Document Detail


Investigating the light absorption in a single pass through the photoreceptor layer by means of the lipofuscin fluorescence.
MedLine Citation:
PMID:  15820514     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Reflection densitometry has been widely used to measure the density difference of the bleachable cone photopigments in human eyes. Most such measurements make a series of assumptions concerning the amount of scattered light to derive an estimate of the true cone photopigment density from the density difference measurements. The current study made three types of measurements of the light returning from the eye before and after bleaching: the amount of light returning in the "directed" reflection, which is a double-pass estimate of the cone photopigment density; the amount of light in undirected or diffuse reflection; and the amount of fluorescence from lipofuscin in the RPE, which provides a single-pass measurement of optical density difference. For a 1 deg foveally fixated field, the density difference estimates for the three measurements were 0.68, 0.21, and 0.22 respectively. The lipofuscin fluorescence was found to be unguided. The background density difference was non-negligible and very close to the single pass estimate from fluorescence. These measurements each involve potentially different pathways of light through the retina, and therefore place different constraints on models of these pathways. A simple model comparing the directional and the fluorescence optical densities produced retinal coverage estimates around 70-75%. Estimates of the shape factor of the single pass optical Stiles-Crawford effect were evaluated from the dark-adapted and bleached fluorescence measurements. The values were closer to those obtained from psychophysical methods than to the double pass optical Stiles-Crawford shape factors obtained directly from retinal reflectometry.
Authors:
Pedro M Prieto; James S McLellan; Stephen A Burns
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Vision research     Volume:  45     ISSN:  0042-6989     ISO Abbreviation:  Vision Res.     Publication Date:  2005 Jul 
Date Detail:
Created Date:  2005-04-11     Completed Date:  2005-09-20     Revised Date:  2014-09-15    
Medline Journal Info:
Nlm Unique ID:  0417402     Medline TA:  Vision Res     Country:  England    
Other Details:
Languages:  eng     Pagination:  1957-65     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Adult
Dark Adaptation / physiology
Fixation, Ocular / physiology
Fovea Centralis / physiology
Humans
Light
Lipofuscin / physiology*
Luminescent Measurements
Male
Pigment Epithelium of Eye / physiology
Psychophysics
Retinal Cone Photoreceptor Cells / physiology*
Retinal Pigments / physiology*
Scattering, Radiation
Grant Support
ID/Acronym/Agency:
EY04395/EY/NEI NIH HHS; R01 EY004395/EY/NEI NIH HHS
Chemical
Reg. No./Substance:
0/Lipofuscin; 0/Retinal Pigments
Comments/Corrections

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