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Danielle J. Nesbitt, Katherine R. Hastings, Dustin E. McGill, Dennis Ireland, Rebecca K. Zoltoski; Development of Vision Therapy Controls for Vergence and Accommodative Disorders. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1365.
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Vision Therapy is the current treatment of many accommodative and vergence disorders; however, most of the therapies have multiple procedures and have not been investigated in a controlled setting. We are reporting preliminary data on controls (CT) for two commonly used therapies.
Young adults were screened using a modified Vision Efficiency Exam (VEE) and a symptom survey (SS), a combination of the COVD and the CITT symptom surveys. Based on the results of this exam and SS, they were diagnosed with either a vergence dysfunction or accommodative dysfunction or both. We used a double-masked, modified cross-over design to randomize subjects into either an experimental therapy (ET) or a CT for six weeks, using one specific therapy. After this time they were screened again using the VEE and SS. They were then placed in another group (CT becomes ET, or ET moves onto the next therapy either CT or ET) for another six weeks. The Brock String (BS) and Monocular Hart Chart (MHC) were the first therapies used. BS ET used push-up, jumps and bug on a string working binocularly within 1 m. The CT for BS used the same procedures but with a working distance of 3 m. The MHC ET used large (at 3m) and small Hart Charts (moved in from 40 cm until just readable), reading a line on the large chart and then reading a line on the small chart. The CT for MHC used the same procedure but the small chart was left at 40 cm. Improvement was based on the results of the SS, near point of convergence (NPC), prism bar vergences (PB) , and subjective (pull-away (PA)) and objective (iTrace) accommodative responses. Objective accommodative responses were collected using the iTrace wavefont analysis, a percentage was made comparing the accommodative response as a fraction of the accommodative stimulus (accommodative efficiency (AccEff). Data are presented as mean ± SEM, with pre- vs post-therapy.
Subjects (n=5) performing BS CT had no changes in their NPC Blur/Break/Recovery (B/B/R) (5.6 ± 2.4/5.6 ± 2.4/6.6 ± 2.8 vs 6.1 ± 1.5/5.5 ± 1.5/7.1 ± 1.8, p=0.9), or PB data (not shown). There was a trend toward decreasing symptoms based on the SS, pre- vs post- therapy (32.8 ± 3.2 vs 46.1 ± 6.3, p=0.07). Subjects (n=3) performing the MHC CT showed no significant differences in any tests, PA (6.7 ± 0.3 vs 8.1 ± 0.6, p=0.2) , AccEff (81.3% ± 16.2% vs 92.3% ± 0.04%, p=0.37) and SS (43.3 ± 9.5 vs 53.0 ± 7.5, p=0.48).
The current controls do not appear to be improving the objective measurements used for diagnosing accommodative and vergence dysfunctions; however, therapy may be impacting subjective measures. Further studies to increase our number in both groups will allows us to investigate the effectiveness of each individual procedure on improving binocular symptoms in subjects with dysfunction.
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