Binocular diplopia is double vision. When a person experiences double vision it means that the visual information that the right eye sends to the retina is not being combined, or fused, adequately with the visual information that the left eye contributes. There are many reasons for someone to have diplopia, including poor control of the eye muscles, convergence insufficiency, convergence excess and an assortment of diseases. Some diplopia can be resolved by a program of in-office optometric vision therapy under the supervision of a developmental optometrist who specializes in binocular vision disorders.