Influence of age and spectral power distribution on mesopic visual sensitivity

EDUARDO GARCÍA; ISABEL ARRANZ; LUIS ISSOLIO; BEATRIZ MATEZANZ; ALEJANDRO GLORIANI; JOSÉ ANTONIO MENÉNDEZ; BÁRBARA SILVA; ELISA COLOMBO; SANTIAGO MAR; JUAN ANTONIO APARICIO

ATTENTION PERCEPTION & PSYCHOPHYSICS

PSYCHONOMIC SOC INC

Año: 2018

1943-3921

The ability of the human visual system to detect stimuli at low illumination levels is a feature that provides awareness of potential risks. The influence of age and spectral power distribution on mesopic spectral sensitivity is analysed. Two typical light sources are used, a high-pressure sodium lamp (HPS), with a higher content of long-wavelengths, and a metal halide lamp (MH), with a higher content of short-wavelengths. Two experiments were performed, using a two channel Maxwellian optical system to measure contrast threshold under different experimental conditions. In the experiment 1, three age groups (young, middle-aged and old-aged, n = 2 each), two retinal locations (on-axis and off-axis vision), four background luminances (0.01, 0.07, 0.45 and 3.2 cd/m2) and two photometry systems (photopic and the MES2 systems) were studied. In the experiment 2, contrast threshold measurement was performed in two age groups (young and old-aged, n = 11 each), one retinal location (off-axis vision), one background luminance (0.01 cd/m2) and two photometry systems (photopic and the MES2 systems). In on-axis vision, neither age nor spectral power distribution have an effect on contrast threshold task. In off-axis vision, however, a significant interaction between age and spectral power distribution is obtained only at a background luminance of 0.01 cd/m2 with MH lamp, in both experiments. At only this lowest background luminance, the greater content of short-wavelengths of this lamp was responsible for higher rods stimulation in off-axis vision, whereas the effect of diffused light inside the aged eye counteracted the benefits of increased rod sensitivity for MH lamp.