Latent nystagmus, a variety of congenital nystagmus
At first, the camera is over the right eye, the patient is viewing out of the left eye, and left-beat nystagmus is present. Then, the camera is switched from the right eye to the left eye (noted as Switch Cover in the video), and the patient is viewing out of the right eye, and right-beat nystagmus is present. The fast phase of the nystagmus is ipsiversive to the eye out of which the patient is viewing. This pattern is characteristic of latent nystagmus.