Visual dizziness and visual vertigo are terms used for eye conditions that can cause dizziness, vertigo or balance problems. To evaluate the eyes for visual dizziness and visual vertigo an optometrist trained in vertigo can perform certain tests to exclude abnormalities.
It is very important to understand that balance control depends on primarily 3 systems namely vestibular (inner ear and brain connections), somatosensory and proprioception (tactile and joint receptors) and vision. Visual acuity and eyesight is important but also the movement and mechanical functioning of the eyes. An optometrist trained in vertigo and vestibular disorders should evaluate this.
The following conditions can cause visual dizziness and should be excluded:
1. Ambient visual disorder
After stroke or brain injury a patient may have difficulty with vision or focus in one eye. Not only is the ability to focus on an object impaired but also special orientation, balance control and motion awareness. A patient may then show a tendency to lean to one side, forward and/or backward. Specially designed prisms, partial selective occlusion and physical and occupational therapy attempting to rehabilitate weight bearing for ambulation may be of benefit.
This condition implies the excessive difference in prescription (strength) between the eyes. Aneisokonia causes a significant difference in magnification of images seen between the eyes. An abnormal magnification difference can cause disorientation, headache, tired eyes, dizziness and balance disorders. Contact lenses, or isokonic lenses can correct this disorder.
3. Binocular vision dysfunction
The eyes work together to focus, either close or far. When focusing close (convergence) the pupils constrict and the lenses accommodate. Divergence is the opposite when focusing at a distance. These processes may be altered by disease to be either overactive or weak. The eyes will then drift in or out, inappropriately, causing eyestrain, double vision, muscle spasm and excessive peripheral visual stimulation. This can trigger dizziness and balance problems. Lenses, prisms and therapy may help.
4. Double vision
Strabism (being squint) can cause major problems. It happens when the two eyes do not align and is very troublesome. When one eye turns in a different direction than the other eye when trying to focus a patient may be so disabled such an extent that they even cover one eye to avoid the double picture. Double vision may cause dizziness and balance problems. Lenses, prisms, partial selective occlusion and exercises may help. Sometimes surgery is indicated.
5. Eye movement disorders
Instability of visual gaze (gaze nystagmus), jerkiness of pursuit (eye tracking), or saccades (visual scanning) may cause dizziness and vertigo. Nystagmus is involuntary repetitive eye movements and may be congenital, or acquired. When this occurs suddenly in a patient the brain interprets it as inappropriate motion, causing vertigo, dizziness, imbalance and nausea. Inner ear and neurological conditions can cause abnormal eye movements. Neurological and neurotic logical examination is indicated to rule out treatable causes, otherwise optometric intervention is advised.
6. Focusing problems
The brain accesses how far we are from objects and accordingly changes the focus. This ability declines with age, creating the need for reading lenses or bifocals. Injury and trauma to the brain may reduce this ability, leading to the need for reading correction or bifocals. Spasms of accommodation may occur causing over focusing. Post Trauma Vision Syndrome may impair our ability to interpret spatial relationships and accurately coordinate the focus and convergence mechanism.
7. Vertical imbalance
Usually the eyes work together but sometimes it may happen that after certain conditions (for instance stroke) the one eye may aim higher than the other one. This may be mild but when excessive the patient will tilt their head to adapt. Unfortunately this will cause the fluid of the inner ear to move in an abnormal way, causing dizziness and balance problems. Eye exercises and prism lenses may help.