Research led by the Federal University of Bahia concluded that human tears are not very different from those of reptiles and birds.
A study led by the Federal University of Bahia, Brazil, suggests that the tears of birds and reptiles are not so different from ours. In fact, they could even help in the creation of treatments for eye diseases.
According to the study, published this week in the journal Frontiers in Veterinary Science, tears play a critical role in maintaining healthy eyesight in all species.
So far, however, few studies have been carried out on them, most in mammals such as dogs, horses, monkeys, and camels.
“Discovering how tears are able to maintain the ocular homeostasis, even in different species and environmental conditions, is crucial for understanding the evolution and adaptation processes,” said Arianne Oriá, the study’s leader. “[This] is essential for the discovery of new molecules for ophthalmic drugs.”
Oriá and colleagues worked together with veterinarians from conservation centers, wild animal care centers, and commercial breeders, to collect samples of tears from healthy animals in different contexts.
The study was limited to specimens kept in captivity and evaluated tears of macaws, hawks, owls, and a species of parrot, in addition to tortoises, caimans, and sea turtles.
Looking at the composition of animal tears compared to human tears, the authors found that they all contained close amounts of electrolytes, such as sodium and chloride.
In this regard, the owl and sea turtle samples were the most divergent, as they presented slightly elevated levels of urea and proteins.
The scientists also examined the crystals that form when the tear fluid dries to see if there was a pattern. “But the crystal structures are organized in different ways so that they guarantee the eyes’ health and an equilibrium with the various environments,” Oriá explained.
The researcher points out that this was just another step among several others necessary for a broader understanding of tears in different species.
Still, she believes that the study will allow a better understanding of the evolution and even assist in the development of eye treatments. “This knowledge helps in the understanding of the evolution and adaption of these species, as well as in their conservation,” Oriá said.