Eye movements in heterophoria.

Reference is made to earlier reports by the author in which versional recovery eye movements were observed during the cover test in the non-occluded eye in case of heterophoria. This provided support for Hering's Law, although the magnitude of the versional movement did not relate to the degree of heterophoria. Recent studies of eye movements during the cover test on very small heterophorias have suggested there is a threshold value below which these versional recovery movements are absent, and that is presence depends on such factors as the size of the phoria, the degree of ocular motor dominance and patient concentration.