What is Glaucoma?
Detecting Glaucoma
When the degree of enlargement is different between the two eyes, a doctor can diagnose early
glaucoma from this appearance alone (Figure 4).
New methods of detecting damage to the optic nerve appearance using computers are now available, but standard examination with conventional instruments can often detect even mild damage. Newer methods that may permit even earlier detection also are being developed to examine and measure the nerve fibres as they spread into the retina.
Visual Field Testing
Another important tool used to examine and measure the optic nerve is the visual field test. This measures how well the optic nerve functions in carrying visual information the brain. Most visual field tests measure the ability of the patient to recognise light at each area of the retina. Many new visual field tests also are being developed, using coloured (blue and yellow) light, flickering lights, and special targets (such as rings). Testing of the visual field and examination of the optic nerve are the most important determinants of whether or not there is glaucoma. If glaucoma is present, these tests also allow your eye doctor to determine whether it is stable or becoming progressively worse.
Most patients dislike having their visual field tested. The test is often long, tiring and boring. It is not uncommon to feel that you have performed badly. Most modern visual field machines measure at each location until the testing light is not seen. This is done in order to determine the dimmest light detectable. Thus, even someone with a healthy eye often will not see the testing light during the course of the examination. In other words, not seeing the light may be perfectly normal, and should not cause anxiety.
New methods of detecting damage to the optic nerve appearance using computers are now available, but standard examination with conventional instruments can often detect even mild damage. Newer methods that may permit even earlier detection also are being developed to examine and measure the nerve fibres as they spread into the retina.
Visual Field Testing
Another important tool used to examine and measure the optic nerve is the visual field test. This measures how well the optic nerve functions in carrying visual information the brain. Most visual field tests measure the ability of the patient to recognise light at each area of the retina. Many new visual field tests also are being developed, using coloured (blue and yellow) light, flickering lights, and special targets (such as rings). Testing of the visual field and examination of the optic nerve are the most important determinants of whether or not there is glaucoma. If glaucoma is present, these tests also allow your eye doctor to determine whether it is stable or becoming progressively worse.
Most patients dislike having their visual field tested. The test is often long, tiring and boring. It is not uncommon to feel that you have performed badly. Most modern visual field machines measure at each location until the testing light is not seen. This is done in order to determine the dimmest light detectable. Thus, even someone with a healthy eye often will not see the testing light during the course of the examination. In other words, not seeing the light may be perfectly normal, and should not cause anxiety.