Glaucoma, "the silent thief of sight"

What is Glaucoma?

Glaucoma is a common eye condition where the optic nerve, which is the "cable" that connects the eye to the brain, becomes damaged.

It is estimated that the global prevalence of glaucoma to be 3.54%. Statistical predictions suggest that the number of people with glaucoma worldwide (aged 40 - 80 years) will increase from 64.3 million in 2013 to 111.8 million in 2040.

Despite still not fully understood by researcher, glaucoma is commonly caused by fluid building up in the front part of the eye, which increases intra-ocular pressure leading to damage to the fibres and the cells of the optic nerve.

What are the types of Glaucoma?

There are several different types of glaucoma.

The most common is called primary open angle glaucoma. This tends to develop slowly over many years. It's caused by the drainage channels in the eye becoming gradually clogged over time.

Other types of glaucoma include:

acute angle closure glaucoma – an uncommon type caused by the drainage in the eye becoming suddenly blocked, which can raise the pressure inside the eye very quickly
chronic angle closure glaucoma – caused by a progressive narrowing of the irido- corneal angle (the anatomical site of the internal drainage system of the eye). This is generally linked with an anatomical predisposition and Long-sightedness (or hypermetropia)
secondary glaucoma – caused by an underlying eye condition; for instance a previous or recurrent inflammation in the eye or the use of certain drugs (such as steroids)
childhood glaucoma (congenital glaucoma) – a rare type that occurs in very young children, caused by an abnormality of the eye

What are the symptoms of Glaucoma?

Typically, people with the most common forms of glaucoma don’t experience any symptoms until the later stages of the disease, when severe damage to the optic nerve has already occurred, causing blind spots and vision loss.

Those with acute angle-closure glaucoma, which is less common, may experience pain and redness in the eyes and severe headaches. Some people with secondary glaucoma may also experience symptoms.

Without access to eye health services and regular screening every year, early signs of the disease can be missed, leaving it to progress and cause permanent visual impairment and blindness. Untreated, this can happen within 10 to 20 years.

How Glaucoma is diagnosed?

Glaucoma is usually picked up during a routine eye test, often before it causes any noticeable symptoms. Other tests are usually needed afterwards to diagnose and monitor the condition.

Eye pressure test

An eye pressure test (tonometry) uses an instrument called a tonometer to measure the pressure inside your eye.

A small amount of painkilling eye drops (anaesthetic) and dye are instilled on the front of your eye. Then, a light is shine into the eye and the surface will be gently touched by the tonometer.

The eye pressure can be measured also in other ways; for example by air-puff and rebound no-touch tonometers

Gonioscopy

This is an examination to look at the front part your eye – the fluid-filled space between the coloured part (iris) and the clear window of the front of the eye (cornea). This is where the fluid should drain out of your eye.

A gonioscopy can help to determine whether this area (the "angle") is open or closed (blocked), which can affect how fluid drains out of your eye. This will help diagnosing the type of glaucoma (Open or closed angle glaucoma). This is important because open angle and closed angle glaucoma have different treatment approaches

Visual field test

A visual field test (also called perimetry) checks for missing areas of vision. You may be shown a sequence of light spots and asked to press a button to indicate which ones you can see. Some dots will appear at the edges of your vision (your peripheral vision), which is often the first area to be affected by glaucoma. If you can't see the spots in the periphery, it may mean glaucoma might have damaged your vision.

Optic nerve assessment

The optic nerve, which connects your eye to your brain, can become damaged in glaucoma, so an assessment may be carried out to see if it's healthy.

For the test, eyedrops might be used to enlarge your pupils. Your eyes are then examined using:

a slit lamp (a microscope with a bright light)
optical coherence tomography (OCT) – a type of scan where special rays of light are used to scan the back of your eye and produce an image of it. This exam is safe and not invasive, and carried out in the outpatient department or at the optometrist practice.

The eyedrops used to widen your pupils could temporarily affect your ability to drive, so you'll need to make arrangements for getting home after your appointment.

How Glaucoma is treated?

There are several different treatments for glaucoma, including eyedrops, laser treatment and surgery. The best treatment for you will depend on your circumstances.

Treatment for glaucoma can't reverse any loss of vision that has already occurred, but it can help stop your vision getting any worse.

Treatment Plan

The treatment for glaucoma mainly aims to reduce the eye pressure to the safe level for your glaucoma stage and type (target eye pressure). Your treatment will largely depend on which type of glaucoma you have. The most common type, primary open angle glaucoma, is usually treated with either eyedrops or a type of laser called Selective Laser Trabeculoplasty (SLT). Surgery may be offered if drops and/or laser don't help.

Treatment for other types of glaucoma may include:

Angle closure glaucoma – the acute attack or acute angle closure is an eye emergency and needs to be treated as quick as possible in hospital. The first line treatment include eye drops and systemic drugs to quickly reduce the eye pressure; followed by a laser treatment called YAG laser iridotomy. The chronic version (or slowly progressive) of angle closure glaucoma can be treated temporarily with eye drops, but more definitive treatments include the YAG laser iridotomy and lens replacement (or cataract surgery)
secondary glaucoma – the treatment is mainly based on removing the cause of high eye pressure and, if this is not possible, reducing the pressure with eye drops, laser or surgery depending on the stage of damage.
childhood glaucoma – mainly surgery to correct the problem in the eye that led to the build-up of fluid and pressure

You'll also be advised to attend regular follow-up appointments (the cadence depends on the gravity of glaucoma) to monitor your eyes and check that treatment is working. It's very important not to miss any of these appointments.

Eyedrops

Eyedrops, along with SLT, are the first-line treatment for glaucoma. There are several different types that can be used, but they all work by reducing the pressure in your eyes.

They're normally used between 1 and 4 times a day. It's important to use them as directed, even if you haven't noticed any problems with your vision. Your sight might be at risk if you don't follow to the recommended treatment times.

You may need to try several types before you find the one that works best for you. Sometimes you may need to use more than one type at a time. Despite eyedrops are often considered the least invasive treatment for glaucoma can cause unpleasant local side effects, such as eye irritation, change in colour of iris, eyelashes and skin. Systemic side effects, such has angina exacerbation and breathing problems are also reported in some people with underlying general health conditions; for these people, some class of glaucoma drugs are contraindicated, it is therefore important to have a thorough conversation with your ophthalmologist regarding general health and medications before starting a new treatment.

The following is a general guidance on how to instil eye drops.

Wash your hands before and after applying the drops. To apply eyedrops:

use your finger to gently pull down your lower eyelid
hold the bottle over your eye and allow a single drop to fall into the pocket you have created in your lower eyelid
close your eye and keep it closed for a few minutes

If you're using different types of eyedrops, allow at least 5 minutes between using the different types. After you have put in the eyedrops, gently press in the inside corner of the eye (over the eyelid) for about a minute. This reduces the drainage of the eyedrops from the eye, which helps to increase its effect. It also helps to reduce systemic side effects.

Laser treatment

Laser treatment may be recommended if eyedrops don't improve your symptoms.

This is where a high-energy beam of light is carefully aimed at part of your eye to stop fluid building up inside it.

Types of laser treatment include:

laser trabeculoplasty – a laser is used to open up the drainage tubes within your eye, which allows more fluid to drain out and reduces the pressure inside
laser iridotomy – a laser is used to create holes in your iris to allow fluid to drain from your eye

Laser treatment is usually carried out while you're awake. Local anaesthetic drops are used to numb your eyes – you may just feel a brief twinge of pain or heat during the procedure. For more information on laser procedures please consult the procedures' information session and download your patient information leaflet

Glaucoma Surgery

Surgery may be recommended in cases where treatment with eyedrops or laser haven't been effective or not suitable for your eyes

Glaucoma surgery is divided in: conventional glaucoma surgery (Trabeculectomy and Glaucoma Drainage Devices, also known as "tubes") and minimally invasive glaucoma surgery.