Document Detail


Light scattering in artificial fog and simulated with light scattering filter.
MedLine Citation:
PMID:  19422568     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
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.
Authors:
Gatis Ikaunieks; Mich?le Colomb; Maris Ozolinsh
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists)     Volume:  29     ISSN:  1475-1313     ISO Abbreviation:  Ophthalmic Physiol Opt     Publication Date:  2009 May 
Date Detail:
Created Date:  2009-05-08     Completed Date:  2010-02-22     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8208839     Medline TA:  Ophthalmic Physiol Opt     Country:  England    
Other Details:
Languages:  eng     Pagination:  351-6     Citation Subset:  IM    
Affiliation:
Department of Optometry and Vision Science, University of Latvia, Kengaraga Street 8, Riga, LV-1063, Latvia. gatis.ikaunieks@lu.lv
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MeSH Terms
Descriptor/Qualifier:
Adult
Cataract / complications*
Humans
Light
Models, Theoretical
Photic Stimulation / methods
Retina / radiation effects*
Scattering, Radiation*
Sensory Thresholds / physiology
Visual Acuity / physiology*
Weather*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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