Prisms for inspection of a seesaw nystagmus.
Two eyes may be simultaneously viewed one above the other by using an arrangement of two prisms with their bases arranged to the right and to the left. When these prisms are placed in front of the glabella and tilted slightly clockwise it is possible to view both eyes simultaneously and appreciate the seesaw motion of a nystagmus.
D005133:Eye Movements; D006801:Humans; D009885:Ophthalmology / Q000295:instrumentation*