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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 space the beads out along the string with a greater distance between the beads at the far end of the string than the nearer beads.

3. The patient should choose a bead to fixate on, and notice if two apparent strings are going into that bead. The “X” formed by the two strings should be right on the bead the patient has chosen.

4. The patient should look at each bead carefully. If both eyes are exactly on the bead, they will see an X. If they see the strings crossing in front of the bead or in back of the bead, this means their eyes are not really looking at the bead. Be sure you can get the X at all beads (except the one at the far end, which will just have the 2 strings coming out toward you in a “V.”)

5. When the patient can do this, have them turn their head so their right eye is looking straight down the string & the left eye has to pull inward to see the beads. Have them try to get the X at each bead. Then have them turn so the left eye is looking straight down the string and the right eye has to pull inward to see the bead. Again, see if they can get the X at each bead. NOTE: If one string is disappearing or getting shadowy, try anti-suppression strategies.

If you are interested in learning more about this technique, call our Yakima and Richland Optometrist today at 509-654-9256.


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