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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.
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.
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.
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 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).
This occurs due to the mechanical obstruction of the drainage angle and is associated in a sudden rise in the 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.
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 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.
Although we know 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.