What is a Brock?

The humble Brock consists of a length of string (from 3 to 10 ft) with a series of beads (from 3 to 5 beads) placed at various intervals. This simple instrument is powerful tools in teaching binocular vision skills. While the configurations vary, it is elegantly simple and effective in teaching the brain how to make the eyes convergence.

How does the Brock string work?

The Brock string takes advantage of “physiologic diplopia”. The eyes can only focus clearly on a single point with all other things within the viewing area seen as double. This is a normal way for our eyes to work. The Brock string uses this physiologic diplopia to inform the brain that the eyes are working together correctly.

How do you fix fixation problems with Brock string?

Have the patient alternate from bead to bead, working closer and back to exercise the convergence muscles. Look for difficulty with maintaining the fixation as the muscle fatigue. Here is the video about the Brock String.

How do you use Brock beads?

With the beads evenly spaced (closest bead at about 2cm, furthest about 40 cm), have the patient hold one end of brock string to their nose. The therapist holds the string tight and angled slightly downward.