What Can a Photograph of the Retina Tell Us?
A photograph of the retina is usually taken to examine eye health.
But the retina also contains tiny blood vessels and neural tissue. These structures can reflect processes related to vascular, neurological and systemic health.
Artificial intelligence can analyse patterns within retinal photographs and estimate a person’s age. Researchers call this estimate retinal age.
The next question is more important:
Does retinal age tell us anything about future health?
Retinal Age and Long-Term Survival
One of the first large studies to examine this question used data from the UK Biobank.
Researchers calculated the difference between each participant’s AI-predicted retinal age and actual chronological age. This difference is known as the retinal age gap.
They then followed more than 35,000 adults for approximately 11 years.
During this period, 1,871 participants died.
People whose retinas appeared older relative to their chronological age tended to have a higher risk of death during follow-up.
After accounting for age, smoking, physical activity, general health and several major medical conditions, each additional year of retinal age gap was associated with approximately 2% higher relative hazard of all-cause mortality.
The relationship was particularly apparent among people with larger positive retinal age gaps.
Does This Mean Retinal Age Predict How Long You Will Live?
No.
The study identified differences in risk across a large population. It cannot tell an individual how many years they will live.
A retinal age gap of +5 years does not mean that someone will live five years less. Nor can the study translate a particular retinal age into a personal life-expectancy estimate.
Mortality is influenced by many factors, including cardiovascular and metabolic health, cancer, genetics, lifestyle, environment and medical care.
Retinal age may add information about risk. It cannot provide a countdown of remaining lifespan.
What Might an Older Retinal Age Reflect?
Researchers do not yet have a complete answer.
The retina gives us direct access to small blood vessels and neural tissue, both of which undergo changes with age.
In the UK Biobank study, the artificial-intelligence model appeared to pay particular attention to areas around the retinal blood vessels when estimating age.
An older retinal appearance could therefore reflect some of the cumulative vascular, neural or systemic changes that develop over time.
However, the study did not determine exactly which biological processes were responsible for the association with mortality.
This is an important distinction. Retinal age may capture a meaningful health signal without yet telling us precisely what is producing that signal.
What About Cardiovascular Disease and Cancer?
The researchers also examined specific causes of death.
A larger retinal age gap was associated with all-cause mortality, but after full statistical adjustment it was not significantly associated with cardiovascular mortality or cancer mortality when these were analysed separately.
The association was stronger for deaths from causes other than cardiovascular disease and cancer.
This tells us that retinal age should not currently be treated as a specific test for cardiovascular or cancer risk.
It may reflect a broader pattern related to health and aging.
Could Retinal Age Become Useful in Longevity Medicine?
Potentially.
Retinal photography is fast and non-invasive, and it can be repeated over time.
This makes retinal imaging particularly interesting as researchers search for practical ways to assess aging.
But an important question remains unanswered: does a change in retinal age over time correspond to a meaningful change in health or future risk?
The original study used retinal images obtained at one point in time. It therefore could not show whether improving health makes retinal age younger, whether retinal age can track the rate of aging, or whether reducing the retinal age gap improves outcomes.
Those questions require further research.
For now, retinal age is best interpreted as additional information about aging and health risk, alongside established clinical measures and other assessments of biological and functional health.
