Glaucoma Screening

There are various forms of glaucoma but the common characteristic is that the optic nerve at the back of the eye is damaged and this can lead to a progressive loss of peripheral vision.

The two main types of Glaucoma are Closed Angle Glaucoma and Open Angle Glaucoma

Closed Angle Glaucoma

This is a less common form of glaucoma affecting about 0.2% of the population. It has a sudden onset and is caused by the pressure in the eye rising suddenly. Symptoms typically include severe pain in the eye, headaches and nausea. The patient may also experience blurred vision and haloes around lights. This condition requires urgent referral for treatment to lower the eye pressure.

Open Angle Glaucoma

This eye disease affects approximately 2% of the population over the age of 40 years. It has a gradual onset and usually would not give rise to any symptoms in its early stages. The eyesight is damaged by the creation of small blind spots in the peripheral areas of vision which would become larger if the condition is not controlled. It is often the case that it can be present for years before the sufferer is aware of any loss of vision.

Early detection is vital as the condition can be treated but vision already lost cannot be recovered. Although there is no cure for glaucoma , most patients retain normal vision with ongoing eye drop treatment or occasionally surgery.

The risk factors for this condition are:

Increased pressure within the eye
Age - incidence increases with age
Family history of the condition (mother/father/brother/sister)
Diabetes
High levels of short sightedness

How is Open Angle Glaucoma detected?

1- Checking the eye pressure
The risk of glaucoma increases if the eye pressure is above the normal range. There are however cases of glaucoma where the pressure appears to be within the normal range so we cannot rely on this measurement alone.

2- Examination of the Optic Nerve Head
Our modern instruments allow us to examine this tiny area at the back of the eye in great detail and this is necessary because the changes to the tissue are extremely subtle in the early stages of the disease (see top two images).
Most recently we have a new instrument (called an OCT) which can measure the thickness of the delicate nerve fibres around the optic nerve head. This provides further important information on a person's risk of developing the disease. Use of the OCT is not part of the NHS eye examination but it is included for members of our FOCUS eyecare plan - otherwise a charge will apply.

3- Visual Field Examination
A sophisticated visual field instrument ( Humphrey Visual Field Analyser) is used to detect any areas in the visual field which are not as sensitive as they should be.
Note: It is often necessary to repeat visual field tests to reach a decision whether referral to the Hospital Eye Service is necessary for further investigation.

Open Angle Glaucoma is a good example of the need for regular eye examinations even although vision appears to be normal.

Useful Website: International glaucoma association: www.iga.org.uk

Normal Optic Disc

Optic Disc in Glaucoma

OCT Scanner

Visual Field Analyser