Nystagmus describes involuntary, repetitive eye movements that can occur side-to-side, up-and-down, or in a circular motion. While a professional diagnosis is always necessary for any health concerns, understanding basic eye movements can help identify potential signs of nystagmus. This article provides guidance for observing eye movements at home. These observations are not a substitute for medical evaluation, but serve as a preliminary step to determine if further professional attention is warranted.
What Nystagmus Is
Nystagmus manifests as rapid, uncontrolled eye movements. These movements can vary in speed and amplitude, and they may be horizontal, vertical, or rotary. Sometimes, the eyes drift slowly in one direction before jerking back quickly in the opposite direction, known as jerk nystagmus. Other times, the eyes swing back and forth in a more steady, pendulum-like motion.
While nystagmus is often involuntary, it can sometimes be a normal physiological response, particularly when the eyes are held at extreme gaze positions. This is known as physiologic end-point nystagmus, which typically appears as a few horizontal jerks when looking far to the side. However, persistent or pronounced eye movements that are not related to extreme gaze can indicate underlying issues.
Setting Up for an Eye Check
A quiet and well-lit environment is important for observing eye movements effectively, as distractions can interfere with accurate observation. The person being observed should be seated comfortably in a chair with their head resting against a support to keep it still. This helps to isolate eye movements from head movements.
The person performing the check should position themselves directly in front of the subject, at eye level, approximately 1 to 2 feet away. Maintaining this distance allows for a clear view of both eyes without being too close or too far. A small, easily visible object, such as a pen or a finger, will be used as a target for the subject to follow.
Performing a Basic Eye Movement Test
Begin by observing the subject’s eyes when they are looking straight ahead. Note any spontaneous, uncontrolled movements even before the eyes begin to track an object. This initial observation can reveal persistent involuntary eye movements.
Next, instruct the subject to follow the target (pen or finger) slowly as you move it horizontally. Move the target smoothly from the center to one side, holding it at the extreme lateral position for a few seconds. Then, slowly return the target to the center and repeat the movement to the opposite side, again holding at the extreme position. Observe both eyes for smooth tracking and any rapid, jerky movements or oscillations.
Similarly, assess vertical eye movements by moving the target slowly upwards from the center, holding it at the extreme upward gaze for a few seconds. Bring the target back to the center, then move it slowly downwards, holding it at the extreme downward gaze. Pay close attention to whether the eyes follow the target smoothly or exhibit any abnormal oscillations in these vertical positions.
For convergence, slowly bring the target object towards the subject’s nose, instructing them to keep their eyes focused on it. Observe if their eyes turn inward smoothly and symmetrically towards the object. A normal convergence response involves both eyes turning inward until the object appears double or they can no longer maintain focus.
What to Look For and When to Seek Help
During the eye movement test, look for rapid, repetitive, and uncontrolled eye movements that are not smooth. These movements might be horizontal, vertical, or rotary, and they may occur even when the eyes are looking straight ahead or when attempting to follow an object. Note if the movements are jerky, with a slow drift in one direction followed by a quick return, or if they are more pendular, swinging back and forth.
It is important to differentiate between concerning patterns and normal physiological responses. A few beats of nystagmus at extreme side gaze (physiologic end-point nystagmus) can be normal. However, persistent nystagmus that does not dampen or disappear, or eye movements that occur within the central gaze, may indicate a need for further evaluation.
If the eye movements are significant enough to affect vision, balance, or coordination, or if they are accompanied by symptoms like blurry vision, dizziness, or head tilting, professional consultation is warranted. Any new, persistent, or noticeable involuntary eye movements should prompt a visit to an eye care professional, such as an optometrist or ophthalmologist, or a general practitioner.