Background and Aims: The study was conducted to determine whether visual cortex activity in patients diagnosed with Post Trauma Vision Syndrome (PTVS), particularly eye-to-brain signal strength and delay, can be improved through vision therapy. Brain injuries in PTVS patients affect the propagation of electrical signals from the optic nerves to the visual cortex, which can disrupt normal binocular vision. Normally, the brain combines both eye signals, recorded by a Visual Evoked Potential (VEP) instrument, in ‘summation’, producing a higher amplitude than each eye individually. However, PTVS can cause ‘suppression’ or ‘interference’, where the combined signal is actually equal or lower than the signal coming from strongest eye signal. PTVS can also introduce delays in eye-to-brain signals.
Methods: The study measured patterns of VEP signals when presented with five sizes of targets, 100% contrast, and taking monocular and binocular measures. Eight patients were going through vision therapy and ten did not do VT. Retest measures were done for twenty and forty week intervals. The presence of interference in binocular measurement with no delays assumed to serve as objective indicators for BV (binocular vision) dysfunction. Any interference was considered to be at some level of BV dysfunction, causing levels to be 20% to 80% in both groups initially. Results: In terms of signal summation amplitude, a comparison between the therapy and control results after 40 weeks showed improved summation in 90% of Therapy subjects (P=0.00941vs) and no significant improvement in Control subjects (P=0.78). Of the subjects in the Therapy Group that experienced signal delay, 64% showed improvement in this delay (P=0.014). This compared favourably to the Control Group P, which showed improvement in only 10% of subjects that experienced delay.
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