Rethinking dizziness after concussion

Excerpted from page 20 of the Fall 2025 edition of AOA Focus.

Over the past decade, there has been an increasing awareness of dizziness secondary to a traumatic brain injury. It is estimated that between 1 million and 3 million people visit the emergency room with a concussion in the U.S. each year. Some have suggested this number is only a small portion of the total number of concussions, including those that are never evaluated. Sports-related concussions may alone account for 3.8 million concussions yearly. Following a concussion, dizziness is one of the most common symptoms reported in up to 80% of cases within the first few days of the concussion.

It is imperative that eye care providers understand the relationship between visual and vestibular processing in these cases. They can often provide a critical part of the recovery and rehabilitation process.

Vision and vestibular processing explained

Dizziness is often thought of as a vestibular condition; however, equally important is the visual component and how the two integrate in our daily lives. Primary eye care providers may be hesitant to address the dizziness as it is often thought of as primarily a vestibular disorder. The key for the primary eye care provider is to understand the relationship of vision and vestibular processing and how a patient can quickly be screened for vision concerns with the dynamic visual acuity test (DVAT).

The vestibulo-ocular reflex (VOR) gain represents the brain’s ability to process visual input (motion) and head rotation. These are integrated, and a mismatch is commonly the basis for dizziness secondary to a concussion. To maintain clear vision with head movement, the visual motion and head rotation are integrated through the nucleus prepositus hypoglossi (horizontal movement) and the interstitial nucleus of cajal (vertical/cyclorotation movement). These are further modulated by the cerebellum. A disturbance along any of these pathways can result in symptoms of dizziness. The VOR gain should be 1.0 in which they are matched, and the visual and vestibular input complement each other. In the case of a concussion, there is commonly a relative hypofunction in the peripheral vestibular system. This results in the VOR gain becoming <1.0 and the onset of symptoms of dizziness. Often the use of vestibular and vision therapy with lenses can be implemented, allowing the patient’s findings to return to baseline and return to a normal functioning life.

It is important to consider what the VOR comprises. In infancy, the VOR gain is primarily driven subcortically with the integration of visual motion and vestibular input. By age 1, the pursuits and saccades are developing and they become cortically integrated with the VOR gain to maintain clear vision. Essentially, any injuries affecting the integration of the vestibular system with the pursuits and saccades can pose a risk for blurred vision and subsequent dizziness with visual motion or head rotation.

Optometrists’ critical role

A primary eye care provider can often be a critical member of the rehabilitation team. After routine visual acuity testing at far, the eye care provider should add an extension to their routine visual acuity testing called the DVAT. The patient is instructed to rotate their head two cycles per second with the chin tipped down 30 degrees while looking at the distance acuity chart. This places the semicircular canals in the horizontal position and provides an accurate response of the VOR gain. The patient is to report if there is a drop in distance visual acuity during the rotation. A loss of two lines is pathognomic of a visual-vestibular dysfunction and can confirm the possible origin of the dizziness, according to an article titled “Applications of dynamic visual acuity test in clinical ophthalmology,” in International Journal of Ophthalmology.

During testing, the provider should be aware if the patient has a progressive bifocal as it may interfere with the testing. We have observed patients with blurred vision who were incorrectly diagnosed with visual-vestibular dysfunction when they were unable to deal with the distortion of the progressive. The patient had previously adapted to the distortion of the progressive, but after the concussion they had less resilience and were now symptomatic with head movement. These issues can also be found with cases of monovision. The appropriate treatment consideration would be to have these patients switch to two pairs of glasses and also consider a prescription change if it may benefit image magnification.

The refraction can be critical because an increase in magnification can increase the VOR gain to stabilize the visual acuity with head movement. These patients are commonly found to have a prescription that is over-minused or some may be uncorrected for small amounts of hyperopia. The DVAT may improve not because of providing a sharper image, but rather from the increase in magnification, which results in an increased VOR gain, per the book “Clinical Pearls in Refractive Care.” They may have had enough resilience to cope with the mismatch prior to the concussion; however, after the concussion they may not be able to. By decreasing the minus or prescribing the low plus, their symptoms can improve or set the stage for gaze stabilization and eye movement therapy to become effective.

Physical therapists often become involved in these cases and provide gaze stabilization therapy. These are exercises in which the patient looks at a target and rotates the head slowly to faster movements and habituates to the dizziness resulting in less symptoms. Because pursuits and saccades can also stabilize the VOR gain during head movement, eye movement therapy can also be implemented by an eye care professional. Following a concussion, we would recommend that patients be evaluated by an eye care provider for a comprehensive vision evaluation including refraction. The eye care provider is in the position to prescribe the most appropriate lenses and/or contact lenses to reduce the dizziness. This sets the stage for more success in recovery from the concussion.

Occasionally, patients who have not been successful in vestibular rehabilitation therapy are referred to a primary eye care provider because vision wasn’t concurrently addressed in treatment. Therapy alone can result in an increase in symptoms during head movement with no apparent improvement in visual acuity. In these cases, the eye care provider may add relative plus (or drop minus) to the habitual refraction. A myopic patient may also be moved from glasses to contact lenses, which can increase the relative magnification and increase the VOR gain. The patient may then respond more appropriately to traditional gaze stabilization and eye movement therapy. Upon successful completion of therapy, the patient may eventually go back to their full minus prescription and often can return to the use of progressive lenses or monovision.

Written by Curtis Baxstrom, O.D., M.A., member of the AOA’s Vision Rehabilitation Committee.

Disclaimer: The information contained in this article represents the opinion of the author and not the AOA. These are not clinical practice guidelines, nor has the evidence been peer-reviewed. There are additional aspects to this topic that may not be presented, or considered, based on the specifics of the case