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Authors
Thiagarajan, Preethi; Lakshminarayanan, Vasudevan; Bobier, William R.

Effect of Vergence Adaptation and Positive Fusional Vergence Training on Oculomotor Parameters

publication date
March 10, 2010.
Category
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Abstract/Introduction

Purpose

Clinical studies have shown that positive fusional vergence (PFV) can be trained through a program of orthoptic exercises. Models of accommodation and vergence predict that training PFV would require a reduction in the convergence accommodation (CA) cross-link. Recent investigations have found that the CA/C ratio is not changed in a clinical population after orthoptics. We hypothesized that such orthoptic programs may instead act to reduce CA through changes in the relationship between fast and slow vergence components.

 

Methods

Eleven visually normal subjects were tested. Phoria adaptation to a 12-Δ base-out (BO) wedge prism and the resulting CA responses were monitored every 3 min for 15 min to a DoG target at 0.4 m. These measures were repeated after 2 weeks of orthoptics. Phorias, stimulus accommodative convergence (AC)/A and CA/C ratios, and PFV amplitudes at near were also determined. Before the orthoptics program, these measures were repeated under “adapted” conditions.


Conclusion/Results

Results

Phoria adaptation following prolonged viewing through the 12-Δ BO wedge prism was associated with a concomitant reduction in the CA. These changes were asymptotic over time with 95% of the change occurring within the first 3 to 6 min. After 2 week of orthoptics, the rates and magnitudes of both phoria adaptation and CA reduction increased significantly (p < 0.01). PFV at 40-cm limits showed increases with orthoptics and under vergence adaptation. CA/C and AC/A ratios were unchanged after orthoptics, but the former was reduced, and the latter increased under the vergence adapted condition.

 

Conclusions

Orthoptics acts to change the time constant and magnitude of vergence adaptation to BO prisms, which leads to a concomitant reduction of CA over a similar time course. This process appears to underlie the increase in positive fusion limits. Although reductions in CA/C ratio occur under the vergence adapted state, this ratio is not directly changed with orthoptics.


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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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