What is coloboma, Madeleine McCann’s eye defect? What causes it and how rare is it? Here’s all you need to know


DOZENS of images of missing Madeleine McCann were released over a number of investigations to find her.

Police officials always urged people to look out for the mark in her right eye. But what exactly is it?

The most common form of coloboma makes a person’s pupil look like a keyhole – rather than a round shape

What is coloboma?

Coloboma is a gap in part of the eye’s structure, normally towards the bottom of the eye.

It can affect just one or both eyes, and does not mean that there is a hole in the eyes – just that they did not fully form during pregnancy.

Madeleine McCann has coloboma in her right eye
PA:Press Association

Coloboma can affect the iris, lens and retina. It is hard to tell how much a child’s vision has been affected until they are older.

The most common form of coloboma is the one affecting the iris – often giving the sufferer a pupil shaped like a keyhole.

Children with this form tend to have fairly good vision, although they might dislike bright lights.

How common is coloboma?

Coloboma is extremely rare, only occurring in one in 10,000 births.

While Maddie’s mark could affect as few as seven out of one million people.

This mock-up image of Maddie aged nine, made four years ago, shows the tell-tell mark in her eye
PA:Press Association

Speaking of facial recognition software, retired detective chief inspector Mick Neville told The Sun: “If an image search was carried out for females in an age range of three to 15 with this eye marking then you may only have a few hundred in the UK and tens of thousands worldwide.

“It would be an easily manageable number to scan through.”

What causes coloboma?

Coloboma occurs when a baby’s eye or eyes do not develop properly during pregnancy – which happens between the fourth and 15th week after conception.

Sometimes it is inherited, but in most cases there is not a genetic link.

However, if your child has coloboma then you yourself should get your eyes tested – in case you have undiagnosed problems.

Not much is known about other causes of coloboma.

How is coloboma treated?

Coloboma cannot be cured – but is monitored with six monthly and then yearly eye checks.

Some children with coloboma may need to wear glasses, and adults can get cosmetic contact lenses to make the pupil look round.

Prescription sunglasses are sometimes advised, because of the light sensitivity.



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