What is glaucoma? A guide from an expert

Glaucoma is a common cause of vision loss. It can develop over time, slowly chipping away at the individual’s eyesight. But what exactly is this condition? We asked leading ophthalmologist Mr Suman Biswas for answers.

Glaucoma is a condition which can cause blindness if not detected early, and is due to raised pressure of the fluid within the eye (intraocular pressure, or IOP). It does not usually cause any symptoms in the initial stages.

There are two main types of glaucoma:

• Asymptomatic (open-angle) glaucoma – the most common type doesn’t cause symptoms in the early stages, so people are often not aware they have glaucoma. When high pressure has damaged the optic nerve, they develop symptoms of restricted peripheral vision, and by the time they seek help, they have already irreversibly lost their field of vision. However, the progression of the disease can still be arrested and further damage prevented by treatment.
• Closed-angle glaucoma – less common. The IOP increases to very high levels very quickly, and that can cause painful red eye with headache, for which the patient should immediately come to A&E.

There are various other sub-types/variants. For example, in normal-pressure glaucoma, the IOP is not high, but damage to the optic nerve still occurs, as do a reduction of the patient’s field of vision and loss of sight.

What causes glaucoma?

The cause is essentially not known, but it is thought that genetics are involved, with genes being identified as playing a role. It is important to know that glaucoma runs in families. Therefore, people with family histories should keep regular appointments with opticians to check the pressure in the eye and have their field of vision checked in addition to the normal glasses check-up.

Glaucoma cannot be prevented, but when it starts, the main thing is to identify it quickly so that adequate treatment can be done to prevent the condition from worsening.

What are the possible treatment options for glaucoma?

Traditionally, the initial line of treatment had been medication in the form of eye drops. If the condition is progressing despite eye drops, then the next line of treatment could be lasers or surgery.

There are different types of lasers, but the most widely accepted modern type is SLT (selected laser trabeculoplasty). Lasers are an alternative to treatment with eye drops. However, because SLT is very safe, it has also been advocated as the primary treatment.

SLT works best in the early stages of glaucoma, with open anterior chamber angles. It can also be useful as adjunctive therapy alongside medical treatment in the form of eye drops.

If the glaucoma is progressing despite the above treatment, surgery is considered as it is very effective in lowering the intraocular pressure.

How is glaucoma surgically treated?

There are different kinds of surgery. Trabeculectomy is the gold standard and has stood the test of time.

There are various stents and tubes which have also been developed to lower the pressure, and are still in evolution. Notable among them are the iStents® and Xen® implants. There are tube implants like Baerveldt®, Molteno®, and Ahmed implants, which are used for refractory glaucoma which has not been controlled with any other types of surgery.

In glaucoma with very poor vision, cyclodiode lasers are sometimes used to reduce the eye pressure and relieve pain, although it cannot improve vision.

The prime consideration is that, because glaucoma damage is irreversible, it is necessary to diagnose in the early stages and treat effectively to prevent sight loss.

Learn more about glaucoma, other eye conditions, and how to treat them at Mr Biswas's profile, or book an appointment.