DIPLOPIA
Disorders of binocular fixation are regularly accompanied by corresponding disorders of projection. Of these the most common is double vision or diplopia.
Pathologic diplopia, due to derangement of binocular coordination, is to be distinguished from physiologic diplopia, which is the regular accompaniment of normal vision and which is a potent factor in the production of stereopsis.
The two conditions are differentiated as follows :
Both physiologic and pathologic binocular diplopia are distinguished from monocular diplopia by the fact that in the two former one of the double images at once disappears when either eye is shut. When this happens, the remaining single image, if indistinct before, at once becomes distinct, provided the eye has good vision.
In pathologic diplopia the distinct image of the objects of fixation, i. e., the one seen by the fixing eye, is called the real image ; the indistinct image seen by the nonfixing