Microinvasive glaucoma surgery (MIGS)

Glaucoma drainage microimplants, the so-called MIGS techniques (minimally invasive glaucoma surgery) or microinvasive techniques are new surgical options for the control of eye hypertension and the treatment of glaucoma.

One thing they all have in common is the slight manipulation of the eye tissue, with the highest level of safety and efficacy possible. As they are less invasive techniques, they also bear lower risks and fewer postoperative troubles for the patient.

In the last decade, various surgical devices have been developed to control eye hypertension and glaucoma. To fit under the term MIGS, they have to meet the following five criteria:

1. Ab-interno approach [from the inside] to preserve the conjunctiva (although lately ab-externo approaches [from the outside] have been considered). 
2. That they are minimally traumatic for the target tissue.
3. Contrasted efficacy in terms of the reduction of intraocular pressure. 
4. High safety profile to avoid major complications in comparison with other glaucoma surgeries
5. Quick recovery with a minimum effect on the patient's quality of life.

These new surgical methods may be beneficial for patients with open angle glaucoma who are at an early to moderate stage of the disease, as it may be an alternative to some medical and laser treatments.   

MIGS are an option to consider in the approach to commonly associated pathologies like cataracts and glaucoma in one single operation, which is a huge advantage for the control of the disease. 

In terms of the available MIGS, the criteria to apply for one technique or another basically depends on the stage of the disease, characteristics of the eye like the state of the conjunctiva and the cornea as well as the degree of the angular width. 

Patients with more advanced glaucoma are candidates for other surgical techniques like filtration surgery (trabeculectomy and non-penetrating deep sclerectomy) and glaucoma drainage devices (Ahmed or Baerveldt are the most typical).

Glaucoma is normally due to an increase in eye pressure due to an excess of fluid (aqueous humour) when the eye's drainage channels are blocked. The job of these devices, which are made from biomaterials, is to encourage this aqueous humour to filter, in order to restore the balance of the entry and exit thereof and, therefore, regulate the intraocular pressure. 

An injector is normally used to implant them. As we have mentioned, these surgical techiques can be performed on their own or in combination with cataract removal.

The main result of these micro implants is a reduction of eye pressure.

Compared with hypotensive eyedrop treatment, which leads to fluctuations in eye pressure between doses, and requires patients to be very consistent in applying it, MIGS give them more regular levels of pressure.

Compared to the other "classic" filtration surgeries for the treatment of glaucoma, these devices are advantageous as the implant procedure is shorter, less invasive and usually required less postoperative check-ups. 

These new devices save on possible complications. The MIGS implants shorten the duration of surgery as well as the postoperative period, reducing it to just a few weeks. This translates to fewer risks for the patient. 

During surgery there are usually very few complicaitons. There may be minor bleeding in the eye during the operation. In this case, the eye might be affected and the patient's vision might be blurred for a few weeks until its complete reabsorption. 

As in all glaucoma procedues, with the passing of time, the hypotensive effect of these implants stops being so effective. In the majority of cases, this occurs because of the scarring of tissue and appearance of fibrosis. When this happens, additional measures can be taken to control eye pressure. 

Altough they are exceptional, like in all surgeries there is a possible risk of infection.