Risk of pedestrian collisions ID'd in peripheral visual field loss

December 22, 2016

(HealthDay)—For patients with retinitis pigmentosa, the risk of collision is highest from pedestrians at an angle of 45 degrees from the patient's walking path, according to a study published in the December issue of the Journal of Vision.

Noting that prisms can create artificial peripheral islands of vision, Eli Peli, O.D., from the Schepens Eye Research Institute at Harvard Medical School in Boston, and colleagues examined the visual angle at which these islands can be most effective for preventing pedestrian collisions. They modeled the collision risk density as a function of bearing angle of pedestrians relative to the patient. They assumed pedestrians at all possible locations were moving in all directions with equal probability.

The researchers found that the risk density was highly anisotropic, and peaked at about 45 degrees eccentricity. The risk shifted to higher eccentricities with increasing pedestrian speed. The risk density was found not to be dependent on time to collision. On comparison of the model results with the binocular residual peripheral island locations of 42 patients with , the prevalence of natural residual islands peaked nasally at about 45 degrees, but temporally at about 75 degrees. As a result of this asymmetry, the binocular field of view had complementary coverage. There was good matching for natural residual binocular island eccentricities and the collision-risk density function, with optimization of detection of other walking and other hazards.

"Field expansion prism devices will be most effective if they can create artificial peripheral islands at about 45 degree eccentricities," the authors write. "The collision risk and residual island findings raise interesting questions about normal visual development."

One author has a patent application for the prism that is the motivation for the work.

Explore further: High-power prismatic devices may further expand visual fields for patients with hemianopia

More information: Full Text

Related Stories

Driving with central visual field loss

September 2, 2015

Vision researchers in Boston have published the second paper of a study designed to determine if a driver who suffers from loss of central vision is able to detect pedestrians in a timely manner when driving. Central visual ...

Males hit by vehicles twice as likely to die, study finds

December 11, 2012

(Medical Xpress)—Worldwide, more than 1.2 million traffic fatalities occur yearly, and the lives of pedestrians account for a third of those lost. In the United States, pedestrians make up 12 percent of deaths from traffic ...

Peripheral prism glasses help hemianopia patients get around

November 7, 2013

More than a million Americans suffer from hemianopia, or blindness in one half of the visual field in both eyes as the result of strokes, tumors or trauma. People with hemianopia frequently bump into walls, trip over objects, ...

Recommended for you

Surgery can restore vision in patients with brain injuries

December 12, 2016

Surgery can restore vision in patients who have suffered hemorrhaging in the eye after a traumatic brain injury, even if the operation doesn't occur until several months after the injury, according to a small study from vision ...

An eye on young specialists' success

December 5, 2016

Graduates from several medical and surgical specialties are having difficulty securing practice opportunities, especially in specialties dependent upon limited resources, according to new research from Queen's ophthalmologist ...

'Halo' effect common after lasik eye surgery

December 3, 2016

(HealthDay)—Nine out of 10 Lasik laser eye surgery patients report satisfaction afterwards. But a sizable percentage experience new visual disturbances—like seeing halos around lights—up to six months after the procedure, ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.