A vision therapy examination is conducted once it’s known that the eyes are healthy and that the need for glasses, or a change in eyewear, has been considered. The examination includes the following tests:
- Keystone Visual Skills: eye muscle balance profile at distance and near including lateral phoria and fusion in a stereoscopic instrument.
- Cheiroscopic Tracing: how both eyes direct the hands (eye-hand coordination) to produce a geometric figure in a stereoscopic instrument.
- TNO Anaglyphic Random Dot Stereo Test: pure binocular (two-eyed) depth perception based on accurate alignment of the two eyes.
- King-Devick Saccade Test: speed and accuracy of the eye movement skills used in the reading process, standardized for children age 6 and above.
- Accommodative Dynamics: lens tests to study the accuracy, efficiency, and stamina of the focusing system, as in shifting from the desk to blackboard and back.
- Vergence Dynamics: prism tests to study the accuracy, efficiency, and stamina of the binocular system, as in sustaining reading for extended periods of time.
- Computerized Mentor B-VAT Test: liquid crystal polarized testing of distance binocular functions including suppression. Depth perception, and fixation disparity.
- VISAGRAPH Eye Movements: computerized infrared recording and analysis of eye movements used in reading.
At the conclusion of these tests, our doctor will review all findings in a conference. If the doctor has access to the results of a recent comprehensive eye examination, within the last six (6) months, our comprehensive eye examination may be waived. When our evaluation centers on visual performance related to learning, an assessment of visual perception in conducted.
Testing – Visual Brain Waves
Visual Evoked Potential
The visual evoked potential, or VEP, measures visual brain waves. We use this information to better understand how well the eye is sending signals to the main visual portion of the brain. It is a very useful technology that determines how your eye communicates to your brain in a way that no other instrument, computer, or test can. This is crucial in determining if vision is developing normally, and in helping to determine what is wrong when there is visual difficulty. Here are some common questions and answers about the VEP.
Q: What is the VEP procedure used for?
A: The VEP is used primarily to determine how well each eye sends its signals through the optic nerve to the rest of the brain. This is important information in amblyopia, strabismus, and suspected neurological conditions such as multiple sclerosis. It is uniquely valuable for infants and toddlers, and any patients who have difficulty with verbal communication.
Q: How is the VEP recorded?
A: The VEP is the visual form of the EEG (electroencephalogram) and is recorded with three electrodes that are briefly pasted to the front, middle and back of the head. It is non-invasive and very safe.
Q: How much time does the VEP take?
A: About 40 minutes total, though obtaining the recordings once we’re ready is a matter of only 10 or 20 seconds of looking at a checkerboard pattern on a screen for each recording.
Q: What if my child can’t pay attention?
A: Sometimes an assistant will tap the screen or flash finger puppets. There is a version of the VEP that we use to help evaluate infants that interposes cartoon figures and songs. Features of the VEP may even give us objective information about visual attention.
Q: Is there any special preparation needed?
A: It helps to get a good night’s sleep before and to shampoo the hair before coming in. We clean a few areas of the scalp carefully before applying the electrodes with some paste, so the scalp is a little sticky when we’re done.