Mastering the "X": Taking Brock String to the Next Level
- Robert Nurisio, COVT
- 5 days ago
- 3 min read
One of the most iconic tools in vision therapy is the Brock String, a simple string with a few beads that offers surprisingly powerful training for the eyes and brain. In Level One, the focus is on learning to aim both eyes at a single bead and perceive the image with clarity and balance. When this happens, the string appears to cross in an "X" at the bead, an indication that both eyes are working together and the brain is accurately interpreting depth. This "X" is more than a visual cue. It is a sign of binocular fusion, depth perception, and spatial awareness. The ability to see the X clearly relies on strong central-peripheral integration, which is the brain’s way of combining sharp focus with a broad sense of where things are in space.
Level Two, known as Moveable X, adds a layer of complexity by using multiple beads and shifting attention between them in random order. The goal is to be able to instantly see the X at whatever bead you are looking at. This sharpens vergence flexibility, or the ability of the eyes to align quickly and accurately across different distances. It also builds a sense of feeling tone, that internal moment of recognition when the visual system feels aligned and comfortable. Therapists or home helpers reposition the beads every few minutes, encouraging the eyes and brain to re-establish that comfortable alignment in new zones of space. As the visual system adjusts, patients gain a deeper understanding of where things are located relative to themselves, which ties into Skeffington’s “Where is it?” circle of visual function.
Level Three introduces Variations of Gaze, taking the activity into more dynamic territory. The same bead-jumping task is repeated, but now the head or string or sometimes both are in motion. The head might turn up, down, left, or right while the string remains still. In other versions, the string moves while the head remains still, or both move together in a circular path. These variations challenge the brain to keep the eyes aligned even when posture changes or motion is introduced. This is where Skeffington’s “Where am I?” system comes into play, as the brain must organize not just the visual space but also the body's position in it.
This level of training helps develop visual adaptability, which is the ability to keep vision clear and single even when we are in motion or interacting with a constantly changing environment. The eyes must quickly reorient, the brain must process spatial location, and the body must stay balanced and responsive. When these systems work together, the patient gains more than visual control. They gain awareness of their place in space, the direction of their gaze, and the relationship between their body and the visual world around them.
By moving through these levels of Brock String therapy, patients are doing far more than strengthening their eye muscles. They are building a flexible and responsive visual system that supports reading, learning, sports, and everyday movement. Each level reinforces not only what the eyes can do but also how they work with the brain and body to create a stable and confident sense of orientation. When the visual system becomes fluent in finding and forming the "X" anywhere in space, the world becomes easier to navigate, more focused, more centered, and more in sync.
The Brock String progression is just one of 20+ vision therapy activities you'll master in our Emergent 101 Course. Get the complete foundation that transforms your practice and patient outcomes!