They say beauty is in the eye of the beholder, but could the opposite be true? Could people who have tired, bloodshot eyes be seen as unattractive? In fact that's exactly what researchers from the University of Maryland are suggesting.
Writing in the journal Ethology, the experts tested 208 volunteers and asked them to rate the attractiveness of 200 images of eyes, some of which had clear whites and others of which had the whites tinted red using digital imaging.
The pictures of the reddened eyes were unsurprisingly rated as less attractive and less healthy than the pictures of the eyes with clear whites. But why they should be rated as sadder is anyone's guess - perhaps because if you have red eyes it suggests you've been crying.
"Standards of beauty vary across cultures, however, youth and healthiness are always in fashion because they are associated with reproductive fitness," says lead researcher Dr Robert Provine. "Traits such as long, lustrous hair and smooth or scar-free skin are cues of youth and offer the beholder a partial record of health.
"Now clear eye whites join these traits as a universal standard for the perception of beauty and a cue of health and reproductive fitness."
We're off to buy some eye drops right now. How about you?