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Hideaki Hirose, Yoshiki Tanaka, Rie Horai, Toshio Mori, Takashi Kojima, Kazuo Ichikawa; Quantitative evaluation of glare perception using steady state visual evoked potentials. Invest. Ophthalmol. Vis. Sci. 2018;59(9):3413. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
One of the causes of discomfort visual stress or eye pain in daily life is perception ability of glare of each person. Despite clinical protocols for objectively diagnosing it have developed, the issue still remains unsolved. The primary aim of this study was to elucidate that brain signals measured from the visual area were useful to evaluate it.
We employed 12 participants who consisted of 8 males and 4 females with a mean age of 39.7 years old (range 27-50). All participants had healthy eyes and body. Three persons of them had experienced any discomfort visual stresses in their life. Especially, a participant (subject S.J., female, 43 years old) had a chief complaint of strong photophobia considered to be scotopic sensitivity syndrome or Mears-Irlen syndrome. She always wore light-shielding glasses to reduce opportunities of encountering annoy glares. We presented the same visual stimuli to the participants in a visual task. Shape of the stimuli was similar to the Ishihara plate, but they were achromatic. Luminance contrast was randomly changed from 5% to 100% every trial. Presentation duration was 5 seconds per a trial. Luminance pattern were reversed at 4 Hz frequency. Apparent size was 10 degrees. Average luminance of the stimuli and background were 40 cd/m2. We measured electroencephalograms (EEGs) from the back of the head over the primary visual area of brain while the participants performed the visual task. EEG electrodes were located on POz and Oz. After the experiment, we detected steady state visual evoked potentials (SSVEPs) from the measured EEGs and investigated the relationship between the luminance contrasts and the SSVEPs.
In the case of the participants who had experienced discomfort visual stresses, amplitudes of SSVEPs tended to be the largest when luminance contrast of the stimuli was low (10-50%). In the case of the normal participants, amplitudes of SSVEPs became the largest when luminance contrast was high (50-100%). When the subject S.J. performed the task with light-shielding glasses, her amplitude changes of SSVEPs were close to the ones of the normals.
These results suggest that amplitudes of SSVEPs are influenced by not only luminance contrast of visual stimuli but also participant’s perception of them. Our conclusion of this study is that SSVEPs are useful tool to quantitatively evaluate perception ability of glare of individuals.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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