Glaucoma

What Is It?

Glaucoma is thought to be a group of conditions and is caused by the pressure of your eye being too high for your eye to cope with so that nerves are damaged and do not work. The nerves that are damaged carry the information on what you see to the brain to be processed, so when they are damaged you start to lose sight. (I like to think of the nerves as telephone wires and if the pressure gets too high, these wires are cut and so the message doesn’t get through.)

The eye needs some pressure to keep its shape and work. To do this, the eye produces a liquid (aqueous) to keep it pressurised. This liquid is continuously replaced and drains out of the eye between the iris and the cornea. This is not to be confused with tears, which is an external system, whilst the aqueous system is totally internal. Eye pressure is mainly independent of blood pressure.

How many people have glaucoma? 2 in every 100 people in the UK have glaucoma.

Types of Glaucoma

There are 2 main types of glaucoma – acute and chronic. There are others but these are the main ones.

Acute

This is a rare condition and is more common in people of Asian ethnic origin and more common in women. In acute glaucoma, there is a rapid increase of the pressure of usually one eye due to blocked drainage channels of the aqueous.

Sign and Symptoms

Pain – can be so bad that you feel nauseous and even vomit

Sight deteriorates

Red eyes

Misty haloes around lights

The symptoms can start with a series of mild attacks which occur mainly in the evening and disappear during the day.

Treatment. If diagnosed early, the pressure can be quickly lowered (within hours) using drops. This is followed by a small operation, usually with a laser, to improve the drainage. As there is a risk of the other eye developing the condition the operation is usually bilateral. Prognosis is good with early diagnosis and you may get complete vision recovery. Delay in treatment may cause permanent vision loss.

Chronic

Chronic glaucoma is by far the most common form of glaucoma. The risk factors are

Age – uncommon in the under 40’s. 1% of population between 40 and 65 have it and 5% over 65 have it.

Race - People of African ethnic origin are more at risk and also the disease is more severe. (Approximately 10 times more likely to get the disease)

Family History – a close relative with the disease increases your risk. (Approximately 4 times more likely to get the disease)

Myopia (Short sighted)

Diabetes

Poor circulation – cold hands and feet, increase the risk of low tension glaucoma.

The problem with this type of glaucoma is that it is painless – the eye looks normal and you are unaware you are losing sight.

If not treated, the sight loss starts as very small areas where you are unable to pick up the difference between light and dark. This is called visual field loss. (Even at this stage it is thought that a large number of nerves are dead. Any loss is permanent). These areas will increase in number and size with time if left untreated until they join together to form large areas. ( At this stage you may still be unaware that you have a problem). This progresses to tunnel vision, where you have a small area of central vision only and this too will vanish eventually. To see what tunnel vision is like, close one eye and put the kitchen towel cardboard inner tube in front of the open eye.

Detection This is hard for the patient to do and most glaucoma’s are picked up at routine eye examinations at the optometrist or ophthalmologist. The 3 basic tests are

Examination of the optic nerve head. This is the area where the nerves group together to leave the eye and is thought to be where the nerve damage occurs.

Measurement of eye pressure

Visual field checks to check for damage

Treatment is twofold – lower the eye pressure and increase the blood supply to the optic nerve head. This is usually done in the form of regular eye drops (for life). If drops do not have the required effect then an operation may be necessary.

Prognosis. Any damage done before treatment is permanent, but early detection can keep this to a minimum and good vision is hopefully maintained. Early detection and treatment is the best way to reduce vision loss – it is estimated that 95% of early diagnosed patients maintain useful sight for life, as long as no other diseases occur. The main problem with visual field loss is that you may be stopped from driving if it is too great.

Lifestyle. Whilst you cannot change most of the factors that cause glaucoma you can change some small aspects of your life. Thing that increase your eye pressure include smoking so please stop. Things that decrease the pressure include physical activity, saunas and even smoking marijuana (this is not a recommendation to start smoking pot!)

The main way to help yourself is to have a regular eye examination (yearly if you have a risk factor otherwise 2 yearly), stop smoking and take regular exercise.