Visual Field Testing (Goldmann perimetry)
Before and after pituitary surgery (or Yttrium implantation)
Before and during pregnancy in patients with macroprolactinomas.
- There is now an automated Visual field (Allergan Humphrey) testing machine in the eye room of clinic A (room A11). It is computer controlled and fairly user friendly.
- Switch machine on. It will perform a self test taking about 5 minutes. Once this is complete the computer will ask you several patient details, such as which eye you are testing. These can be easily fed in using the screen touch sensitive pen.
- Cover one eye with the eye patch present on top of the machine. Place the patient's chin on the rest at the centre of the hemisphere and the head against the upper band. You will need to manually adjust the position of the chin rest (using the rotating control) until the patient, when looking straight ahead, can see a yellow dot.
- The patient must be given the hand held pushbutton and told to fix on the yellow dot. He must press the button whenever he sees a flash of light anywhere in the sphere. The patient may need his glasses to allow him to see the object.
- When the patient is ready, simply select "AUTOMATIC DIAGNOSTIC TEST" from the menu. The machine will automatically find the blind spot and proceed to check the entire visual field by flashing lights at random. It will also check that the patient continues to fixate on the yellow dot by occasionally checking his blind spot.
- When complete, a printout of the field can be obtained. Repeat the procedure for the other eye.
- At the end of the test, remove the patch and switch off the machine.
Formal perimetry is highly accurate and reproducible. Field loss is always significant; it can occur as the result of the pituitary tumour or from the treatment of the tumour. If an increasing field loss is noted it is vital that the patient has a CT scan on that admission.