What is iris surgery?
The iris, commonly known as the colour of the eyes, is a muscle that has an orifice in the centre called the pupil. This muscle makes the pupil change size depending on the light conditions, allowing the light to enter the retina to a greater or lesser degree, and it also influences the eye's capacity to focus.
The smaller the pupil, the better things focus from a distance. When there is less light, the pupil needs to expand so that more light enters and we can see better in the dark, such as at night.
The iris can be damaged in many ways and with surgery we aim to reform the eye diaphragm.
When is this surgery indicated?
When the iris has suffered trauma, or with corneal and anterior segment disease affecting it.
It may also be indicated in situations where the iris stops working, which is called paralytic mydriasis, in which the sphincter muscle of the iris or the dilator muscle of the iris is affected. It may have been broken or severed, or may even be completely missing in cases of aniridia.
Aniridia may be traumatic, a blow may make the iris come out of the eyeball or it may be expelled through trauma. In the case of congenital aniridia, patients are born without an iris.
The aim of iris surgery is to try to reshape the eye diapragm. Evidently, restoring mobility to the iris when it has a neurological problem caused by a trauma is not within the scope of science these days, but we can implant artificial irises or suture the iris in the case of losses.
In general, we have two large groups of techniques, the so-called pupilloplasties or iridoplasties in which by using sutures, we can try to reconstitute the meridian diagram, by suturing the fragments and trying to close the defects, which may be large or small.
Another group of techiques is one whereby artificial irises are implanted or segments of the iris are implanted using a series of prostheses that are placed inside the eyeball. Generally, this type of surgery is usually associated with cataract or cornea transplant surgery, since the whole anterior segment is usually affected.
How is it performed?
It is a surgical procedure performed with local or general anaesthesia. It is carried out by making small incisions in the peripheral part of the cornea.
If a corneal transplant has to be undertaken, iris surgery is much easier since we have an opening of about 8 or 8.5 mm and we can gain access to perform the iris suture in a much easier way.
In general, iris surgery is not carried out in isolation except in cases such as tumours: the so-called iridocyclectomy. When there are iridian tumours, usually melanomas, it is also necessary to cut off part of the iris root or even the ciliary body.
The results are usually good and, although the mobility cannot be restored to the iris if the sphincter muscle was affected, we can try to create a pupil of an intermediate size of 3.5-4.5mm, which gives the patient better quality vision.
Therefore, in general, the results are good but they will always depend on the state of the remaining or affected tissue associated with the iris.