Glaucoma

Causes

The most common cause of glaucoma is excessive intraocular pressure. Intraocular pressure is generated in the chambers of the eye between the cornea and the lens. The chambers of the eye contain a fluid, known as the aqueous humour, which is formed in the eye itself. It flows continuously from the posterior to the anterior chamber of the eye and from there out again through a very fine channel. This circulation ensures a constant pressure in the healthy eye.

If the aqueous humour is no longer able to drain properly, it builds up, resulting in an increase in intraocular pressure. This process strains the optic nerve and there is a risk of nerve cells dying off. The resilience of the optic nerve determines whether the increase in intraocular pressure leads to damage or not.

Fortunately, the optic nerve is only susceptible enough to actually become damaged in some of those experiencing increased intraocular pressure. However, if the aqueous humour no longer flows at all, the intraocular pressure suddenly increases excessively; the reason for this is that drainage of the aqueous humour is completely blocked in such cases (known as narrow-angle glaucoma).

The intraocular pressure is measured in mmHg (millimetres of mercury) – this is the same unit that is used for measuring blood pressure. “Healthy” intraocular pressure is between 10 and 21 mmHg. However, intraocular pressure in glaucoma is not always above normal levels. In almost half of all people suffering from glaucoma, damage to the optic nerve can be detected, but no increased intraocular pressure can be observed. In the medical profession, this form of glaucoma is known as “normal tension glaucoma”, because it is assumed that normal intraocular pressure is already too high for those affected.

Inadequate blood supply to the optic nerve can also be the cause of glaucoma. In this case, the nerve cells are not adequately supplied with oxygen and nutrients. Glaucoma can also occur as a consequence of inflammation, injuries and vascular diseases. Experts refer to this as secondary glaucoma. And there are even rare cases where glaucoma is congenital.

In addition, old age, family history, severe short-sightedness and diabetes increase the risk of glaucoma.

Treatments

Conservative therapies

Long-term reduction of intraocular pressure can help to delay or stop the gradual loss of vision. However, glaucoma cannot be completely cured, as damage to the optic nerve is irreversible. In the case of glaucoma, intraocular pressure is usually treated with eye drops. Depending on the preparation, it can be used once or several times a day.

Regular check-ups by an ophthalmologist are also important. These are offered one to three times a year (depending on how far glaucoma has already progressed).

Laser treatment or surgery

If the prescribed medication is no longer sufficient or poorly tolerated, a procedure using laser technology or surgery (known as minimally invasive glaucoma surgery) may be considered.

If you need glaucoma surgery, your ophthalmologist will suggest the surgical method they believe is most appropriate to maintain your vision for as long as possible and to best reflect the current situation. Surgery for glaucoma can neither eliminate it nor improve vision. The aim of minimally invasive glaucoma surgery is to reduce intraocular pressure by creating an alternative drainage channel to slow down or even stop the progression of the disease.

Surgical treatment

1. Filtration surgery involves placing a drain between the anterior chamber of the eye and the scleral (from sclera; this encases the eyeball up to the edge of the cornea) or subconjunctival space, i.e. below the conjunctiva. In certain cases, it may be necessary to use mechanical devices, i.e. implants, or chemical agents to facilitate filtration. As regards filtration surgery, the surgeon again has two procedures at their disposal to reduce intraocular pressure: With the procedure known as trabeculectomy, a recess is cut into the trabecular meshwork (part of the anterior chamber angle and the main drain for the aqueous humour in the eye; it consists of loose tissue that looks like a sponge when viewed under a microscope), which requires the eye to be opened during the procedure. With the procedure known as sclerectomy, on the other hand, the outer wall of the eye is thinned out in a defined “window area” – not at the surface, but deep inside the eye – so the aqueous humour can flow out of the eye more easily via the now wafer-thin membrane.
    

2. Operation with Baerveldt implant: Here, the sclera is opened in order to insert a Baerveldt implant. A Baerveldt implant is a silicone tube that can be used to drain aqueous humour from the anterior chamber (the part of the eye between the cornea and the iris) into the eye socket behind the eye. The tube is connected to a base plate, also made of silicone, which is curved so it can be easily placed on the eyeball. This base plate is secured behind the eye. This allows eye water to drain into the eye socket and lowers intraocular pressure.
    
3. The third option also uses an implant, namely the eyeWatch system, the world’s first adjustable system for treating glaucoma. The system functions as a non-invasive controllable switch. The eyeWatch implant is the heart of the system. This is a microscopic device that can be implanted directly into the eye. It is comparable to a tiny tap with remote control via a magnetic plate. When treating refractory glaucoma (immune to influence, showing a lack of sensitivity) it is possible to control the amount of fluid in the eye affected by glaucoma.

Please note: A glaucoma episode must be treated quickly to avoid damage to the optic nerve. This is why it is important to go to a doctor’s surgery or eye hospital immediately if symptoms such as acute visual disturbances and eye pain occur.