Glaucoma

Primary Open Angle Glaucoma

Definition

Glaucoma is an eye disease which can lead to an irreversible loss of vision, which is notoriously difficult to detect and treat. The most common form, "primary open-angle glaucoma”, results in a slow, painless deterioration with no noticeable discomfort, which means that the sufferer is unaware of their condition and so does not seek medical help. Early diagnosis is of paramount importance to prevent loss of vision.

Causes

Loss of vision due to Glaucoma is caused by irreversible damage to the optic nerve (which transmits the images to the brain) Origins of this optic neuropathy are still unknown. Factors which increase the risk of getting Glaucoma have been identified, but their roles are still not fully understood. Several factors seem to increase the likelihood of developing Glaucoma :

• Raised intraocular pressure (greater than 21mm Hg – ocular hypertension) is present in 70% of glaucoma patients. The increased pressure affects nerve cells in the optic nerve. But only a third of people with moderate ocular hypertension (21-30 mmHg) will develop glaucoma in their lifetime.
• Glaucoma becomes much more common after the age of 40, and after the age of 75 you become ten times more likely to suffer from it than before.
• Those of African descent are 4 times more likely to suffer from Glaucoma.
• People with a family history of Glaucoma are at a higher risk, (twice as likely to suffer from glaucoma if a parent did)
• Other diseases such as cardiovascular disease (especially ones resulting in changes in blood pressure), myopia, diabetes, migraine etc.

Magnitude

Glaucoma affects more than 1 million people in France (or almost 2% of the population). Amongst them, 800,000 received medical care for glaucoma whereas 400,000 remained unidentified. With an ageing global population, there will be 60.5 million people with glaucoma in 2010 and by 2020 there will be almost 80 million sufferers.

Diagnosis

The diagnosis of glaucoma is currently based on the results of two tests.

• Changes to the field of vision
• Damage and changes to the optic disc

A third indicator of glaucoma is the intraocular pressure. If it is over 21 mm Hg then there is an increased chance of glaucoma, however if a patient has a high intraocular pressure it does not necessarily mean they have glaucoma and vice versa.

Treatment

The only known effective treatment against the progression of glaucoma is to lower the intraocular pressure to a predetermined target depending on what stage of the disease has been reached. Ophthalmologists have 3 ways of treating the disease :

• Medical treatment : primarily eye drops, which must be administered at regular fixed intervals. They are often all that is needed to control the disease.
• Laser therapy (trabeculoplasty) may complement medical treatment. The results are not definitive and are more of a temporary solution. It is usually then necessary to strengthen or resume treatment with eye drops after a few months or years.
• Surgery (trabeculectomy, sclerectomy) is usually the last resort if the previous 2 treatments have failed to improve the intraocular pressure. It is sometimes offered immediately, especially in developing countries where it is more economically viable.

The patient is not cured of the disease, but treatment helps to stabilize the condition.

An Increasing Public Health Problem

With around 15,000 cases, it is the second highest cause of blindness in France after Age related macular degeneration (AMD).

In the least developed countries, glaucoma is also the second highest cause of blindness (12% of cases) after cataracts. In 2002, it was estimated that globally the number of people who had been blinded by glaucoma was 4.5 million. By the end of 2010 it is estimated that this figure will have increased to 8 million.

Currently, health systems do not have a simple and effective screening process for glaucoma. A major eye examination (intraocular pressure, field of vision and fundus) of people at high risk of the disease is still required.

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