Here is more on motion sickness and see-sick syndrome. An Australian study conducted in 1996 concluded that visual information is more important than vestibular input in causing motion sickness. Here is the abstract:
Aviat Space Environ Med. 1996 Oct;67(10):955-62.
Visual and vestibular components of motion sickness. Eyeson-Annan M, Peterken C, Brown B, Atchison D.
Source
Centre for Eye Research, School of Optometry, Queensland University of Technology, Brisbane, Queensland, Australia.
Abstract
BACKGROUND:
The relative importance of visual and vestibular information in the etiology of motion sickness (MS) is not well understood, but these factors can be manipulated by inducing Coriolis and pseudo-Coriolis effects in experimental subjects.
HYPOTHESIS:
We hypothesized that visual and vestibular information are equivalent in producing MS. The experiments reported here aim, in part, to examine the relative influence of Coriolis and pseudo-Coriolis effects in inducing MS.
METHODS:
We induced MS symptoms by combinations of whole body rotation and tilt, and environment rotation and tilt, in 22 volunteer subjects. Subjects participated in all of the experiments with at least 2 d between each experiment to dissipate after-effects. We recorded MS signs and symptoms when only visual stimulation was applied, when only vestibular stimulation was applied, and when both visual and vestibular stimulation were applied under specific conditions of whole body and environmental tilt.
RESULTS:
Visual stimuli produced more symptoms of MS than vestibular stimuli when only visual or vestibular stimuli were used (ANOVA F = 7.94, df = 1, 21 p = 0.01), but there was no significant difference in MS production when combined visual and vestibular stimulation were used to produce the Coriolis effect or pseudo-Coriolis effect (ANOVA: F = 0.40, df = 1, 21 p = 0.53). This was further confirmed by examination of the order in which the symptoms occurred and the lack of a correlation between previous experience and visually induced MS.
CONCLUSIONS:
Visual information is more important than vestibular input in causing MS when these stimuli are presented in isolation. In conditions where both visual and vestibular information are present, cross-coupling appears to occur between the pseudo-Coriolis effect and the Coriolis effect, as these two conditions are not significantly different in producing MS symptoms.
Many patients come to us with motion-sickness type symptoms. Dizziness and sensitivity to light are common symptoms. Many of these patients have been to many other specialists, such as the family physician, neurologists, vestibular specialists, ear, nose and throat specialists and even acupuncturists.
Typically, all of these professionals tell the patient that there is nothing wrong. That may be true as far as their particular specialty is concerned. This is not surprising, as studies have shown that vertigo is an underestimated symptom of eye and vision disorders. Many professionals that a patient consults are simply not equipped with the knowledge or experience to diagnose an eye or vision problem that can cause vertigo-like symptoms.
However, something is definitely wrong. Many of these patients can no longer drive safely and cannot even go to the supermarket without feeling nauseous.
One recent case found us after she went to her optometrist after consulting various doctors for over a year. The optometrists found that the patient's eyes were misaligned, a condition that commonly causes the dizziness and vertigo-like symptoms she was experiencing. The patient was referred to our Vancouver eye clinic for treatment.
Patients like this often suffer from "see sickness syndrome", also known a neuro-ocular vestibular dysfunction - it has also been referred to as supermarket syndrome because trips to the supermarket often trigger nausea in these patients.
Dynamic adaptive vision therapy is an effective treatment. Vision therapy relies on the principle of neuroplacticity and involves a doctor and therapist treating the patient with exercises to "re-wire" the eye-brain connection, teaching the patient new eye and motion related skills. In this way, vision therapy is similar to speech therapy or occupational therapy but focused, of course, on the eyes and visual system.
See Sick Syndrome (SSS) is the combination of motion sickness and photophobia. SSS is not well understood by many professions and is not typically diagnosed during a standard eye or medical examination. However, many patients will recognize themselves when presented with a list of symptoms.
Based on clinical observations by Dr. Gillilan (an American optometric physician and a leading doctor in this field), SSS occurs in approximately 6% of the female population and 1% of the males, and it is usually familial. Dr. Gillian's website is at http://www.seesicksyndrome.com/.
Symptoms of see sick syndrome
The severity and frequency of various SSS symptoms can vary widely. Most SSS patients have at least two of the following:
repeated eye movement, especially when observing rapid motion
unusual sensitivity to light.
The symptoms of SSS and the ability to manage motion can vary from day to day. One reason is that motion effects can be cumulative. An exposure to motion can make one less able to handle a new exposure for up to three days later.
SSS symptoms are usually mild in children but become more severe over a period of years. This is may be caused by an avoidance of symptom producing activities by adults and the resulting loss of adaptation and coping strategies.
Almost all SSS patients have life-long histories of carsickness, which occurs almost exclusively in the daytime. The reason for this is that you see less peripheral motion when driving at night. Reduced awareness of objects in the periphery (functional tunnel vision) also occurs in SSS but patients usually don't notice this although the often report a history of clumsiness, which is consistent with having reduced peripheral awareness.
The following conditions can make SSS worse:
fatigue,
pre-menstrual syndrome (PMS),
hypoglycemia
inner ear conditions
Here is a chart of symptoms organized according to severity and symptom category that proves more detail and outlines the breadth of the SSS cases that we encounter.
Mild
Moderate
Severe
Car Sickness
·Mild car sickness.
·Cannot read (look down) in a car more than a
few seconds without nausea, headache and/or dizziness.
·Necessity to be the driver to avoid nausea
while traveling in a car, even on a straight road.
·Inability to look backwards in a car without
nausea.
·Nausea when driving on tree lined roads when
the sun casts shadows across the road.
·Riding in or even driving a car for more
than a few minutes may result in severe HA, fatigue, and/or nausea.
Light sensitivity
·Unusual sensitivity to light to a moderate
degree.
·Must wear sunglasses outdoors, even on
cloudy days.
·Feels uncomfortable in brightly lit
buildings or places with shiny floors such as grocery stores, classrooms,
offices, or malls.
·Eye pain or headache when exposed to a
“flash of light” or being outside without sunglasses, even on cloudy days, or
being in a brightly lit place.
·Unusually long after images after looking at
most sources of light (several minutes).
·Computer screen brightness causes
discomfort.
·Sensation of being “blinded” when looking at
oncoming headlights.
·Severe sensitivity to light both indoors and
out.
·They are the type of person to turn off
lights and pull down shades.
·severe dislike of light
Visual
·Inability to sit close to a movie screen or
watch movement of a train or a carnival ride without nausea, headache, and/
or dizziness.
· Inability to look at stripes or watch
rapid movement on television without nausea,headache, or dizziness.
·Inability to watch more than minimal
motion without dizziness or nausea, such as watching ones own hand while
eating.
Headache
·Frequent and sometimes daily “dull” or
“pressure” headaches.
·Exposure to any activities which involve
observations of movement or eye movement for more than a few minutes can
cause severe headaches which may last a few days.
·Constant or very frequent nausea, headaches,
or dizziness which can range from mild to severe.
Dr. Gillian has a YouTube channel under the name MotionDoctor1,where you can watch some informative videos. Here are some of them:
