Fixation disparity: clinical implications and utilization

Research suggests that fixation disparity data is extremely useful in the assessment of the binocular and accommodative systems. However, clinicians have been slow to integrate this method of analysis into their practices. Fixation disparity measurement, under different fusional and accommodative demands, aids the practitioner in prescribing ophthalmic prism and/or plus lenses. In addition, it helps determine when vision therapy is appropriate and provides an objective assessment of the effectiveness of a vision therapy program. This paper discusses significant aspects of horizontal and vertical fixation disparity measurement, with particular emphasis on its clinical usefulness in understanding and resolving asthenopic symptoms attributable to vergence and/or accommodative dysfunction. The goal of this paper is to provide the practitioner with information so that fixation disparity testing can be incorporated within the clinical regimen.