The iris: the most attractive part of the eye

Without a doubt, the iris is one of the most attractive parts of the eye. Especially if they are blue or green tones. Many people with dark eyes would like to change the color of their iris but is this possible? In this article you will discover the different possibilities that exist as well as their advantages and possible complications.

What is the iris?

Let’s start at the beginning: what exactly is the iris?

It is a muscle that regulates the entry of light into the retina. It is an extension of the uvea -a vascularized structure that is located between the retina and the choroid (the white part of the eyeball)-. Anatomically it is located between the cornea and the crystalline lens.

Although it may seem so, it is not flat but rather a reticulated structure that forms quite pronounced ridges and valleys, although we can only see this through magnified images like the one in this image.

What gives the characteristic color to the iris?

Whether the iris has a lighter or darker color depends solely on one factor: the amount of pigment. Melanin is responsible for hair and skin color, but also for the color of our eyes. The greater the amount of melanin, that is, the pigment, the darker the eyes will be and the less amount they will have a more bluish or greenish hue.

But having light-colored eyes, which seems very attractive to the vast majority of us, has a great disadvantage and that is that the less pigment our iris has, the more light will penetrate the eye. That is why people with light eyes are much more bothered by clarity and often suffer from photophobia.

What is the iris for?

The function of the iris is to act as the diaphragm of a camera, that is to say, to regulate the entry of light into the eye. The more dilated it is, the more light it will let through. That is why at night our pupils are more dilated, to try to let in as much light as possible. On the other hand, during the sunniest hours of the day the iris contracts so that the light does not bother us.

What pathologies can the iris suffer?

It is not a structure that usually gives many ophthalmological problems, but when one appears it can be very annoying and difficult to treat. Next we will see the most common pathologies and also some others that are rare:



As we mentioned at the beginning of the article, the iris is an extension of the uvea, in fact it is where this structure ends. The uvea is highly vascularized and any condition that appears can easily be transferred to the iris. The most common uveitis. It is an inflammation of this structure. The symptoms are redness, pain, photophobia and poor vision. 


This is a notable difference in the size of the pupils. That is, in one of the eyes the iris will always be more dilated than the other. One of the most famous celebrities who suffered from this pathology was singer and actor David Bowie. Many people think that he had an eye of each color, but what really happened to him is that one of his pupils was always dilated.

Anisocoria can have a physiological origin and be present from birth or it can be caused by some type of trauma. In the case of Mr. Bowie, it was this second cause that caused him permanent paralysis. He specifically received a punch when he got into an argument over a girl. Curiously, the person who punched him ended up being one of his best friends.


This pathology is what causes a difference in tone between the two eyes of the same person. It does not cause any dysfunction or present a major problem beyond that color difference. It may be due to a problem present from birth or it may be a degenerative process through which pigment is lost and therefore changing its hue. Heterochromia can be total, when it affects the entire iris, or partial, if it affects only one part.



 Literally aniridia means absence of iris. People affected by this pathology have quite poor vision, especially during the day, since they are unable to regulate the entry of light. This causes photophobia in addition to a greater propensity to suffer from other diseases such as cataracts or glaucoma.


Albino people, in addition to having a very very light skin color, also suffer from other conditions derived from their disease. One of them is that they lack pigment in the iris, or have very little. This makes your eyes extremely light and let in too much light. The consequence is extreme photophobia that forces them to practically always wear sunglasses.


It is an inflammation of the iris and the ciliary body. The causes can be of an autoimmune nature or also due to some type of trauma. To treat it, it is best to go to the ophthalmologist who will decide the most appropriate treatment.


They have the appearance of a freckle on the eye. There is a growth of cells that provide the iris with a different coloration. The vast majority are benign and asymptomatic, but periodic control is recommended to assess their growth and evolution.

Castanera Ophthalmological Clinic is one of the most prestigious ophthalmological centers in Barcelona. We have the latest diagnostic instruments to treat any of these diseases. Our team of doctors, nurses and optometrists will answer any questions you have about these or other pathologies, providing you with fast and effective treatment.

How to keep the iris healthy?

The best prevention we can have to keep our iris in good health is to protect it from the sun’s rays. Choosing good sunglasses -always purchased in a certified establishment- will be our best ally not only to take care of our iris but also of the rest of the structures that make up our eye.

It is also recommended to have a complete ophthalmological check-up every year to control any alteration that may appear. At Clínica Castanera we always defend that the best ally to defeat any disease is prevention. Anticipating the appearance of certain diseases or stopping them at the beginning is key to maximizing the chances of success

Can you change the color of the iris?

And finally we go with the key question, can we really change the color of our eyes? The answer is no. The only recommended way to change the color of our eyes is by using colored contact lenses. Does this mean that there are other methods to change eye color? Yes. If we search the internet we will surely find different centers that offer some type of treatment or technique to vary the tonality of our eyes. The problem is that these techniques are not recommended because their side effects can seriously affect eye health. Let’s see some of these treatments and why we should not submit to them:


It consists of pigmenting the cornea, which is the transparent part of the eye that is in direct contact with the outside. To get an idea, it is like getting a tattoo on the cornea with the desired color. The problem with this technique, in addition to not changing the color of the iris but simply coloring the cornea, is that when the color is performed in front of the iris, it loses its functionality. In other words, even if the iris expands or contracts, it will always have an element in front of it that will prevent the entry of light, so the visual problems that this can cause are obvious.


 There is a type of laser capable of acting as a kind of scalpel at a distance. That is, without the need to perform any type of external injury, the laser is capable of treating an internal area of ​​the eye. With this technique we can de-pigment the iris based on shots on its surface, which causes it to lighten. The problem is that each shot releases a certain amount of pigment that can end up on the inner edge of the iris. Through this area is where the passage of a liquid, called aqueous humor, occurs, through which we regulate the pressure of the eye. If the released pigment obstructs the free circulation of the aqueous humor, it can cause an increase in intraocular pressure and cause serious pathologies such as glaucoma.


In our center we have witnessed many patients who have received this type of intraocular implant with truly terrible results. From totally destroyed iris, through damage to the crystalline lens and, above all, serious injuries to the optic nerve that cause irreversible loss of vision. These types of implants have a terrible quality and are excessively thick that blocks the free circulation of aqueous humor. The consequences are the aforementioned and the patient’s visual prognosis is usually not very good.

In  this video made by Fernando Castanera MD you can clearly see what type of implant it is, observing its poor quality thanks to some spectacular images obtained through a scanning microscope. The only solution is to flatten the artificial iris and give the patient the best treatment to recover his visual acuity to the maximum, but this will always depend on the magnitude of the damage caused.

In summary, the iris is a very beautiful structure, regardless of its color, the most important thing is to take maximum care of it so that it does not lose its functionality, as this would lead to a series of important visual problems.