New research points to source of peripheral vision problems

by Thea Singer
Psychology professor Peter J. Bex and colleagues have reached a new understanding of why our peripheral vision is poor. The discovery could lead to treatments for eye diseases such as age-related macular degeneration.
You’re hus­tling across Hunt­ington Avenue, eyes on the Marino Center, as the “walk” sign ticks down sec­onds: Seven, six, five…. Sud­denly bike brakes screech to your right. Yikes! Why didn’t you see that cyclist coming with your periph­eral vision?
Researchers in the lab of North­eastern psy­chology pro­fessor Peter J. Bex may now have the answer—one that may lead to relief for those with age-​​related mac­ular degen­er­a­tion, or AMD, an eye dis­order that destroys cen­tral vision: the sharp, straight-​​ahead vision that enables us to read, drive, and deci­pher faces. AMD could affect close to 3 mil­lion people by 2020, according to the Cen­ters for Dis­ease Control.
The problem with periph­eral vision—which people with AMD par­tic­u­larly rely on as their cen­tral vision fails—is that it’s noto­ri­ously poor because it’s sub­ject to “crowding,” or inter­fer­ence from sur­rounding “visual clutter,” says William J. Har­rison, co-​​author of the study and a former North­eastern post­doc­toral fellow. “You know something’s there, but you can’t iden­tify what it is.”
Bex and Harrison’s break­through paper, pub­lished last month in the journal Cur­rent Biology, uses com­pu­ta­tional mod­eling of sub­jects’ per­cep­tions of images to reveal why that visual befud­dle­ment occurs, including the brain mech­a­nism dri­ving it. That knowl­edge could pave the way for treat­ments to cir­cum­vent crowding.
An evo­lu­tionary compromise
Our vision oper­ates on a gra­dient: It has high res­o­lu­tion in the center and pro­gres­sively coarser res­o­lu­tion in the periphery. The dimin­ish­ment is an evo­lu­tionary neces­sity. “If we were to have the same res­o­lu­tion that we have in the center of our vision across our whole visual field, we’d need a brain and an optic nerve that were at least 10 times larger than they cur­rently are,” says Bex, who spe­cial­izes in basic and clin­ical visual science………
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Source: News @ Northeastern