RT Journal Article
A1 Barrionuevo, Pablo A.
A1 Nicandro, Nathaniel
A1 McAnany, J. Jason
A1 Zele, Andrew J.
A1 Gamlin, Paul
A1 Cao, Dingcai
T1 Assessing Rod, Cone, and Melanopsin Contributions to Human Pupil Flicker Responses
JF Investigative Ophthalmology & Visual Science
JO Invest. Ophthalmol. Vis. Sci.
YR 2014
DO 10.1167/iovs.13-13252
VO 55
IS 2
SP 719
OP 727
SN 1552-5783
AB    We determined the relative contributions of rods, cones, and melanopsin to pupil responses in humans using temporal sinusoidal stimulation for light levels spanning the low mesopic to photopic range.    A four-primary Ganzfeld photostimulator controlled flicker stimulations at seven light levels (−2.7 to 2 log cd/m2) and five frequencies (0.5–8 Hz). Pupil diameter was measured using a high-resolution eye tracker. Three kinds of sinusoidal photoreceptor modulations were generated using silent substitution: rod modulation, cone modulation, and combined rod and cone modulation in phase (experiment 1) or cone phase shifted (experiment 2) from a fixed rod phase. The melanopsin excitation was computed for each condition. A vector sum model was used to estimate the relative contribution of rods, cones, and melanopsin to the pupil response.    From experiment 1, the pupil frequency response peaked at 1 Hz at two mesopic light levels for the three modulation conditions. Analyzing the rod–cone phase difference for the combined modulations (experiment 2) identified a V-shaped response amplitude with a minimum between 135° and 180°. The pupil response phases increased as cone modulation phase increased. The pupil amplitude increased with increasing light level for cone, and combined (in-phase rod and cone) modulation, but not for the rod modulation.    These results demonstrate that cone- and rod-pathway contributions are more predominant than melanopsin contribution to the phasic pupil response. The combined rod, cone, and melanopsin inputs to the phasic state of the pupil light reflex follow linear summation.  
RD 3/5/2021
UL https://doi.org/10.1167/iovs.13-13252