Modified Brock String for Peripheral Vision

Published on
February 28, 2022

Brock string is commonly used in vision therapy which comprises a white cord or string that is about 10-15 feet long, along with colored wooden beads that move along the length of the cord. The brock string is used for central vision as well as improving peripheral vision. 

Why is it called Modified Brock string?

Typically, a brock string is used to test the ability of the eyes to focus on an object at various distances and therefore useful in working with patients who have issues like convergence insufficiency, amblyopia (lazy eye), and strabismus.

A modified  Brock string is the same tool with slight modifications and different exercises which enables it to be used as a tool to work on peripheral vision (side vision). 

What are some of the exercises included in the Brock string procedure?

  • The Brock String for Central Vision  - It is one of the most common procedures used in the therapy room to train binocular vision (both eyes working together). The patient will hold the string up to their nose and will be asked to focus on various beads and make the two strings cross at each bead. This is a central activity which means it is working on the central part of the vision.
  • The Brock String for Peripheral Vision - The patient may be asked to open their stance a little bit wider when they are having trouble opening their periphery, so they will move their feet apart and by opening their stance, they will be able to open their periphery a little bit more.

Another thing that is done for peripheral vision is to have the patient focus on the beads while the vision therapist brings their fingers over to the side and the patient's vision,             the patient is asked to move their fingers when this happens which forces them to be aware of their peripheral vision.

         Another exercise to develop peripheral vision with the brock string is to have the patient name objects that are in their periphery as they look at the beads. In cases where the              patient ignores one eye more than the other, they may be asked to tighten up or increase their muscle tone on that side. 

         Another way to increase peripheral awareness is to use lighted buttons, which light up intermittently and the therapist will set them on the table. Then, if it lights up on either             the right or left side of the periphery, the patient would tap that light to turn it off.


Why is the modified Brock string a powerful exercise to work on central and peripheral vision during vision therapy? 

When a patient is taught to combine both central and peripheral vision they are taught a valuable skill that is used in sports and reading. Their brain is now able to go back and forth from central and peripheral visual processes and organize that visual information. 


Vision therapy is well worth the response, time and effort. Our Son had a hard time focusing and writing neatly. After vision therapy Seth could complete a task in half the time if previously took. His abilities to focus improved greatly and so did his handwriting.

Also, he was better at listening. As a parent, we wanted learning to be fun for our Son, and vision therapy made this possible.

Amanda T.

Vision Therapy is well worth the expense, time and effort. Our son had a hard time focusing handwriting neatly. After vision therapy Seth could complete a task in half the time it previously took his abilities to focus and improved greatly and so did his handwriting.

Also, he was better at listening. As a parent you wanted learning to be fun for our son and vision therapy made this possible.

Alexa H.

Vision Therapy has given or son the tools he needs to be able to scan and read the written word more effectively and efficiently.

He love working with John and these working sessions give him the motivation to gladly work on his homework assignments.

It amazed us to see the difference in the tracking of his eyes and along a line of it's from the beginning to the end of the treatment.

Dr. McBryar , Kristen and John  are all marvelous and we would recommend them to anyone I only wish that we would have found them sooner!

Charlotte M.

Prior to coming to the institute for vision development my son complained of daily headaches. Therapy has eliminated his headaches completely. I love knowing my son is able to learn pain-free for the rest of his life because of the work that has been done over just a few weeks in this office. He he absolutely loved coming that didn't even feel like going to a doctor or therapy. We are grateful for the relief he was able to find by coming here.

Thank you!

Olivia C.

Seems much less frustrated with life

Reads non-stop and fast

Spelling abilities have been hugely improved

Seems much more confident

Thank You!!!

Kelly O.

When we first came to the practice, my son did not have huge issues, but lots of small ones- trouble with reading, sports (hitting the baseball consistently), coordination, etc- that were not easily detectable,but when put together presented issues. The staff here were all very professional and loving towards him. While I was concerned in the reading, my son was concerned with the athletic side. Seeing improvement night off the bat gave him confidence that i have nor seen in him and made him want to not only Come to therapy, but also made him want to work hard. He has surpassed his grade level and above in reading and hit his first home run this year! Thank you!!!

Alice M.
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