What Is Oscillopsia?
Oscillopsia is the perception of the environment, or your visual field, moving when it’s actually stationary. This symptom can feel like the world is shifting, bouncing, shimmering, or “jiggling,” particularly when a person moves their head or walks. This visual disturbance occurs because of abnormal or unstable eye movements, which prevent the brain from maintaining a steady image on the retina (the back part of the eye). It can significantly impair balance and daily activities.
Symptoms of oscillopsia include:
- Blurred or shaky vision, especially during head or eye movements.
- Difficulty reading or focusing on stationary objects.
- Dizziness or disorientation.
- Headaches and/or nausea.
Oscillopsia often results from conditions affecting the stability of eye movements, such as nystagmus (uncontrolled repetitive eye movements) or damage to the vestibular or oculomotor systems. Fixational eye movements play a critical role in how we perceive our surroundings. While they are generally subtle and involuntary, disruptions to these movements can lead to visual symptoms, including oscillopsia—a sensation of the world appearing to “bounce” or move. In this blog post, we’ll explore the mechanics of fixational eye movements, their importance for viewing a stable world, and how they relate to oscillopsia. We’ll also include insights for both patients and healthcare professionals.
What Are Fixational Eye Movements?
We fixate our eyes on stationary objects during the majority of our waking hours, but interestingly our eyes are NEVER still. They make constant microscopic eye movements to make sure that the image is clear, stable, and perfectly aligned on the fovea of our retina. The fovea is the central area of the macula that has a very high density of cone photoreceptors, which allows us to see 20/20 and do high acuity tasks such as reading or working on the computer. If the eye is not perfectly pointed at the target you are looking at, then the visual clarity of the image gets worse.
Fixational eye movements are small, involuntary eye movements that occur even when you try to keep your gaze steady on a single point. They are essential for visual perception and include three main types:
- Microsaccades: Small, rapid eye movements that help reorient the visual field and prevent visual fading.
- Drifts: Slow, meandering movements that subtly shift the position of the eye when fixating on a target.
- Tremor: Tiny, high-frequency oscillations, superimposed upon drift.
At a high level, these movements prevent the image from fading due to sensory neural adaptation. Without them, the photoreceptor cells in the retina would adapt to a static image, causing a loss of visual clarity or visual fading within 80 milliseconds.
We use every lobe of the brain, the brainstem, and cerebellum to control our eye movements. When a neurologic or systemic condition impacts the regions of the brain in charge of controlling eye movements, then eye movements can be impaired.
The Connection Between Fixational Eye Movements and Oscillopsia
When fixational eye movements are disrupted or exaggerated, the visual input from the retina to the brain becomes unstable. For example:
- Involuntary overactivity of microsaccades or drifts may lead to unstable fixation, causing visual jitter or excess retinal slippage.
- Neurological impairments that affect the control of fixational movements can worsen oscillopsia.
- Oscillopsia can also arise from vestibulo-ocular dysfunction, where the coordination between head movements and eye stabilization is impaired, affecting fixation.
In essence, any disruption in the neural mechanisms responsible for steady gaze and fixation can lead to symptoms of oscillopsia.
For Patients: What You Need to Know
If you experience oscillopsia, it’s crucial to seek professional evaluation. Common causes include:
- Neurological conditions such as multiple sclerosis or stroke.
- Vestibular disorders, like vestibular neuritis.
- Eye movement disorders, including nystagmus.
Tips to Manage Oscillopsia
- Consult an eye care provider: They can perform specific tests to evaluate eye movements and rule out underlying causes and/or conditions.
- Vestibular therapy: If a vestibular issue is the cause, rehabilitation exercises can help to stabilize vision.
- Adaptation strategies: Using stable visual cues in the environment, like stationary objects, can reduce symptoms temporarily.
- Eye Tracking Technology: Since fixational eye movements are microscopic, they cannot be seen by the human eye. Using an eye-tracker could help to objectively quantify your oculomotor function. Keep in mind that fixation requires very specific and precise eye tracking technologies that are able to detect fixational eye movement abnormalities.
For Healthcare Professionals: Key Insights
Evaluation of Fixational Eye Movements
- Aside from testing the usual suspects like saccades, vergence, and smooth pursuit, recognize that patients may have symptoms of oscillopsia due to microscopic fixational eye movement abnormalities that you are unable to see.
- Using tools like high-resolution eye trackers can help you analyze microsaccades and drift.
- Not all eye trackers are able to see fixational eye movements because the eye motion is so small.
- The average size of microsaccades is about 1 deg, and that is the largest fixational eye movement, tremor (the smallest) is the motion of about 5-30 sec of arc, or approximately one photoreceptor.
- *Martinez-Conde S. Fixational eye movements in normal and pathological vision. Progress in Brain Research. 2006. 154;151-176
- Check your eye-tracker’s reported tracking sensitivity or tracking error. These manufacturing limits are typically quantified using healthy eyes and can be massively impacted by an individual’s screen-based calibration. Many clinically available infrared pupil trackers are only accurate down to roughly 1-2 deg of motion and will not be able to detect microscopic motions accurately.
- Newer technology that uses smaller and more robust ocular structures like the retinal photoreceptors to track eye motion can be used. These trackers use technology like tracking scanning laser ophthalmoscopy (TSLO) or adaptive optics (AO).
- The average size of microsaccades is about 1 deg, and that is the largest fixational eye movement, tremor (the smallest) is the motion of about 5-30 sec of arc, or approximately one photoreceptor.
Differential Diagnosis for Oscillopsia
- Rule out systemic or neurological conditions (e.g., MS, Parkinson’s disease, TBI).
- Investigate vestibular causes, such as central vestibular dysfunction, VOR dysfunction, and peripheral vestibular dysfunction like benign paroxysmal positional vertigo (BPPV).
- Assess ocular conditions like nystagmus, as well as other oculomotor or nerve palsies.
Treatment Approaches
- For vestibular-related oscillopsia, coordinate care with vestibular therapists.
- For vision-related oscillopsia, coordinate with an eye care professional to see if glasses can improve clarity or stability. Progressive lenses may make oscillopsia more pronounced for patients, so changing them to single vision glasses modalities may stabilize their symptoms. Offer prism glasses or contact lenses for symptomatic relief in specific cases of nystagmus.
Patient Counseling
Educate patients about the role of eye movement stability and set realistic expectations for symptom management.
About the author/speaker: Dr. Jacqueline Theis is the Chief Medical Officer for C. Light Technologies and is a residency trained neuro-optometrist, clinical researcher, international lecturer, and author. She received her doctoral and post-doctoral residency training in Neuro-Optometry and Binocular Vision disorders from the University of California at Berkeley, School of Optometry. She is a previous Assistant Clinical Professor and Founder & Chief of the UC Berkeley Sports Vision and Concussion Clinic, and currently serves as an Assistant Professor for the Uniformed Services University, School of Medicine, Department of Physical Medicine and Rehabilitation. She has extensive clinical experience in post-traumatic brain injury visual dysfunctions including oculomotor dysfunction, photophobia, visual processing, and visuo-vestibular symptoms. Her areas of expertise are in the objective evaluation of double vision, binocular vision, oculomotor dysfunction, photophobia, visual dysfunctions in brain injury and neurologic disease.
Check out Dr. Theis’ presentation on unlocking unseen eye movements on VeDA’s YouTube channel: