Abstract
Dear Sir I would like to comment on certain aspects of the paper entitled “Migraine and motion sickness independently contribute to visual discomfort” by AB Conforto et al. (1).
In this paper, the conclusion that migraine and motion sickness independently contributed to visual discomfort in migraine patients is based only on the varying degree of discomfort elicited by drifting striped patterns in migraine with or without motion sickness.
I wonder why, in addition to the dynamic evaluation, a static evaluation was not also performed for these patients.
It is widely known that the visual patterns that cause the most discomfort are black-and-white–striped gradings with a stripe spacing of three to four cycles of black and white per degree of visual arc. The authors should know that these visual patterns may induce discomfort as well as illusions of colour, shape and motion (2).
The assessment of all these parameters would have yielded more thorough information on the responses of migraine patients with and without motion sickness to “visual stress” (3).
Black-and-white stripes are commonly used because high-contrast patterns induce more discomfort (2–4). It is not clear why the authors used grey patterns in this paper given that their aim was to assess discomfort. Their results may have been influenced by this factor.
In addition, only drifting (up or down) striped patterns were presented to the patients. The inclusion of patterns with horizontal, wavy or rotation motion would have increased the value of the results. A 0–3 scale to grade discomfort, as opposed to 0–4, would also have yielded more reliable results.
In my opinion, the visual patterns that were used in this paper are not sufficient to demonstrate that migraine and motion sickness independently contribute to visual discomfort in migraine patients.