Utilizes physiologic diplopia: patient will become aware of crossed physiologic diplopia when dots are nearer than the fused one, and uncrossed when a nearer dot is fused.
Exercise has added difficulty because the fusion of 2 different colors creates retinal rivalry.
This ergonomically designed handheld device features 4 peripheral porthole LEDs (Light-Emitting Diodes) and 4 central porthole LEDs with a constant brightness.
The peripheral porthole lights test for peripheral suppression; the central porthole lights test for foveal fusion/suppression.
A momentary rocker switch allows for peripheral or central testing.