All about Perimetry

Where it all began

Perimetry is the standard functional test in Glaucoma and many more eye related pathologies. Haag-Streit is the pioneer and technology leader when it comes to perimetry. This started with the development of the original Goldmann Kinetic Perimeter by Professor Hans Goldmann in 1945. Then, in 1972 Professor Franz Fankhauser did lay the foundation to the Octopus, the first computer automated static perimeter. With the Octopus 900, kinetic and static Perimetry finally come together in today's most advanced perimeter.

  • Why Perimetry: Testing the visual sensitivity is a key to the diagnosis and management in eye care
  • A team work: Perimetry is a team work between the examiner and the patient. Cooperation and understanding are key to good results. This is reflected in our mountaineer theme where a trustful relationship leads to the top

A simple task

Standard perimetry is a rather simple task. You look into a bowl or into an optical lens and get a response button in your hand. Then:

  • Always look in the center of the green fixation marks
  • Lights flash up in different places. Whenever you think you've seen a light, push the button
  • If you need a break, keep the response button pushed. The instrument will continue when you release the button.
  • Finally, don't worry if you make mistakes, a small amount of "wrong" answers is well tolerated by the test.

How long does it take?

Up to date Octopus perimeters with the optional TOP strategy take less than 3 minutes per eye for testing. This is especially recommended for children and patients above 70 years of age but provides good results for glaucoma testing and follow up in all age groups. The dynamic strategy takes 4..7 minutes per eye. The normal strategy as used in older instruments can take anywhere between 10..30 minutes per eye but is not recommended anymore.

Reliability with fixation control

You often need to blink for your comfort? Don't worry in an Octopus perimeter. The unique Octopus fixation control - even if set to minimum sensitivity -recognizes blinks. If you can't see a light because you blink at the time of presentation, this same light will be shown again later in the test.

One eye at a time

For detection of eye diseases and in glaucoma management, each eye is examined separately. The other eye is covered with a white, translucent eye patch. The eye patch should let some light through, so the second eye will not dark adapt.

Refraction and eye distance

To get accurate results, the refraction must be corrected. This includes near distance correction if examined in a cupola perimeter. If the green fixation marks can be seen in focus, the refraction is ok. Just make sure the lenses are as close to the eye as possible. If the lens is more than 15mm away from the eye, the lens rim may cover some areas that should be examined.

During the examination

The examination can be experienced quite lengthy since there is nothing but the lights and some buzzing sounds of the motors moving in the instrument. Just remember to only push when you think you have seen a light. Sometimes the ambient light appears to get darker and then brighter again. This is a common illusion and you don't need to worry. If you shift on the chinrest, the examiner or the instrument itself will bring you back into an optimum position now and then. Though it is always good if you sit comfortable and straight up from the start.