What is the Brock String?

by jacobsvision on November 7, 2011

What is the one activity performed by 99% of Dr. Robert Jacobs’ vision therapy patients throughout their course of treatment?  Its the Brock String, a technique developed by Dr. Fred Brock over 50 years ago.

What is a Brock String?

It is a length of white string normally attached to a wall at one end and held to the tip of a patient’s nose at the other end.  When looking down the length of the string, a person with normal binocular abilities (using both eyes simultaneously) will see 2 strings which cross at the point of focus or fixation.  This is because of physiological diplopia, a phenomenom in which objects outside the area of fixation are seen as double.  Dr. Jacobs uses the Brock String for both testing/diagnosis purposes as well as treatment.

Testing/Diagnosis with the Brock String

The following are a few examples of the type of information revealed by using a Brock String:

  • Suppressions:   The patient sees only 1 string or one of the strings fades in and out.  Patients with suppressions are unable to use both eyes as a team, and they frequently experience headaches and neck strain.
  • Convergence Issues:  The string does not cross where the patient is actually looking.  These patients are often slow to react to moving objects (like a ball or car) and they often fatigue when trying to sustain activities like reading or tv.

The Brock String in Therapy

The Brock String is a 4-5 minute visual therapy activity used by most patients beginning with their 1st session.  There are many levels of difficulty and variations of the activity.

  • Early Brock String Activities:  The patient needs to be able to see 2 strings and have them cross at the appropriate distance.
  • Advanced Brock String Activities:  The patient maintains balance on a balance board,  uses varying head positions and changes the alignment of the eyes while looking down the string.  Reaching this level of proficiency often takes many months of work, and once a patient reaches this level, the Brock Stringis still used as a good warm-up activity at the beginning of a therapy session.

Dr. Robert Jacobs tells his patients that the Brock String is not an “eye” exercise, but rather an activity giving the patient feedback as to how the brain is processing visual information.  In otherwords, the activity answers “Where am I looking?’ and “Am I using both eyes?”  Please ask Dr. Jacobs if you’d like to see a quick demonstration of the Brock String!

Previous post:

Next post: