New Study Finds Images Placed In Front Of Smartphone Screen Increase Visual Discomfort

Several reports indicate that prolonged viewing of mobile devices and other stereo 3D devices leads to visual discomfort, fatigue and even headaches. According to a new Journal of Vision study, the root cause may be the demand on our eyes to focus on the screen and simultaneously adjust to the distance of the content.

Scientifically referred to as vergence-accommodation, this conflict and its effect on viewers of stereo 3D displays are detailed in a recent Journal of Vision article, The Zone of Comfort: Predicting Visual Discomfort with Stereo Displays.

"When watching stereo 3D displays, the eyes must focus - that is, accommodate - to the distance of the screen because that's where the light comes from. At the same time, the eyes must converge to the distance of the stereo content, which may be in front of or behind the screen," explains author Martin S. Banks, professor of optometry and vision science, University of California, Berkeley.

Through a series of experiments on 24 adults, the research team observed the interaction between the viewing distance and the direction of the conflict, examining whether placing the content in front of or behind the screen affects viewer discomfort. The results demonstrated that with devices like mobile phones and desktop displays that are viewed at a short distance, stereo content placed in front of the screen - appearing closer to the viewer and into the space of viewer's room - was less comfortable than content placed behind the screen. Conversely, when viewing at a longer distance such as a movie theater screen, stereo content placed behind the screen - appearing as though the viewer is looking through a window scene behind the screen - was less comfortable.

"Discomfort associated with viewing Stereo 3D is a major problem that may limit the use of technology," says Banks. "We hope that our findings will inspire more research in this area."

The team of investigators suggests future studies focus on a larger sample in order to develop population-based statistics that include children. With the explosion of stereo 3D imagery in entertainment, communication and medical technology, the authors also propose guidelines be established for the range of disparities presented on such displays and the positioning of viewers relative to the display.

"This is an area of research where basic science meets application and we hope that the science can proceed quickly enough to keep up with the increasingly widespread use of the technology," adds Banks.

Source:
Katrina Norfleet
Association for Research in Vision and Ophthalmology

Behavioral Treatment For Migraines A Cost-Effective Alternative To Meds

Treating chronic migraines with behavioral approaches - such as relaxation training, hypnosis and biofeedback - can make financial sense compared to prescription-drug treatment, especially after a year or more, a new study found.

Longtime behavioral therapy researcher and practitioner Dr. Donald Penzien, University of Mississippi Medical Center professor of psychiatry, coauthored the study. He said the costs of prescription prophylactic drugs - the kind chronic migraine sufferers take every day to prevent onset - may not seem much even at several dollars a day.

"But those costs keep adding up with additional doctor visits and more prescriptions," Penzien said. "The cost of behavioral treatment is front-loaded. You go to a number of treatment sessions but then that's it. And the benefits last for years."

Published in the June issue of the journal Headache, the study compared the costs over time of several types of behavioral treatments with prescription-drug treatments. The research team included investigators from Wake Forest University, UMMC and the University of Mississippi.

The researchers found that after six months, the cost of minimal-contact behavioral treatment was competitive with pharmacologic treatments using drugs costing 50 cents or less a day. Minimal-contact treatment is when a patient sees a therapist a few times but largely practices the behavioral techniques at home, aided by literature or audio recordings.

After one year, the minimal-contact method was nearly $500 cheaper than pharmacologic treatment.

"We have a whole armamentarium of behavioral treatments and their efficacy has been proven. But headache sufferers are only getting a tip of these options," said Dr. Timothy Houle, associate professor of anesthesiology and neurology at Wake Forest University, and the study's principal investigator.

"One reason is people think behavioral treatment costs a lot. Now with this study, we know that the costs are actually comparable, if not cheaper, in the long run."

At a time when health-care costs are under national scrutiny, the study offers a framework for comparing costs that researchers can update and use for years to come.

"We thought, 'Wouldn't it be fun to model this and see how it comes out over time?'" Penzien said. "All the figures are there so if someone disagrees with it, they can plug in their own numbers."

The researchers didn't compare the effectiveness of methods, nor did they calculate the costs over time of individual drugs, since dosages and prices vary widely. Rather, they figured the per-day costs of each method based on fees of physicians and psychologists. For the physician group, they added in the cost of prescription beta-blocker drugs at various prices.

For instance, among the psychologists surveyed, one-on-one behavioral sessions cost between $70 and $250 for the intake visit and $65 and $200 for follow-up visits. That put the median intake cost at $175 and median follow-up cost at $125 for a median 10 visits.

The researchers calculated the median cost of pharmacologic approaches at $250 for the intake session and a professional fee of $140 per session. Median time to the first follow-up was 52.2 days, rising to 60 for the second with a median five visits per year.

To get information on behavioral treatments, the researchers surveyed members of the Behavioral Issues Group of the American Headache Society. For figures on pharmacologic treatments, the researchers surveyed a group of Headache Society-member physicians they knew treated substantial numbers of headache sufferers.

The most expensive behavioral treatment method - individual sessions with a psychologist in clinic - cost more than pharmacologic treatment with $6-a-day drugs in the first months. But at about five months, individual sessions become competitive. After a year, they are cheaper than all methods except treatment with drugs costing 50 cents or less a day.

Overall, group therapy and minimal-contact behavioral treatment were cost-competitive with even the cheapest medication treatment in the initial months. At one year, they become the least-expensive headache treatment choice.

Grant funding from the National Institute of Neurological Disorders and Stroke supported the research.

Source:
Jack Mazurak
University of Mississippi Medical Center