What CAUSES glaucoma?… by suz
I have high pressure readings, does this automatically mean i have glaucoma?
Best Answer:
Glaucoma is not one disorder but a range of conditions in which the pressure inside the eye becomes too high. This results in damage to the optic nerve at the back of the eye which can lead to loss of vision if left untreated. Glaucoma is one of the most common causes of blindness worldwide.
How does glaucoma develop?
There is a constant flow of fluid through the eye. The flow into and out of the eye is carefully monitored in order to ensure that the eye maintains its round shape and does not become too hard or too soft.
This fluid is called the aqueous humour. It is secreted into the eye from an area behind the iris (the coloured part of the eye) and flows around through the pupil and drains out of the eye through several microscopic channels.
Glaucoma usually develops when this flow of fluid becomes obstructed and there is a build-up of pressure within the eye.
There are two main sub-groups of glaucoma:
primary open angle glaucoma (formerly known as chronic simple glaucoma) is a slowly progressive condition which occurs when the tiny microscopic drainage channels gradually become blocked.
primary angle closure glaucoma (also known as closed angle or acute glaucoma) occurs much more rapidly when the flow of fluid inside the eye cannot pass through the pupil, causing a rapid rise in pressure inside the eye.
There are other types of glaucoma which are much rarer and can be caused by a variety of reasons:
inflammation inside the eye (uveitis or iritis).
the growth of new vessels inside the eye, which may occur in connection with diabetes or after blood vessel blockage at the back of the eye.
treatment with certain medicines (eg corticosteroids).
following an eye injury.
other rare abnormalities affecting the structure of the eye.
Congenital glaucoma
It is very rare for children to be born with glaucoma but it is a recognised condition. There is a tendency for this to run in families, although it may occur in children with no family history of glaucoma at all.
What are the symptoms of glaucoma?
Primary open angle glaucoma
The build up in pressure in this condition is very slow. Therefore visual loss is gradual and patients often do not notice any problem until there is evidence of severe visual impairment.
The peripheral (or side) vision is affected first and therefore the eyesight is not obviously affected. These peripheral areas of visual field loss increase until eventually the central vision is damaged leading to blindness.
Because primary open angle glaucoma is not usually recognised until it is advanced, people are screened for the condition as part of the optician's routine examination when eye tests are carried out.
The optician will check the pressure, examine the nerve at the back of the eye and test the field of vision if this is indicated. As primary open angle glaucoma is rare in people under the age of 40, these screening tests are usually only carried out after this age.
How is primary open angle glaucoma treated?
There are a number of different types of eye drops which are available to treat primary open angle glaucoma:
beta-blockers
prostaglandin analogues
adrenaline type drops (sympathomimetics)
carbonic anhydrase inhibitors
miotics (parasympathomimetics).
Beta-blockers
These drops are usually used twice a day. They reduce the amount of fluid being secreted into the eye. These drops may need to be avoided in people with asthma or heart disease as they can be absorbed into the circulation, thereby causing problems in these areas. Timolol (Timoptol) is an example of a beta-blocker.
Prostaglandin analogues
This drop is used once a day in the evening. It works by increasing the drainage of fluid out of the eye. The best recognised side effect of this drop is that it can change the colour of the eye. Latanoprost (Xalatan) is an example of a prostaglandin analogue.
Adrenaline-type drops (sympathomimetics)
These are used twice a day and are generally well tolerated. They reduce the amount of fluid secreted into the eye. Patients with heart disease may be unsuitable for this treatment. Dipivefrine (Propine) or Brimonidine (Alphagan) are examples of adrenaline-type drops (sympathomimetics).
Carbonic anhydrase inhibitors
These drops are used twice a day if used with beta-blockers, or three times a day if used alone. They reduce the secretion of fluid into the eye. Dorzolamide (Trusopt) is an example of a carbonic anhydrase inhibitor.
Miotics (parasympathomimetics)
These drops are usually used four times a day. They increase the drainage of fluid out of the eye. These drops cause a small pupil which may mean that they cause a reduction in vision.
They may give rise to headache. These drops were the original drops to be used for glaucoma but are now less commonly used because of the other newer drops as outlined above. Pilocarpine (eg Pilogel) is an example of a miotic (parasympathomimetic).
Other treatments
Carbonic anhydrase inhibitor tablets
In some cases these tablets are prescribed, but this is usually only as a temporary solution as they can have many side effects such as general nausea, tiredness, tingling of the fingers and, occasionally, if used for a long time, a tendency to cause kidney stones. Acetazolamide (Diamox) is an example.
Laser treatment
This treatment is used to increase the flow of fluid from the eye. The effect of this treatment may be temporary and therefore may not be suitable as a long-term solution.
Surgical treatment
Many patients have surgery to treat glaucoma. The operation used (trabeculectomy) allows drainage of fluid from inside the eye to the outside of the eye. This type of surgery usually results in a small 'blister' on the eye which is usually positioned under the upper eyelid. This type of surgery may include the use of anti-metabolite medicines in order to make the success of the operation higher, although this may increase the potential for complications.
Complications of such surgery include transient reduction in vision after the operation, but this usually recovers. Long-term effects of infection must always be considered.
Powered by Yahoo Answers