The retina of the eye contains cone cells that distinguish colors in bright light and rod cells that work in dark.It has long been thought that humans can see and discriminate objects using only these two types of photoreceptor cells.On the other hand, retinal melanopsin ganglion cells (ipRGCs), which were discovered around 2, have been reported to have effects on "circadian rhythm adjustment," "pupil's light reflex," "brightness," and "mood." It isThis cell is one of the photoreceptor cells, but it was thought to play a role other than seeing things, and its function was unknown.

　Professor Tsujimura's laboratory has developed the world's first device that can stimulate only melanopsin cells by adjusting the color of light (light spectrum), and has conducted experiments on the contribution of melanopsin cells to contrast sensitivity.Contrast sensitivity is the ability to discriminate differences in brightness between characters and images, and is one of the most important characteristics in vision.High contrast sensitivity allows us to distinguish between objects and the background behind them.In general, contrast sensitivity is low in dark places and increases in bright places, but the sensitivity does not improve further even in bright places.In this study, we found that human contrast sensitivity was enhanced by increasing the amount of stimulus to melanopsin cells without changing the luminance or chromaticity of the illumination light.

　The results of this research are expected to contribute to the development of new lighting devices and displays that will lead to improved vision in the future, and to help improve the eyesight of the elderly.

Paper information:[Vision Research] Enhanced human contrast sensitivity with increased stimulation of melanopsin in intrinsically photosensitive retinal ganglion cells