There seems to be no limit to the things people are willing to do in order to achieve the perfect look.

Whether that's getting their teeth shaved down and fitted with implants to having strips of skin from their head removed and re-inserted to treat baldness. No matter how risky such cosmetic procedures are, there are always people willing to pay the price.

Some people are now even undergoing procedures to permanently alter the colour of their eyes.

This can be done in a variety of ways – such as having implants to change the appearance of their iris, having their irises tattooed or having laser depigmentation.

While these procedures may give people their desired look, they also come with a whole host of risks and complications – one of which is blindness.

The iris is the coloured ring that surrounds the pupil. It's every bit as complex as it is beautiful.

It consists of two layers of smooth muscle (which we cannot control). These muscles are responsible for shrinking and expanding the size of the pupil and iris in order to control the amount of light going into the eye. These muscles also protect the sensitive receptors cells within the eye from permanent damage.

The iris also has two pigmented layers containing melanin which determine your eye colour. There are six main recognised colours: brown, amber, hazel, green, blue and grey.

If you have lots of pigment in both layers, your eyes will be a darker colour – such as brown, which is the most common eye colour (occurring in around 80% of the world's population).

If you have less pigment in the front layer, you will have hazel or green eyes (the rarest colours, found in only 2% of the population). Those with little or no melanin in the front layer will have blue or grey eyes.

Fixing the problem or creating one?

Surgeries on the eye, particularly the iris, aren't a new thing. Eye operations for cataracts date back to the 5^th century BC and colouring scars in the eye has been around for over 2,000 years.

Until recent years, surgeries were performed in order to reconstruct the iris or repair a defect. But cosmetic procedures to permanently change the colour of the iris are now starting to become more common.

Keratopigmentation is an example of one of these procedures. A series of small incisions are made with a needle into the cornea (the clear protective layer of the eyeball). Pigments are inserted into the layer to permanently change it. This technique dates back thousands of years, with a variety of pigments having been trialled, including soot.

Similarly, the use of lasers to remove pigment from the outer layer of the iris can change brown eyes to light blue or grey. Depigmentation procedures do this by burning away the pigment and the cells that make the pigment using a laser.

This technique can only be used to go from darker to lighter eyes and won't work on people wanting to go the other way. This is because it's currently not possible to add or deposit more melanin into the iris if it's already absent, or there isn't very much.

Depigmentation was originally developed to treat ocular dermal melanosis, a condition where the pigment cells don't migrate where they need to be, causing other parts of the eye (such as the whites) to darken.

This condition may require a number of rounds of treatment but is usually permanent, as is cosmetic alteration.

Both keratopigmentation and laser depigmentation hold significant risk of infection as they compromise the eye's outermost layers.

These procedures can also cause light sensitivity and vision changes – including blindness, thinning and perforation of the cornea, glaucoma, and cataracts. Some patients who have had keratopigmentation procedures have even complained about experiencing eye pain during MRI procedures.

Another procedure some people are using to change their eye colour is having silicone implants inserted into their eyes.

One Instagram model who had this procedure done experienced significant complications which left her with the sight of a 90-year-old – losing 50% vision in one eye and 80% in the other. Others have reported similar complications too.

These implants bring a high risk of infection and other complications – such as changing the shape of the eye and how the fluid within the eye exerts pressure on the optic nerve. As this nerve controls vision, blindness can occur if it's compressed.

There isn't sufficient evidence to support the use of any of these procedures cosmetically. As with so many things that are done for cosmetic reasons, a short-term gain sets you up for potential longer-term pain. Even when these procedures are used to treat medical conditions, complications are reported.

If you're considering undergoing one of these procedures, ask yourself if it's worth potentially going blind just because you don't like the colour of your eyes.