bifoveal fixation
Bifoveal fixation is the state in which both eyes fixate the same object point at once, so the image of that object is held steady on both foveae. Fixation by one eye alone is called uniocular, or monocular, fixation.1 True bifoveal fixation probably does not develop until about 2 to 3 months of age.2
The term bifixation comes from Parks, who contrasted it with monofixation to separate normal from deficient foveal function under binocular conditions. Some authors avoid the term, because fixation can remain bifoveal even when one fovea is suppressed under binocular conditions.1
Stereoacuity of 40 seconds of arc or better indicates bifoveal binocular single vision and a well-compensated binocular status.3 In the four-diopter prism test, a base-out prism goes before the eye with better acuity, and a rapid inward refixation movement of the other eye confirms bifoveal binocular single vision. An eye with a central suppression scotoma makes no corrective movement.4
Sources (7)
- von Noorden and Campos, Binocular Vision and Ocular Motility, ch. 4
- Pickwell's Binocular Vision Anomalies, ch. 3
- Eperjesi and Rundström, Practical Binocular Vision Assessment, ch. 7
- Eperjesi and Rundström, Practical Binocular Vision Assessment, ch. 6
- Noorden, G.K. and Campos, E.C. 2002. Binocular vision and ocular motility: theory and management of strabismus. 6th ed. St. Louis: Mosby.
- Rutstein, R. and Daum, K. 1997. Anomalies of Binocular Vision: Diagnosis & Management. St. Louis: Mosby.
- Steinman, S.B., Steinman, B.A. and Garzia, R.P. 2000. Foundations of binocular vision: a clinical perspective. New York: McGraw-Hill.
Reviewed October 2026