Example of a different case with a poor prognosis for establishing binocularity. Each pattern reversal of a black and white, 64X64 checkerboard stimulates the normal visual system to oscillate in harmony with the stimulus frequency rate. In this case, the pattern reversal rate is 7.5 cycles/sec (just outside the alpha rhythm of the brain which is 8-13 cycles /sec) which induces the brain to oscillate at 7.5 responses/sec. The analysis time is half a sec or 500 msec and hence the number of responses should be half of 7.5 or about 3.75 positive peaks as shown above. In this case of a patient with a left esotropia and amblyopia, note that the response with both eyes open (OU) is essentially the same as the response of the right eye (OD) alone. The VEP from the left eye (OS) is “out of phase” with the normal response from the right eye. The left eye response will likely be suppressed by the binocular cortical cells. Patients such as this one demonstrate little or no binocularity on clinical tests. Since the monocular VEPs are so “out of phase” the chances of establishing binocularity are quite guarded.