TL;DR
The amount of melanin in your iris does more than determine whether your eyes are blue, brown or green. It can also play a part in how vulnerable your eyes are to certain conditions, from age-related macular degeneration (AMD) to cataracts.
How does melanin determine your eye colour?
Eye colour comes down to melanin, the same pigment responsible for skin and hair colour. Brown eyes have the most melanin, blue and grey eyes have the least, and green and hazel are somewhere in the middle.
Melanin acts as a natural filter, absorbing UV radiation and reducing the amount of light that scatters inside the eye. The more melanin your iris contains, the more shielding your eyes get from harmful light. That’s why eye colour can have a genuine, measurable effect on your risk of developing certain conditions.
Your eye health genetics go beyond just colour, but iris pigmentation is one piece of the puzzle that’s often overlooked.
Lighter eyes and the link to AMD
People with blue, green or grey eyes tend to carry a higher risk of developing age-related macular degeneration. AMD affects the macula, the part of the retina responsible for sharp central vision, and it’s the leading cause of sight loss in people over 50 in the UK.
With less pigment in the iris, lighter-eyed individuals may have less natural defence against UV and blue light damage. Over decades, this can contribute to the oxidative stress that drives AMD progression.
Eye colour is only one risk factor among many, though. Age, smoking, diet and family history all play a bigger part. But if you have lighter eyes, it’s worth knowing that your natural protection against light-related damage is lower than average.
Brown eyes and cataract risk
Having darker eyes doesn’t make you immune to eye problems. Studies have found that people with brown eyes may face a slightly higher risk of developing cataracts, which occur when the eye’s lens becomes cloudy and gradually reduces vision.
One theory is that higher melanin concentrations absorb more heat from light exposure, potentially contributing to lens changes over time. The link may also be partly geographic, since people with brown eyes are statistically more likely to live in sunnier climates where cumulative UV exposure is higher. More research is needed to separate the direct effect of eye colour from other factors.
In the UK, cataracts affect roughly one in three people over 65, and cataract surgery remains one of the most commonly performed procedures in the NHS.
Light sensitivity and glare
If bright sunlight bothers you more than it seems to bother others, your eye colour could be a factor. People with lighter irises tend to experience greater sensitivity to glare because less melanin means less absorption of incoming light, so more of it reaches the retina.
This doesn’t usually indicate a medical problem on its own, but it can make driving on sunny days or working near reflective surfaces more uncomfortable. Sunglasses with full UV protection will make a noticeable difference, and polarised lenses can be particularly helpful.
If light sensitivity is something new or getting worse, it’s always best to get it checked by your optician, as it can also be a symptom of dry eye, migraines or post-surgical recovery.
Uveal melanoma: a rare but real concern
Uveal melanoma is the most common primary cancer of the eye in adults, though it’s still rare overall. Research has consistently shown that people with light-coloured eyes, fair skin and an inability to tan are at higher risk. A Dutch study from Leiden University Medical Center found that individuals with green or hazel eyes had over three times the risk compared to those with brown eyes.
The likely explanation comes back to melanin. Pheomelanin, associated with lighter pigmentation, appears to behave differently under light-induced stress compared to eumelanin, the pigment dominant in darker eyes.
Uveal melanoma accounts for around 600 to 700 new cases per year in the UK, so regular eye examinations are particularly important if you fall into a higher-risk group.
How to protect your eyes, whatever their colour
Eye colour gives you useful context about your individual risk profile, but the steps that protect your eyes are the same whether they’re blue, brown or anything in between.
Wearing sunglasses that meet the UV400 standard, or CE-marked lenses is one of the simplest things you can do. This matters year-round, since UV radiation can penetrate cloud cover. Keeping up with regular eye tests is another priority, as many conditions develop without obvious early symptoms.
Our expert’s opinion
Supporting your eye health with a diet rich in leafy greens, oily fish and antioxidant-rich fruit will also help, since nutrients like lutein and zeaxanthin support the macular pigment that protects your retina.
Ultimately, eye colour is something you can’t change. But knowing how it might influence your eye health puts you in a stronger position to look after your vision for the long term.
