A Review of Convergence Insufficiency: What Are We Really Accomplishing with Exercises? Kyle Arnoldi, C.O., C.O.M.T. James D. Reynolds, M.D. CONVERGENCE INSUFFICIENCY: DEFINITION AND ETIOLOGY Convergence insufficiency (CI) is an un- common disorder of ocular motility char- acterized by an inadequate amount of ocu- lar convergence needed to achieve and maintain comfortable, clear, single binocu- lar vision at near fixation. Exodeviations are found in 1% of the general population, 1 American Orthoptic Journal 123 © 2007 Board of Regents of the University of Wisconsin System, American Orthoptic Journal, Volume 57, 2007, ISSN 0065-955X, E-ISSN 1553-4448 ABSTRACT Introduction: Orthoptic exercises have been the primary treatment for convergence insufficiency since this condition’s first description in 1855. It is presumed that exercises work by improving fu- sional convergence. In recent years, research from eye movement laboratories has challenged our theories on the nature and dynamics of convergence, the effect of convergence exercises, and the eti- ology of primary convergence insufficiency. Methods: A review of the ophthalmological, optometric, and basic science literature was done to re- trieve the most recent research on vergence eye movements and convergence insufficiency. Results: Convergence appears to be a bi-phasic response to a change in stimulus position in depth. The first phase, which may represent the contribution of proximal convergence, is not under visual feedback, is fast with a short latency, and is triggered by stimuli moving rapidly in depth or by large, sudden changes in fixation. This phase is followed by a slow vergence movement with a slightly longer latency, triggered by small disparity vergence errors. The second phase is under the control of visual feedback, and represents the contributions of fusional and accommodative convergence. Eye movement recordings indicate that the velocity and amplitude of the first phase of convergence are temporarily adaptable with exercises. The second phase does not appear to be amenable to training. Tonic con- vergence is also trainable. Conclusion: Convergence exercises are effective in temporarily improving the dynamics of proximal and tonic convergence, but have little effect on fusional or accommodative convergence. From the State University of New York at Buffalo, Buffalo, New York. Requests for reprints should be addressed to: Kyle Arnoldi, C.O., C.O.M.T., University Ophthalmology Services, 3580 Sheridan Dr., Suite 140, Amherst, NY 14226; kylea@buffalo.edu This research was supported in part by a Challenge Grant to the Department of Ophthalmology from the Research to Prevent Blindness, Inc., New York, NY.