Led by Kara Maki, the researchers analyzed how tears moved across the surface of an eye and with the help of software called Overture, they recreated the flow of tears, moving from the upper corner and draining through the ducts at the opposite corner.
The researchers found that as the tears moved up the eyelid and joined a column of fluid that travels along the lids, lower pressure sucked this fluid into the meniscus and away from the centre, leading to dry spots on the tear film which can compromise vision and irritate the cornea. The study has been published in the journal Physics of Fluids.
"One thing we were able to find is that when your eyes are open, the tears get thin right along the edge of the eye, and that is referred to as the 'black line'. We confirmed that blinking is necessary to stop this thinning from happening. Every time you blink, the tear film gets repainted on the front of your eye", Maki said.