Glaucoma

A group of conditions that cause a characteristic pattern of damage to the eye that is in part related to an intraocular pressure (eye pressure) that is too high for the eye.

The factors that cause glaucoma are not fully known. However, in many cases the pressure in the eye is thought to be responsible, at least in part, for the damage caused. The pressure in the eye is usually higher than the normal range but in some cases it is within the normal range but is considered to be too high for the individual eye. Other factors that are related to the damage caused include alterations in the bloodflow to the optic nerve head (the front part of the optic nerve) , changes in the tissues supporting the optic nervehead, and genetic factors.

Primary open angle glaucoma is the commonest type of glaucoma and affects 1-2% of the population. It increases with increasing age and is more common in black races than whites. Risk also increases if a family member is affected. Use of steroids may cause a rise in intraocular pressure and hence glaucoma.

Usually asymptomatic. Most patients are unaware of their condition and it is discovered only on routine testing by the optician. For most patients the main problem is loss of the field of vision. Central vision and visual acuity (i.e. the smallest things that can be seen) tend to be affected later on, although localised areas of loss of central vision can occur. "Tunnel vision" is only seen in advanced disease. One important aspect is that it may affect your vision to the level that you fail the legal requirements to drive. You should inform the DVLA and your insurers if you have this condition. Many people however will still meet the legal visual requirements for driving.

A complete eye examination, with measurement of the intraocular pressure, an examination of the drainage angle (gonioscopy) and optic disc, and a assessment of the visual field.The tests are usually repeated for monitoring at regular intervals.

This is usually done in a stepwise fashion:

• Medical—eye drops to reduce the intraocular pressure
• Laser—a laser trabeculoplasty, to reduce the intraocular pressure
• Surgery—a trabeculectomy, to reduce the intraocular pressure

In the majority of cases the progression of the visual loss can be halted or greatly reduced. However, despite good intraocular pressure control a minority of cases can still show progressive changes.