The dangers of cosmetic procedures to permanently change eye colour

There appears to be no shortage of extremes people will consider in pursuit of an ideal appearance.

That may mean transferring their own fat to their buttocks, filing down teeth before fitting implants, or removing strips of scalp and inserting them elsewhere to address hair loss. However hazardous these cosmetic procedures may be, some people will still choose to accept the cost and risk.

Now, some are also opting for treatments intended to alter their eye colour permanently.

There are several ways this can be attempted, including implants that alter the visible appearance of the iris, iris tattooing and laser depigmentation.

Although these procedures can produce the look a person wants, they carry a wide range of possible complications, including blindness.

How the iris determines eye colour

The iris is the coloured ring around the pupil, and its structure is as intricate as its appearance is striking.

It contains two layers of smooth muscle, which operate without conscious control. By contracting and relaxing, these muscles alter the size of both the pupil and iris, regulating how much light enters the eye. They also help shield the eye's sensitive receptor cells from lasting injury.

The iris additionally contains two pigmented layers with melanin, the substance that determines eye colour. Six principal colours are recognised: brown, amber, hazel, green, blue and grey.

People with substantial pigment in both layers tend to have darker eyes, such as brown. Brown is the most prevalent eye colour, occurring in around 80% of the world's population.

With less pigment in the front layer, eyes may be hazel or green. These are the rarest colours and occur in only 2% of the population. People with very little or no melanin in this front layer have blue or grey eyes.

Eye colour procedures: solving a problem or causing one?

Surgery involving the eye, and particularly the iris, is far from recent. Cataract operations can be traced to the 5th century BC, while the practice of colouring eye scars has existed for more than 2,000 years.

Until comparatively recently, such operations were carried out to rebuild the iris or correct a defect. Cosmetic procedures designed to permanently alter iris colour, however, are becoming increasingly common.

Keratopigmentation is one such procedure. A needle is used to make a series of tiny cuts in the cornea, the transparent protective outer layer of the eyeball. Pigment is then placed within this layer to create a permanent colour change. The method has roots going back thousands of years, and many pigments, including soot, have been tested.

Lasers can likewise be used to remove pigment from the iris's outer layer, changing brown eyes to pale blue or grey. In depigmentation procedures, a laser burns away pigment along with the cells that produce it.

This method is only suitable for moving from darker to lighter eye colours; it cannot achieve the reverse change. At present, it is not possible to introduce or deposit additional melanin into an iris where it is absent or present in only small amounts.

Depigmentation was first developed for ocular dermal melanosis. In this condition, pigment cells fail to migrate to their intended locations, which can make other parts of the eye, including the whites, become darker.

Treatment for this condition can involve several sessions, but its effects are normally permanent, just as they are when the technique is used for cosmetic alteration.

Risks of iris implants, keratopigmentation and laser depigmentation

Both keratopigmentation and laser depigmentation present a substantial infection risk because they disrupt the eye's outermost layers.

They may also lead to sensitivity to light and changes in vision, including blindness, corneal thinning and perforation, glaucoma, and cataracts. Some people who have undergone keratopigmentation have also reported eye pain while having MRI procedures.

Another method used by some people seeking to alter their eye colour involves inserting silicone implants into the eyes.

An Instagram model who underwent this procedure suffered serious complications that left her with the vision of a 90-year-old: she lost 50% vision in one eye and 80% in the other. Similar complications have been reported by others.

These implants carry a considerable risk of infection and further problems, including altering the eye's shape and changing how fluid inside the eye applies pressure to the optic nerve. Because this nerve governs vision, compression can result in blindness.

There is not enough evidence to support the cosmetic use of any of these procedures. As with many treatments undertaken for appearance alone, a short-term benefit may bring the prospect of longer-term harm. Complications have been reported even where these procedures are used to manage medical conditions.

Anyone considering one of these procedures should ask whether changing an unwanted eye colour is worth the possible risk of blindness.

A well-established, safe alternative for changing eye colour is to use prescribed coloured contact lenses.

Adam Taylor, Professor and Director of the Clinical Anatomy Learning Centre, Lancaster University

This article is republished from The Conversation under a Creative Commons licence. Read the original article.