Glaucoma is caused by raised pressure in the chamber of the eye immediately in front of the lens and behind the cornea. There is a continuous flux of fresh fluid being produced in the eye and old fluid being drained out which normally remains in balance. If for any reason too much is produced, or not enough drained out, or the drainage route becomes blocked, pressure will rise in the eye. This pressure will damage the optic nerve or its blood vessels feeding it causing varying amounts of lost visual field.
There are two types of glaucoma, acute (rare in the Western world) and chronic.
Acute glaucoma will produce rapid loss of vision during an attack and much pain. This must be treated immediately at Hospital, often in an A & E department.
Acute pressure attacks can sometimes be milder normally seen at night after emerging from a darkened room and displaying coloured haloes around lights. If these occur you should still obtain urgent investigation
The more common chronic open angle glaucoma causes no pain and no symptoms except a slow and often un-noticeable loss of visual field, usually from the outer field inwards. It is almost always detected at an eye examination but can sometimes take a period of assessment to agree the diagnosis. It is recognised by a characteristic view of the back of the eye by an optometrist, a loss of visual field and a higher than normal intra-ocular pressure. All of these signs are recognisable by the eyecare professional but normally not by the patient.
Treatment is by drugs or if necessary surgical intervention by clearing the drainage routes. It can be caused by other eye conditions and is occasionally seen in the newly born infant.
Some people are more prone to glaucoma than others, particularly those with a history of its discovery in close relatives, those from an African and Caribbean origin, those with a large degree of short-sightedness, and it is more prevalent after the age of 40.
Treated regularly glaucoma’s effects can be kept to a minimum and good vision can normally be retained. However vision lost before its recognition can not be repaired.
All those with Glaucoma and all their close relatives aged above 40 years old without any diagnosis of Glaucoma are allowed an annual NHS paid for sight test