments in the field.
What do you think were some of the most significant advances in the history of adaptive optics for vision correction and testing?
Pablo Artal: Adaptive optics is already a mature technology—it has been used for military and astronomical applications, microscopy, communications and many other fields. And we have also been using it in the eye for more than 30 years.
Researchers have been making possible what had looked to be impossible. For example, 30 or 35 years ago, getting images of the retina in microscopic detail seemed impossible. The only way to get information about photoreceptors, cones or rods in the retina was from the eyes of cadavers—there was no way to do it in vivo. But then we took these adaptive optics technologies into ophthalmoscopes. And we get beautiful images of many of the retinal structures, including different cells in the retina. So this has been a really amazing improvement.
Also in the early days, we had these in big optical tables in only a few laboratories in the world. Now we can have this in instruments that are in some cases commercially available in different hospitals. So it’s really getting close to practical and clinical application. I often joke in my talks that the first people working in adaptive optics were military personnel and astronomers. These two communities—they are great, right? But they don’t really care too much about money. So they were spending a lot of money on these devices—they were extremely expensive.
“Now we can have this in instruments that are in some cases commercially available in different hospitals. So it’s really getting close to practical and clinical application.” —Pablo Artal
We realized, well, for vision science, for biological applications—this is impossible. You cannot put a device that costs a million dollars or a million euros in an instrument for clinical applications. And so this has been a change; we’ve started using lower-cost devices, so we can have instruments that can be applied for many people.
What do you hope to see this technology achieve for vision correction?
I can see basically three main applications. One is using high-resolution ophthalmoscopes to detect retinal diseases in earlier stages, so you can do early diagnosis of diseases.
A second application is vision correction. We can have devices that can address issues that are more complex and not easy to fix with spectacles or contact lenses. This has not been very common thus far, but I think in the future, for a special type of patient who otherwise might need a corneal transplant, this could be a very good solution, at least temporarily.
And the third potential and real application is as a visual simulator. You can use adaptive-optics technology to see into the eye, but you also can use it basically to simulate vision for people. If you are getting spectacles or contact lenses, well, it’s not a big deal if you are not happy with the result because you can change it easily. But if you are having a surgery—you’re having an intraocular lens put into your eye, you’re reshaping your cornea—and you are unhappy after that, you’re unhappy forever.
So, in my mind, this is a very nice tool. Before doing permanent surgery, you can really test in advance what the result will be. Having refractive surgery to avoid spectacles is often very successful, and there are a lot of people who are extremely happy with it. But there is also a fraction of people who are extremely unhappy.
“You can use adaptive-optics technology to see into the eye, but you also can use it basically to simulate vision for people.” —Pablo Artal
We have data showing that if you really tested in this type of instrument before a surgery, then people could really experience the result and think, “Oh, I’m going to have this type of halo [artifact in my vision]; maybe I should wait, maybe I should look for another solution.” So I think this is this can be a very important application.
How does the use of adaptive optics for vision correction differ from its other applications?
Let’s compare it with astronomy. The only difference is the scale of the big telescopes—everything is big. You have images of the stars, and then you have the atmosphere, you have the optical degradation. And you want to measure the degradation, and you want to correct it with different technologies.
In the case of the eye it is exactly the same: you have objects outside the eye, and you have optical aberrations in the eye that you want to measure and correct. So you can apply exactly the same principles. The difference is that the pupil in your eye is five millimeters in diameter, and the big telescope can be several meters. And there is a temporal difference, too. In astronomy, the degradation is changing much faster than it does in the eye. So telescopes, military applications, communications: things are going much faster, so they need devices that go faster.
In our case, we can do it a little bit slower, and that has an advantage. Initially in all these astronomical applications, they used deformable mirrors that were very expensive and bulky. Now we use liquid crystal spatial light modulators that are much smaller and also can be significantly less expensive. But on the other hand, their response is not so fast. So for astronomy, they sometimes they don’t like that, but for us it’s not a problem.
What do you think are the biggest challenges right now in using adaptive optics for wearable devices?
It’s a technological limit, it’s not fundamental. We are using wavefront sensors, wavefront correctors—all these things are relatively big. We need to do all kinds of simple things in optics, but we need extra lenses, extra mirrors—it’s easy to build in an optical table. But when you want to really compress it in size, this makes a big difference. So there’s complexity in terms of reducing size and keeping image quality. And I think it’s possible; we have some prototypes.
“But when you want to really compress it in size, this makes a big difference. So there’s complexity in terms of reducing size and keeping image quality.” —Pablo Artal
The other limitation is the electronics, the control and power. We are using external computers in some of our lab instruments, we even have several computers for different things. And that’s fine in lab instruments, but when you need to put all this in a frame, then it’s not so easy. But I’m also convinced this is going to be possible, we already have several prototypes that are basically controlled with Wi-Fi and mobile phones. So all the computation is done in in the phone, and you can have the phone in your pocket.
And of course, we are scientists, and our aim is to have a prototype that works. But very often these prototypes are not very nice looking, and people are not necessarily going to accept that appearance in a commercial product. And they are still relatively expensive; this is not going to be an easy thing to take to the market. So there are other barriers, not just those in the scientific development, that I think we will manage.
We are lucky in the sense that we have all these big companies working in virtual reality and augmented reality devices, but even these companies with so many resources and so many years, they have been very slow, right? That shows that this is not an easy task. It’s difficult for everybody, but I’m pretty confident it’s going to be step-by-step moving in the right direction.
Personally, it has been kind of frustrating that many of these efforts in these companies have been for games rather than for correcting vision in people who really need it. But that is probably a niche market, which is why the big companies aren’t interested.
“Personally, it has been kind of frustrating that many of these efforts in these companies have been for games rather than for correcting vision in people who really need it.” —Pablo Artal
It’s not only having these devices that work. Ophthalmologists, doctors—sometimes they are used to the typical way of doing things, and it can be difficult to get them into new technologies. In surgery it’s very tricky. Because you have a patient, and you use one of these [visual-simulator] devices, and you say, “After the surgery, this is what you’re going to see.” But that is what the patient is going to see if the surgery went well. If it didn’t go well, that’s probably not the case. You can imagine that many doctors would say, “Well, I’m not sure I want that.”
You mentioned companies that are working on augmented and virtual reality for entertainment. Have you been able to leverage any of that technology for your purposes?
This is a very good point. And actually, we do try to keep track of the work that is going on, and I have my students looking for things that [the companies] are developing, especially because in comparison with off-the-shelf components, they can be inexpensive. And it can also provide inspiration, seeing what might be useful.
But it is kind of tricky to really use the technology because there is no real open software to use for control, and for us that is very important. We are developing not only the optics; we are also developing the software control. In many cases, we have been developing everything ourselves.
And I know this is a little bit of academic bias; when you are in a university, you like to control the different pieces as much as possible. For example, there are many commercial eye trackers out there, and we got some of them, but finally I decided, okay, let’s do our own eye tracker. Because we know exactly where it is going, we know how to integrate it—and it is a little bit the same for other things.
I don’t believe that companies are really facilitating this much, either. Typically, if you get one of these headsets, and then you start to open it and try to use it for different things, it’s difficult unless you know some people at the company. But another good point is that at many of these companies, there are now more and more of our former students—people that we know. And these are different worlds, but those people can help bridge the divide.