Effects of ambient 455 nm and 610 nm monochromatic light on photopic spectral sensitivity in rhesus monkeys

Abstract

Objective To study the effects of ambient monochromatic light on spectral sensi- tivity in rhesus monkeys. Methods Photopie ERG was recorded in six infant rhesus monkeys (2 months old) with different monochromatic light stimuli. Light intensity was attenuated by 0.25 log units from the maximum intensity. The V-Ⅰ (vohage vs intensity) function was set according to the ERG results. The spectral sensitivity curves were plotted by wavelength as the abscissa and log values (1/Ⅰ) as the ordinate (Ⅰ defined as the flash intensity while the amplitude of the b-wave reached a maximum of 80 μV). Then the monkeys were raised under three different illumination conditions: red light (peak at 610 nm), blue light (peak at 455 nm) and white light (color temperature 5000 k) (n=2 for each group, 12 h light cycle: 8 am-8 pm). Spectral sensitivity curves were analyzed before and 6 weeks after illumination for each group. Results The monkeys' spectral sensitivity curves peaked at 455～475 nm (short-wavelength), 515～535 nm (middle wavelength) and 595～610 nm (long-wave-length) before illumination. After 6 weeks of illumination, spectral sensitivity curves in the white-light group were almost the same as those before illumination. In the red-light group, a loss of the long- wavelength peak was observed, while no change occurred in the blue-light group except for a broad decline in spectral sensitivity curves. Conclusion Ambient monochromatic light has an effect on the spectral sensitivity of monkeys' eyes and could result in the modification of amplitudes and peak val-ues. These may be associated with the changes in the signal contrast of different chromatic channels. Key words: Color vision; Spectral sensitivity; Eleetroretinogram; Rhesus monkey