[Disparity of fixation in asthenopic syndrome]

This study provides the first description of a test of fixation disparity that can be used in daily clinical practice. Exploration of this problem lays a basis for understanding, and allows rational prescription of the use of small prisms for the treatment of asthenopia associated with horizontal heterophoria. The fixation disparity is opposite to the heterophoria in almost 30% of cases. The test has a specificity of 71,5% for a study population of 55 patients. When the disparity test was abnormal, use of this examination demonstrated that the prescription of an adapted prism was effective in all cases in eliminating the disparity. This prescription usually involved asymmetric prisms. We also found that complaints of non-specific neck and back pains tended to improve in parallel to the improvement in the asthenopia and the elimination of the disparity. We feel that these postural pains ares part of the asthenopia related to symptomatic heterophoria. The ability to study disparity in daily clinical practice will also provide the physician with a means to study the genetic relationships underlying tropias and phorias when disparity is abnormal.