FYFD

Tag: eyes

  • Collecting Animal Tears

    Collecting Animal Tears

    Like humans, most vertebrates rely on tear films to keep their eyes moist and protected from the environment. But compared to humans, some animals’ tears have superior staying power. The caiman, for example, can go up to 2 hours between blinks without their eyes drying out; in contrast, humans have to blink about 15 times per minute – and sometimes even that isn’t enough to keep our eyes moist!

    Researchers are collecting animal tears and studying their composition to better understand how their tears protect vision. Subtle changes in chemical make-up can lead to large variations in performance; just look at the many dried tear patterns in Image 2. Scientists hope that understanding other species’ tears will help us develop better treatments for our own vision problems. As someone who struggles with dry eyes at times, I’d be happy for some caiman-tear-inspired eye drops! (Image credit: A. Oriá; research credit: A. Raposo et al.; via NYTimes; submitted by Kam-Yung Soh)

  • How Eyelashes Work

    How Eyelashes Work

    New research shows that eyelashes divert airflow around the eye, serving as a passive filter that reduces dust collection and controls evaporation. Mammal hairs in places like the nose act as ram filters that trap the particles that hit them and which require regular cleaning via sneezing. Eyelashes, on the other hand, prevent dust collection by altering airflow at the surface of the eye. At the optimal length of roughly 1/3rd the width of an eye, eyelashes create a stagnation zone near the eye surface that forces air to travel above rather than through the eyelashes. This results in lower shear stress and lower flow speeds at the eye surface, both of which help reduce evaporation and shield the eye from dust. Lashes can get too long, though; the researchers found that longer lashes tended to channel higher flow speeds toward the eye surface, leading to faster evaporation rates. Thus, donning longer fake eyelashes may dry out your eyes. (Image credit: G. Diaz Fornaro; research credit: G. Amador et al.; via skunkbear)