Bott Confrontation Field Target - MK II
Also known as the Bott Confrontation Wand
The Bott confrontation field target was designed by New Zealand Optometrist Alan Bott who recognised the need for a small reliable low cost target to assess the visual fields of patients.
It has been well documented that a flashing light of know intensity and size is a suitable target for visual field testing. It is the purpose of this device to provide a suitable target when assessing fields by confrontation.
The quality aluminium handle fits comfortably into the hand. Two AA size batteries power the instrument. The handle supports a 330mm long black wand which contains the flashing light. The light is fitted into the side of the wand which allows it to be easily turned away from the subject to allow for false positive tests.
* Place subject directly in front of examiner in subdued light.
* Patient covers one eye with card and told to watch examiners opposite eye (i.e. if testing the right eye the subject is asked to look at the examiners left eye).
* The device is held in the blind area beyond the subject's field of view and switched on.
* The wand is slowly brought forward and the subject is asked to say when they see the flashing light while still looking at the examiner
* The extent of the field can be estimated by the examiner.
* The device can be used as a target for the Bjerrum Screen for assessment of gross areas of field loss.
Should the examiner feel that the subject either does not understand or is commenting when he sees something other than the light, then the wand can be rotated through 180° which will prevent the light from being seen by the subject. If the examiner still gets a response, he will know he has a false positive and will need to re-instruct and test the subject.
* Approved by NZ Land Transport Authority for assessing peripheral fields by confrontation.