High blood pressure inside your eye could cause it to age faster, scientists say: ScienceAlert

Like most parts of the human body, our eyes gradually deteriorate over time. A new study now shows how stress can speed up this aging process, a finding that could help us treat eye problems that develop with age, including the group of diseases that cause vision loss called glaucoma.

While the research is based on tests carried out on mice, the team believe the same principles are likely to apply to human eyes as well.

A common consequence of psychological stress, even in the healthiest humans, is an increase in intraocular pressure (IOP, aka ocular hypertension) or fluid pressure in the eye. Known to be linked to the development of glaucoma, it appears that the physiological stress of elevated IOP could also be linked to markers of biological aging, which may appear as changes in the molecular tags of DNA and proteins that control which genes are on or off.

“The epigenetic changes we observed suggest that changes at the chromatin level are acquired cumulatively, following multiple instances of stress,” says ophthalmologist Dorota Skowronska-Krawczyk, of the Faculty of Medicine of the University of California at Irvine (UCI).

“This gives us a window of opportunity for the prevention of vision loss, if and when the disease is recognized early.”

The team looked at the optic nerve head in mouse eyes – the place where retinal cells at the back of the eye converge to form the nerve that goes to the brain – in which IOP had been artificially elevated. In younger mice, there was little difference from control animals, but in older mice, those with mildly elevated eye pressure showed loss of axons or nerve fibers, which also occurs in cases of glaucoma.

In other words, older mice seemed more sensitive to changes in pressure on their eyes, leading to damage from inflammation and a gradual loss of cell function that would normally take years to develop naturally.

Loss of axons in the optic nerve head of aged mice (lower right). (UCI School of Medicine)

In humans, IOP is not fixed, but fluctuates throughout the day. More extreme and prolonged fluctuations have already been linked to the progression of glaucoma, and the researchers behind the new study believe that the cumulative effect of these fluctuations – and the pressure they put on the eye – is responsible for tissue aging.

“Our work shows that even moderate hydrostatic elevation of IOP leads to retinal ganglion cell loss and corresponding visual defects when performed on aged animals,” says Skowronska-Krawczyk.

“We continue to work to understand the mechanism of cumulative changes in aging in order to find potential targets for therapeutics. We are also testing different approaches to prevent the accelerated aging process resulting from stress.”

Now that they’ve detected these pressure-induced changes, the researchers think they can use it as a way to assess the epigenetic age of tissues in the eye – the amount of wear, essentially – and thanks to this make the treatments more targeted and more personalized for each patient.

Aside from psychological stress, there are a number of other factors that can lead to increased pressure inside the eye, from genetics to eye trauma to medications. Regardless of the increase in IOP, having a way to study its impact could save the sight of millions of people.

As the world’s population ages, cases of glaucoma are expected to increase and could reach as many as 110 million by 2040. If left untreated, these conditions can eventually lead to blindness.

While there’s no way to completely reverse the damage of glaucoma, it can be managed – and being able to detect it (and the causes leading to it sooner) would make a significant difference to vision loss.

“Our work emphasizes the importance of early diagnosis and prevention as well as age-specific management of age-related diseases, including glaucoma,” says Skowronska-Krawczyk.

The research has been published in aging cell.

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