The OCULUS perimeters also differ in the way the stimuli are presented. The Easyfield® makes use of a fixed grid of light emitting diodes (LEDs) to generate light spots. The Smartfield performs static perimetry measurements using an LCD display of very high luminance to create the standard background illumination and the test stimuli simultaneously.
By contrast, the Centerfield® and Twinfield® models make use of a rear-surface projection system with which stimuli can be presented at any desired point on the projection surface. Rear-surface projection systems have the advantage of being able to project undeformed circular stimuli onto any desired location, making them suitable for kinetic examinations.