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Pablo Sanz Diez, Siegfried Wahl, Frank Schaeffel, Arne Ohlendorf; Accommodative response following contrast adaptation. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1794.
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© ARVO (1962-2015); The Authors (2016-present)
To analyze the effect of adaptation to contrast on the accommodative response (AR).
Five subjects (mean age 25.40±2.15, mean spherical refraction: -0.73±0.78D) participated in the study. Subjects were exposed to natural grayscale images whose blur and contrast were manipulated digitally in the Fourier domain. A 2-stage procedure was used: (1) to determine the minimum spatial frequency content necessary to produce a proper AR on an individual level; and (2) measuring the accommodation response, before and after adaptation to low-pass (s=-0.5), control (s=0) and high-pass (s=+0.5) filtered images for two different adaptation times: 60 (short) or 120 (long) seconds. The adaptation image was preceded earlier and later by an image with the spatial frequency content calculated in the first stage and was characterized by the same amount of spatial frequency as those images, but with a modified contrast slope. The visual stimuli subtended 8° of visual angle and were displayed on a monitor positioned at a fixed distance of 50cm. Subjects were corrected with their distance correction and the AR was continuously monitored under monocular viewing conditions using eccentric photorefraction with a sampling rate of 80Hz.
In stage (1), an average Sinc-blur of λ=4.4±1.95cpd was required to elicit a proper response of the accommodative system. (2) For the short adaptation time, the AR increased by 0.46±0.31D in case the low-pass image was used, while the increase was 0.92±0.36D for the high-pass filtered image. When adapting for 120 seconds, the AR showed an increase of 0.48±0.39D after adaptation period to the low-pass filtered image, however there was no significant effect after the high-pass manipulated image (p=0.84, Wilcoxon test). The control paradigm showed a stable AR without any increase of the AR, for both, the short and the long adaptation paradigm (p>0.10, Wilcoxon test). Individually the short low and high-pass adaptation periods triggered a significant increase in the AR in four subjects, reaching a maximum increase of 1.28D and 1.92D, respectively (p<0.01, Wilcoxon test). A reduced increase was observed during the long adaptation periods with a maximum increase of the AR of 0.74D for 5 subjects in low-pass and 0.68D for 2 subjects in high-pass condition (p<0.01, Wilcoxon test).
Our measurements show that contrast adaptation can modify the accommodation response to low pass filtered targets.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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