Consumers Unable to Properly View 3D a Big Unknown for Set Makers

Sony raised the question recently when the company told reporters it had learned from ophthalmologists that some patients who have had Lasik surgery can’t view 3D well (CED Feb 17 p1). No one knows how many millions of people may have similar problems with 3D and what can be done to prevent dissatisfaction with the product. Concern among CEA members reached the point that the organization formed a working group chaired by Peter Fannon, Panasonic’s vice president of government affairs, to look into how well 3D TVs may fly with those who have vision issues, CEA said. There’s private talk that some makers are thinking about putting advisory labels on their products warning consumers to consult with eye-care professionals before buying if they have reason to think that a 3D TV may not be for them.

For a 3D movie to seem “natural” to the human eyes and brain, its two stereoscopic “eye images” need to be “identical in every aspect, except for the perspective of the scene,” Bill Mead, DCinemaToday.com’s publisher, said in a recent post. The left- and right-eye images “need to remain symmetrically balanced and must not blend or ‘crosstalk’ before they reach the viewer’s eyes,” said Mead, a board member of the International Cinema Technology Association, which is sponsoring a 3D symposium at this week’s ShoWest trade show in Las Vegas. “The left-eye and right-eye images should remain isolated, balanced in color and light levels, and most importantly, presented at the same time. If these requirements are not met, the 3D experience is degraded with artifacts leading to eye-strain or headaches."

But what happens when a 3D film is beamed flawlessly to a viewer’s eyes that can’t properly receive left- and right-eye images for the brain to process and fuse into a single 3D experience? In addition to those who can’t achieve the “stereopsis” needed to view 3D, such as patients with vision in one eye only, there are other people over 40 for whom the 3D experience may well fall flat if they don’t deal with the issue with their ophthalmologists.

People over 40 who are having Lasik and want to lower their dependence on reading glasses “may want to consider a strategy called monovision,” the American Academy of Ophthalmology said in an October 2008 advisory called “Is Lasik for Me? A Patient’s Guide to Refractive Surgery.” Monovision “corrects your vision to allow for near or intermediate vision in one eye and distance vision in the other eye,” the academy said. “This means that each eye is working independently instead of together. For monovision, your dominant eye —- the one you would use to look into the viewfinder of a camera -— would become the distance eye and the other would be used for near vision. With this technique, the brain learns to adapt to eyes set to focus at different distances. Not everyone is comfortable with this difference in focus, especially those who spend a lot their time playing sports or do a lot of night driving. However, many people find they adapt well to monovision when they try it out first, using contact lenses, before having Lasik.” The academy advised that it’s “important to discuss your lifestyle, including your work and recreational and leisure activities, with your prospective surgeon before deciding to go ahead” with monovision or any other laser procedure.

The academy referred us to two prominent ophthalmologists who told us that 3D entertainment is so new that it hasn’t come up in discussions with patients about how surgery might affect their quality of life. One, a California doctor, told us that monovision patients will see a blurry 3D movie unless they correct for it by wearing the glasses they use for driving. The other, from upstate New York and a monovision patient himself, said monovision won’t thwart a patient’s ability to view proper 3D.

"Certainly 90 percent of the Lasik patients who've had the surgery are going to have no trouble with 3D,” said James Salz, who runs an ophthalmology practice in Beverly Hills, Calif., and is described by academy as a pioneer in refractive surgery. “In fact, if anything, I think they're going to find it easier than they used to with very thick glasses. People who are very nearsighted wear very thick glasses, and the image that you see in a nearsighted eye with a thick glass is reduced because the lens is in front of the cornea rather than on the cornea, like a contact lens, or like Lasik. So they shouldn’t have any trouble."

The 10 percent who may have trouble viewing 3D are the patients who have had “monovision Lasik,” Salz said. Patients who have had monovision surgery “don’t have good binocular vision, they have OK binocular vision,” he said. “In most cases they can drive a car without glasses. But they're going to have a little more trouble fusing the image than patients who have had both eyes corrected for distance. But I'd say almost all patients who are younger than 40 who have had Lasik -- regardless of whether it was done on one or both eyes -- they should have no trouble fusing the images, assuming that they had fusion when they were younger.” To see 3D images effectively, “you have to have stereopsis, stereoscopic vision,” Salz said. “You have to have really good depth perception.” That means both eyes need to have “pretty equal refractive errors,” he said.

Ophthalmologists typically perform three “levels” of monovision, Salz said. “If you're very young, like late 30s or early 40s, we typically make one eye only one diopter more nearsighted than the other eye.” A diopter is the unit of measure optometrists use when writing prescriptions for glasses or contact lenses. “If you're off by only one diopter, there’s a good chance you could fuse the 3D images anyway,” he said. “If you're older, like in the 50s or 60s, we'll often do 1 1/2 to 2 diopters. Those are the patients who are more likely to have trouble fusing the images and getting a true three-dimensional effect. And what they would have to do -- and a lot of them have this -- we'll often give them a pair of glasses to balance their eyes, so when they drive at night, they have good fusion.” Monovision Lasik patients “would not be prevented from stereoscopic three-dimensional vision, as long as they're willing to put on a pair of driving glasses” under their 3D eyewear, he said.

Like many, but not all, ophthalmologists, Salz won’t do monovision Lasik on patients without first fitting them with contact lenses to simulate the monovision effect, he said. That’s to be sure they like it, because “not everybody” does, he said. “Women actually like it and do better than men.” He said “the published literature” bears this out statistically. “We're a different breed,” he said of males. “Women want to go out to dinner and not have to put their glasses on to read the menu, and most guys don’t care about putting on a pair of glasses."

Monovision “is very handy” for people older than 40 who spend $4,000 for Lasik and don’t want to be told that they'll need to wear glasses for reading, Salz said. “So if you can eliminate their glasses so they can see a cellphone, they can read a menu, they can sign a credit card without putting on glasses, they'll put up with that and will be willing to wear the glasses maybe an hour a day in order to drive the car. We do a lot of monovision and [in] general, we have been very successful. I have only rarely had to reverse monovision on patients."

Still, through the eyes of a monovision patient, 3D will look as “blurry” as to those not wearing 3D glasses or who lack vision in one eye, unless they wear glasses to correct the monovision, Salz said. Because the 3D phenomenon is so recent, he hasn’t begun advising monovision patients that they may not be able to properly view 3D, though he has long told them the procedure probably will affect their depth perception, he said. There “could well be” millions of people “walking around out there with monovision right now who might be disappointed with that 3D experience if they're not told how to eliminate it,” he said. “And the way they're going to eliminate it is wear the glasses” that correct the monovision, he said. “I would say that the majority of them have driving glasses."

Another ophthalmologist that the academy referred us to disagreed with Salz on monovision’s effect on the ability to view 3D properly. “If somebody lacks depth perception in a regular, normal world, they would lack depth perception in a 3D world,” said Scott MacCrae, a professor of ophthalmology and of visual sciences at University of Rochester’s School of Medicine in Rochester, N.Y. “But people with monovision actually have good 3D perception,” he said. “I've got monovision. I'm looking at a tree. I can see the image of the tree with both eyes. The near eye is just slightly more blurred, but I certainly get a depth perception through my monovision."

MacCrae thinks viewing 3D would be just as compelling for patients with monovision as for those with 20/20 vision in both eyes, he said. “I think it’s about the same. I don’t think it makes a lot of difference.” He said he read somewhere that director James Cameron wanted to incorporate snowflakes into the 3D effects he used in Avatar. “Very fine spatial-frequency objects” like snowflakes “might make a slight difference” to people with monovision, he said. “But for most things that we look at in a three-dimensional world, I'm sitting here looking at a car, looking at a tree, a streetpost, I can see them three-dimensionally. When you do monovision, the distant targets actually become defocused, but you can still see the object. It’s just a little bit fuzzy with the monovision eye. So I don’t really think you give up a whole lot in terms of three-dimensional optics. People who do have monovision, when you measure stereopsis, essentially it has no effect on stereopsis."

MacCrae said he hasn’t seen a 3D movie, and the version of Avatar he saw was in 2D. He’s convinced that he wouldn’t have trouble enjoying a compelling 3D experience with monovision, nor would anyone else, he said. “I even do surgery with monovision,” he said. “I have plenty of depth perception.” Since it’s not a “significant issue,” MacCrae sees no purpose in advising monovision patients about any risk they may not be able to view 3D movies properly, he said.

Monovision works with only half the people who simulate the effect by wearing contact lenses in a trial, MacCrae said. The rest ultimately decide monovision isn’t for them, he said. For those patients, “we fully correct them for distance,” and then prescribe them reading glasses, he said. Even for people who wind up happy with monovision, “it does take some time for your brain to that,” McCrae said. “It’s called neural adaptation. Some people adapt to that very well, some people don’t at all. Some people need to have both images focused at the same focal point.”

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Salz said he has had a personal interest in 3D since the early 1970s, when he joined the Los Angeles practice of his senior partner, Julian Gunzburg, whose brother Milton held many of the early patents on stereoscopic 3D. Julian Gunzburg, an ophthalmologist, consulted for his brother on their Hollywood startup, Natural Vision, which tried to license the stereoscopic 3D technology to the major studios, Salz said. Its technology was used in Bwana Devil, a 1952 United Artists drama starring Robert Stack and is deemed the first American color 3D feature film. he said. The Gunzburgs also worked on the 1953 classic horror film, House of Wax, starring Vincent Price. Released by Warner, it’s considered the first 3D color feature film from a major American studio. Through House of Wax, Milton Gunzburg “made a fair amount of money, not so much on the movie itself, but on the polarized lenses that were sold at the theaters for like 10 cents apiece,” Salz said.