The impact of melanopsin activation levels on color perception

CAO, DINGCAI; BARRIONUEVO, PABLO A.

Seattle

Congreso; ARVO 2016; 2016

The Association for Research in Vision and Ophthalmology

Purpose: Melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs) are important for several sub-conscious non-image-forming functions, such as circadian photoentrainment and the pupil light reflex. However, ipRGCs also project to the lateral geniculate nucleus (LGN) that relays retinal visual information to the visual cortex, suggesting that melanopsin activation may contribute to conscious visual perception. The purpose of the study was to assess the impact of melanopsin activation levels on color perception.Methods: A lab-developed five-primary photostimulator was used to control rod, cone and melanopsin activation levels. The stimulus field was a 30° circular field with the central 10.5° blocked to minimize the potential artifact of spectrally selective macular pigment absorption. For steady lights with eight cone chromaticities [L/(L+M): 0.73-0.8; S/(L+M): 0.1-0.3], the perceived hues were rated by a hue scaling method at two melanopsin activation levels (IB and IINC, with IINC 38% higher than IB). Three light levels (200, 2,000 and 20,000 Td) were tested.Results: At the baseline melanopsin activation level, the steady lights were perceived as greenish-yellow or reddish-yellow. An increase in melanopsin activation levels by 38% with fixed rod and cone excitations shifted the perceived hues to be more greenish or less reddish and more yellowness for some of the cone chromaticities tested. For some other chromaticities, however, melanopsin activation levels did not alter the perceived hues. Further, hue shifts caused by different melanopsin activation levels varied with light levels.Conclusions: A change in melanopsin activation level alone in steady lights can alter perceived hues. However, the impact of melanopsin activation on color perception depends on cone chromaticities and light levels.