This guide has been written to give you an introduction to each of the glaucomas, their causes and their treatment so that you can better understand your own situation and how to help ensure that you retain useful sight for life.
The vast majority of people diagnosed with glaucoma today will not go blind, but this is only the case if they adhere to the treatment regime prescribed by their glaucoma specialist and if they attend their follow-up appointments regularly so that when changes in the level of intraocular pressure of the visual field are noted, the treatment can be altered in order to prevent further damage.
This information has been provided to you because we believe that it is very important for a person to receive the information they need when they ask for it rather than to be given a price list.
The Eye is shaped like a ball. The tough white outer coat is called sclera and its surface is covered by a thin layer called the conjunctiva. The clear outer layer called the conjunctiva. The clear outer layer at the front of the eye is called the cornea which is covered by the tear film. Behind the cornea is the iris – the colored part of the eye – with the pupil forming a hole in its center. The Space between the Cornea and the lens is filled with a clear fluid, called aqueous humor, which maintains the pressure in the eye (the Intraocular Pressure).
The Pressure is determined by the balance between the fluid production in the eye and its drainage out of the eye. On the inside of the back of the eye is the retina, which is the light sensitive layer onto which an image of what is being seen is focused by the cornea and the lens working together.
The central area of the retina where the most detailed vision is to be found, known as the macula, has a very high density of cells, Further away from this central detailed vision area is the area of the retina which is more sensitive to dim light and which also provides our peripheral vision.
Immediately below the retina is the choroid, which is the layer of the eye that provides the blood supply to the cells of the retina and onto which the retina is attached. Light that has passed through the front of the eye and is focused onto the retina is finally converted into a series of complex electrical rods and cones. These signals pass along the optic nerve in the back of the brain, where the final image is processed.
Glaucoma is the name given to a group of eye conditions in which the optic nerve is damaged where it leaves the eye.This nerve carries information about what is being seen from the eye to the brain and as it becomes damaged vision is over the age of 40.
Although any vision which has been lost to glaucoma cannot be recovered, with early diagnosis, careful monitoring and regular use of the treatments the vast majority of patients retains useful sight for life.
The Damage to the optic nerve in glaucoma is usually associated with excessive pressure within the eye. A Certain level of pressure is needed for the eye to keep its shape and to work Properly, but if the eye pressure gets too high, it squeezes the optic nerve and kills some of the nerve fibers, which leads to sight loss. The first areas to be affected are the off-central parts of the vision. If the glaucoma is left untreated, the damage can progress to In some forms of glaucoma, the eye pressure is not raised. Glaucoma can develop where eye pressure is within the statistical ‘normal’ range but the optic nerve still becomes damaged. This is known as normal ( or low ) Tension glaucoma.
High eye pressure does not always cause glaucoma. A common condition is ocular hypertension, where the eye pressure is above the statistically ‘normal’ level, but there is no detectable damage to the field of vision or optic nerve. This condition may be monitored or may be treated in the same way as glaucoma, depending on the specialist’s view of the risk of developing glaucoma.
Eye Pressure (intraocular pressure ) is controlled by a watery fluid called aqueous humor, which fill the front part of the eye. This fluid is made in ciliary body (a ring of tissue behind the colored Part of the eye, which is called the iris). It flows through the pupil and drains away through tiny drainage channels called the trabecular mesh-work.
This is situated in the drainage angle between the cornea (the clear window at the front of the eye ) and the iris. In a normal eye there is a balance between the production and drainage of this fluid, but in some eyes this balance becomes disturbed . Most cases of glaucoma occur because the flow of fluid out of the eye becomes restricted and the pressure in the eye rises.
Yes, there are several risk factors which make the onset of glaucoma more likely and they tend to the cumulative in their effect.
POAG becomes much more common with increasing age. It is uncommon below the age of 40, but the number of people with conditions rises from about 2 per cent of people over the age of 40 and doubles for those over age of 80.
People of African-Caribbean origin have about a four times increased risk of POAG when compared with those of a European origin. The condition also tends to come on at an earlier age and be more severe. Regular testing is therefore vital if visual impairment is to be avoided. People of Asian origin are at an increased risk of developing primary angle closure glaucoma.
There is at least a four times increased risk of developing glaucoma if you have a close blood relative with the condition ( father, mother, brother, sister, or child). Eye examinations are founded by NHS for such people from the age of 40 years, but an earlier test is recommended, especially if you have glaucoma, don’t forget to tell your relatives about the condition and the need for them to be tested. More information can be founded in the IGA leaflet titled ‘Glaucoma and your relatives’.
People with severe myopia (very short sight) are known to be at increased risk of developing glaucoma, and should ensure that they are regularly tested for glaucoma.
Long sighted people are known to be increased at risk of developing angle closure.
People with diabetes may be at increased risk of developing glaucoma, although it is not known whether there is a direct link between the two conditions. However, all people with diabetes eye diseases and glaucoma tests can usually be requested at the same time.
A check of the visual field to see if there are any sign of sight loss in the off-centre part of the vision which could be a sign of the development of glaucoma.
A combination of all the three tests has been shown to increase the likelihood of detecting POAG by 4 times when compared with ophthalmoscopy alone.
Treating primary open angle glaucoma
The aim of treating POAG is reduce the pressure within the eye to a level at which no further damage occurs to the optic nerve.
Treatment is usually by means of eye drops.These can work to reduce the amount of fluid being produced by the eye,or improve drainage from the eye or both.
There have been major advances in medical (eye drop) treatment in recent years, and the newer drops are far more effective and have fewer side effects than those which were previously available. If the eye drops do not provide a sufficient pressure lowering effect, laser or surgical treatments are available.
Normal Tension Glaucoma(also called Normal Pressure Glaucoma)
Some people develop glaucoma with a normal eye pressure (this is called normal tension or low tension glaucoma). It is believed that poor blood flow to the eye may contribute to the development of the optic nerve damage . In these people, pressure-lowering drops are still the first choice of treatment, with a view to reducing the eye pressure to a level at which further damage to the optic nerve is prevented. However, the eye doctor may want to ensure that the blood pressure is not too low and may review blood pressure treatment,if it is being taken.
Treating Primary angle closure glaucoma
Acute angle closure is initially treated with drops and an intravenous injection to lower the eye pressure. Once the pressure is lowered, a laser (Iridotomy – laser spots are applied to make a small hole through iris) or surgical procedure (Iridectomy – a small part of iris is removed) is carried out in order to bypass the blockage in your eye’s drainage system and prevent a recurrence of the problem. Normally the same procedure is also performed in the other eye, in order to prevent an attack of acute angle closure in that eye. These treatments are not painful and usually done on a day patient basis, although a short stay in hospital may occasionally be required. If acute primary angle closure is diagnosed and treated without delay there may be an almost complete and permanent damage to the affected eye. Occasionally the pressure may remain raised and ongoing treatment will be required as for POAG
Chronic primary angle closure is treated in a similar way to POAG, with drops to lower the pressure. In addition, laser treatment is often given to prevent further angle closure
If the eye drops do not provide a sufficient pressure lowering effect , other treatments, such as tablets, laser therapy and surgery are available
laser spots are applied to the drainage system to stimulate the flow of fluid out of the eye. The treatments is painless.
This is the most common operation. In a trabeculectomy, the surgeon makes a flap valve over a small hole in the outer wall of the eye. This creates a new passage for the fluid to leave the eye, under the white skin of the eye, forming a small bump under the upper lid, called a trabeculectomy bleb.
Initial treatment is usual with eye drops. These are sufficient to keep the pressure in the target range in most people. There are several different types of eye drop for glaucoma and your eye doctor may need to change your treatment until the right drop, or combination of drops, is found. Once eye drops have been started, they usually need to be taken for life ( there is no such thing as a ‘course of treatment’ for glaucoma).
It is worth getting into a routine so that the drops are not forgotten. For instance you could keep the bottle or phial by your toothbrush, which will be a reminder when you brush your teeth. Rarely drops need to be stored in the ‘fridge once they have been opened.
There are various ways to put drops in the eye and everyone will decide which is best for them. One of the simplest is to sit or stand in front of mirror, pull down the lower lid with a finger of one hand, squeeze or tap the bottle according to instructions with the other hand, and let the drop fall into the pocket between the eye and the lid.
Another method is to tilt your head backwards while sitting, standing or lying down. If your drops are gel and not liquid, it may be easier to lie down in order to spread the gel along the inside of the lower lid.
After putting the drop in your eye, close your eye and gently press in the inside corner with a finger for one or two minutes. This will help to slow the rate ar which drops drain out through the tear duct into your system, rather than staying in the eye where they are needed. A small amount may, even then, drain through the tear duct and be swallowed, which is not normally harmful but which may lead to unwanted side effects in susceptible people.
- If you take more than one type of drop, It is important to leave ten minutes between each differing drop to prevent the second one washing out the first.
- If you take a drop more than once a day spread the dose over the day eg if twice a day use the drop at the same time morning and evening i.e. 12 hours apart
- If you have difficulty knowing if a drop has gone into the eye, keep your drops in the door of the ‘fridge (not the freezer); you will then feel the coldness of the drop entering the eye. Be sure to check with the drug information leaflet or pharmacist that your drops can be stored this way
Because damage to vision in glaucoma is permanent, it is important to prevent it getting worse. For this reason, it is essential to take your eye drops regularly if you want to preserve your vision
More than 90 percent of people diagnosed with glaucoma today will retain useful vision (blindness is rare).
In certain cases however, it may not be possible to control the glaucoma well enough to retain useful vision. This is often where the condition has been diagnosed at the late stage, treatments have been ineffective, or where the person with glaucoma has had difficulty taking the prescribed medications.
If your vision has deteriorated to an extent where you have difficulty carrying out normal daily tasks, much can be done to help you to use your remaining vision effectively. You should contact your ophthalmologist to find out about low vision aids.
There are four main types of glaucoma:
Primary open angle glaucoma, Primary angle closure glaucoma,Secondary glaucoma and Developmental glaucoma.
Primary open angle glaucoma ( POAG)
This is the most common form of glaucoma. It is a chronic (slowly – developing) condition in which the eye pressure rises because the drainage channels themselves are not good enough at the draining fluid out of the eye. This is not because of an obstruction blocking the flow: as the name of this type of glaucoma suggests, the drainage angle remains ‘open’. The eye pressure rises very slowly and there is no pain to warn of a problem, even though the optic nerve is being damaged. When part of the field of vision in one eye is damaged. When part of the field of vision in one eye is damaged, the other eye may ‘fill in’ the gap because the damage may not have occurred in the same part of the field of vision in both eyes. For this reason, much damage will often have been done before the person with glaucoma realizes there is a problem with his/her sight. It is important to diagnose and start treating sight threatening early on, before it has advanced to a stage where there has been an extensive sight loss
Primary angle closure glaucoma (PACG)
This sort of glaucoma is less common in western countries and more often found in people of Asian origin. It may be acute (sudden onset) or chronic (slowly developing).
Acute primary angle closure (sometimes called ‘acute glaucoma’) develops when the access of the aqueous humor to the trabecular mesh-work is blocked because the iris has come forward, causing the drainage angle to ‘close’. This means that fluid cannot escape from the eye and the pressure rises. This tends to be very painful because the rise in pressure happens suddenly. Symptoms include seeing halos around light sources, a red eye, cloudy vision and occasionally, sickness. It must be treated straight away and in most cases, the vision recovers completely. However, if treatment is delayed, there is often permanent damage to the nerve has occurred, the term Primary angle closure glaucoma is used. The tendency for this glaucoma to develop depends on the shape of the eye and is more common in ‘long-sighted’ eyes. Sometimes people experience a series of mild attacks of angle closure. These are called sub-acute attacks and often occur in the evening. Vision may Sen misty, with colored rings around with lights and there may be some discomfort and redness in the eye, if you have these symptoms, you should consult your doctor without delay. Chronic angle closure develops slowly, usually without symptoms, although the reason for the rise in eye pressure is similar to acute primary angle closure. When damage to the nerve has occurred, the term chronic primary angle closure glaucoma is used. The treatment is given to reduce the eye pressure to a level at which no further damage to the optic nerve occurs.
This kind of glaucoma can either be open angle or closed angle in nature – in other words, there are various ways in which the eye pressure rises. It has an identifiable cause , being ‘secondary’ to another condition which has caused the glaucoma must also be addressed. The eye may then return to a normal state and not require further treatment, or it may have been damaged so the ongoing glaucoma treatment will be required
This is a rare condition where the eye has failed to form properly. It is present in about 1 in 10,000 babies and may be associated with other developmental abnormalities in the eye. For full details of symptoms and treatments, contact the International Glaucoma Association and ask for our booklet ‘Glaucoma in Babies and Children’.
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