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Flicker Sensitivity in Normal Aging—Monocular Tests of Retinal Function at Photopic and Mesopic Light Levels
摘要： PURPOSE. Aging can affect many aspects of visual performance. In general, the effects become more significant in those older than 40 to 50 years, with increased intersubject variability and stronger dependence on ambient illumination. This study aimed to establish how healthy aging of the retina affects the detection of 15-Hz flicker under photopic and mesopic lighting. METHODS. We investigated 71 participants aged 20 to 75 years. Thresholds were measured for detection of 15-Hz flicker at the fovea (0°) and at an eccentricity of 4° in each of the four quadrants. The background luminance ranged from 0.6 to 60 cd/m2 and pupil size was measured continuously. Participants were excluded if they had signs/history of ocular disease, substantial interocular differences in flicker thresholds, or were unable to detect 100% flicker modulation in the high mesopic range. RESULTS. Mesopic and photopic flicker thresholds were used to calculate an index, the health of the retina index, to determine the limits of flicker sensitivity in healthy aging. Log flicker thresholds changed bilinearly with age; they remained stable until 40 to 50 years, with a linear decline with increasing age. This bilinear pattern of the change in flicker thresholds with age is consistent across photopic and mesopic light levels. CONCLUSIONS. The health of the retina index captures the lowest threshold, usually obtained under photopic conditions, as well as the loss of flicker sensitivity with decreasing light level. The established limits of healthy aging may benefit from future studies in patients with ocular hypertension and/or glaucoma that are known to experience loss of flicker sensitivity.
关键词： photopic,monocular vision,flicker,aging,mesopic
更新于2025-09-23 15:23:52
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Contour interaction under photopic and scotopic conditions
摘要： In the present study, we asked whether contour interaction undergoes significant changes for different luminance levels in the central and peripheral visual field. This study included nine normal observers at two laboratories (five at Palacky University Olomouc, Czech Republic and four at the University of Houston, USA). Observers viewed a randomly selected Sloan letter surrounded by four equally spaced bars for several separations measured edge-to-edge in min arc. Stimuli were viewed foveally under photopic and mesopic luminances and between 5° and 12° peripherally for four different background luminances of the display monitors, corresponding to photopic, mesopic, scotopic, and dim scotopic levels. The extent of the contour interaction in the fovea is approximately 20 times smaller than in the periphery. Whereas the magnitude of foveal contour interaction markedly decreases with decreasing luminance, no consistent luminance-induced change occurs in peripheral contour interaction. The extent of contour interaction does not scale with the size of the target letter, either in the fovea or peripherally. The results support a neural origin of contour interaction consistent with the properties of center-surround antagonism.
关键词： contour interaction,photopic,crowding effect,mesopic,scotopic,luminance,peripheral vision
更新于2025-09-23 15:22:29
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Efficiency in Street Lighting Projects by Employing LED Luminaires and Mesopic Photometry
摘要： This paper discusses the importance of adapting conventional photometric quantities when lighting systems with low luminance levels are under analysis, as public lighting or external lighting in general. In this sense, it is presented an alternative methodology for lighting projects in street lighting, considering the mesopic photometry. The CIE recommendation 191:2010 proposes correction factors that convert conventional photometric quantities (photopic) into quantities adapted to the corresponding mesopic level. However, a necessary parameter to obtain these correction factors is the relationship between the scotopic and photopic light fluxes of a light source (S/P ratio), which requires special equipment that it is not easily available to engineers, technicians and lighting designers. Thus, this paper proposes a general equation that provides the S/P ratio as a function of the correlative color temperature and the color rendering index of the light source, which are information provided in the manufacturers’ catalogs or electric lamp packages. To illustrate the application of the experimentally derived relationship, a typical street lighting project is considered, specifically a retrofit from HPS lamps to modern LED luminaires. In this case, the conventional routine must be changed, allowing the adaptation of conventional quantities to mesopic quantities without need for specialized equipment. The case study evidences that the use of mesopic photometry in conjunction with more appropriate technologies, such as LED luminaires, lead to a higher energy efficiency of the system.
关键词： Scotopic/photopic ratio,Human visual system,Mesopic vision,CIE 191:2010 report,Street lighting,Photometry,outdoor lighting,energy efficiency
更新于2025-09-12 10:27:22
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[IEEE 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Trebic, Czech Republic (2018.9.18-2018.9.20)] 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Meaning of Scotopic/Photopic Ratio of Light Sources in Lighting of Outdoor Spaces
摘要： This paper deals with the issues of meaning S/P factor of light sources in lighting of outdoor spaces. The first part describes the problem of photopic, scotopic and mesopic vision, as well as functions and activities of the human eye which define the meaning of the S/P factor lamps. The second part is dedicated to the measurement of luminous flux a selected light source used to lighting outdoor spaces, calculating S/P (scotopic/photopic) factor and ELF (Effective Luminance Factors) and finally to drawing conclusions from their measurements and calculations.
关键词： s/p factor,elf factor,mesopic vision,street lighting,outdoor lighting
更新于2025-09-10 09:29:36
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Effectiveness of an alternative model for establishing mesopic luminance
摘要： To determine mesopic luminance for a given photopic luminance and scotopic/photopic (S/P) ratio, the Commission Internationale de l’Eclairage (CIE) recommended system utilizes an equation. Whilst being accurate, it requires several iterations to achieve a stable result and requires the use of an adaptation coefficient. This article proposes an alternative approach, a model developed using a Rational Taylor function which does not require either iteration or an adaptation coefficient. Road lighting tends to use average photopic luminances in the range of 0.1 to 3 cd/m2; within this range, the model has an average error of 0.28% against the iteration approach, which is sufficient for most practical purposes.
关键词： road lighting,scotopic/photopic ratio,photopic luminance,Rational Taylor function,mesopic luminance
更新于2025-09-09 09:28:46
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Comparison of Intraocular Straylight in Patients with Clear and Photochromic Intraocular Lenses
摘要： Purpose: To compare visual acuity and intraocular straylight after implantation of clear and photochromic intraocular lenses (IOLs) in a mesopic lighting condition. Methods: Clear IOLs were implanted in 95 eyes of 72 patients (clear IOL group), and photochromic IOLs were implanted in 22 eyes of 16 patients (photochromic IOL group). Best-corrected visual acuity (BCVA) was measured indoors before surgery and 1 month after surgery. Straylight values were measured indoors before surgery and 1 and 2 months after surgery using the C-quant straylight meter (Oculus GmbH, Wetzlar, Germany). Results: There were no significant differences between the 2 groups in BCVA at 1 month postoperatively (p = 0.587). Mean straylight values of clear and photochromic IOL groups were 2.76 ± 1.89 log (s) and 2.88 ± 2.04 log (s) preoperatively, 1.39 ± 0.84 log (s) and 1.32 ± 0.26 log (s) at 1 month postoperatively, and 1.43 ± 0.92 log (s) and 1.45 ± 0.50 log (s) at 2 months postoperatively. There were no significant differences between the 2 groups in indoor straylight values (p = 0.778, 0.709, 0.929, before surgery, 1 and 2 months after surgery respectively). Repeated-measure analysis of straylight values also showed no significant difference between the 2 groups (p > 0.05). Conclusions: There were no significant differences in BCVA and straylight values between clear and photochromic IOL groups under a mesopic light condition. Therefore, photochromic IOL could be suitable choice for cataract patients who spend significant time under mesopic conditions.
关键词： C-quant,Photochromic intraocular lens,Blue light,Straylight,Mesopic
更新于2025-09-09 09:28:46
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Macular Inner Retinal Layer Thickness in Relation to Photopic and Mesopic Contrast Sensitivity in Healthy Young and Older Subjects
摘要： PURPOSE. To examine relationships between the thicknesses of ganglion cell (GC)-related macular layers and central photopic or mesopic contrast sensitivity (CS) in healthy eyes. METHODS. Measurements were made in 38 young and 38 older healthy individuals. Total, inner, layer (IRL) thicknesses were measured in the macula region through and outer retinal spectral-domain optical coherence tomography (SD-OCT) across three sub?elds, or rings, centered at the fovea: central foveal, pericentral, and peripheral. Ganglion cell complex and circumpapillary retinal nerve ?ber layer thicknesses were also measured. Low-spatial-frequency CS for gratings presented at the central 108 visual ?eld were measured through computerized psychophysical tests under photopic and mesopic conditions. Relationships were examined by uni- and multivariate regression analysis. RESULTS. Peripheral IRL thickness emerged as the only independent predictor of photopic CS (P ? 0.001) in the young group and of photopic (P ? 0.026) and mesopic CS (P ? 0.001) in the older group. The slopes of regression lines used to predict CS from peripheral IRL thickness were signi?cantly different for pair-wise comparisons of both photopic CS and age group (P ? 0.0001) and mesopic CS (P ? 0.0001) and age group. These models explained 37% of the variability in photopic CS and 36% of the variability in mesopic CS. CONCLUSIONS. Macular IRL thinning likely due to GC loss was related to reduced photopic and mesopic CS in older healthy eyes. In contrast, in the young eyes, a thicker macular IRL, possibly indicating transient gliosis, was associated with reduced CS.
关键词： contrast sensitivity,optical coherence tomography,retinal ganglion cells,macular inner retinal layer thickness,mesopic vision,glial cells
更新于2025-09-04 15:30:14
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Mesopic luminance assessed with minimally distinct border perception
摘要： In photopic vision, the border between two fields is minimally distinct when the two fields are isoluminant; that is, when the achromatic luminance of the two fields is equal. The distinctness of a border between extrafoveal reference and comparison fields was used here as an isoluminance criterion under a variety of adaptation conditions ranging from photopic to scotopic. The adjustment was done by trading off the amount of blue against the amount of red in the comparison field. Results show that isoluminant border settings are linear under all constant adaptation conditions, though varying with state of adaptation. The relative contribution of rods and cones to luminance was modeled such that the linear sum of the suitably weighted scotopic and photopic luminance is constant for the mesopic isoluminant conditions. The relative weights change with adapting intensity in a sigmoid fashion and also depend strongly on the position of the border in the visual field.
关键词： minimally distinct border,mesopic,border perception,luminance
更新于2025-09-04 15:30:14