Nevus of Ota: why that birthmark needs an eye doctor, not only a laser

People come to a clinic about this for the way it looks. That is completely reasonable, and it is usually how the condition gets found. The part that often goes unsaid is that in a large share of cases the same pigment is sitting inside the eye, where it cannot be seen in a mirror and cannot be reached by any laser.

So this article is not about whether to treat the skin. It is about the appointment that should happen alongside it, and that in my experience is the one people skip.

What is nevus of Ota?

It is a birthmark made of pigment cells that sit deeper in the skin than the cells that make an ordinary freckle or age spot. Because they are deeper, the light they scatter reads as blue, slate or grey rather than brown, which is why the patch often looks bruised or shadowed rather than pigmented.

Its distribution is the giveaway. It follows the territory of the upper branches of the trigeminal nerve, so it covers some combination of the forehead, temple, upper cheek and eyelids, almost always on one side of the face. It does not respect the boundaries a cosmetic problem would, and it does not fade the way post-inflammatory marks do.

It is considerably more common in Asian populations than in white ones, which matters for a Malaysian readership: this is not a rare curiosity here. It affects women far more often than men, at roughly five to one. About half of cases are present at birth, and most of the rest appear around puberty, sometimes in pregnancy, which points to a hormonal influence.

Why is it sometimes mistaken for dark circles?

Because a blue-grey shadow under one eye is exactly what dark circles look like, and dark circles are far more common. I have met patients who spent years on eye creams, concealer and pigment-lightening routines for something that was never going to respond to any of them.

Two features separate them. Dark circles are almost always symmetrical, on both sides, and they sit in the hollow under the eye where the skin is thinnest. Nevus of Ota is usually one sided and does not stop at the lower lid: it continues onto the temple, the upper lid or the cheek in a way that ordinary shadowing does not. If the white of the eye on the same side also has a slate-coloured patch, the question is settled.

The distinction matters practically. Genuine dark circles are often a mix of hollowing, thin skin and shadow, which is a different problem with different answers, and I have set that out in the piece on tear trough hollowing and why it is not the same as eye bags. Nevus of Ota is a pigment condition with an eye component, and it belongs on a different pathway entirely.

What does it do inside the eye?

The same pigment cells appear in the tissues of the eye itself, which is called ocular melanocytosis. The commonest place to see it is the sclera and episclera, the white of the eye and the thin layer over it, where it shows as a slate-grey patch. Pigment can also involve the iris, sometimes making the two eyes different colours, and deeper structures including the choroid, the vascular layer behind the retina.

None of this causes symptoms in itself. You cannot feel pigment. That is precisely why it needs looking for rather than waiting for.

What is the glaucoma risk, in plain terms?

Higher than average, because pigment accumulates in the part of the eye that drains fluid away. The eye continuously produces fluid and drains it through a mesh in the angle where the iris meets the cornea. When pigment cells collect in that mesh, drainage becomes less efficient, pressure rises, and sustained pressure damages the optic nerve. That is glaucoma, and in its usual form it is painless and silent until sight has already been lost.

The published figures vary with how strictly glaucoma is defined. Frank glaucoma is reported in a small percentage of affected eyes. When raised pressure and glaucoma suspects are counted as well, the proportion rises substantially, and it is markedly higher in people with eye involvement than in those whose pigmentation is confined to the skin. Both of those findings point the same way: if the eye is involved, the pressure needs watching, and watching it is straightforward.

The risk is on the same side as the pigmentation, and it can appear at any age rather than only in childhood. That is the reason monitoring is lifelong rather than a single clearance.

What about melanoma inside the eye?

This is where a lot of what you will read online does not apply to you, and I want to be precise rather than reassuring for its own sake.

There is a well known figure, roughly one in four hundred lifetime risk of melanoma inside the eye, which circulates widely. It comes from studies of white patients, in whom nevus of Ota is rare. The published evidence does not demonstrate the same increase in Asian populations, where the condition is far more common. Repeating a white-population figure to a Malaysian patient would overstate the risk considerably.

What is fair to say is this. Any pigmented tissue can, rarely, change. Routine dilated examination of the back of the eye is part of ordinary monitoring for anyone with ocular involvement, and it is the same appointment that checks your pressure. It is a reason to attend once a year, not a reason to worry between visits. If you want the broader picture on pigmented changes around the eye that do warrant attention, the article on eyelid skin changes that are not normal ageing covers what actually makes a lesion suspicious.

Does laser treatment deal with the eye as well?

No, and this is the single sentence I would like everyone with this condition to carry away. Q-switched and picosecond lasers work by breaking up pigment in the skin so the body can clear it, and they do this well, usually over several sessions. The result on the skin can be excellent. Dr Ong Jin Khang explains what a picosecond device actually does to pigment, and for anyone weighing up why one pigment modality is chosen over another, he has also set out how picosecond, Q-switched, IPL and topical options compare. Neither answers the question this article is about.

The pigment inside the eye is in different tissue, behind the cornea and the sclera, and no skin laser reaches it or is intended to. Clearing the visible patch changes nothing about the drainage angle, the pressure, or what is happening at the back of the eye. A treated face and an untreated eye is a real and fairly common combination, and it is the situation this article exists to prevent.

The skin side is properly the territory of a clinic that does pigment work. Dr Ong Jin Khang sets out what a pigment laser can and cannot reach, which is a more useful account of the treatment options than I could give, since that is his daily work and not mine. If the birthmark you are reading about belongs to a baby rather than to you, the paediatric half, including the baseline check an infant needs and when it should happen, is written by Dr Chan Li Yen in what a blue-grey birthmark around a baby's eye needs. What I would add to both is only this: book the eye appointment in the same week you book the first laser session, and keep it in the diary every year afterwards.

What monitoring do I actually need?

An ophthalmic examination once a year, for life, if the eye is involved. It should include a measurement of eye pressure, an examination of the drainage angle using a special contact lens, and a dilated look at the retina and choroid. That appointment takes under an hour and it is the whole of the surveillance.

If you have never been examined, that first visit is also the one that establishes whether your eye is involved at all, because some people have skin pigmentation alone. Either answer is useful. For a child, arrange it through a paediatric ophthalmologist rather than waiting for symptoms, since roughly half of cases are present from birth and an early baseline makes every later comparison meaningful.

The rest of the periorbital picture, what is ageing, what is structure and what is pigment, is worth understanding separately, and I have mapped it in what actually makes eyes look tired and across the aesthetics section. But for this condition the priority is simple and it is not cosmetic. Have the pressure checked.