Why our eyes don't blur when we blink

Ever wondered why we are not plunged into intermittent darkness when we blink? Researchers in Singapore may have the answer. It is because our brain works extra hard to stabilise our vision, without which our surroundings would appear shadowy, erratic and jittery after we blink, a study has showed.

Blinking lubricates dry eyes and protects them from irritants. However, when we blink, our eyeballs roll back in their sockets and do not always return to the same spot when we reopen our eyes.

This misalignment prompts the brain to activate the eye muscles to realign our vision, the researchers said. The finding showed that when we blink, our brain repositions our eyeballs so we can stay focused on what we are viewing.

"Our eye muscles are quite sluggish and imprecise, so the brain needs to constantly adapt its motor signals to make sure our eyes are pointing where they're supposed to," said lead author Gerrit Maus, Assistant Professor at Nanyang Technological University in Singapore.

"Our findings suggest that the brain gauges the difference in what we see before and after a blink and commands the eye muscles to make the needed corrections," Maus added.

For the study, healthy young adults participated where they sat in a dark room for long periods staring at a dot on a screen while infrared cameras tracked their eye movements and eye blinks in real time.

Every time they blinked, the dot was moved one centimetre to the right. While participants failed to notice the subtle shift, the brain's oculomotor system registered the movement and learned to reposition the line of vision squarely on the dot.

After 30 or so blink-synchronised dot movements, participants' eyes adjusted during each blink and shifted automatically to the spot where they predicted the dot to be. The study was published in the journal Current Biology.