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Vanessa Fimreite, Kenneth J Ciuffreda, Kevin Thomas Willeford; Effect of Band-Pass Chromatic Filters on the Visually-Evoked Potential Amplitude and Latency in the Visually-Normal Population. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):460.
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© ARVO (1962-2015); The Authors (2016-present)
Patients with mild traumatic brain injury (mTBI) often use band-pass chromatic (BPC) filters that restrict the spectral composition and decrease the overall luminance of a stimulus to reduce symptoms of photosensitivity and/or to enhance reading efficiency. However, there are no baseline data to quantify objectively the effect of such chromatic filters in both the visually-normal (VN) population and in those with mTBI. Therefore, the present study assessed quantitatively the effect of BPC filters on the visually-evoked potential (VEP) amplitude and latency, with a goal toward optimization of the clinical VEP protocol in the visually-normal populations, for subsequent testing and comparison in those with mTBI.
VN individuals (n=20, 14 females and 6 males; ages 21 to 26 years, mean age of 23 years) participated in the study. Pattern VEP testing was employed using the DIOPSYSTM NOVA-TR system (170 H x 150 V field size, 20 min arc check size, 1 Hz temporal frequency, 20 second trial duration, 1 meter test distance, binocular viewing with spectacle correction), with 74 cd/m2 luminance serving as the baseline condition. Luminance levels were then reduced to a mean lens transmission of 39% with four BPC filters from the Intuitive Colorimeter test system: grey (neutral density), yellow (peak= 570nm), blue (peak=425nm), and red (peak=650nm), presented in a randomized manner. All trials were compared to the baseline response and also between filters. Four trials were averaged for each test condition.
The mean VEP amplitude was not significantly reduced for any of the filters when compared to baseline nor when compared between filters (p=0.194). In contrast, the mean VEP latency significantly increased under all four filter conditions when compared to baseline (p<0.0001) and was significantly different between the BPC filters, except for: grey vs blue and grey vs yellow.
The VEP amplitude was robust to BPC filters. In contrast, the VEP latency was more sensitive to spectral variations, with latency significantly increasing when compared to baseline for all conditions, with the red filter producing the largest increase in latency. This study provided the baseline comparative data in the VN population for future testing and potential therapeutic use in those with mild traumatic brain injury.
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