Primary open angle glaucoma

A review of the presentation and management of the commonest cause of irreversible blindness.

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Glaucoma is a non-specific term used for several ocular disorders that almost invariably cause an increase in pressure that is sufficient to cause damage to the optic nerve head and cause changes in the visual field. A proportion, however, have pressures within the normal range.

Glaucoma is a non-specific term used for several ocular disorders that almost invariably cause an increase in pressure that is sufficient to cause damage to the optic nerve head and cause changes in the visual field. A proportion, however, have pressures within the normal range.

Glaucoma is a non-specific term used for several ocular disorders that almost invariably cause an increase in pressure that is sufficient to cause damage to the optic nerve head and cause changes in the visual field. A proportion, however, have pressures within the normal range.

In primary open angle glaucoma (POAG), it is thought that the pressure in the eye rises because of an increased resistance to outflow through the trabecular meshwork. The reason for this remains unknown.

Glaucoma can also occur in patients with ocular pressure in the normal range, (normal tension glaucoma).1 Up to a third of open angle glaucoma patients have a normal IOP.

In a healthy eye, the optic disc is slightly elongated vertically and looks pink. The central cup varies in size, but is approximately one quarter of the disc with a healthy rim of retinal ganglion cells.

The tissue of the optic disc rim is damaged as ganglion cells are lost in glaucoma. A loss in the field of vision accompanies the loss of ganglion cells. It occurs away from the central vision in arcuate scotomas. These visual field defects are characteristic. Vision may still be 6/6 at a terminal stage, but will be limited in the form of tunnel vision.

Epidemiology 2,3

Primary open angle glaucoma affects about 2% of people in the UK older than 40 years. The prevalence increases with increasing age. About 1% of people aged 40, about 3% of people aged 60, and about 8% of people aged 80 years are affected. Around half of all people in the UK with POAG…


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