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Glaucoma
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Glaucoma

Glaucoma is a disease caused by high ocular pressure which compresses and damages the optic nerve fibres which leads to a progressive loss of vision starting at first on the periphery and then progressing towards the centre.

This disease is often the result of an incorrect balance between the production of intra-ocular fluid and its evacuation. In rare cases, ocular pressure is not the cause but inadequate blood circulation causes necrosis of the optic nerve cells and the retina. This leads to the same result.

There are many forms of glaucoma. The two main types are open-angle glaucoma – the most common form – and closed-angle glaucoma, much rarer.

What are the symptoms?

In the case of open-angle glaucoma, most people show no symptoms or particular signs. In effect, this type of glaucoma develops slowly and sometimes without any apparent loss of vision for many years. However, ultimately the appearance of blind spots is noticed in the peripheral field of vision.

The symptoms of closed-angle glaucoma are acute and may include headaches, eye pain, nausea, halos around lights at night time, very blurred vision.

Who is affected?

Glaucoma can affect anyone. However, some groups are more at risk than others:

People over 45 years of age
People who have a history of glaucoma in their family
People who have a particularly high intraocular pressure
People of African origin
People suffering from diabetes, short-sightedness who have used steroids or cortisone
People who have suffered an eye injury

What are the causes?

Glaucoma results from high ocular pressure, generally caused by insufficient evacuation of the fluid produced in the eye. Optic nerve damage results. Certain illnesses may also contribute to an increase in ocular pressure.

Although, in the case of open-angle glaucoma, things develop slowly, in closed-angle glaucoma, intraocular pressure rises suddenly. The cause of this phenomenon is due to insufficient space between the iris and the cornea, which causes sudden obstruction of the drainage system. In this type of glaucoma, ocular pressure rises in the space of a few hours up to very high levels and can destroy the optic nerve within 2 or 3 days. This causes blindness.

Lastly, there are secondary forms of glaucoma which can result from an eye trauma, an inflammatory eye disease or taking certain drugs such as steroids.

What is the evolution?

If open-angle glaucoma is not diagnosed and treated, it causes a progressive loss of vision. The visual field defects are permanent and irreversible. Without treatment, this disease can lead to blindness.

If closed-angle glaucoma is not diagnosed and treated, it leads to blindness within 2 to 3 days.

How is it diagnosed?

The examination which enables glaucoma to be detected includes five main tests:

Tonometry

The tonometer is used to measure intraocular pressure. When an applanation tonometer is used, the eye has to be anesthetised either using drops, or using an air puff tonometer. A puff of air is then projected onto the eye to take the measurement. Given that this device does not come into direct contact with the eye, prior instilling of anesthetising drops in not necessary.

Ophthalmoscopy

The ophthalmoscope is used for examining the inside of your eye. An ophthalmologist examines the optic nerve through the pupil. Its shape and colour enable the presence of lesions characteristic of glaucoma and their size to be detected. An examination after dilation of the pupil enables an even more complete examination of the inside of the eye.

If intraocular pressure is not normal, or if the aspect of the optic nerve does not seem normal, then other specific tests are carried out.

Examination of the field of vision

During a computerised examination of the field of vision, the patient is asked to look towards a set point located in the centre of a screen and to press the button each time a light signal appears on the screen. At the end of the tests, the doctor receives a printed report of your field of vision. This test measures the overall visual function, including peripheral vision.

In patients suffering from glaucoma, peripheral vision is lost first. This loss is characterised by a shrinking of the field of vision outside central vision.

Gonioscopy

Gonioscopy is a test where a contact lens with mirrors is applied on the eye. This examination is not very pleasant but lasts no longer than 2 minutes. It enables checking if the angle where the iris joins the cornea is open or closed, which enables defining whether it is an open- or closed-angle glaucoma.

Optical Coherence Tomography (OCT)

This is a recent examination method which enables obtaining “cross-sections” of the retina or optic nerve significantly superior to that of ultrasound. The OCT device uses a technique called optical coherence tomography which creates images by using different light rays. The OCT device can create a map of the contours of the optic nerve and measure the thickness of the retina’s nerve fibre. It enables better monitoring of the loss of optic nerve fibres.

Recent discoveries concerning the cornea have shown that the thickness of the cornea is an important factor in assessing the impact of ocular pressure on the optic nerve.

The thickness of the cornea may distort the exact value of the ocular pressure measurement. The real pressure may be under estimated in patients with a thin cornea and overestimated in patients with a thicker cornea. Therefore, a thick cornea constitutes a protective factor for the optic nerve.

How can it be prevented?

From 45 years of age, it is recommended to have an ophthalmological examination with, among others, measurement of ocular pressure each time you change prescription glasses.

If you consider yourself to be at risk, it is highly recommended to have a complete eye examination every two years including dilation of the pupil. This is important, because early detection, making a diagnosis and treatment are the only solution to prevent vision deterioration and blindness.

how to treat it?

    Introduction

    Treatment with eye drops

    Argon laser trabeculoplasty treatment

    YAG laser iridotomy treatment

    Laser trabeculectomy treatment

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