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Fang Hou, Luis A Lesmes, Woojae Kim, Hairong Gu, Mark Pitt, Jay Myung, Zhong-Lin Lu; Predicting the Contrast Sensitivity Function in Different Luminance Conditions. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4221.
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© ARVO (1962-2015); The Authors (2016-present)
The contrast sensitivity function (CSF) provides a comprehensive assessment of spatial vision in both normal and clinical populations. CSF change in low luminance conditions is especially informative for aging vision as well as the diagnosis of AMD (Sloane, Owsley, & Alvarez, 1988; Liu, Wang, & Bedell, 2014). One important question is whether the shapes of CSF measured in different luminance conditions are the same. An affirmative answer would enable us to use the CSF in the standard test condition to predict human performance in a wide range of luminance conditions.
CSFs of 112 college students with normal or corrected-to-normal vision were measured using the quick CSF procedure (Lesmes, et al, 2010; Hou, et al 2015) in three luminance conditions (2.65, 20.2 and 95.4 cd/m2). The detailed experimental procedure is described in Hou et al, 2016. CSF is modeled by a truncated log parabola with four parameters: peak gain, peak frequency, bandwidth, and truncation level (Watson & Ahumada, 2005).
Using a maximum likelihood procedure, we found that (1) For 89.3% of the observers, the shape of the CSF, determined by its bandwidth and truncation level, was invariant across luminance conditions, although the peak gain and peak spatial frequency varied across conditions; and (2) the shape of the CSF significantly varied across observers (p < 0.001). Further examination of the fits showed that the peak gain, peak spatial frequency and log luminance fell on a straight line in the three-dimensional space. Using the average slope of the straight line from 112 observers, we were able to accurately predict the CSF in 2.65 and 20.2 cd/m2 with the CSF measured in 95.4 cd/m2 for each individual observer, with mean r = 0.98.
The results suggest that the shape of the CSF is invariant under different light conditions, and we can predict CSF in a range of luminance conditions based on the CSF measured in the standard luminance condition.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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