NOVATO, Calif. — The health of your eyes may have a direct impact on how the rest of your body is feeling and how long you’ll live, a new study finds. A team from the Buck Institute for Research on Aging has found a link between diet, circadian rhythms, eye health, and lifespan. It’s the first time scientists have connected all of these different aspects of health to a person’s eyes.
“Our study argues that it is more than correlation: dysfunction of the eye can actually drive problems in other tissues,” says senior author and Buck Institute Professor Pankaj Kapahi, PhD, in a media release.
Researchers note that Kapahi’s lab has also demonstrated that fasting and cutting calories can improve multiple functions throughout the body — including eye health.
“We are now showing that not only does fasting improve eyesight, but the eye actually plays a role in influencing lifespan.”
During this new report, study authors examined the link between eyes health and lifespan among Drosophila — the common fruit fly.
“The finding that the eye itself, at least in the fruit fly, can directly regulate lifespan was a surprise to us,” adds lead author, Brian Hodge, PhD, who did his postdoctoral studies in Kapahi’s lab.
The internal clock is the key
Hodge believes the connection lies in the circadian rhythms, the 24-hour “clock” with regulates a person’s bodily functions during the day and night. This internal clock affects every cell in the body, adapting to light and temperature changes as the Sun rises and sets. It also controls out sleep/wake cycles, gene transcription, and protein translation.
In a 2016 study, Kapahi’s lab showed that fruit flies on a restricted diet experienced “significant changes” in their circadian rhythms. In turn, this extended their lifespans.
“The fruit fly has such a short lifespan, making it a really beautiful model that allows us to screen a lot of things at once,” Hodge says.
Researchers started their new study by examining which genes oscillate with a circadian pattern when flies are on an unrestricted diet. They also compared these insects to another group eating just 10 percent of the protein in the unrestricted diet.
Results show that multiple genes responded to diet changes and also displayed “ups and downs” at different points during the day — just like the body’s internal clock. The team then discovered that the rhythmic genes activated the most by dieting come from the eyes. Specifically, diet restrictions activated photoreceptors, specialized neurons in the retina which respond to changes in light. From there, the team conducted experiments which revealed that flies in constant darkness actually had longer lifespans.
“That seemed very strange to us,” Hodge explains. “We had thought flies needed the lighting cues to be rhythmic, or circadian.”
Do genes in the eye influence your lifespan?
Study authors say yes, they do.
“We always think of the eye as something that serves us, to provide vision. We don’t think of it as something that must be protected to protect the whole organism,” Kapahi says.
Researchers explain that, since the eyes have constant exposure to the outside world, their immune defenses are always active. This can lead to inflammation and, over a long period of time, can cause worsening health and chronic diseases to develop. Moreover, light itself can cause the photoreceptors to deteriorate — causing more harmful inflammation.
“Staring at computer and phone screens, and being exposed to light pollution well into the night are conditions very disturbing for circadian clocks,” Kapahi adds. “It messes up protection for the eye and that could have consequences beyond just the vision, damaging the rest of the body and the brain.”
So, does this work with fruit flies really apply to humans as well? Researchers say the lifespan of a fruit fly definitely depends more on this relationship because the majority of the energy a fly uses goes into its eyes.
For humans, however, “the stronger link I would argue is the role that circadian function plays in neurons in general, especially with dietary restrictions, and how these can be harnessed to maintain neuronal function throughout aging,” Hodge says.
The findings appear in the journal Nature Communications.