Our blind spots can be shrunk with training: study

You might have heard that when driving a car there is a "blind spot" that you cannot see, yet there is also one in the human eye and researchers have found out that it can be minimized with training.

To find your blind spot, draw two dots spaced approximately 15 centimeters apart, close one eye and focus the other on one of the dots.

Move the paper slowly away from you and watch how the dot that you hadn't been focusing on disappears.

This happens because the optic nerve that sends visual messages to the brain passes through the retina, creating a smudge in the tissue that's sensitive to light, blocking us from seeing images that project to that spot.

While the smudge in our visual field won't change in size, the blind spot may be able to be minimized, according to a recent study with implications for age-related macular degeneration, which can lead to blindness.

"We did not confidently expect to see much reduction in functional blindness, as you can never develop photosensitivity within the blind spot itself," says Paul Miller of The University of Queensland in Australia. "You can only enhance sensitivity at the blind spot periphery, but this proved sufficient to bring about a ten percent reduction in functional blindness."

In the study, the research team trained 10 people for 20 consecutive weekdays to perform a direction-discrimination task in which they viewed a drifting waveform in a ring positioned near the blind spot of one of their eye's field of vision.

They adjusted the size of the ring until participants were able to gauge the direction in which it was moving approximately 70 percent of the time, according to the study, published in Current Biology.

When training was over, participants showed improvements in their ability to detect the direction and color of the waveform.

Training one eye did not affect the untrained eye, which indicates the shrinkage was due to more than repetitive practice, but rather enhanced sensitivity neurons around the blind spot, some of which may overlap it.

This makes the eye more keen on soft signals that originate from the blind spot.

If it's possible to reduce the blind spot in our field of vision, it could also be possible to do so in other cases of reduced vision.

The researchers believe their training protocols could be used in vision rehabilitation alongside other emerging technologies like the bionic eye or retinal stem cell therapy.

Plans are underway to further explore the training protocol in subjects of normal vision as a prelude to testing it for subjects with age-related macular degeneration.

For some fun with your blind spot: http://pbskids.org/zoom/activities/sci/blindspot.html