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Glaucoma | Types, Assessment and Treatment

In most cases, but not always, glaucoma is associated with a rise in intraocular pressure. Intraocular pressure is generated through a balance between the production of aqueous fluid (which keeps the eye formed) and its outflow through the eye. It is measured using a number of different tools and these can be divided into non-contact (for example air puff tonometer) and contact (for example Goldman applanation tonometer) tonometers.

What is glaucoma?

Glaucoma is a family of disorders which if left untreated can cause progressive and irreversible damage to the optic nerve. The optic nerve is essentially the cable wire transferring visual information from the eye to the brain. The damage to the visual system tends to be in a characteristic pattern with a corresponding loss in visual field. It is the commonest cause of irreversible blindness worldwide and by 2020, there will be an estimated 80 million people suffering with glaucoma.


Types of glaucoma

Glaucoma can be divided based on whether or not the drainage angle within the eye is open or closed as well as if there is a secondary cause for the glaucoma or not.

Open angle glaucoma:

This is the commonest type of glaucoma. In most cases, the patient is asymptomatic and it is incidentally identified, often at a routine eye test. It can be associated with high eye pressure or normal eye pressure. This can be primary (without another identifiable cause) or secondary (due to other conditions such as pseudoexfoliation or pigment dispersion syndrome).

Risk factors: age, family history, glaucoma in the fellow eye, race (more common in Afro-Caribbean), systemic disease (for example high blood pressure).

Closed Angle glaucoma:

This occurs due to the mechanical obstruction of the drainage angle and is associated with suddenly high eye pressure. Again, the cause for this can be primary (anatomically narrow angle) or secondary (for example diabetes, and previous inflammation). The eye pressure can suddenly rise and cause an attack of acute angle closure. This is an ophthalmic emergency and will need immediate treatment. The symptoms of acute angle closure include severe headache, nausea, vomiting, blurred vision and haloes. During an attack, the eye becomes red and the pupil (the black circle in the eye) can look distorted.

Glaucoma assessment

As glaucoma is a progressive disease, normally, a series of examinations are required before a definitive diagnosis is made.

At the initial assessment, you will have a number of investigations, some of which will need to be repeated at every visit. A thorough medical history will be taken, and then you will undergo a slit lamp examination, first looking at the front segment of the eye, checking the intraocular pressure, assessing the drainage angle and looking for any secondary causes for glaucoma. If it is safe to do so, you will have dilating drops instilled to the eyes and the back (posterior segment) of the eye will be examined. You will also undergo imaging of the optic nerve to objectively assess the nerve fibre layer and keep an accurate record of the optic nerve status.

Finally, you may be asked to perform a visual field test that will show if there is damage to the vision.

The results of the examination and the glaucoma tests will then all be explained in detail and if the diagnosis of glaucoma is made, we can then proceed to talk about the various treatment options.


Glaucoma treatment

Although we know high eye pressure is not the only cause of glaucoma, at present our only way to halt any further glaucoma damage is by controlling the pressure. All the different treatment modalities in principle work in 2 ways: decrease production of aqueous fluid or increase its outflow in order to lower the eye pressure.

Please read our glaucoma procedure page for the different treatments and surgeries available for treating glaucoma.

Glaucoma FAQs

Find out the answers to some of the most frequently asked questions about glaucoma, from our expert surgeon Ms Sally Ameen.

Is glaucoma hereditary?

It can be. Research suggests that genetic and hereditary factors can increase not only the risk of developing glaucoma but the severity of the disease. Studies have shown those with a first-degree relative (parent or sibling) with glaucoma have an almost 10-fold risk of developing early onset glaucoma. There are a number of genetic mutations that have been identified, but it is felt there is still more to learn about the genetic makeup of glaucoma and how it is passed on.

What is the first sign of glaucoma?

In most cases, glaucoma does not cause any signs or symptoms in the early stages of the disease. This is why it is known as the thief of sight. For the commonest type (primary open angle glaucoma), the eye pressure rise is so gradual that the patient remains asymptomatic and it is detected incidentally. As the disease progresses, the patient can develop a visual field defect, which is like an enlarged blind spot, where part of the vision is blurry or completely missing.

In a subgroup of glaucoma, the angle closure type, there is a sudden rise in the eye pressure, which can cause pain in the eye, redness, blurring of the vision as well as systemic signs like headache, nausea and vomiting.

Can glaucoma be cured?

Any damage to the vision from glaucoma whatever its subtype cannot be reversed. The optic nerve is an extension of the brain and it does not re-generate once lost. The treatments provided are to halt the disease progression as opposed to reverse it.

There is a subtype of glaucoma that can be “cured”: for patients where the cause of glaucoma is a narrow drainage angle, the condition can be indefinitely reversed following surgery. But again, if the nerve has already been damaged from glaucoma, even changing the drainage angle will not reverse this.

Can you drive with glaucoma?

The simple answer is yes. The DVLA have strict guidelines to follow and someone who is diagnosed with glaucoma undergoes annual assessment of their vision. The assessment includes visual acuity (sharpness) as well as a field of vision assessment that is performed with both eyes open and with the use of any correction to the vision needed. If the disease is too advanced at the time of diagnosis or continues to progress, then the person may be deemed unfit to drive. This decision is made by the DVLA and not your ophthalmologist based on their assessments that are performed at independent centres.

What does glaucoma vision look like?

Glaucoma affects “field of vision” and not “acuity” (until much later on in the disease). This means parts of the vision, usually the outer parts, are blurred or completely missing. This continues progressing and can leave the patient with only a central island of vision and if the disease is not halted, the vision can be lost completely and glaucoma will cause irreversible blindness.

Why take glaucoma eye drops at night?

There are a number of different groups of eye drops that can be used to control eye pressure. One of them (prostaglandin analogues) have been shown to be most effective if taken at night time. That would be the reason your ophthalmologist would recommend taking the medication at night time – to increase its effectiveness.

Are eye floaters a sign of glaucoma?

No, eye floaters usually occur to the ageing breakdown of the vitreous- the jelly cavity inside the eye. This is a natural ageing process that happens for most people and is not linked to glaucoma.

Can eye drops affect the heart? Can they cause headaches?

Yes, a specific group of drops (Beta blockers) can cause a number of systemic side effects. These include reducing both the heart rate and blood pressure. They can also cause headaches as well as sleep deprivation. One way to minimise the systemic effects of the eye drops is to reduce their absorption into the circulation. This can be done by pressing on the side of the nose next to the inner eye corner to block the tear duct immediately after the drop is installed. Then, the pressure can be removed after 20 seconds.