For many people, osteoporosis is only diagnosed following their first broken bone. Finding a cheap, accessible method for predicting this common bone-weakening condition early could help prevent the pain, debilitation, and potential death from serious fractures in more people around the world.
A recent study led by researchers from the Duke-NUS Medical School in Singapore has shown that the inside of a person’s eye could hide signs of declining bone density. The results could lead to new screening tools that indicate who may be at increased risk of developing the disease.
Osteoporosis is a chronic condition that affects around one in five people around the world. It arises as bones lose minerals faster than they can be replaced, resulting in a weaker, more brittle skeleton prone to breaking.
Driven by aging and changes in hormones, it’s a disease linked closely with menopause, with women over the age of 50 accounting for around 80% of known cases. It’s also likely that the condition is underdiagnosed in men, adding further incentives to improve screening tools.
Right now, the gold-standard method for measuring bone mineral density is via dual-energy X-ray absorptiometry (DEXA). Despite being accurate and noninvasive, the procedure isn’t cheap, nor is it widely accessible, relying on large, expensive devices to deliver the low doses of radiation to targeted areas of the body.
That means in practice, it is reserved for those most in need, such as those who have already experienced a serious fracture.
Having an inexpensive and mobile means of distinguishing who may benefit from health interventions long before they break a bone could be a literal lifesaver for many.
Blood vessels running across the retina inside the eye are sensitive to a variety of changes in the body, including factors connected to osteoporosis.
“However, direct evidence connecting retinal aging to bone mineral density loss remains limited, and few studies have examined whether a homogeneous biological aging process underlies changes in both tissues,” the researchers write in their recently published report.
To determine whether a map of the eye’s interior may provide a sound indication of osteoporosis risk, the researchers behind this latest study turned to a system called retinal biological aging marker, or RetiAGE.
Based on a deep-learning analysis of retinal scans, RetiAGE uses images of vasculature within the eye to predict a person’s age. The team compared retinal scans from just under 2,000 adult participants with their DEXA scores, finding ‘old’-looking retinas were more likely to have lower bone densities.
A second investigation confirmed the link using retinal images and medical records taken from nearly 44,000 participants in the UK Biobank.
The association was consistent across men and women and was further strengthened when combined with existing tools for predicting osteoporosis risk.
While the RetiAGE model was trained on more than 100,000 eye images, they were largely of individuals of Korean descent, limiting the tool’s predictive power.
Expanding the database of retinal scans and testing the process in other demographics could determine whether the retina truly is a suitable window into bone health.
This research was published in PLOS Digital Health.
Fact-checked by Bronwyn Thompson
