Purpose: To provide immediate feedback as to whether both eyes are turned on, whether they are pointed to the same place in space, and whether perception of where a target is matches its real location. Also, to increase familiarity with the feeling of converging and diverging, aiding conscious control of the process.

Materials: Brock String Doorknob or other Fixture

Procedure: 1. Tie one end of string to doorknob, screw eye, etc. Hold the string taut and with the other end on the bridge of the nose, directly between the eyes.

2. The helper should move the beads to the far end of the string.

3. As the helper slides one bead up the string slowly, count aloud (about a count of 10 to go the length of the string). The patient should focus on the bead, but be aware of the room and its surroundings. The patient should try to keep the “X” at the bead all the way up. Bring the bead close to the nose, hold it about 5 seconds, then move down slowly, still counting to 10 as the eyes follow the bead.

4. Repeat 2 or 3 times. Slower speeds are more difficult, but are most desirable as this shows more control.

5. Have the patient try to replicate this eye motion independently, moving the eyes slowly down the string and slowly back. This should be a smooth motion of the eyes, not jumps.

6. Continue practicing with the bead and independently.