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Stereoacuity at Distance and Near

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Because previous studies have reported conflicting evidence, we examined a possible difference in stereoacuity between distance and near, in particular using a random-dot display. We compared distance and near stereoacuities using identical presentation formats at the two distances.



Twelve young adults with low, stable refractive errors and apparently normal binocular vision participated. Stereoacuity was determined with a Mentor B-VAT II using Random Dot E (BVRDE) and Contour Circles (BVC) stereograms presented on a standard monitor (25 × 19.3 cm) at 518 cm (distance-habitual) and a small monitor (2.0 × 1.4 cm) at 40 cm (near-habitual). To examine whether accommodation-convergence influenced stereoacuity, testing at 40 cm was repeated with the addition of +2.50 DS lenses and base-in prisms (near-compensated) that created the same accommodation and convergence demands as for distance-habitual viewing.



The two stereotests produced similar findings. Stereoacuity was not significantly different for distance-habitual and near-habitual viewing of the BVRDE (p = 0.43) and BVC (p = 0.79) stereotests. Near-compensated stereoacuity was worse than near-habitual (BVRDE, p = 0.005; BVC, p = 0.004) and distance-habitual (BVRDE, p = 0.05; BVC, p = 0.003) for both stereotests. Because near stereoacuity with yoked prisms (control condition) was the same as without prism (near-habitual), prism-induced optical distortions cannot account for the difference.



Stereoacuity was not different at distance and near under normal viewing conditions. The conflict between subject knowledge of target proximity and the optically-induced relaxation of accommodation and convergence, or an inaccurate accommodative-convergence response, might have caused poor near-compensated stereoacuity.


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!!!

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