Instead of correcting the eyes, this new technology corrects the display screen. The applications are broad and can be used on many devices, from personal computing to a car’s dashboard.
When it comes to helping people see clearly, eyecare professionals traditionally think in terms of correcting refractive errors with lenses or solving medical issues using pharmacology or surgery. Brian Barsky, PhD, a professor of computer science and vision science at the University of California, Berkeley, is investigating a different approach to aiding those who need corrective lenses to see clearly, programmable displays.
The idea is brilliantly clever: program the screen a person is viewing so that it compensates for the optical errors in their visual system. The concept emerged from earlier research Barsky conducted into what he calls vision realistic rendering (VRR). In VRR, careful measurements are taken of a patient’s visual system, and a simulated image is created of an object that illustrates what that person sees as they view it, while considering the refractive problems they have. Imaging of this kind uses patient data that may be acquired from ophthalmic instruments, such as aberrometers, that measure both lower order and higher order aberrations. In that application, it is used to simulate to a patient how each eye sees the world with their refractive error and higher order aberrations, and how their vision might be improved with lenses or surgery (such as LASIK).
Once this technology was developed, it led to the question of whether the screen displaying the VRR image could be programmed to compensate for the person’s optical errors, essentially helping them see the display clearly without the use of corrective lenses. That led to Barsky’s current work on programmable displays.
BEYOND THE LENS
Barsky enthusiastically points out that programmable displays might transcend the limits of traditional eyeglass lenses if the display were programmed to correct both lower order and higher order wavefront aberrations such as spherical aberration, coma and trefoil. “What is very exciting to me is to go beyond anything eyeglasses can correct by the laws of physics,” Barsky explained. “We’re not putting eyeglasses on top of the display. We’re creating an image that is distorted but in the opposite way to the distortions patients experience due to their refractive situations.” It’s what you might call “equal but opposite” correction of the display for the intended user.
Barsky offers a simple description: “Let’s assume you’re looking at a display while wearing sunglasses, which of course causes the image to appear to be too dim. To compensate, you use an excessively high brightness on the screen. Programmable displays are analogous to this. They provide sharp vision by showing an image that compensates for the vision problems of the intended viewer, which would appear strange to someone else. “What is being displayed
is distorted, but it is done so with the knowledge that it will be viewed by a particular person with a specific refractive error, and that person should see it in sharp focus.”
“We can do some fancy optics with some fancy mathematics,” observed Barsky. “Knowing the details about the aberrations in the vision system of the viewer, we insert the inverse aberrations. This should produce an image in sharp focus on the retina.”
Correcting displays this way involves hardware, but most of the technique is accomplished through software. One of the challenges Barsky’s team faced in developing the software was that distorting the display’s image the way they wanted to resulted in a reduction in contrast. Current techniques use hardware that improves this situation.
The potential applications for programmable displays are broad, including desktop and laptop computer screens, tablets, smartphones and televisions. The technology also has applications for instrumentation such as automobile gauges and medical equipment displays. For example, presbyopes corrected for distance only might benefit from an automobile instrument panel that is corrected for near vision. “Imagine that with keyless entry, an automobile’s computer could identify the driver, and the instrument panel would then compensate for that person’s presbyopia,” Barsky theorized. Since these displays are compensated using software, a person’s Rx can be updated anytime. It also means that different users could use the same device; they just have to identify themselves.
With millions of people using electronic devices, the application for programmable displays is nearly universal. It’ll be fascinating to see how many devices embrace this technology.
Ed De Gennaro MEd, ABOM, is director, professional content of First Vision Media Group.