Brock String – ROM OKR Pursuits 1

The Brock String is the basis for some wonderful activities, helpful in developing visual skills. Brock Strings are used to

  1. Create awareness of space and depth.
  2. Increase the range of motion of the eyes.
  3. Increase accuracy and range of targeting.
  4. Improve scanning ability.

ROM OKR Pursuits 1

ROM means ‘range of movement’, that is, this activity is designed to increase the range of movement of the eyes. Movements of particular interest in the classroom include inwards and outward movements of the eyes. This activity is designed to encourage greater range generally, while other activities are concerned with more specific areas of concern. Increasing functional ranges are not so much a matter of ‘stretching muscles’ as reminding the brain that the eyes can move in a broader range than they normally do during day to day living.

OKR refers to the human optokinetic reflex, which automates the tracking of moving objects. Take for example a bird in flight: You remain perfectly still, yet your eyes can follow the bird with very little conscious input. In fact, by not thinking about anything and simply being aware or ‘on stand-by’, we can increase the speed at which we acquire targets. The trap shooter waits for the clay pigeon with a clear mind and can respond more quickly by relying on his reflexes than on input from the frontal lobes. When we impose our will on the decision of ‘where’ to look, we are in effect overwriting our visual reflexes (residing primarily in the brainstem and modulated by the cerebellum) and this adds to the time required to calculate the decision of where to shoot, then plan the motor responses in the brain. If we simply wait but knowing what to expect, our reflexes provide the quickest response possible.

In these exercises, you will use the Brock String with one bead to engage one of two key visual reflexes to assist in building range of movement of the eyes. Other Brock String activities will engage more voluntary eye movements, that is, those movements we direct our eyes to make. Voluntary movements require more input and processing from the frontal lobes and is generally more tiresome. Voluntary eye movements are generally slower compared to reflexes.  The Saccades activity below helps with voluntary saccades of the type required for reading automaticity. Other activities on the site help with involuntary saccades.


  1. Glasses should be worn.
  2. Begin with the Starting Position, described in Physiological Diplopia: When seeing double is correct. Use only one bead positioned at the Harmon distance. Let the remaining beads drop to the far end of the string and keep them out of the way.
  3. The client can hold the string in place and move the bead, or the therapist can move the bead. It is preferred that the therapist move the bead but it’s quite acceptable to teach the client to do this on their own as well.
  4. The client is to remain still and upright, facing forward, holding the string to the nose.
  5. The bead is moved in a repetitive manner in the sequences given below. The client maintains fixation on the bead while the therapist observes the targeting of the eyes. You can generally tell if the eyes are on target, but many people have difficulty maintaining good targeting with both eyes at some distances. Never scold a child/client if they cannot align both eyes on a target/bead, and do not tease them or comment. Simply move on to a different exercise. Consult your optometrist if you have questions.
  6. The following is a list of movement guidelines, therapists should explore all combinations and vary the activities at each session. Do a variety of these variations for perhaps 5-10 minutes. Never exceed what a client can comfortably achieve, but ensure the tasks are reasonably challenging (remember, going slower can sometimes be a challenge, just as going fast can be). Keep the pace quick and move from one task to the next.
  7. Construct your activities using a combination of these ideas, again, keep the pace moving:
    1. Use an alternating patch for perhaps half of the time. So, if you do 4 minutes of this activity, do 1 minute with a patch on the left, then one minute with the patch on the right, then 2 minutes with no patch.
    2. Move the bead up and down. Be sure the client’s head does not move. It’s ok if the bead goes out of reach for the eye, as in if it goes to high or too low to see anymore, this is actually preferred. Simply move it back into view and allow the client to see it again. Continue moving through to the other side, moving the bead back and forth first out of view, then returning back into view.
    3. Move the bead side-to-side. As above, move the bead out of view, then back into view.
    4. Do bead rotations in progressively wider circles. Be sure to keep the bead within view of the eye(s). Work in alternating directions, clockwise, then counter clockwise.
    5. Vary the speed. For example, you should move the bead from the left side vision to the right in no more than perhaps 5 seconds. Try going progressively faster.

See Also:

You should study all notes relating to Brock String activities prior to attempting them. Always follow the guidance of your vision care provider. Do not exceed what clients can comfortably tolerate.