Fusion Slides (green binding)
To assess sensory fusion (the second grade of Binocular Single Vision) two similar pictures each with an incomplete ‘control’ (i.e. rabbit’s tail and a bunch of flowers) are presented to the patient. One tube is locked at zero and the patient is instructed to move the image, as with Simultaneous Perception (SP), and create a composite image of the rabbit holding a bunch of flowers. It is important to question the patient about the ‘controls’ to prove sensory fusion or assess for the presence of suppression. Yet again, if this is difficult for the patient, large slides may be beneficial.