infravergence
Also called negative vertical vergence, deorsumvergence, vertical fusional vergence (base-up), infra-vergence
The vertical fusional vergence in which one eye rotates downward relative to the other to keep an image single; supravergence is the upward counterpart, and together they form the vertical fusional reserve1,4. Vertical vergences exist only as small compensating adjustments of muscle tone: a slight vertical misalignment, from a hyperphoria or a prism, drives one eye to shift until the two images fuse4.
Infravergence should not be confused with infraversion, in which both eyes move down together. It is measured by adding base-up prism before one eye until double vision (the break) and reducing it until the image is single again (the recovery), and the normal range is small, about 2 to 3 prism diopters1,2,5.
More detail
Infravergence of the right eye is the movement that compensates a right hyperdeviation1. Older texts call the pair deorsumvergence and sursumvergence4. There is no blur finding, because accommodation does not change during a vertical vergence2. A large vertical reserve points to a long-standing deviation such as a congenital fourth nerve palsy, and a small one to a recent deviation3.
Sources (5)
- Scheiman and Wick, Clinical Management of Binocular Vision, ch. 2
- Carlson and Kurtz, Clinical Procedures for Ocular Examination, ch. 4
- Eperjesi and Rundström, Practical Binocular Vision Assessment, ch. 6
- von Noorden and Campos, Binocular Vision and Ocular Motility, ch. 4
- Kanski, Clinical Ophthalmology (2024), ch. 18
Reviewed October 2026