F Thorn, J Gwiazda, A A Cruz, J A Bauer, R Held

The development of eye alignment, convergence, and sensory binocularity in young infants

publication date
see more


Purpose: To measure and compare the development of ocular alignment, sensory binocularity, and convergence in infants during the first 5 months of life.

Methods: Healthy infants were tested between 2 and 21 weeks of age. Ocular alignment was measured by the Hirschberg test; convergence was determined by visual examination as an illuminated toy approached an infant's face; and sensory binocularity was measured by preferential looking for fusible versus rivalrous gratings. In experiment 1 we compared the proportion of infants at different ages demonstrating orthotropic ocular alignment with those showing convergence. In experiment 2, we compared the age of onset of convergence to that of sensory binocularity.


Results: Experiment 1: Most infants were orthotropic during the first month, and almost all of the others showed small amounts of exotropia. None of the infants showed accurate convergence until 6 weeks of age. By 4 months of age virtually all were orthotropic and had good convergence. Experiment 2: The onset of sensory binocular fusion occurred at 12.8 +/- 3.3 weeks. Full convergence did not occur until 13.7 +/- 3.2 weeks, although the first signs of convergence occurred slightly earlier. For individual infants there was a high correlation between the age of onset of sensory binocularity and convergence, and both onsets occurred earlier in girls than in boys.

Conclusions: Ocular alignment did not require the development of binocularity mechanisms, and the development of binocularity mechanisms did not await the onset of good ocular alignment. The relatively sudden onset of binocularity, both sensory (preference for fusion and stereopsis) and motor (convergence) at about 3 months of age and the high correlation between these measures indicate a common causal mechanism that probably involves refinements in striate cortex circuitry.


  • 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.



Vision Among Us

One of the challenges with visual impairments and visual deficits is that it's difficult to detect them just by looking […]

Read More

Vision Therapy for Neurological Conditions

Each year an estimated 1.5 million Americans sustain a traumatic brain injury (TBI). According to the Neuro Optometric Rehabilitation Association, […]

Read More

Vision Therapy for Adults

Adults generally accept changes in themselves as part of aging, and think that there's nothing they can do about it. […]

Read More
see all blogs

Contact Us To Amplify Your EyeCare

Working Hours

Monday - Thursday
8:00 am - 5:15pm
1043 Executive Drive Suite #101 Hixson, TN 37343
Website Accessibility Policy
Safety protocols page
phone-handsetarrow-uparrow-right linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram