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George Zikos, Samantha Slotnick, Rocco Robilotto, Arkady Selenow, Steven Ali; Novel method to objectively evaluate visual comfort during sunglass use. Invest. Ophthalmol. Vis. Sci. 2013;54(15):585.
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Several studies connect visual comfort with squinting, and muscle tension (Nahar et al. 2007, Sheedy et al. 2005, Aaras et al. 2005). In a previous study we demonstrated that polarized lenses improve CSF and reaction times in a simulated driving environment (Zikos et al. 2009) We have further developed this method by adding simultaneous evaluation of pupil size and squint amount during either distance or a near task in the presence of glare, in order to further evaluate objectively different sunglass types.
Four subjects were tested during simulated outdoor distance and near activities: The distance task was similar to the 2009 investigation’s simulated driving environment (CSF and response times tested with Cambridge Research Systems Ltd. ViSaGe system). The near task included a reading task and FACT Near CSF in the presence of glare. A modified ISCAN eye movement system with IR cameras was used to track pupil and aperture size (squinting level) during testing. Three types of lenses were tested: polarized, tinted and clear.
Both distance and near CSF results show increased contrast sensitivity when using polarized lenses vs. tinted or clear lenses. (mean increase 124% distance and 134% near). Pupil measurements were similar between the two sunglasses (Mean pupil size 4.2mm) Good correlation between measuring squint levels with ISCAN and photographically was found. Mean squint levels were 0.8mm less on average with the sunglasses.
The addition of measuring pupil size and squint levels may prove useful in objectively measuring comfort levels with different spectacle lenses.
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