Influence of age and spectral power distribution on mesopic visual sensitivity.

The ability of the human visual system to detect stimuli at low illumination levels provides awareness of potential risks. The influence of age and spectral power distribution on mesopic spectral sensitivity is analyzed. 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.

Effect of eccentricity and light level on the timing of light adaptation mechanisms.

We explored the complexity of the light adaptation process, assessing adaptation recovery (Ar) at different eccentricities and light levels. Luminance thresholds were obtained with transient background fields at mesopic and photopic light levels for temporal retinal eccentricities (0°-15°) with test/background stimulus size of 0.5°/1° using a staircase procedure in a two-channel Maxwellian view optical system.

Influence of background size, luminance and eccentricity on different adaptation mechanisms.

Mechanisms of light adaptation have been traditionally explained with reference to psychophysical experimentation. However, the neural substrata involved in those mechanisms remain to be elucidated. Our study analyzed links between psychophysical measurements and retinal physiological evidence with consideration for the phenomena of rod-cone interactions, photon noise, and spatial summation.

Integration of an intensified charge-coupled device (ICCD) camera for accurate spectroscopic measurements.

Intensified charge-coupled devices (ICCD) are used in a great variety of spectroscopic applications, some of them requiring high sensitivity and spectral resolution. The setup, configuration, and featuring of these cameras are fundamental issues in order to acquire high quality spectra. In this work a critical assessment of these detectors is performed and the specific configuration, the optical alignment, featuring, and the dark and shot noise are described and analyzed.

Temporal retinal sensitivity in mesopic adaptation.

Purpose: Night driving is a complex visual task with important ramifications for driver and pedestrian safety. It is usually performed under mesopic or scotopic conditions and frequently, in the presence of transient glare sources that can adapt parts of the central retina. The objective of this work was to analyze the time response of adaptation for the central 15° of the retina when part of it is exposed to transient or steady mesopic adapting fields.

Quantitative and functional influence of surround luminance on the letter contrast sensitivity function.

Aim: To determine the influence of surround luminance on the letter contrast sensitivity function.

Method: The binocular contrast sensitivities of 31 young and ocularly healthy individuals were measured with letters of sizes calculated to obtain the targeted fundamental frequencies of 3, 10, 20, and 30 c deg(-1), respectively; with surround luminances from 1 to 1000 cd m(-2), always with a test chart background luminance of 200 cd m(-2).

Results: The letter contrast sensitivity increased with surround luminance up to 100 cd m(-2) and decreased when surround luminance increased from 100 to 1000 cd m(-2).

Influence of surround illumination on pupil size and contrast sensitivity.

Lighting plays a major role in contrast sensitivity (CS) measurements. Both the test and surround illumination influence the results although they are not usually considered in clinical practice. The effects of test luminance are well known, but the influence of surround luminance seems to be less investigated.