Runway Age Care: Glaucoma

Glaucoma is one of the most common causes of preventable blindness. It can be picked up as part of a normal eye test and once treatment starts, its progress can be halted.

Here we explain what glaucoma is and how it affects your sight, how certain groups of the population are at particular risk, the simple tests that can lead to its detection and the treatments you may be offered.

Treatment cannot reverse damage already done and is likely to be necessary for the rest of your life… but your sight can be protected if it is picked up in time.

What is glaucoma?

Glaucoma is the name of a group of eye conditions that affect your vision.  Of the many types of glaucoma, chronic glaucoma is the most common. It usually affects both eyes but can start in one eye before the other.

Often in chronic glaucoma the pressure in your eye is higher than it should be and over time this causes damage to the optic nerve at the back of your eye. The optic nerve carries visual information from the light sensitive part of your eye to your brain, where it is translated into a picture. Damage to the optic nerve can affect your sight.

Why does it occur?

Your eye produces a fluid (aqueous fluid) that helps maintain the shape of your eyeball and transports nutrients to your eye.  This fluid is produced by cells behind the coloured part of your eye (the iris) and is not the same as the fluid that forms tears.

Normally the amount of fluid produced is balanced by the amount draining away through special drainage channels. In glaucoma, the balance between the production and draining away of fluid may not be correct.  If the fluid doesn't drain away properly then eye pressure can build up and damage the optic nerve.  Why some eyes don't deal with the balance of fluid properly, is still not clear.

 Diagnosis

An optometrist is the health professional who conducts routine eye tests at the opticians.

This test should include all three tests for glaucoma, as having all three is more effective at detecting glaucoma than having one or two.

1. Measuring the pressure inside your eye – known as the eye pressure test or tonometry.  This test usually involves a puff of air being directed at each eye from a special machine.
2. Looking into to your eye at the optic nerve - using an ophthalmoscope, a special instrument, rather like a torch, to take a close look at the area of your eye where your optic nerve leaves the retina.
3. Testing your field of vision – known as the visual field test or perimetry. This involves sitting in front of a special machine, looking straight ahead.  It tests first one eye, then the other. Points of light come in from different directions and you press a button every time you see one. This produces a computer print out showing which lights you saw and identifying if you missed lights from a particular direction.

If you have signs of glaucoma, the optician refers you to an ophthalmologist (eye specialist) for more detailed tests that also identify the appropriate treatment.

Treatment

It is not possible to restore sight lost due to glaucoma. This is why regular eye tests and treatment are so important.

Treatment aims to lower the pressure in your eye and so prevent further damage to the optic nerve. In most cases this is achieved using eye drops. There are several types of eye drops. You must use the eye drops for as long as your doctor advises, which could be for the rest of your life. Taking your prescribed drops regularly, even if your sight is good, is very important as this helps prevent any sight loss.

You will probably be monitored at least once a year by the ophthalmologist at the hospital or sometimes by your optometrist, to make sure your treatment is working and your eye pressure is under control.

If eye drops are not successful there are a number of different laser treatments that can be used to control the pressure in your eye. In some cases surgery may be suggested.

Undiagnosed glaucoma cases causing needless blindness among Irish adults

DICK AHLSTROM Science Editor

HALF OF all cases of a preventable form of blindness go undiagnosed in Ireland. The result is needless vision loss, a conference in Dublin has heard.

Glaucoma was a major cause of blindness yet the condition was readily treated if diagnosed, delegates to the Irish College of Ophthalmology’s annual conference in Dublin were told yesterday.

It affects 2 per cent of adults over 50 years old and 5 per cent of those over 70, said Colm O’Brien, professor of ophthalmology at University College Dublin.

Relatively symptomless in its early stages, an estimated 50 per cent of cases go undiagnosed, he said. He highlighted the importance of regular screening in preventing the damage caused by glaucoma.

Prof Balwantray Chauhan told delegates about a new method for picking up early changes in the eye to gauge the progress of glaucoma.

He is based at Dalhousie University in Canada and is the principal investigator of the Canadian Glaucoma Study.

“All the evidence indicates that if we can diagnose a patient in the early stage of glaucoma, it is highly likely that treatment will prevent progression of the condition,” he said.

Being able to detect the small initial changes in the patient’s field of vision or in the optical disc where the optic nerve joins the retina at the back of the eye was one of the “most challenging issues” in clinical practice, he said.

His study allowed patients to be tracked over a long period. This helped the research team to pick up on very small changes in the eye and identify those who needed “customised management” to treat their condition, he said.

Useful Links:

http://www.ncbi.ie/