The Brock String is a vision therapy tool consisting of a cord with 4 small beads of different colors placed at specific intervals along the string. What is the Brock String used for? In Brock String eye exercises, individuals focus on each colored bead in succession, observing the adjustments their eyes make to maintain single and clear vision. By shifting focus between the beads, the eyes improve: - eye coordination, - focusing flexibility, - depth perception, and - visual processing skills.