How is glaucoma diagnosed?

A thorough clinical assessment by your optometrist or ophthalmologist will detect any damage to your eye, or whether you are likely to develop the disease. Early detection is the best way to prevent vision loss.

History

A thorough history is taken to identify any risk factors.

Intraocular pressure (IOP)

A special instrument called a tonometer is used to measure the IOP. A small pressure-sensitive plastic tip is gently placed on the eye after a drop of anaesthetic has been used. In air tonometry, a stream of air is puffed against the eye.

Gonioscopy

A special contact lens is placed on your eye to examine the drainage angle to see if it is blocked.

Ophthalmoscopy

After drops have dilated your pupil, the ophthalmologist examines the optic nerve for damage (see below). This is done on the slit-lamp (the special microscope used for the general eye examination) with a lens which gives a stereoscopic, colour view. This technique has largely replaced the hand held ophthalmoscope.

Visual field testing

Computerised visual field testing, or perimetry, is an important measure of the extent of damage to your optic nerve. During these tests you will be asked to look into a computer screen and push a button when you see a light flash. A map is then built up of your peripheral vision and the results printed off. If a defect is found in your peripheral vision repeat visual field tests will enable the ophthalmologist to determine if this field defect is stable or if it is getting larger.

Retinal Topography

Camera-like device takes 3-dimensional colour images of your optic disc using a scanning laser ophthalmoscope. There are no X-rays involved and the painless test only takes a few minutes. These images are used as a baseline, and the appearance of your optic nerve is compared to them at each visit. In this way, early changes, or progression, of glaucoma can be detected. Often the retinal topographer will be able to detect early signs of glaucoma before there is any evidence of visual field loss allowing treatment to be commenced at an earlier stage.

It may not be necessary for you to have all these tests each visit. If glaucoma is suspected, or your glaucoma worsens, more tests may be added or the tests repeated more frequently.

For more information on private Glaucoma Care packages check your local CESP office website.