Off-axis Mesopic Contrast Sensitivity. The contribution of rods and cones from the interactions among SPD, luminance level and spatial frequency

BÁRBARA SILVA; MARIA CONSTANZA TRIPOLONE; LUIS ISSOLIO; ELISA COLOMBO

Erlangen

Conferencia; THE 24TH SYMPOSIUM OF THE INTERNATIONAL COLOUR VISION SOCIETY; 2017

INTERNATIONAL COLOUR VISION SOCIETY

The basis ofthe human color vision across visual field demands more studies about therelative weights of cones and rods along the whole mesopic range. For studyingthe interaction of the SPD with luminance level, spatial frequency (fs) andage, we select two different SPDs of the stimulus/display in such a way thatone of these has an important peak in 448nm. The used conditions were: a)CCT=3900K with S/P=1.79, and b) CCT=8600K with S/P=2.79.In thisexperiment took part 4 observers, (2 young and 2 older adults). We measured monocularCS for 1, 2 and 3 c/d under four photopic luminances (0.1, 0.3, 1 and 3 cd/m2)to an eccentricity of 10° in temporal area of the retina. The subject task wasto discriminate the grating orientation of a single stimulus presentation witha 2AFC method, by pressing a button. Stimuli were presented in a TRC monitorcontrolled by a ViSaGe MKII Stimulus Generator from CRS. In meantime aneyetracker controlled the fixation.Results show:1) For S/P=1.79 mesopic CS increases with the luminance independently ofspatial frequency and age, 2) The values of mesopic CS for 0.1cd/m2much lower than those found for SP=2.79, 3) For S/P=2.79 for the two lowestvalues of luminances mesopic CS decreases as spatial frequency increases, whilefor the highest two luminances mesopic CS increases with spatial frequency.These results highlight the transition from dominance of the rods to cones andwe also speculate about a contribution of the S cones for the high mesopic rangethat is evidenced in the growth of SC for the fs=3 c/d for both age groups.