Perimetry is subject to many errors because it requires cooperation on the part of the patient. Several techniques and types of equipment have been devised to increase the accuracy and ease of this examination.1-8 We were particularly interested in performing accurate central and peripheral field examinations on the same apparatus and monitoring the accuracy of fixation by an objective means. In addition, the equipment should be self-recording and have constant factors of lighting and test object control. A simple hemisphere and manually operated projection light has been in use by one of us (E.W.D.N.) for about eight years (Fig 1). More recently, another perimeter has been built incorporating objective monitoring of fixation and a self recording device. It is this piece of equipment which will be described in detail.
—A 1,700 mm (five-foot) diameter spun aluminum hemisphere is mounted on a stand at an appropriate height so that
DONALDSON DD, NORTON EWD. A New Perimeter for Central and Peripheral Fields. Arch Ophthalmol. 1963;70(4):448-452. doi:10.1001/archopht.1963.00960050450003