30 participants with normal binocular vision and 30 with CI will be recruited for this prospective study. All participants with CI will be treated with 12 weeks of office-based vergence/accommodative therapy. The primary outcome measure will be the average peak velocity for 4° symmetrical convergence steps. Other objective outcome measures of disparity vergence will be time to peak velocity, latency, and accuracy. Changes in clinical measures [near point of convergence (NPC), positive fusional vergence at near (PFV)] and symptoms will be evaluated.