How do I interpret the data?

The following are some theoretical sample form four made up subjects.  This show only the amplitudes of the electrical signal measured at V1 (visual cortex).  All measurements are in micro-volts.  


Eye Subject 1 Subject 2 Subject 3 Subject 4
Right 18 18 18 18
Left 18 9 9 9
Both 23 18 12 22


Subject 1 shows the normal binocular summation with the signal from both eyes being significantly bigger than the signal from either eye alone, and both eyes signals are the same.

<p> Subject 2 shows decreased amplitude in the left eye as compared to the right (9 μV compared to 18 μV) with the binocular signal the same as the non-amblyopic eye.  Here no binocular summation is occurring but neither is the amblyopic channel causing a decrease in the signal from the non-amblyopic channel.  

<p> Subject 3 shows decreased amplitude in one eye that is actually interfering with the signal from the non-amblyopic eye and indicates a problem NOW that will lead to more of a problem over time.  This is seen by the binocular amplitude actually being less than the right eye amplitude alone.  This implies that the reduced left eye flow is actually causing “noise-on-the-line” when both eyes are open causing a reduction in the binocular amplitude to less than that of the right eye. Most people will not stay in this condition for a long time as it can be quite bothersome.

<p> Subject 4 shows decreased amplitude in one eye but that eye's flow is being used and there is a bigger binocular signal than with the non-amblyopic eye alone.  This is rare but it does happen.

<p> The following slides are real data from a real patient shared by Paul Lederer, OD from Arlington HeightsIL Time increases from left to right and the amount of electrical potential are measured in the deflection up and down of the lines. 

The right eye here shows a classic normal pattern.  The right eye recordings show a small dip down before rising to their peaks.  The peaks, marked with the small vertical line at the highest point of each line, occur at the normal time of around 100 milliseconds.  The left eye has the dip down at about the right time but the lines keep rising to a smaller degree at a later time (more to the right).  Here the peaks are easily 40-50 milliseconds later than they should be and the total amount of signal from the lowest point to the highest point is smaller than for the right eye.



This second diagram shows two binocular recordings group together at the top with the right eye recording below that and the amblyopic left eye being the lowest one.  You can see that the shape of the right and binocular recordings are very similar in pattern and timing of the highest peak.  In the left eye recording here there is very little of the dip down before the slow rise to a later time.  Here the late shift is smaller than in the example just prior to this.




Here there are two right eye recordings grouped at the top, with two left eye recordings in the middle with the two binocular recordings at the bottom.  Now all of the recordings have the same pattern but with differing amplitudes.  The right eye by itself has a larger amplitude than the left eye.  However, the timing of the peaks is nearly the same (115-116 milliseconds for the right eye to 122-123 milliseconds for the left eye).  It can easily be seen that the binocular recording has the largest amplitude yet and the timing of the large peak is between the timing of the peak times of the right and left eyes respectively at 119-120 milliseconds.   The following table has the averages of the six recordings from above.


Eye Amplitude Latency
Right 15.4 115.5
Left 12.0 122.5
Both 17.8 119.5


Here even though the amplitude of the left eye is below that of the right it is obviously contributing to the binocular signal because the binocular pattern is larger than the right eye amplitude alone.  This is a powerful demonstration of the ability of optometric treatment to change signal transmission from the eye to the primary visual cortex and to normalize a system that appeared to be beyond care.