Glaucoma Surgical Treatment

What does it entail?

The aim of surgical treatment of glaucoma, like medical treatment of the same disease, is to control intraocular pressure by reducing and stabilising it for 24 hours in order to prevent fluctuations. Most surgical techniques achieve this goal by creating a new pathway for aqueous humour drainage. We could say that the aim of surgical procedures for glaucoma is to construct a new “drainage canal”. All such surgeries are classed as Filtering Surgery because they help to filter aqueous humour outflow.

Which patients and diseases are suitable for such treatment?

All patients can undergo an operation to create a new “drainage canal” to reduce intraocular pressure, but not all techniques are equally effective and not all have the same requirements to achieve their goal. Therefore, the ophthalmologist must decide which technique is most suitable for each patient. The effectiveness of surgery will depend on the type of glaucoma being treated, the eye being operated on and its previous condition.

What is the position of ICO regarding these surgical techniques?

ICO and its Glaucoma Unit is and has been the reference centre for glaucoma surgery techniques for more than 20 years, both nationally and internationally. A large number of professionals have received surgical and clinical training at our centre under the watchful eye of Dr Susana Duch.

What are the different procedures?

The aim of classic techniques is to create a pathway for aqueous drainage by forming a fistula between the anterior chamber and the subconjunctival space. Once the aqueous humour leaves the inside of the eyeball and reaches the subconjunctival space, it is absorbed into the general circulation.

The latest techniques, many of which are still being studied, try to achieve the same goal by returning the aqueous humour to the general circulation using micro-invasive techniques, called MIGS. These techniques are less aggressive and aim to minimise complications.

Is there any major risk?

As with any surgery, glaucoma surgery carries two main risks, infection and bleeding. With glaucoma surgery, these complications are very uncommon. The biggest hurdle of glaucoma surgery is scarring. A healthy body's ability to close wounds causes the fistula created in order to drain the aqueous humour to heal, closing up the drainage canal we have made. We could say that a healthy body makes it more difficult for filtering surgery to be successful.

Other risks of glaucoma surgery include: excessive filtration (over-filtration), appearance of a filtering bleb due to poor wound closure, abnormal deviation of the aqueous humour to the posterior chamber of the eye and late-onset leakage.

Is it a good idea to have any tests done before the operation?

It is vital to check for adequate clotting prior to the glaucoma surgery to avoid complications. All other pre-operative requirements are the same as for any ophthalmic surgery.

What is the post-operative period like?

The post-operative period following glaucoma surgery may be quite tedious as scarring of the wound and fistula is different in each patient. Therefore, check-ups and treatment are personalised. We cannot say that surgery has been a success until a month has passed and all scarring phenomena have been controlled. Even so, the risk of fistula closure is always present, even years after the operation. Therefore, intraocular pressure should continue to be monitored regularly, despite having had a successful operation.  During the post-operative period, the ophthalmologist will monitor and assess the state of the fistula and the scarring reaction by performing actions that increase or decrease scarring, according to the needs of each patient.

What are the possible outcomes and what does this depend upon?

The outcome depends on each technique chosen, the type of glaucoma treated and the anatomical state of the eyeball. For the time being, there is no surgical technique for glaucoma with 100% guaranteed success.

The second, but equally important variable is the surgeon's experience, which in this case is vital for personalising and monitoring not only the processes of the operation itself but also the progress of each individual patient, with expert vision.

What are the different surgical techniques exactly?

From least aggressive to most aggressive, we have:

MIGS (minimally-invasive glaucoma surgery)

• Non-Penetrating Deep Sclerectomy
• Canalostomy and Canaloplasty
• Trabeculectomy and Trabeculotomy

Subconjunctival Drainage Implants: implants with or without a valve system

At the same time, many of the surgical techniques for glaucoma are accompanied by anti-scarring substances that limit the eye's ability to close and heal the fistula. The most commonly used are 5-fluorouracil and mitomycin-C.