Optical performance is evaluated using the point spread function (PSF), the modulation transfer function (MTF) and so on. In evaluating, we must consider the differences between the optical and neural factors of the eye. In defocused condition, MTF decreases and spurious resolution occurs, affecting the variation of visual acuity. Using optical simulation, we investigated the effect of spurious resolution on estimated visual acuity.

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The purpose of our study was to measure the change in blink rate and pupil diameter following a visual display terminal (VDT) task. Participating in our study were 11 subjects, all having a visual acuity of 1.0 and normal ocular health. All were asked to play a game for 60 minutes on a personal computer as a VDT experiment. Results showed that, the anterior corneal higher-order aberrations exhibited no significant difference. However, results also showed that miosis is delayed by bright stimulation. The blink rate increased after the VDT experiment. The temporary change in pupil diameter due to blinking reduced after the experiment. Also, after the experiment, the time required for pupil diameter minimization was shorter than before the experiment. However, the pupillary function reduction caused by VDT use was improved by consecutive blinking. Our results therefore suggest that the visual function diminishment was compensated by blinking.

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Protans and deutans have low ability in color discrimination along the red-green direction. However, it has been reported that in the color-naming task, they can distinguish chromatic stimuli along that direction, which gives rise to the suggestion that dichromats may name colors using some non-chromatic cues. Nishita et al. (2013) showed in psychophysical experiments that dichromats performed trichromat-like color-naming by using surface luminance cues. In this study, we measured changes in the oxy-Hb concentration of the lateral occipital regions of the brain during the performance of color-naming tasks using near-infrared spectroscopy, in order to investigate which cortical level of the color-naming mechanism of dichromat luminance cues were involved. Results showed that cortical activity exhibited no significant difference among all stimulus conditions ; however, the color-naming results showed clear differences between dichromats and trichromats, with some differences among stimulus conditions for dichromats. These results suggest that dichromats may perform trichromat-like color-naming using luminance cues at higher color-processing level.

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