Eye Colour - when pigment becomes a problem...

We often think of eye colour as something fixed — a defining part of who we are. But inside the iris, tiny shifts in pigment can sometimes tell a deeper story. Most of the time, these changes are perfectly harmless. Occasionally, though, they can point to something more serious.

In this post, we’re looking at what happens when the pigment that gives your eyes their colour starts to misbehave — and why even rockstars like Bono have personal experience with pigment-related eye conditions.

When Pigment Misbehaves…

The coloured part of your eye — the iris — gets its shade from melanin, the same pigment that colours your skin and hair. Sometimes, little specks or patches of extra pigment can appear on the iris surface. These are known as iris freckles or nevi (pronounced “nee-vye”).

They might look unusual — like tiny moles or dots on the eye — but most of the time, they’re completely harmless. Still, just like freckles on the skin, it’s important to keep an eye (no pun intended!) on them for any changes over time.

Iris Freckles — Usually Harmless ✨

Iris freckles are very common. They’re simply small deposits of pigment cells sitting on the surface of the iris. Many people have them, and they don’t usually cause any symptoms or affect vision.

You might notice them more in bright light or if your eyes are lighter in colour. They can also become more noticeable with age or sun exposure.

Generally, they’re nothing to worry about — but regular eye exams help ensure they stay that way. An optometrist can easily photograph and track them over time to check for changes in size or shape.

But Nevi Can Rarely Turn Into Melanoma 🎗️

Here’s where things get a little more serious.

Iris nevi look similar to freckles but are deeper — more like moles within the iris tissue. They’re still usually benign, but in rare cases, a nevus can transform into a type of cancer called ocular melanoma.

Ocular melanoma is uncommon, but early detection makes a huge difference. Warning signs include:

• A spot that grows or changes in colour or shape.

• Distortion in the pupil.

• Vision changes or flashes of light.

If your optician notices anything suspicious, they’ll refer you to an ophthalmologist for detailed imaging.

Think of it like a mole on your skin: most are harmless, but you wouldn’t ignore one that started changing. The same logic applies to your eyes.

Pigment Dispersion — When Pigment Travels Where It Shouldn’t ⚠️

There’s another way pigment can cause trouble — when it starts to flake off the iris. This is known as pigment dispersion syndrome (PDS).

In PDS, tiny bits of melanin break loose from the back of the iris and float into the eye’s internal fluid (the aqueous humour). These pigment particles can clog the eye’s drainage system, causing pressure to build up — a condition known as pigmentary glaucoma.

High eye pressure can damage the optic nerve and, if untreated, lead to permanent vision loss. The tricky part? It often develops slowly and without pain, so you might not realise anything’s wrong until damage has already begun.

Regular eye exams can spot early signs long before symptoms appear, which is why routine check-ups are so important — especially if you’re short-sighted, male, or have a family history of glaucoma, as these are known risk factors.

Even Rockstars Get It 🎵

You might not know it, but Bono, Dublin’s own U2 frontman, has glaucoma — and he’s spoken openly about it. The tinted glasses he’s famous for wearing aren’t just a fashion choice; they help reduce the light sensitivity that often comes with the condition.

It’s a reminder that eye health affects everyone, no matter how cool your sunglasses are or how famous you might be.

So next time you put on your shades, think of it as doing what Bono does — looking after your eyes while looking good.

In Summary

✨ Iris freckles — usually harmless, but worth monitoring.

🎗️ Iris nevi — rare risk of melanoma; check for change.

⚠️ Pigment dispersion — can raise eye pressure and cause glaucoma.

🎵 Even Bono’s got it! Regular eye care is for everyone.

Your eyes are masterpieces — tiny canvases of pigment and light. Keep an eye on those little details, because sometimes the smallest changes can tell the biggest stories.