What is Perimetry?
A perimetry test measures all areas of your eyesight
including your side or peripheral vision.
How is it done?
To do the test, you sit and look inside a bowl-shaped
instrument called a perimeter. While you stare at the
centre of the bowl, lights flash. You press a button
each time you see a flash. A computer records the
spot of each flash and if you pressed the button when
the light flashed in that spot.
At the end of the test, a printout shows if there are
areas of your vision where you did not see the flashes of light.
These are areas of vision loss.
Loss of peripheral vision is often an early sign of glaucoma.
Why it is done?
A perimetry test can help find certain patterns of vision loss. This may mean a certain type of eye
disease is present. It is very useful in finding early changes in vision caused by nerve damage
from glaucoma.
Regular perimetry tests can be used to see if treatment for glaucoma is preventing further vision
loss
Perimetry can also help detect field loss that may happen due to neurological diseases.
