Light scattering in artificial fog and simulated with light scattering filter

Abstract

Disability glare, affecting e.g. road safety at night, may result either from intraocular light scattering or from external conditions such as fog. Measurements were made of light scattering in fog and compared with intraocular straylight data for normal eyes and eyes with simulated cataract. All measurements were made with a direct compensation flicker method. To estimate light scattering levels in fog, straylight measurements were carried in a fog chamber for different densities of fog. Density was characterized by the meteorological term visibility V and ranged from 7 to 25. Test distance for measurements in the fog was constant at 5 m. Cataract eye conditions were simulated by placing a light scattering polymer dispersed liquid crystal (PDLC) filter with scatterers of submicron size in front of the normal eye. All measurements were made using each of three broad-band color stimuli - red, green and blue (produced either with LEDs or a color CRT monitor). Differences were found in both the level and the spectral characteristics of scattering under the different conditions. The measured values of the straylight parameter, s, in artificial fog showed no noticeable spectral dependence at any visibility range. Increasing the visibility range caused an exponential decrease in the straylight. Intraocular straylight measured with the clear eye showed an increase at the red and blue ends of the spectrum as compared to the green. Straylight measured using PDLC plates with different transparency levels showed a spectral dependence which decreased with wavelength. The scattering introduced by the PDLC plate therefore failed to give a valid simulation of cataract and fog conditions for polychromatic stimuli, due to its erroneous spectral dependence.

Influence of Interocular Differences and Alcohol Consumption on Binocular Visual Performance

“…These visual disturbances can also be associated with different ocular pathologies, such as keratitis [54,55], age-related macular degeneration (AMD) [56,57], cataract [58,59], and amblyopia [60,61]. Considering ocular pathologies, some filters have been used both to simulate an early cataract, such as the BPM2 fog filter [62,63], and for the treatment of amblyopia, such as Bangerter foils [64,65]. In addition, these filters have also been used to simulate different degrees of interocular difference to better understand the effect on binocular visual performance [27].…”

Effect of interocular differences on binocular visual performance after inducing forward scattering

“…37 In this context, various levels of visual degradation and interocular differences can be simulated using Bangerter foils and fog filters (such as the Black Pro-Mist 2; tiffen.com). [42][43][44][45][46] Bangerter foils are most commonly used to treat amblyopia in children, penalising the visual acuity of the non-amblyopic eye. 47,48 Additionally, the Black Pro-Mist 2 fog filter has been shown to simulate early cataract by inducing forward scatter.…”

Factors Influencing Light Scattering in the Eye

“…[9]). Briefly, an annulus flickering symmetrically to the gaze direction with a frequency of ~8 Hz is shown to the subject (person under test) (Fig.…”