Retinal Or Train Nystagmus.docx

Retinal or Train Nystagmus Procedure 1. 2. 3. 4. 5.

Allow the subject to be seated comfortably. Ask the subject to fix gaze at the drum with alternating black and white vertical lines. Now turn the drum clockwise/counterclockwise at different speeds, from slow to very fast. Observe the movement of the eyes of the subject. Record your observations.

Questions Explain the basis of naming the nystagmus. Explain briefly the types of eye movements.

2 classes of eye movements: (eye movements work closely with vision, purpose is to facilitate vision) 1. REFLEX (involuntary) eye movements: stabilize the world on the retina. 2. VOLUNTARY eye movements: shift eyes so that images of objects of interest fall on the fovea, central 4 degrees of visual field. Nystagmus Also called Optokinetic Nystagmus Physiological reflex when the eyes follow a passing object (slow phase) and when the limit of the eye movement has been reached the eyes jerk back in the opposite direction (fast phase). Its presence indicates an intact visual pathway

Train Nystagmus is a physiologic event where the eyes follow a moving object. However, the rapid involuntary movement of the eyes don’t last for long since the eyes tend to fix its gaze. Pursuit Movement allows the eyes to closely follow a moving object. This is completely voluntary, the patient may decide whether to follow the object or not. Smooth pursuit movement is designed to keep a moving stimulus on the fovea. Train nystagmus have 2 phases: - Slow Phase: When the eyes follow the object. - Fast Phase: When the eyes go back to the midline